Kolkata: While high amount of pollutants in the air is a significant concern during the winter months in India, a recent study by Climate Trends reveals that elevated temperatures can also lead to occasional spikes in PM2.5 levels. This increase is attributed to the formation of secondary pollutants through chemical reactions and the heightened emission of volatile organic compounds (VOCs).
The study highlights that secondary organic aerosols (SOAs) are created from the oxidation of VOCs, which then condense into particulate matter. Additionally, peroxyacetyl nitrate (PAN) forms from the reaction of NOx with hydrocarbons, contributing to photochemical smog.
“While we are alarmed by the record-breaking levels of air pollution in winter months, the sudden spike in air pollution in the summer months could harm us in different ways. Understanding the interplay between PM2.5 levels and temperature is crucial for developing effective strategies,” said Palak Balyan, research lead, Climate Trends.
The study of PM2.5 data for Kolkata indicates its significant rise levels from 2022 to 2023, followed by a notable decrease in 2024.
Interestingly, the temperature remained relatively stable between 2022 and 2023, with a minor decrease from 30.28°C to 30.27°C. However, 2024 saw a temperature rise of 2.5% to 31.04°C. This correlation suggests that higher temperatures can exacerbate air quality issues by facilitating the formation of secondary pollutants.
Based on the PM2.5 levels and temperature from April 2022 to May 2024 in Kolkata, a clear relationship between these variables can be observed.
PM2.5 levels in Kolkata tend to rise during warmer months, particularly from April to May in both 2023 and 2024. During these periods, temperatures are consistently higher, reaching their annual peaks. Conversely, lower PM2.5 concentrations are often recorded during cooler months, such as in early 2022 and the latter parts of each year.
“Policymakers must undertake measures that reduce sources of air pollution throughout the year and not just mask them during the winter months,” said Harshal Salve, additional professor, Community Medicine, AIIMS New Delhi.