Centre for Science and Environment (CSE) has welcomed the release of the much-awaited national Air Quality Index (AQI). The AQI will be used to inform people about daily air quality and to provide advisories on health consequences. It will tell how clean or polluted the air is, and what associated health effects might be of concern. This can help people take precautions on 'bad air' days.
The AQI was released here today by prime minister Narendra Modi. CSE has been demanding adoption of this Index for a long time.
Anumita Roychowdhury, executive director in charge of the clean air and sustainable cities programme in CSE, says: "For the first time, the government has taken the initiative to inform people about daily air quality with simple descriptions that people can understand. It is cautioning them about possible health consequences. This can help build public awareness as well as public support for hard decisions needed to get cleaner air."
The new AQI has been hosted on the website of the Central Pollution Control Board. About 10 cities that have the capacity for real time air quality monitoring are expected to be linked a continuous 24-hour average data will be available daily from them. The AQI has been developed for six pollutants PM2.5, PM10, nitrogen oxides, sulphur dioxide, ozone, and carbon monoxide.
Air pollution levels have been classified in six bands with simple descriptions to help people understand. Each band has cut points of concentration with a colour code to visually express the level of severity that people can comprehend easily. Air quality is classified good if the pollution levels are at least 50 per cent below the regulatory standards.
The government is also making efforts to inform people about the health consequences of air pollution. For instance, good air quality days mean minimal health impacts. But on 'moderately polluted' days, it may cause breathing discomfort in those suffering from lung or heart diseases. On severely polluted days, pollution may cause respiratory effects even in healthy people and serious health impacts in people with lung disease. The ministry has also taken additional steps to report on two toxic pollutants lead and ammonia -- that also have harmful effects over time.
CSE applies the new Index to PM2.5 levels. Shows interesting results
CSE has applied the national Air Quality Index to PM2.5 levels recorded by the air quality monitors of Delhi
Pollution Control Committee from October 2014 until March 2015. It shows:
Number of days with severe levels the worst category -- has remained consistently high all through. In December, 65 per cent of the days were in severe category; in January, it was about 47 per cent.
Globally, a smog episode is defined as three consecutive days when the pollution levels are elevated and remain in the worst category of the Air Quality Index. When CSE applied the criteria to the city's pollution levels, it found there were at least 12 smog episodes this winter! This is a critical situation -- in other countries, if cities are afflicted in a similar manner, immediate steps are taken to reduce car numbers, shut industrial units, and close down schools.
Post-winter, as pollution peaks tapered off to some extent, the share of days with severe pollution levels declined. In March 2015, despite the rains, about 17 per cent of the days were in 'poor' and 30 per cent in 'very poor' categories.
It is also possible to have 'good' air days when pollution levels dip to 50 per cent below the standards. In March, 7 per cent of the days had good air quality. Cities need to act to increase the number of good air days, says CSE.