Rain shortfall has kept Capital’s air ‘poor’ for most of summer
Delhi has seen more “poor” and “very poor” days than “moderate” or “satisfactory” days since March this year, as experts called for a year-round action plan to tackle air pollution in the city.
The Delhi government last month formulated a 14-point action plan to combat air pollution during summer.
Central Pollution Control Board (CPCB) data from March 1 to May 11 shows Delhi recorded a total of 55 “poor”, one “very poor”, 16 “moderate” and no “satisfactory” or “good” air quality days.
In comparison, there were 35 “poor” days and just three “very poor” days during the same period last year. An air quality index (AQI) of 0-50 is termed “good”, 51-100 is “satisfactory”, 101-200 is “moderate”, 201-300 is “poor” and 301-400 is “very poor”.
The last time Delhi recorded “satisfactory” day was when the AQI fell to 92 on February 27, as a result of rain across the city.
Between February 16 and May 10, Delhi’s average PM 2.5 concentration was 100 micrograms per cubic metre (μg/m3) -- 2.5 times higher than the national annual safe limit for PM 2.5 (40μg/m3) and 20 times the WHO limit of 5μg/m3 -- as per CPCB’s real-time data analysed by the Centre for Science and Environment.
SN Tripathi, a professor at IIT Kanpur and steering committee member of the National Clean Air Programme (NCAP), said dust has been a primary factor behind pollution, and attributed it to the absence rainfall, and other sources including emissions from coal power plants and farm fires which begun across Punjab and Haryana following the rabi harvest season.
“This indicates the need to once again identify sources and until that is done, immediate or long-term action cannot be taken. The primary problem for Delhi has been re-suspended dust, but also dust particles transported from other states, particularly from Rajasthan. With power problems also common, coalbased power plants are running at a high capacity and the high PM 2.5 concentration over Delhi indicates combustion is a factor, which could be partially from farm fires and some localised burning, such as garbage burning or landfill fires,” he said.