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land access rights

Land access rights in England and Wales severely restrict the public from freely accessing local outdoor green spaces for leisure and exercise. Improving these rights is crucial to moving towards a more sustainable outdoors that is fairer to people of different backgrounds, less polluted, and more natural. Recent campaigns which have gained popularity during the pandemic have called for more public and government action on this issue. In this article, we analyse various sources of public data to show that, while public appreciation of the outdoors and local nature has increased since the pandemic, there is a need to give the public wider access to paths and areas of land to sustain this trend. It is hoped that this article will promote awareness of the importance of land access rights in striving towards a more sustainable and fair outdoors for the population of England and Wales and inspire others to follow suit. 

The Benefits of Outdoor Spaces

Access to the outdoors, nature, and green spaces is vital to humans for exercise, mental well-being, creativity, and many other benefits. In the UK, not long ago, coronavirus-induced lockdowns removed the public’s freedom to explore the outdoors, forcing us to make the most of whatever local green space we had on our doorstep. However, two years of these restrictions have changed the UK’s attitudes and we can now expect more interest in exploring these local outdoor spaces for recreation and exercise. As well as the restrictions of the pandemic, increased awareness of sustainability and environmental issues amongst the population has also contributed to this shift. From a sustainability point of view, better access to local natural spaces is desirable, paving the way for a wide variety of social and environmental benefits:

It is unsurprising that access to and within local outdoor spaces highly depends on land access rights. However, in England, (figures are similar in Wales, but rights differ in Scotland and Northern Ireland), current rights dictate that the public have the right to freely access only 8% of land around the country and are excluded from the remaining enclosed private land under the fear of trespass. Such places include high-walled aristocratic country estates (G. Shrubsole, Who owns England?, 2019), golf courses or gardens hidden behind a National Trust membership. Campaigns, such as those of the Ramblers, Wildlife and Countryside Link and Right to Roam, are advocating for the reclamation of land to support nature and for public access, arguing for its environmental and health-related benefits as well as its historical and legal importance.

land access rights

Photo: Andrew Wang.

In this article, we argue that a data-backed approach can support these campaigns to reclaim local outdoor spaces. We present recent data reflecting how the public interact with the outdoors and nature around the country and discuss why this necessitates an improvement in land access rights in the UK.

Importance of Local Natural Spaces

During the multiple UK coronavirus lockdowns, UK restrictions prohibited travelling “outside your local area” to exercise and walk, and permitted local “public outdoor places” to stay open, including parks, “countryside accessible to the public”, gardens, and “the grounds of a heritage site”. This automatically highlighted the importance of having access to local outdoor spaces, which for most of the public meant nearby public urban parks and paths crossing local countryside, but for a select few, also the grounds of their own estates. 

Data collected during this time showed that the number of people around the country walking for leisure and exercise rose higher than before the pandemic, especially those getting out several times a week, with walking one of the few things one could do out of the house (Figure 1). Local green spaces were crucial in giving the public the opportunity to get outside and improve their mental health. Furthermore, another survey’s data showed that an increasing proportion of the public said that they were spending more time outside than before the pandemic. To encourage people to continue exploring and exercising outdoors and having an interest in nature after the pandemic, we must ensure that more natural spaces are accessible to the public in England and Wales (as explained here).

land access rights

Figure 1: Proportion of adults who walk for leisure averaged across all of England from 2016 to 2021, according to the Active Lives Survey by Sport England. This graph incorporates the recently released 2021 survey data not included on past reports; 2022 survey data is scheduled for release in summer 2023.

To support the idea that these outdoor spaces remain important even after the pandemic has ended, recent data presented in Figure 2 showed that both interest in exercising locally and leisure visits to green spaces has stayed at an elevated level compared to before the pandemic – in particular, local exercise interest remains at a statistically significant higher level than before. This suggests the prolonged importance of local outdoor spaces, supporting the focus on sustainable access to the outdoors long after the pandemic.

land access rights

Figure 2. Left: Google search interest in “walks near me” and “local walks”, according to Google Trends data from 2018 to present, inspired by this article. Each series is normalised according to its own data within the timeframe, so the units are arbitrary and comparison cannot be made between series. An unpaired t-test between pre- and post- pandemic search results suggests a highly statistically significant difference (p≈10-11) for both series (assuming stationarity). Right: proportion of adults who visited green and natural spaces for leisure in the past fortnight from April 2020 to March 2022 in England, according to the People and Nature Survey. This incorporates recently released monthly indicator data not presented on government reports. Data before this period is not available since the data was collected in a different format, and data after this period is unreleased. 

Towards A Public-Informed Approach to Land Access Rights

The data above has shown that green and natural spaces in the local area are important to people seeking to go outdoors for leisure and have an interest in nature. However, the public is legally barred from setting foot on the vast majority of the outdoors around the country – 92% – because of poor land access rights dictating the few places granted access to the public and defining the rest as trespass. In this section, we consider a direction for a possible solution.

In line with the data-backed approach of this article, we compare where there is land granted public access by law with where the public are actually walking and moving. The hypothesis is that there may be private paths or areas of land which show public activity, whether out of convenience, unawareness, or simple desire to explore local green spaces. Surely land access rights should evolve to reflect and protect by law the places where people want to walk? Suggestions from these findings could then strengthen existing campaigns to reclaim private areas for the public, such as that of the Ramblers.

For our approach, we take the English and Welsh network of publicly accessible paths, called public rights of way (PRoW), as a proxy for land access. As a simple illustrative analysis using openly available data, we compare the rights of way network with a large dataset of public GPS traces recorded around the country by members of the public. Example results for Bedfordshire are shown in Figure 3.

It must be mentioned that there are many other interesting data-oriented avenues of highlighting regional need for access to outdoors spaces. For example, in hyper-urban settings such as Greater London, a tool was built to suggest areas for green space creation based on current green space access and demand, pollution and land availability.

Figure 3. Interactive map showing GPS activity recorded by the public (such as walking, running and cycling) in Bedford and Central Bedfordshire up to 2013, taken from a dump of GPX file data from OpenStreetMap in 2013. Black represents activity data that coincides with public rights of way, that is, where the activity was legal. Red/magenta represents activity data that does not, that is, where the activity counted as trespass. Deeper red indicates higher activity levels. Read more and get started with analysing other areas by following the instructions in the code: github.com/Andrewwango/prow-ml

We see that, while most activity coincides with where it is legal (and often signposted), there are paths of interest that are not public, which therefore can be fenced or blocked without notice. For such a path, this information could be used to support a campaign to change their status, especially if the path has already been identified as, for example, a former historic right of way (cf. the Ramblers). Of course, our identified paths will inevitably be a subset of all possibilities since trespass that is recorded is a subset of the total desire to trespass.


Nature should be accessible for all, and survey data presented in this article has shown us that the public’s interest in nature and accessing the outdoors for exercise and recreation locally is now higher than before the pandemic. This is important in moving towards a more sustainable approach towards the outdoors. 

The limited public land access rights in England and Wales mean that for the majority population, access to much of the outdoors and countryside is illegal, behind closed doors or subject to a fee. By looking at data showing public activity on footpaths, we can identify possible paths to protect with the status of being free for the public to access. 

