New Delhi’s air is the worst among world megacities, the World Health Organisation (WHO) confirmed recently, even as a network of air quality sensors reported fine particulate matter (PM2.5) levels were almost four times above daily safe levels, on average, for the seven-day period from September 22 to 28, 2016.
For long-term exposure, these 24-hour levels are nearly 11 times above the WHO health standards.
Over the monsoon, Delhi’s air was relatively cleaner because the rain and wind diminished the impact of pollutants. But with the season changing, three of our five sensors in the National Capital Region (NCR) registered “poor” to “very poor” air quality levels from September 22 to 28, meaning prolonged exposure affects healthy people and “seriously impacts” those with existing disease.
In December 2015, week-long analysis of data from the sensors showed Delhi’s air pollution was one-and-a-half times worse than in Beijing.
In 2012, with 1mn deaths, China reported the highest toll from PM2.5 and PM10 pollution. At the time, India followed, reporting 621,138 deaths, nearly 10% of the global toll (6.5mn deaths) associated with outdoor and indoor air pollution.
However, between 2011 and 2015, in a comparison of megacities with population above 14mn, Delhi’s ambient air pollution levels were worse than Beijing and Shanghai.
Most air pollution deaths are caused by fine, invisible particles, called PM2.5, about 30 times finer than a human hair. These pollutants, if inhaled deep into the lungs, can cause heart attacks, strokes, lung cancer and respiratory diseases, and are known to pose the greatest risk to human beings. Their measurement is considered to be the best indicator of the level of health risks from air pollution, according to the WHO.
Up to 97.5% of Delhi’s 16.8mn people live in urban areas, and the city has a density of 11,297 persons per sq km - making it one of the densest regions in the country - according to Census 2011 data.
“Air pollution continues to take a toll on the health of the most vulnerable populations - women, children and the older adults,” said Dr Flavia Bustreo, assistant director general at the WHO.
Some 3mn deaths every year are linked to exposure to outdoor air pollution, according to the WHO. Nearly 90% of air pollution-related deaths occur in low- and middle-income countries, with nearly two out of three occurring in WHO’s Southeast Asia region (of which India is a part) and the Western Pacific region.
Inefficient modes of transport, household fuel and waste burning, coal-fired power plants, and industrial activities are the major sources of air pollution, WHO said.