India's most polluted cities


The Delhi region is experiencing one of the harshest lows of environmental conditions in India—the worst smog in 17 years, according to the India Meteorological Department.

According to some reports, this sudden sharp dip in air quality is directly related to the Diwali weekend, which fell on October 28 and 29 this year. The post-Diwali days had a higher pollution rate, almost 62 per cent higher than the Diwali weekend. To add to the woes, there was an overall lower wind speed during this time, due to which the particles remained stagnant in air.

Gwalior, Kanpur, and other polluted cities
However, Delhi was not the only city with high pollution in India, according to a report published by WHO in May this year. Based on data from 2012-13, the Global Urban Ambient Air Pollution Database compared annual PM2.5 (tiny particulate matter measuring 2.5 microns present in the air) concentration levels across 3,000 cities around the world.

The report named Zabol, a Iranian city, the most polluted city in the world, with PM2.5 levels of 217 µg/m³. The next two cities were Indian—Gwalior (176 µg/m³) and Allahabad (170 µg/m³). Patna (149 µg/m³) came in at number 6, following by Raipur (144 µg/m³), while Delhi (122 µg/m³) was at the eleventh spot. Of the top 20 most polluted cities, 10 were Indian. From Uttar Pradesh, Kanpur (115 µg/m³), Firozabad (113 µg/m³) and Lucknow (113 µg/m³) were in the top 20, while Ludhiana (122 µg/m³) and Khanna (114 µg/m³) from Punjab were also included.

A look at real-time air quality measurement maps today shows Lucknow, Delhi and Agra to have the highest levels of pollution.

PM2.5 levels should be as low as 25 µg/m³
A high level of PM2.5 is capable of reducing visibility and leads to the air appearing hazy, such as the air in Delhi. According to the World Health Organisation (WHO), inhaling particulate matter has been known to cause respiratory diseases, heart attack, stroke and lung cancer. It is even said that air pollution was the sixth leading cause of death in India.

Reports state that in parts of north India, especially Delhi, Uttar Pradesh and Bihar, the PM2.5 levels were measured at over 500 µg/m³. Paddy burning in Punjab and Haryana also led to a direct increase in air pollution this time.

Ideally, the PM2.5 level that is considered tolerable over an average period of 24 hours is 25 µg/m³. At the end of September, Delhi's level clocked in at 229 µg/m³, while smaller cities like Gwalior in Madhya Pradesh and Allahabad in Uttar Pradesh, had 176 µg/m³ and 170 µg/m³ of particulate matter respectively.

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The Week

Topics : #Delhi | #environment

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