The Pune air, during Diwali time, has shown a steady decline in quality in the last five years, according to an analysis done by the scientists at the System of Air Quality Forecasting and Research (SAFAR). In the months of October and November in 2013, there were 54 days when the air quality was either good or satisfactory. Last year, there were only 29 such days during these months.
Air quality is analysed by measuring, among other things, the level of particulate matter (PM) in the atmosphere. Particulate matter in the atmosphere that is less than 10 microns in size (PM 10) and less then 2.5 microns in size (PM 2.5) is dangerous. An increase in PM 2.5 levels is the most dangerous as it can penetrate deep into the lungs and enter the bloodstream.
SAFAR uses a unit-less number, within a certain range, to indicate the level of pollution — good, moderate, poor etc — and Air Quality Index.
As per SAFAR’s analysis, the lead pollutant causing the most damage is PM 2.5, said Project Director Dr Gufran Beig. In 2017, of the 61 days in October and November, the PM 2.5 levels were within permissible limits on only 29 days.
In 2016, there were only 28 such ‘good days’ while 2015 saw as many as 52 days in the two months when the pollution level was down. In the year before that, 2014, there were 36 days when the air quality was good or satisfactory.
To asses air quality levels in Pune Region, SAFAR uses a high-resolution atmospheric chemistry transport prediction model and also gathers feedback from 10 air quality monitoring stations in and around the city. The ratings by the AQI are colour coded – green indicates ‘good’ air quality when there is no risk of air pollution, and the unit-less number is between 51 and 100. Yellow indicates moderate air quality where the unit-less number is between 101 and 200, while red indicates poor air quality and the unit-less number ranges between 201 and 300.
While moderate quality of air is tolerable for most people, it can lead to health concerns for those who have a higher sensitivity to changes in air quality. Scientists say an advisory of poor air quality should be taken seriously by people with a history of heart or lung disease, and the elderly and children, and these groups should reduce prolonged or heavy exertion.
Beig said long-term sustainable measures were required to ensure that the quality of air didn’t deteriorate further. Now, SAFAR scientists are working towards assessing air quality during the festive days of Diwali. As the temperatures have not dropped much this year, the pollution level is likely to be lower, said Beig.