PM2.5 low, PM10 high on dense fog days: SAFAR

Between 2012 and 2015, while the level of PM2.5 has shown a decreasing trend during dense fog days, concentration of PM10 has increased.

Particulate Matter 10 is a pollutant found in windblown dust, smog, pollens, construction activities, which cause respiratory problems and aggravate asthma. Particulate Matter 2.5 is finer and found in vehicular emissions, high temperature combustion, heavy metals. PM2.5 has long-term health effects such as lung diseases and even cancer.

The trend was highlighted after a 62-day study was conducted by System of Air Quality and Weather Forecasting And Research (SAFAR), an agency that gives data on air quality in India.

“Fog occurrence are maximum during December and January, air quality data was evaluated for these respective months only (62 days) in 2014-2015,” said Gufran Beig, project director, SAFAR, Indian Institute of Tropical Meteorology, Pune. Beig was talking at a fog brainstorming meeting organised by India Meteorological Department (IMD).

Apart from the 62 days, SAFAR has also analysed the trends from 2012 to 2015 as well.

So categorising the fog days into dense, moderate and no fog, the study shows that in the year 2012-2013 on 23% fog, the PM10 level was 283.73, while in 2014-2015 as dense fog rose to 44%, the PM10 concentration climbed to 323.2.

However in contrast, the level of PM2.5 has decreased, when on 23% dense fog, the PM2.5 in 2012-2103 was 189.09 in 2014-2015 the PM2.5 concentration came down to 108.22.

“A decreasing trend from 2012-2015 of PM 2.5 is good news in terms of health. The local weather is playing a dominant role. Also on the other hand the particulate matter presence is playing an important role to determine the thickness and intensity of the fog,” said Beig.