The new National Air Quality Index launched by Prime Minister Narendra Modi on Monday, gives current as well as 24-hour average data on particulate matter – PM2.5 or very fine particles smaller than 2.5 micrometres in diameter, and PM 10 which are less than 10 micrometers in diameter – as well as other pollutants including nitrogen dioxide, ozone and carbon monoxide. PM 2.5 levels are commonly used as the best indicator of severe air pollution, while PM 10 particles are also a cause of public health concern, but less lethal.
India now grades air quality along a colour-coded chart based on pollutant levels.
Officials from the Central Pollution Control Board warned that the quality of new monitoring stations was mixed across the country, and said Delhi was likely to have the most rigorous data. “There is still a lot of standardisation work we need to do to get all cities and all monitoring stations comparable. The new index should be seen as indicative,” the official said, asking not to be named.
The Hindu analysed data from 17 location across the country based on this data and found that despite its reputation, Delhi had better air quality that south Bangalore for the first week of April.
While comparable data for these 17 locations is available only for the last few weeks, particulate matter is heavily influenced by weather patterns. Anumita Roychowdhury, head of the Centre for Science and Environment’s air pollution and clean transportation programmes, compiled data for Delhi from October 2014 onwards. The data shows that while there were “moderate” days in October, February and March, the second halves of November and December, and the first half of January were consistently “very poor”.Delhi the worst
In 2014, the World Health Organisation compiled average annual PM 2.5 numbers for over 1600 cities across the world, including 124 from India. Delhi had the worst air quality in the world by that estimate, but 12 other Indian cities were among the world’s worst 20 – Patna, Gwalior, Raipur, Ahmedabad, Lucknow, Firozabad, Kanpur, Amritsar, Ludhiana, Allahabad, Agra and Khanna.
The Centre for Science and Environment, which has for long advocated the adoption of the AQI, welcomed the government's move “For the first time, the government has taken the initiative to inform people about daily air quality with simple descriptions that people can understand. This can help build public awareness as well as public support for hard decisions needed to get cleaner air,”said CSE's executive director Anumita Roychowdhury.No preventives
However, in stark contrast with other countries that have air quality warning systems, India does not yet have a mechanism or measures in place to bring down peak pollution levels. Beijing for instance, puts in motion a slew of operations when the warning signal for severe pollution is issued. On such days kindergartens, primary and middle schools close, there is a cap on the number of cars allowed on the roads and polluting factories either cut down emissions or shut down completely. Similarly, when the air quality index rose in Paris recently, the city made public transport free and removed almost 50 per cent of the vehicles off the road.