There is much more work to be done in providing fairer access to the outdoors in England and Wales. For readers from other countries, I would love to hear about attitudes towards how land access rights shape the sustainability of the outdoors – please get in touch!

Featured image by Andrew Wang

Note: all statements about availability of released data is true as of date of publication.

You might also like: Indigenous Community Wins Recognition of its Land Rights in Panama

While deforestation is intended to increase economic productivity, its relationship with our standard of living is less conspicuous. This article inculcates how deforestation is related to economic achievement using empirical analysis and recent data, aiming to help contingent readers better fathom the topic and motivate them to take action. For policymakers, who are concerned about the impact of deforestation on economic growth or vice versa, the stated insights and evidence may be conducive to implementing related policies.

Deforestation Trends Around the World

Our World Data evinces the share of forest area to the total land across countries, as assessed by the UN Food and Agriculture Organization (FAO). Based on the available data, the average world forest cover during the five-year period 2015-2020 was approximately 31%. 

If we look at specific countries, however, things look different. In the case of Surinam, French Guyana, Guyana, Micronesia, and Gabon, for example, over 90% of forests were preserved over the same 5-year parameter. Still, most of the countries exhibit less than 50% of forest available across their territories, except for some nations that have greatly limited forest cover owing to their geographical condition. 

Among the Organization for Economic Co-operation and Development’s (OECD) 38 member countries, Finland is the nation with the highest forest retention, with a coverage of around 74%. Oppositely, Iceland figures at the bottom of the list, with 0.5% of forest at hand, despite a positive forest-restoring growth trend of 6.6% between 2015 and 2020. 

The tendency of afforestation or reforestation over the span of five years is also observed in Guam (+12%), Bahrain (+16.7%), and Malta (+31.4%). In comparison, forest loss has continued in Northern Mariana Islands (-17.4%), Oman (-16.7%), Israel (-15.2%), and Nicaragua (-12.8%). 

Why Are We Losing Forests?

Deforestation is primarily aimed at creating agricultural lands. The proclivity of forest clearance is closely related to the national economic status and development plan of a specific country. 

For developing economies, mowing down forests is indispensable to gain wealth, supplying agricultural and forestry products. In other words, deforestation can be seen as a direct conduit for economic growth. 

For advanced economies, however, forest clearance is not an obvious way of expanding income. Industrialised countries are more likely to experience technological progress and have solid infrastructure than developing economies, as they can count on advanced manufacturing industries, such as automobiles or heavy machinery, as well as service sectors, including health and education. Moreover, they have enough resources and capital to produce intellectual property products such as patents and software programmes, which further benefit the economy. 

The repercussion of deforestation is inimical to our environment, society, and economy. More specifically, biodiversity loss, poor air quality, soil destabilisation, water vulnerability, desertification, flooding, erosion, CO2 emission, and global warming are all, in some way or another, associated with forest loss. Besides, the local community living off forests will suffer from it. As a result, the development of local economies is likely impeded. To revitalise local markets, governments should take the responsibility of aiding local residents in settling into new circumstances by offering ephemeral pecuniary support. 

Deforestation affects not only our surrounding systems but also extant human beings and other species. For instance, the worsened environmental quality is more likely to influence human health conditions, both physically and psychologically, likely lowering labor productivity. This will end up having a negative impact on economic performance. Therefore, as an intelligent species, humans need to care about our forests and embrace other living organisms to enhance our quality of living. In order to do that, it is vital to understanding how deforestation is interrelated with our economy.

Research shows that numerous factors contribute to the increase or decrease of deforestation. Representatively, the extent of forest loss can be attributed to the dynamics of the labor market. If agricultural-intensive labour is more lucrative than other sectors in a nation, a surge of deforestation will occur. Meanwhile, empirical analysis bolsters that creating off-farm employment and increased remuneration in rural areas tend to reduce deforestation. This is because such discretionary employment opportunities induce more financial rewards compared to engaging in agricultural and forestry labor. 

The ever-growing world’s population is also mentioned as a major catalyst for deforestation because the desire of satisfying food demand and accumulating monetary assets

inevitably leads to the conversion of forests. A scholar claims that “increasing population will cause more pressure on forests.” On the other hand, however, while the world’s urban population reached around 56% in 2021 and is projected to keep growing in the future, the declining population in rural areas will likely undermine the force of deforestation, given that remaining rural lands have the potential to contribute to saving forest areas. 

The rise of trade openness, defined as the ratio of exports and imports to gross domestic product (GDP), is also assumed to have a crucial impact on exacerbating forest conservation, especially if the transaction of forestry and agricultural commodities is ratcheting up between countries. However, unlike the premise, Ririn Tri Ratnasari and co-researchers at the Department of Sharia Economics of Airlangga University in Indonesia behind an empirical examination found that international trade has nothing to do with deforestation for the case of 15 Organization Islamic Cooperation (OIC) countries – including Algeria, Indonesia, and Uzbekistan – over the period of 2010-2019. 

Empirical Evidence From Cross-Countries Analysis Over the Period 2010-2020

If we are able to postulate how a nation’s forest cover will change over time, it might be conducive for us to make a decision ahead to reduce any accompanying loss or maximise benefits. 

In the empirical analysis that follows – which endeavours to predict the change in forest cover employing cross-sectional data from 2010 to 2020 – the initial period of deforestation and economic growth are introduced as explanatory variables. In other words, the significance of beta convergence and environmental Kuznets curve (EKC) will be perused. 

The existence of so-called beta convergence will expound the change rate in forest areas. The concept of beta convergence is mostly applied in Economics studies, where the “per capita growth rate tends to be inversely related to the starting level of output or income per person. In particular, if economies are similar in respect to preferences and technology, then poor economies grow faster than rich ones.”

The bottom line is that an initially rich country will slowly grow while an initially poor country will grow rapidly.  In this case, the variable is only replaced, shifting the focus from gross domestic product (GDP) to a deforestation-related proxy. 

In 2020, Boka Stéphane Kévin Assa, Economic Policy Analysis Unite of CIRES (CAPEC) of University Felix Houphouet Boigny in Côte d’Ivoire, examined the relationship between deforestation and economic development for 85 tropical developing countries over the period of 1990-2010. According to his study, “beta convergence effects are also important in explaining changes in forest cover.

Following Assa’s research, more empirical analysis is needed to demonstrate whether the beta convergence effect is valid in the recent period spanning from 2010 to 2020. 

Due to the data availability, the sample period concludes in 2020. In this perusal, the short-run Green Solow model is deployed for estimation. A distinction from the original study is the omitting of additional control variables such as population density and institutional indicators, allowing for a more focused analysis of the deforestation proxy. The relevant data is garnered from two sources: UN FAO and World Bank. The forest cover is divided by the total population because a demographic effect needs to be taken into account when conducting a comparison between countries. 

Figure 1: Scatter plot created using data sources from UN FAO and World Bank. Graph: Goen Chang.

Figure 1: Scatter plot created using data sources from UN FAO and World Bank. Graph: Goen Chang.

Table 1: This table presents the result of the regression analysis . Notes: *** p0.01, ** p0.05, * p<0.10, Standard error is presented in parenthesis. All variables take log transformation. GDP per capita (2015=100, US$). Table: Goen Chang.

