Clearing The Air: Combating pollution for a healthier global urban future

The impact of early-season Canadian wildfires is felt from Washington DC up the coast to Boston and beyond. The impact of the fires is a combination of an early and large start to the wildfire season in Canada and some unfortunate meteorology.  While the meteorology is not unusual, it is just unlucky to have two systems set up to have airflow and winds send wildfire smoke right into the eastern US.

However, the early and dramatic start to the wildfire season is certainly an impact from a warming climate, resulting in an early start to what looks to be an unprecedented fire season. While the levels of particulate matter (PM) in the eastern US are going to be extreme in the coming days, they are transient. Unfortunately, in many parts of the world including areas of South Asia the levels of PM observed are not unusual and do not go away when the wind changes.

The smoke stacks piercing the sky of Beijing, the perpetual haze over New Delhi, the exhaust fumes choking the traffic-clogged streets of Los Angeles, and the cloud of smog looming over London are a testament to a global crisis that is dangerously escalating. As we continue to exhale a harmful cocktail of pollutants into the atmosphere, the problem of air pollution has reached a critical juncture, taking an increasingly devastating toll on our urban habitats worldwide.

Not only is this crisis damaging our ecosystems and human health, but it is also significantly exacerbating the urban heat phenomenon. The world's most populated countries, including India and China, are bearing the brunt, but so too are developed nations such as the United States and those across Europe. These landscapes, heavily imprinted by human activity, are showing a disconcerting correlation between rising air pollution and heat surges. A myriad of research studies has unveiled the insidious interplay of these two factors, revealing the urgency to tackle air pollution head-on in our quest to cool the simmering cities and safeguard our planet.

ALSO READ| More than 1,200 children die every year due to air pollution in Europe, says report

A study published in the Science of the Total Environment journal this year examined the mutual response of temperature and black carbon (a type of PM2.5) in the city of Kolkata, the study explains a high correlation between high black carbon concentration and rising urban temperature. Yet another paper published in this journal in 2021, focused on the Yangtze River Delta in China, a highly urbanised region with severe air pollution.

It found that aerosols significantly enhanced the urban heat island intensity, particularly during the summer and on non-precipitation days. A study published in the Nature Communications journal 2018, examined how fine particulate air pollution in urban areas could exacerbate heatwaves. Researchers at the University of California, Los Angeles, found that high levels of PM2.5 – tiny particles produced by burning fossil fuels – can significantly amplify the intensity of urban heat islands.

The research team used data from more than 9,000 weather stations across the United States, and their analysis revealed that on days with high PM2.5 pollution, the daytime temperature of the most polluted urban areas could be up to 1°C hotter than that of neighbouring regions. The study also suggested that the presence of these particles can inhibit the dispersal of heat overnight, resulting in warmer nights.

A comprehensive NASA study published in AMS in 2017 used Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) data and reported that aerosols from human-made sources could impact rainfall patterns and temperatures locally. This study revealed that particulates from air pollution served to intensify heat waves in cities and change local weather patterns.

The combination of industrial and vehicular emissions, biomass burning, and other anthropogenic activities leads to the formation of a cocktail of pollutants - particulate matter, ozone, sulphur dioxide, nitrogen dioxide, and more. Among these pollutants, particulate matter, particularly PM2.5, is one of the significant contributors to the increasing temperatures.

The PM2.5 particles are so minute that they can be absorbed into the bloodstream through the lungs. These particles pose severe health risks and directly contribute to atmospheric warming. These microscopic particles can absorb solar radiation and subsequently re-emit it as heat, thereby increasing the temperature of the surrounding air. In addition, these particles can serve as nuclei for cloud droplets, affecting cloud formation and properties, leading to alterations in local and regional weather patterns, including temperature.

Black carbon, a component of PM2.5, is a significant contributor to the local heating effect. It absorbs sunlight efficiently, converting it to heat and contributing to atmospheric warming. This effect is magnified in India, where biomass burning is a significant source of black carbon. Black carbon is responsible for a significant portion of the observed warming trend in India over the past few decades. High levels of these pollutants in Indian cities, often related to energy production and transportation, further exacerbate the urban heat island effect.

Simultaneously, the vast urban landscapes, characterised by concrete and asphalt, absorb more solar radiation and re-emit it as heat, significantly contributing to urban heat islands' formation and intensity. This phenomenon, coupled with air pollution, leads to higher temperatures in cities compared to surrounding rural areas.

However, the implications of air pollution stretch beyond rising temperatures. There is an increasing body of evidence linking air pollution to a range of health issues. Prolonged exposure to air pollutants, such as PM2.5, is associated with respiratory and cardiovascular diseases, neurodevelopmental issues in children, and even premature death.

This is compounded by the impact of elevated temperatures, leading to an upswing in heat-related illnesses such as heat exhaustion, heatstroke, and exacerbation of existing medical conditions. Moreover, the ripple effects of air pollution and escalating temperatures have profound economic consequences. From the healthcare perspective, rising costs are incurred to manage the multitude of health issues arising from air pollution. Loss of productivity due to illness and the reduced quality of life significantly affect the economy. On the agricultural front, extreme heat and degraded air quality threaten crop yield, endangering food security, and farmers' livelihoods.

The grim picture painted by air pollution and its allied consequences might seem overwhelming. The path to significant air pollution reduction is filled with challenges, requiring comprehensive policy reforms, stringent regulations, and active public-private sector collaborations. However, effective strategies aimed at mitigating air pollution offer a ray of hope in this scenario. Steps such as strengthening vehicle emission standards, promoting renewable energy, and improving public transportation infrastructure are crucial.

However, the responsibility lies not only with the authorities. Individuals can significantly contribute by adopting cleaner practices, reducing vehicle usage, proper waste disposal, and supporting renewable energy. These actions can lead to multi-faceted benefits including, temperature reduction, healthier citizens, a more sustainable economy, better food security, and a decrease in the urban heat island effect, making our cities more liveable.

Text by:  
Shivang Agarwal with Suresh R, Area convener at The Energy and Resources Institute (TERI), an air quality and source emissions monitoring expert.


Disclaimer: The views of the writer do not represent the views of WION or ZMCL. Nor does WION or ZMCL endorse the views of the writer.

WATCH WION LIVE HERE