Chennai air quality worsened by 11.5% in 2021 compared to 2020. This leaves Chennai with air pollution levels 6 times higher than the World Health Organization’s annual limit. What are the trends in Chennai air quality and how does Chennai air pollution compare to other Indian cities?

Chennai Air Quality: 2020 vs. 2021

Chennai’s 2021 PM2.5 air pollution levels worsened 11.5% compared to 2020. With the 11.5% decline in air quality, Chennai averaged 29 micrograms of PM2.5 air pollution in 2021.

Chennai Monthly Air Quality

Breaking down the data by month reveals exactly when air pollution was the worst in Chennai. The data shows that 2021 Chennai air quality was worse across the whole year, except briefly in the summer.

Analyzing the air quality data for the previous six years suggests that Chennai’s air pollution levels start peaking during winter with PM2.5 typically rising in September, and it remains high until March of the next year. 

Chennai’s Air Quality Compared to Other Cities in India

Chennai’s air pollution averages about 30% that of air pollution leader Delhi, making it one of the least polluted major cities in India. Despite being better than Delhi and Kolkata, Chennai’s PM2.5 exceeds the World Health Organization’s annual limit every month of the year — even in the cleanest month.

The analysis is based on PM2.5 air pollution, particles smaller than 2.5 microns in diameter. These particles can penetrate deep into the lungs and even enter the bloodstream. Studies have found that PM2.5 raises blood pressure, inflammation, and rates of heart attacks and strokes.

What Next?

Despite the harms of PM2.5, studies have found that wearing masks prevents physiological harm to the body, and placebo-controlled studies of air purifiers have found that removing particulate in the home has positive effects on blood pressure, inflammation, and immune response.

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