Table 1: This table presents the result of the regression analysis . Notes: *** p0.01, ** p0.05, * p<0.10, Standard error is presented in parenthesis. All variables take log transformation. GDP per capita (2015=100, US$). Table: Goen Chang.

Figure 1 describes the adverse relationship between the change rate and the initial level of forest cover per capita for 157 countries. This scatter plot graphically renders the tendency of beta convergence. In the second column of Table 1, the coefficient of the 2010 forest cover is found to be significant with a negative sign. Hence, the presence of beta convergence is empirically confirmed. This finding suggests that countries with lower levels of forest cover per person in the initial period are likely to experience higher growth in forest cover over the next period. The reverse trend is also predicted for countries with higher initial levels of tree cover. After all, countries are conjectured to converge toward a certain point in terms of forest cover per capita. The inclusion of proper independent variables would contribute to capturing forest cover dynamics effectively, enhancing the explanatory power of the investigation. 

But how exactly does deforestation is related to our economy? 

The environment Kuznets curve (EKC) construes a presumed relationship between environmental degradation (Y-axis) and GDP per capita (X-axis). Environmental degradation is measured by forest depletion, greenhouse gas emissions, air quality, etc.

The curve shows an inverted U-shape. Based on the hypothetical explanation behind the EKC, while low-income countries experience rapid growth, environmental degradation is increasing. However, once the economic status starts improving (in other words, when a country enters a division of relatively high-income countries), environmental degradation declines. 

According to a research on the economic causes of tropical deforestation, “with an increase in income, the structure of the economy and energy demand patterns might shift towards coal and petroleum-based fuels, thus reducing forest conversion pressures.” 

While this theoretical concept was popularised in the early 1990s, recent studies emphasise its inconsistency with real-world data and statistical insignificance. Rather, David I. Stern, a professor at Australian National University and prominent scholar on environmental matters, argues that “the true form of the emissions-income relationship is likely to be monotonic, but the curve shifts down over time.” 

This downward shape consistently appeared in the aforementioned study by Assa.

Figure 2: Scatter plot created using data sources from UN FAO and World Bank. Graph: Goen Chang.

Figure 2: Scatter plot created using data sources from UN FAO and World Bank. Graph: Goen Chang.

In addition to assessing beta convergence, the relationship between deforestation and economic growth is also appraised through the EKC theoretical framework. A basic EKC model is employed to run estimation over the period of 2010-2020. The deforestation rate is gained from the change rate of forest cover, multiplied by a negative one. Economic growth is measured by real GDP per capita (2015=100, US$) calculated by the World Bank.

In Figure 2, the scatter plot visualises the EKC for 157 countries. The inverted U-shape is not evident but the general trend shows a downward curve. Notwithstanding the obscure shape, the empirical appraisal confirms the validity of EKC. In Table 1, economic growth and its interaction term are all significantly observed with appropriate signs. The coefficient of economic growth (+1.293) infers that an increase in the growth rate of GDP per capita causes a higher rate of deforestation. However, once GDP per capita is approached around $2,672, deforestation is expected to tamp down as higher economic growth is attained, which is evidenced by the coefficient of the interaction term (-0.164). The addition of relevant control variables would improve the overall explanatory power of the model. 


In conclusion, empirical outcomes manifest that the initial period of forest cover and income per capita significantly influences the changes in forest availability. The further implication is that protecting more forests will be a boon in augmenting our standard of living and ensuring a healthy environment. To persist the mutual benefits, the role of individuals, related institutions, and government will be pivotal. Their responsibilities should be duly assigned and harmonised. Specifically, each individual is instigated to gain germane knowledge through self-education and have sedulous attention to the process of forest clearance. 

Any forest-related institutions need to decide based on accurate information and roll out innovative ideas, propelling forest protection movements. Government should also implement doable and transparent policies and be prepared for handling deforestation-related issues such as conflicts among various interest groups. 

You might also like: 10 Deforestation Facts You Should Know About


Andersen, L. E., & Reis, E. J. (2015). Deforestation, development, and government policy in the Brazilian Amazon: an econometric analysis (No. 69). Discussion Paper.
Assa, B. S. K. (2020). The deforestation-income relationship: Evidence of deforestation convergence across developing countries. Environment and Development Economics26(2), 131-150. 
Barro, R. J., & Sala-i-Martin, X. (1992). Convergence. Journal of Political Economy100(2), 223-251.
Febriyanti, A. R., Ratnasari, R. T., & Wardhana, A. K. (2022). The effect of economic growth, agricultural land, and trade openness moderated by population density on deforestation in OIC countries. Quantitative Economics and Management Studies3(2), 221-234.
Indarto, J. (2016). An overview of theoretical and empirical studies on deforestation. Journal of International Development and Cooperation. 107-120.
Kaimowitz, D., & Angelsen, A. (1998). Economic models of tropical deforestation: a review. 
Our World in Data. (2023). Deforestation and Forest Loss [Data file]. Retrieved from https://ourworldindata.org/deforestation.
Scrieciu, S. S. (2007). Can economic causes of tropical deforestation be identified at a global level?. Ecological Economics62(3-4), 603-612.
Stern, D. I. (2018). The environmental Kuznets curve. Companion to Environmental Studies49(54), 49-54.
UN Food and Agriculture Organization. (2023). Extent of Forest and Other Wooded Land [Data file]. Retrieved from https://fra- data.fao.org/assessments/fra/2020/WO/sections/extentOfForest/. 
World Bank. (2023). GDP per capita (constant 2015 US$) [Data file]. Retrieved from https://data.worldbank.org/indicator/NY.GDP.PCAP.KD. 
World Bank. (2023). Population, Total [Data file]. Retrieved from https://data.worldbank.org/indicator/SP.POP.TOTL.  

Air pollution is a global crisis that has severe implications for the environment and human health. This article provides a comprehensive analysis of the most polluted cities around the world. We look at the main sources of pollution, analyse the efficiency of the measures that are being taken by governments to tackle the issue, and provide insights into the future of air quality.

“Clean air is a human right. Unfortunately, it is not a reality for a large proportion of the world’s population.” – Dr. Maria Neira, Director of the Public Health, Environment and Social Determinants of Health Department of the World Health Organization.

Why Should We Care About Air Pollution?

Air pollution is the greatest environmental threat to public health globally. Improving our air quality will bring health, development, and environmental benefits. With every breath we take, we suck in tiny particles that can damage our lungs, hearts, and brains and cause a host of other health problems. The most dangerous of these particles, which can include anything from soot, soil dust, to sulphates, are fine particles 2.5 microns or less in diameter – shortened as PM2.5.

According to Dr Maria Neira, Director of Environment, Climate Change and Health at the World Health Organization (WHO), about 9 out of 10 people are exposed to air pollution at levels above the WHO air quality guidelines. Researchers found that daily air pollution levels globally exceed 15 μg/m3 – the safe threshold value recommended by the WHO – for more than 70% of days in 2019. As a result, about 7 million people die every year due to ambient or household air pollution. This number is only the tip of the iceberg, as there is also a huge burden of sickness, hospitalisation, reduced life expectancy, and the associated social and economic impacts of lost productivity and healthcare costs. 

