A new study found that air pollution, especially PM 2.5 levels, is no longer just a winter issue in Indian cities. Climate Trends, a weather and environmental studies organization, discovered worsening air quality during the summer in major urban centers across India.
The study analyzed data from the Central Pollution Control Board and ERA5 temperature records, focusing on April and May in 2022, 2023, and 2024. It revealed a significant increase in PM 2.5 levels in Delhi, Patna, Lucknow, Mumbai, and Kolkata, coinciding with rising temperatures.
PM 2.5, or particulate matter smaller than 2.5 micrometers, is a dangerous air pollutant that can penetrate the lungs and bloodstream, causing severe health issues. Traditionally, these particles were associated with winter pollution, but new findings suggest a year-round threat.
High temperatures directly impact PM 2.5 formation through chemical reactions and increased volatile organic compounds (VOCs), leading to the creation of secondary organic aerosols (SOA). SOA significantly contribute to air pollution. The oxidation of VOCs and the interaction of hydrocarbons with nitric oxide form peroxyacetal nitrate, a key component of photochemical smog.
Climate Trends’ study emphasizes that April and May are crucial for particulate matter levels as India transitions from winter to summer. Rising temperatures accelerate the formation of SOA pollutants, while increased solar radiation catalyzes these processes, elevating PM 2.5 density.
The health implications of this phenomenon are severe. High temperatures and elevated PM 2.5 levels can cause serious respiratory problems, reduced lung function, and cardiovascular issues. This toxic mix can increase heart rate, blood pressure, and vascular inflammation, heightening the risk of heart-related ailments.
Delhi saw a 28.4% increase in PM 2.5 levels in April-May 2022 compared to 2023. The situation worsened in 2024, with levels rising by 21.3% compared to 2022. Concurrently, the average temperature increased by 11%, reaching 31.87°C in 2024.
Patna saw temperature and PM 2.5 fluctuations. Pollution decreased in 2023 but surged in 2024, mirroring temperature trends and suggesting a correlation between heat and air quality.
Lucknow had a similar trend, with PM 2.5 levels decreasing in 2023 but rising in 2024, closely following temperature variations.
Mumbai went against the trend, with temperature and PM 2.5 levels gradually decreasing from 2022 to 2024.
Kolkata saw a 28% increase in PM 2.5 levels in 2023 compared to 2022, followed by an 11% decrease in 2024.
The study’s detailed analysis of Lucknow showed a gradual increase in both PM 2.5 levels and temperature in April 2022, following a pre-monsoon pattern. Vehicle and industrial emissions were identified as significant contributors to air pollution in the city.
In Patna, researchers observed two peak PM 2.5 levels in April 2022, both coinciding with temperatures above 32°C. This pattern persisted in 2023 and 2024, reinforcing the link between high temperatures and elevated PM 2.5 concentrations.
These findings challenge the idea that air pollution is mainly a winter issue in India. They highlight the need for year-round air quality management strategies and the interplay between climate change and air pollution.
As Indian cities grapple with rising temperatures due to global warming, the combined threat of heat and air pollution poses a challenge to public health and urban planning. Policymakers and environmental agencies must consider summer-specific measures to combat air pollution, in addition to existing winter-focused initiatives.
