A cocktail of toxic factors — ranging from industrial waste to vehicular emissions and road dust — has put 14 Indian cities on the dubious map of the most polluted places in the world, experts said.
A new World Health Organization report said today that 14 Indian cities were on its 2016 list of 15 with the highest levels of PM2.5 or particulate matter with a diameter of less than 2.5 micrometres. Fine particles stay longer in the air than heavier ones, leading to greater chances of toxic matters being inhaled by human beings and animals.
Here are some possible reasons cited by the experts on what makes the air so dangerous in four hotbeds of pollution.
Kanpur: The WHO report states that the Uttar Pradesh city is the most polluted in the world with an annual PM2.5 average of 173 micrograms per cubic metre (µg/m3) and an annual PM10 (particulate matter of 10 micrometres or less in diametre) average of 319 (µg/m3).
Among the sources of pollution are industrial point sources, defined as single sources from which pollutants are discharged (such as factories, shops or pipes), and industry area sources, where areas lead to pollution.
Greenpeace India experts refer to its study ‘Airpocalypse-I’ to stress that the sources of PM10 in the city include industrial point sources (26 percent), vehicles (21 percent), domestic fuel burning (19 percent), paved and unpaved roads (15 percent), industry area source (7 percent), garbage burning (5 percent) and others.
Delhi: The national capital ranked sixth in terms of PM2.5 with an annual average of 143 µg/m3 in 2016. In terms of PM10, Delhi stood third in the world with its annual average of 292 µg/m3.
Experts from Greenpeace India said the top four contributors to PM10 emissions were road dust (56 percent), concrete batching or equipment that forms a concrete plant (10 percent), industrial point sources (10 percent) and vehicles (9 percent).
Varanasi: In terms of PM2.5 in 2016, Varanasi was the third most polluted city in the world with an annual average of 151 ug/m3. For PM10, Varanasi ranked the sixth most polluted in the world. Greenpeace India said identifying the exact sources of air pollution in Varanasi was not possible because of the absence of an official comprehensive source apportionment study.
However, according to an IIT Kanpur study, one of the possible factors could be emissions from a thermal power plant situated in Singrauli, about 100km south of Varanasi. Power plants within a 300-km radius of a settlement can adversely affect air quality.
Patna: The capital of Bihar has been ranked the fifth most polluted in the world in terms of both PM10 and PM2.5 levels. Experts said transport, road dust, domestic sources, generator sets, open waste burning, the manufacturing industry, brick kilns and construction activities contributed to pollution levels.