Even rains fail to ensure good air quality in Delhi during monsoon, as per the data collated by the Central Pollution Control Board (CPCB).
The comparative data also revealed that air in Varanasi and Faridabad was more polluted during winters but it became better in the two cities during monsoon.
Pollution in Varanasi and Faridabad was less than that in Delhi between July and August (monsoon), making Delhi more polluted on an average in 11 months. Rains wash out a lot of pollutants, especially those related to dust.
Where Delhi recorded an average air quality of 138 in July – the cleanest month – Faridabad recorded 100 and Varanasi 85. Though during winters, both cities were more polluted than Delhi.
According to CPCB data collated between May 2015 and March 2016, out of Delhi, Varanasi and Faridabad (the most polluted), Delhi had the highest average pollution.
Delhi stood at 248 out of 500, Varanasi at 234, and Faridabad was at 223. These quantities are Air Quality Index figures where 500 is the worst and 0 the best.
In 2014, the World Health Organisation had called Delhi the most polluted city in the world.
CPCB’s data in January this year showed that north Indian cities such as Varanasi, Kanpur and Lucknow were highly polluted as were smaller cities such as Agra and Faridabad. Pollution in Varanasi and Faridabad was more than that in Delhi in December and January.
Delhi becomes the most polluted on an average over 11 months because of poor air quality in monsoon months.
Delhi did not see a very robust monsoon last year and the pollution levels in July, August and September remained high. The monsoon, however, was weak in Faridabad as well. Cities in Uttar Pradesh also did not see heavy rains. Their performance on the air quality index was better.
According to air quality expert, Gurfan Beig, the type of data collection could be the reason behind Delhi’s poor show. “In Delhi, the standard of air quality monitoring is very high because it is automated and because it has a number of stations in different locations. Most of these other places, however, have manual stations – only 1 or 2 in number. It is possible that Delhi’s figures are higher because of more accurate reporting,” he said.
According to Centre for Science and Environment executive director, Anumita Roy Chowdhury, one reason for the high pollution in monsoons could be local pollution from combustion,such as emission from industries, vehicles and open burning which cannot be washed away.
“Dust pollution is easily washed away by rains but emissions from combustion are tougher to remove. If the pollution in nearby areas such as Faridabad is reduced, it means local sources of pollution are to blame for the bad air quality,” she said.