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Source- This post on Air Pollution and Mortality in Indian Cities has been created based on the article “Air pollution spikes may raise death rates in cities with cleaner air, says study” published in “The Hindu” on 4 July 2024.
Why in the news?
A new study analyzed the health effects of short-term exposure to air pollution, specifically PM 2.5, in ten Indian cities: Ahmedabad, Bengaluru, Chennai, Delhi, Hyderabad, Kolkata, Mumbai, Pune, Shimla, and Varanasi.
Key Findings of the Study
1. Higher Death Rates in Cleaner Cities: Spikes in air pollution in cities with cleaner air, such as Bengaluru, may lead to higher death rates compared to cities with already high pollution levels, like Delhi. For example, a similar increase in PM 2.5 levels raises death rates more in Bengaluru than in Delhi.
2. Annual Deaths Attributable to Air Pollution: Delhi experiences approximately 12,000 deaths per year linked to air pollution. Bengaluru has about 2,102 deaths per year, while Shimla has the lowest number, with 59 deaths per year.
3. Fraction of Annual Deaths Due to Air Pollution: In Delhi, 11.5% of annual deaths are attributable to air pollution. In Bengaluru, 4.8% of annual deaths are linked to air pollution. Additionally, Bengaluru’s population experiences 30% of the daily air pollution exposure compared to Delhi residents.
4. Impact of PM 2.5 Increases: Nearly 30,000 deaths, or 7.2% of annual deaths in the ten cities, were due to short-term PM 2.5 exposure. The study found that total daily deaths rose by 1.42% for every 10 microgram per cubic metre increase in PM 2.5 exposure over a two-day period.
5. Risk of Mortality and PM 2.5 Levels: The study confirmed that the risk of mortality rose more quickly at lower PM 2.5 levels and plateaued as levels increased. A significant mortality risk of 2.65% was observed even on days with PM 2.5 levels below the Indian national air quality standard of 60 microgram per cubic metre.
Comparative Findings:
A 272-city study in China reported a 0.22% increase in death rates per 10 microgram per cubic metre increase in PM 2.5.
In contrast, higher death rates were observed in countries with lower base pollution levels: Greece had a 2.54% increase, Japan had a 1.42% increase, and Spain had a 1.96% increase.
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