Mapping the Cities With the Most Dangerous Levels of Pollution

Mapping the most polluted cities and countries in the world helps identifying the primary sources of pollution and their causes, as well as understanding the consequences of high levels of pollution on human health and the environment.

According to IQAir’s 2022 World Air Quality Report, most of the world’s 50 most polluted cities are in Asia, particularly India and Pakistan. 

The following are the 10 most polluted cities in the world: 

1. Lahore, Pakistan

2. Hotan, China

3. Bhiwadi, India

4. Delhi (NCT), India

5. Peshawar, Pakistan

6. Darbhanga, India

7. Asopur, India

8. N’Djamena, Chad

9. New Delhi, India

10. Patna, India

While Indian cities top the world’s most polluted cities’ list, India does not place among the five most polluted countries globally. The latter are topped by nations much smaller in geographical area, which brings up the annual average PM2.5 concentration (μg/m³).

The following are the 5 most polluted countries in the world, according to IQAir

1. Chad

2. Iraq

3. Pakistan

4. Bahrain

5. Bangladesh

What is Air Pollution?

Ambient air pollution is caused by a number of air pollutants, including NOx, ozone, carbon monoxide, and sulphur dioxides.  PM2.5 is the air pollutant that has been most closely studied and is most commonly used as a proxy indicator of exposure to air pollution more generally. Particulate matter consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air. 

The major components of PM are sulphates, nitrates, ammonia, sodium chloride, black carbon, mineral dust, and water. The most health-damaging particles are those with a diameter of 10 μm or less, which can penetrate and lodge deep inside the lungs. Both short- and long-term exposure to air pollutants have been associated with health impacts such as lung cancer, heart disease and stroke, according to the World Health Organization.

More on the topic here: What is Indoor Air Pollution?

What Are the Main Sources of Air Pollution?

The primary sources of pollution in each of the most polluted cities are residential pollution, mostly from cooking and heating using biomass, generating electricity from fossil fuels for our homes, and transport. Windblown dust is also a major source in portions of Africa and West Asia that are close to deserts. Windblown dust, emitted from the surface of the earth to the atmosphere, has significant impacts on atmospheric phenomena, air quality, and human health. 

Respiratory and cardiovascular disorders, meningococcal meningitis, conjunctivitis, and skin irritations are among the health problems that have been associated with exposure to dust. Specifically, airborne dust particles (in particular those finer than 10 microns in diameter, called PM10) can penetrate deep into the lungs and impair respiratory processes. Dust that contains heavy metals or other toxic compounds can also cause a wide range of acute and chronic health effects. 

You might also like: 10 Facts About Air Pollution That’ll Take Your Breath Away

Where Are People Dying of Pollution?

Explore the map below to understand the impact of air pollution on human life in each country.

The most common health problems associated with air pollution include stroke, heart disease, lung disease, lower respiratory diseases, and cancer. Explore the map below to find out what percent of death in any given country can be attributed to outdoor fine particles.

Despite the grave health risks associated with air pollution, many countries still face challenges in meeting their clean air targets. However, some countries are making progress, such as the Philippines, Indonesia, and Brazil, among others. The global community needs to take action to reduce air pollution by making lifestyle changes, reducing energy consumption, and adopting environmentally conscious alternatives to wood-burning stoves, among others.

How Does Air Pollution Affect the Environment? 

Air pollution has significant negative impacts on the environment. Acid rain, caused by air pollutants such as sulphur dioxide and nitrogen dioxide, is harmful to natural ecosystems, interfering with the root’s cell division and ability to elongate, reducing essential nutrients for plants, and threatening wildlife, particularly aquatic animals. Eutrophication, the enrichment of a waterbody with minerals and nutrients that lead to excessive algae growth, blocks sunlight from underwater plants and consumes large amounts of oxygen in the water, resulting in the death of aquatic plants and animals. Human activities, such as energy production and fertiliser use, contribute significantly to eutrophication.

While air pollutants are distinguished from greenhouse gases, some air pollutants, such as ground-level ozone, possess warming power and can trap heat in the atmosphere. However, some air pollutants, like aerosol, have a positive effect on resisting climate change, as they possess cooling power by changing the amount of solar energy entering and leaving the atmosphere and forming clouds. Scientists are exploring the possibility of manipulating aerosols to slow down climate change, but controlling the number of airborne particles within a safe range remains a challenge. 

You might also like: 3 Major Effects of Air Pollution on the Environment

What Can We Do?

nitrogen dioxide pollution impacts

Image: World Health Organization.

There are many ways individuals can reduce their personal air pollution footprint, including using public transportation, reducing energy consumption, moderating waste, and using air filtration and purification systems to improve indoor air quality. Additionally, people can limit outdoor activities when air quality is at unhealthy levels and stay informed about real-time air quality conditions using apps.

However, the problem of air pollution requires the collective efforts of individuals, communities, and governments worldwide. Governments can invest in energy-efficient power generation, improve waste management, and promote greener and more compact cities with energy-efficient buildings. Additionally, providing universal access to clean, affordable fuels and technologies and building safe and affordable public transport systems can help reduce air pollution. 

As we continue to map the most polluted cities in the world, let’s also work towards a future where clean air is a fundamental human right, and every individual has the opportunity to live a healthy and fulfilling life.

You might also like: Air Pollution: Have We Reached the Point of No Return?

urban environmental sustainability; cycling; city; bike-friendly city

A city’s environmental sustainability can be measured using a vast set of indicators. Is it sensible to assess urban environmental sustainability with only a narrow set of these? After comparing various indicators across European cities, we conclude that some cities may perform well in one aspect but poorly in another and that cities must simultaneously consider many perspectives in order to ensure a truly environmentally sustainable future.


Cities that are best prepared for a “smart city future” should be sustainable, according to the recent 2022 ProptechOS report which benchmarks cities in the US and Europe on a selection of indicators. This is backed up by the Organisation for Economic Co-operation and Development (OECD) smart cities definition. In the report, sustainability is measured using a “green infrastructure” indicator across 46 European cities, combining:

This prompts the following questions: How do we measure the environmental sustainability of our cities? Do some cities perform well in one indicator but badly in others?

You might also like: What Is A Smart City?

How Do We Measure Urban Environmental Sustainability?

Although they correlate with lower emissions, the numbers of EV charging points and green-certified buildings measure environmental progress in a (current) model of urbanisation centred around cars and buildings. 

According to the UN Habitat World Cities Report 2022, it is important that the goal for a future city should place environmental sustainability at its core, however, we must consider a multitude of desirable outcomes to ensure that any solution benefits the planet and its inhabitants. As an example, electric cars can play only one part in a wider approach to sustainable urban mobility.

The European Environment Agency (EEA) report presents an urban environmental sustainability framework that pulls together many different building blocks for a common goal, described through the lenses of a city that is green, low-carbon, resilient, circular, inclusive and healthy. We will compare ProptechOS’ “green infrastructure” indicator with the following factors:

How Do Different Measures Compare?

Other organisations have recently published indicators measuring the above urban environmental sustainability factors in cities around Europe. We look at how some of these published indicators compare to those published by ProptechOS.

