Not just winter, bad air too troubles Delhi round the yr

HT ANALYSIS Delhi and its neighbouring cities among the most polluted cities in the world

NEWDELHI: Delhi was the most polluted city in the world on Sunday, according to global air quality monitoring website, airvisual.com, as a blanket of dense smog covered the city through the day. Air pollution levels increase in Delhi and other regions in northern India in winter every year, but what often remains underestimated is that Delhi’s air pollution problem is not confined only to the winter.

Delhi and its neighbouring cities — Noida, Ghaziabad, Gurugram and Faridabad — were among the most polluted cities in the world all round the year in 2018, a Hindustan Times analysis with data from airvisual.com shows. The website has ranked these five cities among the world’s 11 most polluted cities in 2018. Gurugram and Ghaziabad topped the list.

The ranking is based on the annual average concentration of fine particulate matter PM 2.5, a hazardous pollutant able to penetrate deep into human respiratory system and, from there, to the entire body. Three other Indian cities — Bhiwadi, Patna and Lucknow — were also among these 11 cities. (See chart 1) The website also gives monthly average of PM 2.5 levels for all 12 months of 2018 for 2612 cities in the world. An analysis of this data shows that at least Delhi, or one of its four neighbouring cities, was among the eight most polluted cities in the world every month.

Average PM 2.5 level of these five cities was less than, or slightly more than, 50 micrograms per cubic meter (μg/m³) — normally considered safe for human life — in only three months: July, August and Sep

CHART 1

1

2

3

4

5

6

7

8

9

10

11

Gurugram, India

Ghaziabad, India

Faisalabad, Pakistan

Faridabad, India

Bhiwadi, India

Noida, India

Patna, India

Hotan, China

Lucknow, India

Lahore, Pakistan

Delhi, India

CHART 3 tember. (See chart 2)

But even in these months, Delhi and its neighbouring cities were among the most polluted worldwide. For instance, Faridabad ranked seventh in July, third in August and first in September even as its average PM 2.5 level was less than 75 μg/m³ in this period. Except in July and August, all these five cities have ranked among 33 most polluted cities in the world. (See chart 3)

These figures suggest that even as air pollution levels in Delhi and its neighbouring region peaks only in winter, it is a significant problem throughout the year.

THREE OTHER INDIAN CITIES, BHIWADI, PATNA AND LUCKNOW, WERE ALSO AMONG THE TOP 11 MOST POLLUTED CITIES IN THE WORLD IN 2018