‘Reducing aerosol pollution could worsen heat risks — we need policy that can handle both’

India faces a double-edged environmental crisis: Efforts to reduce aerosol air pollution — tiny particles in the air from industrial emissions, burning fossil fuels and biomass — may accelerate atmospheric warming, leading to more frequent and intense heatwaves. This raises the risk of hotter summers and more frequent and intense heatwaves in the coming decades.

The country has warmed about half as much as other regions in the northern hemisphere, using 1951-1980 as the baseline, according to data from the United States’ National Aeronautics and Space Administration (NASA). While the precise reasons for this anomaly remain underexplored, contributing factors could include high aerosol loads and extensive irrigation, both of which suppress local temperature increases.

Down To Earth spoke to Bhargav Krishna, convenor of the Sustainable Futures Collaborative (SFC) and coordinator of its environmental governance and policy vertical, about the implications of this paradox and the government’s preparedness.

Akshit Sangomla (AS): What is the current health burden of India’s aerosol air pollution crisis?

Bhargav Krishna (BK): Several studies have quantified the health burden of air pollution in India, both from short- and long-term exposures.  The most comprehensive of these is the Global Burden of Disease study, further analysed in the State of Global Air report by the Health Effects Institute. Their estimates suggested around 2.1 million deaths annually due to air pollution exposure.

Other studies have also examined short-term impacts from daily variations in exposure, such as the Ambient Air Pollution and Daily Mortality in Ten Cities of India: a causal modelling study by the SFC.

AS: How and when, as per current and future policies, can mortality from air pollution be brought down to manageable levels?

BK: I don’t think there is a specific time frame we can put on this. First, we need to understand more deeply the complex relationships between atmospheric aerosols and localised warming. Second, we also need to understand the interplay between heat exposure and air pollution simultaneously.
A new paper I was involved with explored this by examining the impact of fine particulate matter or PM2.5 exposure on heat-related mortality. It found a higher burden of heat-related deaths associated with increasing air pollution levels.
Controlling air pollution will involve understanding the trade-offs between climate mitigation, adaptation and air pollution control. This requires building the research capacity to understand these complex relationships, as well as designing policy that works across sectors rather than in silos, in order to address all of these sources of emissions synergistically.

AS: If aerosol pollution is reduced, surface warming may accelerate. This could worsen health risks from extreme heat. How can India navigate this paradox?

BK: This may likely be the case, but there is a growing body of work in academia and policymaking on adapting to heat. Significant steps have been taken nationally to address heat-related risks and illnesses, especially during periods of extreme heat.

If we only consider the health burden, the burden of air pollution is likely orders of magnitude greater than that of heat, but this is just one part of the picture. As heat rises and pollutants like PM2.5 and sulphur dioxide decrease, we’re likely to see significantly higher levels of ozone during summer. So far, ozone levels have remained relatively manageable.

This adds another layer of complexity to understanding the problem and developing policies for it. When you add in the impact of increased heat and ozone in the coming decades on various other sectors, including agricultural output, labour productivity, housing concerns and rising demand for cooling, you begin to see that there is no real way to address this problem until we begin to think about climate, energy, air quality and sectoral actions in synergistic ways. 

AS: Do you think the Indian government is doing enough to counter the crisis?

BK: Early and promising steps have been taken, especially to address extreme heat. But as my colleagues have pointed out in a recent report, much more needs to be done for long-term preparedness.
The Indian state has developed the capacity to manage crises — whether related to floods, cyclones or heat — but it has not yet built the capability to integrate these concerns into long-term planning and policy implementation.