We include 6 indicators published in the 2019 SDG Index and Dashboards Report for European Cities. These measure subsets of the UN Sustainable Development Goals (SDG) linked to urban environmental sustainability, originally across 45 European cities. We also include 3 indicators published in the Clean Cities Campaign 2022 rankings. These are transparently and robustly researched indicators prioritising zero-emissions mobility, originally across 36 European cities.

Click the dropdown to view the indicators. See Appendix below for descriptions of all indicators used.

Note that this is not designed to be a complete analysis of all European cities, and many originally studied cities have been omitted because of lack of data across datasets. To reproduce this analysis, see the code.


How do each of these indicators compare to the ProptechOS measure of green infrastructure?

1. Climate policies

We also observe a very strong positive trend, showing that the development of certain infrastructure is associated with strong climate-positive policy decisions with regard to other infrastructure, with cities such as London (United Kingdom) and Amsterdam (Netherlands) performing highly and Warsaw (Poland) and Prague (Czech Republic) performing poorly on both indicators.

2. Access to climate-friendly mobility and space for people

We notice a weak positive trend with notable outliers, showing that in some cities, sustainable mobility covers much more than just electric vehicles. For example, London (UK) is known for being poorly cyclable and suffers from high congestion, whereas Copenhagen (Denmark) has the most affordable public transport and is widely ranked among the most cyclable cities in the world.

3. SDG15: Life on land

This indicator measures the quality of natural habitats and the provision of green space in cities. We see an interesting positive and negative trend. Cities like Ljubljana (Slovenia) and Zagreb (Croatia) are at the top of SDG15 despite being lower on the Green Infrastructure scale, whereas cities considered more highly developed such as Amsterdam (Netherlands) or London (United Kingdom) perform worse in SDG15, showing a higher negative impact on the environment and ecology. One notable exception is Oslo (Norway), which is notably prioritising biodiversity in the built environment as a rapidly expanding metropolitan area.

4. Recycling rate

We see a fairly strong positive trend, showing that cities prioritising green infrastructure, such as Berlin (Germany), are also progressive in waste management.

5. Air quality (concentration of particulate matter, PM2.5)

We see cities clustered into groups. A few major cities such as Berlin (Germany), Amsterdam (Netherlands), London (UK) and Paris (France) have highly developed infrastructure but moderate air pollution as measured by the concentration of PM2.5 in the air. Scandinavian cities, along with Madrid (Spain), Lisbon (Portugal) and Dublin (Ireland) perform well in terms of air quality. Predominantly Eastern European cities form the group suffering from the poorest air quality.

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From the above analysis of various indicators covering infrastructure, energy, and nature, we see that urban environmental sustainability must be measured in a wider framework to capture a more meaningful indicator of urban environmental sustainability, which, as the EEA suggests, must act as a foundation of future cities. 

For example, London has a high density of certain green infrastructure and performs well in some related measures, but not so well in others. Notably, its efficient public transport system must be coupled with better cyclability and lower congestion. Paris, with its strong climate-positive policy directions, needs to additionally tackle its low score regarding environmental and ecological quality as part of SDG15.

Of course, every European city is at a different stage on the journey towards fully sustainable development, and each city faces unique challenges in tackling intertwined issues in environmental, social, and economic sustainability. However, we cannot truly laud a city as environmentally sustainable unless it has measured and addressed all components, requiring a shift away from a narrow-scoped model of sustainable urbanisation.


In using the following indicators, we assume that cities are defined in the same way across datasets and that there has been little change between 2019 and 2022.

2019 SDG Index and Dashboards Report for European Cities indicators. We select a few indicators covering SDGs 7, 11, 12, 13, and 15. Further information is available here.

Clean Cities Campaign 2022 rankings indicators. Further information is available here.

Note that individual indicators have limitations. It is difficult to standardise a vast number of metrics that may be measured differently across the continent in order to provide a comprehensive analysis. Furthermore, a comprehensive analysis should also study more complex cross-sectoral effects. Future analyses could compare further indicators such as raw energy and water usage and wastage, further per capita measures, risk measures such as flooding risk, and quantification of effects such as the urban heat island effect.

Featured image by Martin Magnemyr on Unsplash

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Nineteen of the twenty hottest years on record have occurred since 2001, not including 2020 which is on track to top the list. Now, research has found that Saudi Arabia might face deadly heat by 2070. 

Earth.Org takes a closer look.

This case study is based on the paper “Future of the human niche”, published in PNAS by Xu, Chi et al. (2020). 

As a species, we have historically avoided living outside of mean annual temperatures (MATs) between ∼8°C to 20°C. MATs above 29°C, found only in parts of the Sahara and Saudi Arabia, mean deadly levels of summer heat. The hottest inhabited place on Earth today is the city of Mecca in Saudi Arabia, whose MAT stands at 30.5°C, and stays above a 34°C average between May and September. Even in such conditions, an average 2 million Muslim pilgrims go each year, densely packing the streets in temperatures that can reach 54°C.

A decisive factor in whether temperatures go beyond human tolerance is humidity. When high enough and combined with extreme heat, it can inhibit the body’s ability to cool itself off through sweating. With the exception of its western coast, the Kingdom of Saudi Arabia has an arid desert climate with extreme heat during the day, replaced with low temperatures at night and very little rainfall. Lower humidity makes the heat more bearable to a degree, but even healthy, fit individuals need to avoid extended exposure to peak summer heat. 

Hotspots are concentrated along the Southern Red Sea coast, where temperatures are as bad as it gets, so global warming won’t mean higher temperatures, but rather longer periods of intolerable heat. Some places stay cool, like the government officials’ summer favorite, Riyadh (MAT 28°C), though most cannot afford this luxury. Climate change is set to level the playing field by covering over half of Saudi Arabia in potentially deadly heat by 2070. Saudi Arabia summers 2070

The Saudis haven’t “grown used to” these conditions and simply managed, but rather have developed the necessary infrastructure to counter the problem. Most people can move between home and work without ever leaving an air-conditioned space, though ironically, emissions for such extensive AC networks are adding to the problem. The government is considering more efficient systems that could significantly reduce environmental impacts, though whether this will stop temperature rise is doubtful.

There is still a relatively large proportion of Saudi Arabians living in rural areas, where heat mitigation comes through intelligent building and street design, or traditionally vetted nomadic strategies. These people represent a more vulnerable segment because AC may not be accessible to all of them, and extreme heat is likely to destroy agricultural livelihoods.  

Saudi Arabia summer heat vulnerable population

Proportion of Saudi Arabians exposed to MATs above 29°C, with the portion of those highly vulnerable due to decreased access to heat mitigation. Population numbers based on UN predictions for population growth by 2070.

Of course, it is likely that the Saudi government will implement AC for all of its inhabitants by 2070, thus fixing the problem. But picture a world in which you spend 5-6 months entirely indoors because your country has become Mars on Earth. It is also reasonable to imagine that the agriculture and fishing industries will take a severe hit, if not disappear entirely. This would leave the Kingdom dependent on external aid, while it continues to warm our atmosphere with its indispensable AC networks. Things will get hairy quite fast if we reach this point, so let’s make it our responsibility to learn, educate those around us and act where we can while there is still time. 

This article was written by Owen Mulhern. 

