With dry season & pollution, city’s AQI declines on Bihu

Guwahati: The capital’s air quality slipped either to the severe category or remained close to the mark of severe category in the last three days affecting people even with good health and seriously impacting those with existing health problems mainly due to the presence of dust particles generated in the sandbars of the Brahmaputra and in the hills due to construction activities and large-scale vehicular emissions.
According to the central pollution control board (CPCB) data, Guwahati’s air quality never dipped to the severe category in the last three years. The air quality was poor till Friday but slipped to the very poor category on the day of Uruka of Bhogali Bihu on Saturday and degraded further dipping to the severe category on Sunday.
Most people experience breathing discomfort on prolonged exposure to air when the category dips to poor. Some experience respiratory illness on prolonged exposure when the air quality slips to the very poor category.
Senior environmental scientist from the Assam Pollution Control Board, Manoj Saikia, said the air quality degrades during the period from November to March every year as this is the dry season. “There is no rainfall and sandbars form in the Brahmaputra. The hills are levelled for constructions and this is a major cause of pollution. Very light dust particles are generated and this dilutes the air quality,” he added.
He said vehicular emission is the biggest cause of concern with the increase in vehicle population not only in the city but across the country. “The pollutant particles present in vehicular emissions make the air poisonous, particularly for patients with heart and lung diseases. It is always better to reduce the use of vehicles, wherever possible. People can avoid vehicles for travelling short distances, which will help in improving the quality of air,” he added.
Guwahati, along with Nagaon, Nalbari, Sivasagar and Silchar, are among the 131 non-attainment cities in India, according to the CPCB. Guwahati has topped among these five non-attainment cities or towns in Assam. A non-attainment city is one whose air quality did not meet the national ambient air quality standards of 2011 to 2015.
Guwahati has six national air quality monitoring stations at Bamunimaidan, Khanapara, Boragaon, inside the Indian Technical Institute (ITI) at Rehabari, Pragjyoti College at Bharalumukh and the Gauhati University at Jalukbari in the city.
The AQI is based on the measurement of particulate matter (PM2.5 and PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon monoxide (CO) emissions. The state PCB basically monitors the presence of particulate matter PM2.5 and PM10. The former are tiny particles present in the air that reduce visibility and cause the air to appear hazy when the levels are elevated. On the other hand, PM10 are inhalable particles with diameters that are generally 10 micrometers and smaller.