That time of year when Delhi makes the news for its severely polluted air is back with a vengeance. On November 8, the day after Diwali, pollution in the city reached the “severe-plus emergency” category because of the widespread use of firecrackers. And while people in Delhi can testify to just how bad it gets, what’s even more surprising is that there are five other Indian cities that fare even worse when it comes to PM 2.5 levels.
PM 10 refers to particulate matter with a diameter below 10 μm; PM 2.5 refers to that with a diameter below 2.5 μm. PM 2.5 is generally considered more harmful since its smaller size enables it to enter the lungs and cause more damage than larger particles can.
According to a report released by the World Health Organisation in May this year, Kanpur, Faridabad, Varanasi, Gaya and Patna are even more polluted than Delhi. In the list of the 15 most polluted cities in the world, 14 are in India. Almost all of them lie in the northern states of Uttar Pradesh, Rajasthan, Haryana and Bihar.
|Rank||City||PM 2.5 level|
|15||Ali Subah Al-Salem (Kuwait)||94|
While Kanpur ranked at one in the WHO’s list, a Reuters report pointed out that the city has a hard time tracking air quality. “Every week a lung cancer patient walks in; earlier we would get one in three months,” Prem Singh, head of the department of medicine in Kanpur’s Ganesh Shankar Vidyarthi Memorial Medical College, told Reuters.
Varanasi, which ranks third on the WHO’s list, did not see ‘good’ air for even a single day in all of 2015.
In Patna, pollution levels rose sharply on Tuesday. The same trends were visible in Gaya and Muzaffarpur, with air quality in the ‘very poor’ category. S.N. Jaiswal, a senior scientist at the Bihar State Pollution Control Board, told Times of India, “Vehicular emission and dust emanating from damaged roads and construction activities are responsible for the high level of air pollution in Patna and some other cities in Bihar.”
This year, ignoring a Supreme Court order to burst only “green” crackers between 8pm and 10 pm on Diwali, residents burst crackers in several parts of the country at various times of day. In Delhi, which saw a large amount of crackers, PM 2.5 levels reached 999. Yet, post Diwali, Kolkata was worse than Delhi in terms of PM 2.5 levels, with reckless explosions in the city. Patna, Gaya and Muzaffarpur in Bihar were also particularly affected.
While pollution levels in Mumbai rose after Diwali, researchers said the air in the city was cleaner than the same time in other years.
According to Down to Earth magazine, air quality has been deteriorating even before Diwali in all 70 cities for which the Central Pollution Control Board releases an AQI bulletin. Between October 22 and 29, the report says, not one of these cities breathed air in the ‘good’ category. So even while media and public attention has been focused on Delhi and other metropolitans, smaller cities maybe breathing even more harmful air.
The problem is compounded by other factors. In a report by the Times of India, Gufran Beig, director and chief scientist of the System Air-quality Forecasting And Research (SAFAR), said that the convergence of air masses in the Indo-Gangetic plains, together with calmer air during the winter, makes it difficult for stagnant polluting particles to disperse.