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longer summers earth index

Why This Metric?

A February 2021 study, published in the Journal of Geophysical Research Letters, reported that seasons in the Northern Hemisphere are now changing lengths, all except summer becoming shorter. 

They found that over a 60 year period, from 1952 to 2011, winters, springs and autumns shortened together by an average 17 days, which summer assimilated for itself. Modelling revealed that it could become another 12 days longer by mid-century, and 4 to 6 months long by 2100. 

Exploring the Metric

Our natural world is built around biological clocks. The body’s rhythm changes between night and day, and many animals, insects and plants depend on seasonal cues. Longer summers have the potential to throw these systems out of whack. 

The effect on wildlife has already been observed: pollinators emerge out of sync with plant blooms they rely on for reproduction, threatening both parties. An exceptionally warm “false spring” in March 2012 lured vegetation out of dormancy before temperatures dropped again in April, killing many crops. 

But it isn’t only early onsets and length, summers are also getting hotter. There’s a high probability that future generations will face up to 6 times more extreme heat events than ours, and up to 3 billion people could face temperatures beyond human tolerance by 2070. Some scientists have even warned that disease-carrying mosquitoes could expand their range both polewards and elevation-wise thanks to warmer nights. Along with this, scientists expect more droughts and floods, and an acceleration to sea level rise. 

Where the Numbers Come From

The authors of the paper, Changing Lengths of the Four Seasons by Global Warming, looked through daily climate data from 1952 to 2011 and defined the start of summer as the onset of temperatures in the hottest 25% during that period. Conversely, winter was defined as the onset of the 25% coldest. 

Future Outlook

Governments should take stock of this information and prepare accordingly. Potential mosquito range increases have been modelled, and preventive measures need to be taught and promoted among the newly vulnerable populations. 

Agriculture is also an area to keep an eye on. Freakish extremes happen and can be dealt with, but baseline changes could mean rethinking what crops are best suited to new weather patterns, and how infrastructure can be adapted. 

As for summers becoming lethally hot, our actions now will determine the onset. Significant cuts in greenhouse gas emissions will buy time to adapt to or even avoid catastrophic levels of global warming. 

This article was written by Owen Mulhern.



Since Adam and Eve bit the apple, we’ve been burdened with the need for clothing whenever we walk outside. More than a necessity, it’s become a means of expression, a statement, and the vehicle of many trends. However, overconsumption has led to the rise of fast fashion, a wasteful and polluting system that our environment bears the cost of, while its emissions accelerate climate change.

Earth.Org takes a closer look.

In the past 20 years, clothing production has approximately doubled due to higher demand from a growing middle class around the world. Meanwhile, garment usage lifetime has decreased on the consumer side. This embodies the “fast fashion” phenomenon: more options, quicker trend turnaround, lower prices, and unpriced damage to the environment. 

clothing utilisation clothing sales fast fashion

Most shocking in the graph above is the decrease in clothing utilisation: 36% globally. China saw a whopping 70% decrease over the same time period, and 60% of German and Chinese citizens admit to owning more clothes than they need. The picture varies from location to location, with Europeans usually spending more on fewer items each year, while Americans or Chinese buy far more pieces per person. 

clothing bought per person fasst fashion price per item of clothing, pieces of clothing per capita

Fast Fashion and the Environment

The industry is representative of consumerism, creating need and producing excessively. Moreover, our clothing production, distribution and disposal system is horrendously wasteful and polluting. According to McKinsey, the textile industry (60% of which goes into clothing) pumped 2.1 billion metric tons of greenhouse gases into the atmosphere in 2018, accounting for 4% of global emissions that year. For context, that is much as the economies of France, Germany and the United Kingdom combined.

The fashion industry itself consumes an estimated 93 billion cubic metres of water each year, much of which ends up contaminated by toxic chemicals. According to the UN Environment Programme, 20% of global wastewater comes from textile dyeing. Because the bulk of these operations are in countries with less regulation, the wastewater often finds its way to the ocean where it can wreak havoc.

textile dyeing toxic pollution waste water wastewater greenpeace

Industrial wastewater containing hazardous chemicals discharged into the Cihaur River, a tributary of the Citarum River. Source: Greenpeace.

In this age of fast fashion, we discard around 92 million tons of clothes-related waste each year. In other words, a garbage truck full of clothes is either incinerated or sent to the landfill every second, enough to fill one and a half Empire State Buildings every day

Before they’re even thrown out, our synthetic garments produce serious amounts of pollution by shedding microfilaments in the wash or drying machine. Around 50% of our clothing is made from plastic, and they produce half a million tons of microplastics that make their way into the ocean every year. 

Ironically, these absorb the toxic chemicals we let leak, then work their way up the food chain back to us. 

The current system is simply unsustainable due to its high volume, yet linear nature. Massive amounts of resources are extracted, processed, used only briefly, then thrown out.

clothing material flow

Less than 1% of the material used to make clothes is recycled into new clothing, meaning over USD 100 billion worth of material is lost each year. We are missing out on opportunities to reuse, recycle and even profit from a more circular system. 


Fast Fashion’s Societal Impacts

Beyond fast fashion ‘s effect on the environment are the deplorable conditions people work in to satisfy the ever-soaring demand. 

According to non-profit Remake, 75 million people are making our clothes this very day, 80% of which are young women between 18 and 24. 

The Bangladeshi female garment workers make about USD 96 per month according to The Fashion Law. That’s 3.5 times less than is needed to live a “decent life with basic facilities”, based on the Bangladeshi government’s wage board statistics. 

Worse yet, forced child labor is very real, and ongoing in Argentina, Bangladesh, Brazil, China, India, Indonesia, Philippines, Turkey, Vietnam and other countries. 

You can find out where and how your favorite brands make their products anytime. It could be worth it. 


Fast Fashion and Climate Change

As mentioned before, it emitted 2.1 billion metric tons of CO2 equivalent (CO2e) greenhouse gases in 2018, which is highly incompatible with the 1.5°C pathway targeted by the Paris Agreement. If no action is taken, its yearly emissions are expected to surpass 2.74 billion tons by 2030, but if mitigation continues at its current pace, emissions will stay where they are. According to McKinsey’s “Fashion on Climate” report, a 50% reduction is necessary to meet the 1.5°C pathway.

McKinsey Fast Fashion climate change

Source: Fashion on Climate, McKinsey (2020).

The report explains that such a reduction is in fact feasible, but first, let’s break down the industry’s emission sources. 

fast fashion greenhouse gas emission cuts

Source: Fashion on Climate, McKinsey (2020).

The bulk of emissions come from material production and processing, while a little over 20% comes from the consumer side, and 6% from transport and retail. 

In order to comply with the 1.5°C pathway, McKinsey’s report proposes the following:

This essentially consists of replacing all upstream energy sources with renewable-generated electric power. This alone covers 63% of the emission reduction needed. 

The key lever here is reducing oversupplying shops, often leading to markdowns or disposals. Technology investment for producing better forecasts and stock management would deliver.

This one concerns more of us so I will go into further detail. Circular business models, like fashion rentals, re-commerce, repair and refurbishment (think thrift stores) are essential to a sustainable fashion industry. Reduced washing and drying is also important. Consider: by skipping one in six washing loads, washing half loads at below 30 degrees, and substituting every sixth dryer uwsage with open-air drying, we would reduce consumer emissions by more than half.

