The World Health Organization (WHO) recently updated its air pollution guideline limits from the standards set in 2005 . The average 24-hour concentration of PM2.5 (particulate matter with diameter less than 2.5 microns) has been revised downwards to 15μg/m3 from 25μg/m3. In India, according to the National Ambient Air Quality Standards (NAAQS), last revised in 2009, the average daily PM2.5 limit is much higher at 60μg/m3. In 2021, in a majority of the Indian cities, pollution levels exceeded the WHO's 2005 guideline limits on most days. The number of cities which flout the guideline limits increases further if the WHO's current standards are considered. Worryingly, deaths attributable to higher pollution levels are increasing in India .
While the WHO's latest global air pollution standard allows for an average of only 15μg/m3 of PM2.5 concentration in a 24-hour period, India's permissible limit is 60μg/m3. A look at how other parameters set by the WHO compare with Indian standards.
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Pollution linked fatalities
The chart depicts the number of deaths, standardised according to age, recorded due to PM2.5 exposure per one lakh people in BRICS countries between 1990 and 2019. Such deaths are rising only in India among the five nations. As many as 95.6 deaths per one lakh people were recorded in India due to PM2.5 exposure in 2019.
Air quality in cities
The table shows the % of days on which the average daily PM2.5 levels was less than the new WHO limit (<=15), between the new and old WHO limits (>15 but <=25), between the old WHO and NAAQS limits (>25 but <=60) and over the NAAQS limit (>60) across Indian cities. Daily pollution data between Jan. 1, 2021 and Sep. 27, 2021 were considered for analysis. In 2021, Delhi's ITO station recorded an average daily PM2.5 concentration of more than 60μg/m3 on 68% of the days, while only 2.2% of such days were observed at Velachery in Chennai.