The rise of renewables makes clean energy transitions in large industries quite likely, though it remains to be seen how fast it happens. For the appropriate infrastructures to reach production regions might take some time, and their governments are behind on incentivizing renewables. As for brands, their operations might benefit from the democratization of machine learning applications that can be very powerful for forecasting demand and the like.

Beyond this, it is incredibly empowering to know that much of the onus falls on us as individuals, and that our actions can indeed make a difference. By making the right decisions and educating those around us, we can reverse the trend of fast fashion and relieve the pressure it puts on the environment. 


This article was written by Owen Mulhern . Cover photo by Rio Lecatompessy on Unsplash.

You might also like: The History and Future of Air Pollution in Manchester

Air pollution is the third leading cause of death worldwide, and most large cities, have fine particulate matter (PM2.5) levels above WHO health guidelines. Here, we take a look air pollution mapping in Manchester to better understand the current situation, and where things may be heading. 

Manchester is known as being one of the most polluted cities in the United Kingdom. But how did this come to be? In order to understand, let’s go back to the late 18th century when Manchester was a collection of interconnected towns undergoing industrialization.

The agglomeration’s population grew sevenfold in the 18th century, and continued to grow rapidly during the following one as the textile industry boomed and steam power came about. Manchester became the cotton textile hub of the nation, which itself was the cotton textile hub of the world during the 19th century. 

It wasn’t long before the people began reporting the nuisances of heavy industry. In 1800, the Commissioners of Police in Manchester created a committee to oversee the problem; it found that “the increase of steam engines as well as smoak issuing from chimnies used over stoves, foundries, dressers, dyehouses and bakehouses are become a great nuisance to the town”. 

This was only the beginning of course, as the following century saw the appearance of engineering, chemicals and metal working, sulphuric acid and naphthalene production and many more noxious affairs. Reports from local or foreign writers passing through are vivid, like Alexis de Tocqueville’s commentary: “These vast structures keep air and light out of the human habitations which they dominate; they envelop them in perpetual fog; […] A sort of black smoke covers the city. The sun seen through it is a disc without rays.”

The first scientific measurements and analyses of the situation were carried out by R.A. Smith who, in his 1852 paper, described and coined the term “acid rain”. He found that sulphur pollution around Manchester mixed with precipitating water and dropped its pH from the usual ~5.5 to 3.5. He also described its negative effects on the surrounding vegetation, and noted the disappearance of some species from the region, such as the sphagnum mosses. 

The next 50 years saw a succession of local initiatives, like that of the Salford Noxious Vapours Abatement Society that obtained black smoke emission regulations, to the Smoke Abatement Society of Manchester, founded in 1909 and precursor to the Smoke Abatement League of Great Britain.

Around the same time, the first deposit gauges were set up around the city. These rudimentary sulphur deposit measurements often read 170 kilograms per hectare (100 x 100 meter square) per year.   

Better measurement techniques came about during the second World War, and their readings came up with mean sulphur dioxide concentrations of 586 micrograms per meter cube (mg/m3), compared to the 20 mg/m3 WHO guideline value today. Of course, with the sulphur were other pollutants like particulate matter, only these were harder to identify, isolate and measure. 

The result was a high incidence of respiratory disease throughout the 20th century. In December 1930, a December like any other, there were 137 respiratory disease deaths in Manchester. The following year, a severe smog engulfed the city for 9 days and 592 people died of respiratory disease. Catastrophe is often the impetus for change, and following this one, negotiations for the creation of a smokeless zone were launched. Mancunians had to wait for the City to acquire private powers to implement the zone in 1946. Six years later, the great London Smog caused an uproar, leading to the Clean Air Act of 1956.

air pollution manchester

Source: Douglas, Ian, Rob Hodgson, and Nigel Lawson. “Industry, environment and health through 200 years in Manchester.” Ecological Economics 41.2 (2002): 235-255.

As you can see, the Clean Air Act was highly effective in reducing sulphur dioxide (SO2), smoke deposits, and thus bronchitis in the City of Manchester. It is important to note, however, that this was greatly helped by the decline of heavy manufacturing and the substitution of coal with electricity, gas and oil. 

You’ll also notice the subsequent peak in lead (Pb) levels in the mid 1980s. Lead was actually added to fuels in the 1930s, and became progressively more widespread until its extremely negative health effects became apparent. It’s late appearance in the graph is due to a lack of record prior to the first data point, similarly to NO2 (nitrogen dioxide). It can be hard to rein in NO2 because of the amount of vehicles so the road in large agglomerations; still, fuel switching and a range of pre-treatments have helped control it. 

Today, standards are better informed by science, and we able to take things one step further: precise air pollution mapping is possible, both in Manchester and cities around the world. Making this information publicly accessible would allow all to understand what they are exposing themselves to, and possibly make better decisions for their family’s health and their own.

Berkeley Earth made a PM2.5 to cigarette equivalence that has allowed us to map air pollution in Manchester in terms of cigarettes smoked per week.

manchester air pollution pm2.5 cigarettes map

Air pollution mapping in Manchester. PM2.5 data from NASA-SEDAC (2016).

This snapshot of Manchester’s PM2.5 puts things into perspective – what is considered to be a fairly low amount of pollution on the global stage is still equivalent to about 3 to 4 cigarettes per week. The point is, no level of air pollution is good, and the WHO’s guideline of 10 mg/m3 of PM2.5 is just a relatively acceptable level. It is likely we will one day get rid of pollutants (close to) entirely and look back on these times as dangerously and unnecessarily unhealthy. 

Manchester’s Director of Public Health for Air Quality, Eleanor Roaf, says, “We estimate in Greater Manchester that air pollution is the biggest environmental cause of poor health. Up to 1,200 deaths each year are contributed to by poor air quality.”

manchester air pollutiono graph berkeley earth

Source: Berkeley Earth.

On average, PM2.5 is close to the WHO guideline level (green), but the many spikes are the days when hospitalizations for asthma and the like become more likely, especially for children. 

One of the ways the City intends to fight this is by enabling pedestrian and bicycle circulation. They’ve already created one of the largest pedestrian-cycling networks in Britain, covering 1,800 miles. 

Additionally, Manchester was one of the first cities in the UK to declare a climate crisis in July 2019, signaling its intention to assume a leadership role in reducing carbon emissions and ecological footprint. 


This article was written by Owen Mulhern.

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Air pollution is the third leading cause of death worldwide, and most large cities, have fine particulate matter (PM2.5) levels above WHO health guidelines. Here, we take a look at air pollution mapping in Sao Paulo to better understand the current situation, and where things may be heading. 

Since the Industrial Revolution toward the end of the 18th century, energy-intensive tools have spread across the globe and ushered in a new age of exponential growth and technological progress. Unfortunately, because our energy sources are “dirty”, or non-renewable and polluting, we now find ourselves facing the consequences of accumulated particles and gases in our atmosphere: excessive warming and unhealthy air.

While global warming from fossil fuel emissions is more of a long-term problem that will take decades to fix even if we do everything right, air pollution and health can be seen as more of a short-term issue. It has been accumulating and causing death and morbidity for over a century in many places, long noticed yet ignored for lack of hard evidence it was dangerous, and once this was acquired for business interests over public health. 

Large metropolitan areas are usually hotspots for air pollution case studies since they concentrate both industrial activity and transport (the main sources) along with a high density of people who might suffer from it. Sao Paulo is one of these metropolises, having undergone rapid growth in the second half of the 20th century from around 1 million to over 22 million inhabitants.

Its industry boomed between the 1950s and 1980s thanks to the car industry in particular, but also those of chemicals, steel, textile, food and many others. Sao Paulo’s simultaneous urban expansion meant residential and industrial areas often coincided, leading to many complaints in the 60s and 70s. 

The government responded, setting up air pollution control programs which also coincided with less sulfur-heavy fuel, and the rise of hydroelectric and natural gas power plants, resulting in effective pollution reduction. 

As Sao Paulo continued to grow, so did the number of vehicles on the street and the time spent in congestion; industrial emissions were soon overtaken, and vehicular emissions remain Sao Paulo’s largest source of air pollution today. 

Research began linking air pollution to disease burdens in the 80s, but the scopes were not large enough to spur a change in policy. In the last two decades however, evidence has accumulated thanks to studies correlating precise particulate matter (PM) or vehicle traffic density to elderly and child hospitalizations and mortality from respiratory illness. Despite its progress in controlling air pollution, this kind of evidence makes it the government’s responsibility to curb it to the most benign possible levels.  

Today, standards are better informed by science, and we able to take things one step further: precise air pollution mapping is possible, both in Sao Paulo and cities around the world. Making this information publicly accessible would allow all to understand what they are exposing themselves to, and possibly make better decisions for their family’s health and their own.

Berkeley Earth made a PM2.5 to cigarette equivalence that has allowed us to map air pollution in Manchester in terms of cigarettes smoked per week.

air pollution pm2.5 Sao Paulo

Air pollution mapping in Sao Paulo. PM2.5 data from 2016 (most recent gridded global dataset).

The situation has kept improving in Sao Paulo and now fluctuates between “Good” (under 10 micrograms per m3), “Moderate” (under 40 mg/m3) and “Unhealthy” (40 to 60 mg/m3) depending on the season.

air pollution Sao Paulo

Source: Berkeley Earth

Indeed, despite the local authorities’ best efforts, smoke regularly wafts over from the Amazon and Cerrado regions to contribute to the poor air quality in Sao Paulo. In fact, a 2020 study found that around 10% of PM2.5-induced premature deaths are attributable to fire smoke pollution.


Air pollution levels and environmental policy go hand in hand, and in Brazil this is truer than anywhere else. They have made great progress but the truth is that air pollution alone has cost the city of Sao Paulo over USD111 million between the years of 2008 and 2017 in medical costs alone, without accounting for the productivity loss of those who were ill. Even from an economical point of view, it is absurd to let the situation continue. Furthermore, Brazil’ wealth of ecological resources gives it unparalleled responsibility as the warden of our last, largest rainforest. We must all set examples where we are in order to change the global standard. Avoid single use plastics and vote. 


This article was written by Owen Mulhern.

You might also like: The History and Future of Air Pollution in Lagos


Air pollution is the third leading cause of death worldwide, and most large cities, have fine particulate matter (PM2.5) levels above WHO health guidelines. Here, we take a look air pollution mapping in Lagos to better understand the current situation, and where things may be heading. 

Lagos became the capital of the British-controlled protectorate of Nigeria in January 1914, and has since become the largest city in West Africa, with an estimated metropolitan population of nearly 15 million. 

Naturally, its transformation came along with, and thanks to industrialization. From the year 1943 to 1959, pre-independence, a number of industries based around raw materials were flourishing, followed by the production of consumer goods like beer, soft drinks and cigarettes. Coal was the main source of energy until oil and gas were discovered in the early 1950s, and as is always the case, ignorance and hasty development led to damaging levels of pollution. .

Since then, sources of pollution have multiplied and magnified. Taking fine particulate matter (PM2.5) as a reference, the main emitters are road transport, heavy dependence on inefficient diesel and gasoline generators, poor waste management, construction and dirty fuels for household stoves. 

A lack of governmental leadership on the issue has resulted in a paucity of data concerning air pollution in Nigeria. With no official measurement stations nor standardized methods, it is difficult for officials to take informed and decisive action. Still, a number of independent operations have given indicative values for organizations to work with, and a few studies monitored PM2.5 over year-long periods in a few representative locations in Lagos. 

The result is an average 68 micrograms of PM2.5 per meter cube (mg/m3), around 7 times the WHO guideline value and in the range of other highly polluted megacities like Beijing and Cairo. Air pollution is very pernicious, because people living in it get used to the way the air feels and its effects manifest as a range of respiratory and cardiac disease, making it quite elusive. The truth is it’s health cost in Lagos alone was US$2.1 billion in 2018, or around 2.1% of Lagos State’s GDP. 

That translated to about 11,200 deaths in 2018 (the highest in West Africa), 60% of which were children under five years old. While they suffer mostly from lower respiratory tract infections, adults deal with heart disease, lung cancer and chronic obstructive pulmonary disease.

PM2.5 and cigarettes have very similar effects on human health, which is why Berkeley Earth calculated their equivalence, which we used to map the situation in Lagos. 

air pollution lagos pm2.5 particulate matter

Air pollution mapping in Lagos. PM2.5 data from NASA-SEDAC (2016).

The worst of its pollution is spread over less densely populated areas, but in the city center, people are still breathing in the equivalent of over 5 cigarettes per week each year. 

It is imperative for such avoidable death and morbidity to be stopped, so let’s take a look at the sources and what can be done about it.

Road transport is the worst source of ambient air pollution in Lagos, unsurprising considering most vehicles are over 15 years old with old emission technologies and sulfur heavy fuels. The fix here is to implement vehicle emission standards with a progressive rollout to allow the population to adapt. Improving public transport also goes a long way. 

Industrial emissions are the second largest source. Zones with cement, chemical, furniture, refinery and steel activities are concentrated have wildly unhealthy levels of pollution – a PM2.5 concentration of 1,770 mg/m3 was once recorded over 24h in Odogunyan. This can be addressed by switching fuels, using modern energy recycling like combined heat and power, and recycling materials. Of course, this is expensive and requires heavy commitment. 

The next biggest problem is the fact that 50% of energy generation comes from private, diesel-powered generators because of how unreliable the energy grid is. This very poor combustion of gasoline and oil produce a lot of noxious fumes, especially when used indoors. Once again, this can be solved but requires a revamp of the grid, and therefore is more about money and commitment than anything else. 

The World Bank’s Pollution Management and Environment Health Program is campaigning to offer incentives and policies in collaboration with the Lagos State Government to help tackle the problem. There are opportunities for innovative investing in the area too thanks to initiatives like the IFC’s Breathe Better Bond that creates climate-friendly infrastructure projects. Still, it is the government’s job to take the lead, improve monitoring and take action for its citizens well-being. 


This article was written by Owen Mulhern.

You might also like: The History of Air Pollution in Tokyo

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