Rain shortfall has kept Delhi’s air ‘poor’ for most of summer
The Delhi government last month formulated a 14-point action plan to combat air pollution during summer
Delhi has seen more ‘poor’ and ‘very poor’ days than ‘moderate’ or satisfactory’ days since March this year, as experts said that air pollution is not more a winter-specific problem and 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.
Action to abate pollution’: Air Quality monitoring body raises Delhi’s annual plantation target
No land for growing trees, revise plantation norms: DDA tells Delhi govt
Central Pollution Control Board (CPCB) data from March 1 to May 11 shows Delhi recorded a total of 55 ‘poor’, 1 ‘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. Delhi’s AQI was 156 (moderate) on Wednesday, with strong surface winds from Cyclone Asani helping Delhi’s air quality. However, the AQI is forecast to return to the ‘poor’ category by the weekend, owing to a return of dry and dusty westerly winds.
Between February 16 and May 10, Delhi’s average PM 2.5 concentration was 100 micrograms per cubic metre -- 2.5 times higher than the national annual safe limit for PM 2.5 (40 micrograms per cubic metre) and 20 times the WHO limit of 5 micrograms per cubic metre -- as per CPCB’s real-time data analysed by the Centre for Science and Environment (CSE). In comparison, the average PM 2.5 concentration last winter was 197 micrograms per cubic metre (15 October till 15 February).
S.N 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-based 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, coal-based 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, adding that there is a need for a one-year study of pollution sources.
Anumita Roychowdhury, executive director, research and advocacy, said that though pollution level is half the winter level, the PM 2.5 and PM 10 levels are still fairly high, especially considering that this is despite better meteorological conditions in summer.
“As the lower layer of the atmosphere is warmer and lighter in summer compared to winter, air can easily rise upwards and disperse pollution. The intensity of summer pollution is lower than winter and shows higher influence of dust but these levels are still beyond the safe limits and indicates the need for sustained action,” said Roychowdhury, stating that while emergency-level measures are needed during winters, the summer and monsoon months need to be utilised to continue pollution control efforts and to scale up systematic changes, such as emission control from vehicles, industries, waste burning and dust sources. “We don’t need reactive measures alone during the winters, but sustained action through the year to meet clean air targets.”
She also suggested holding regular meetings during the summer months as well, allowing for agencies to plan and take action based on the air quality.
Only last week, the sub-committee on the Graded Response Action Plan (Grap) met after a period of nearly three months, asking for Delhi and NCR states to intensify certain Grap measures including dust control activities such as mechanised sweeping, enforcement of dust control measures at construction sites and speedy redressal of pollution-related complaints. The sub-committee last met on February 16, 2022, prior to the review meeting on May 4.
Farm fires a problem in summers too
While crop burning has been a prominent source of pollution for Delhi in winters, largely occurring between October 15 and November 15, the rabi harvest season causes a similar action from farmers across Punjab and Haryana.
As per Nasa’s VIIRS satellite data, analysed by the Council on Energy, Environment and Water (CEEW), 14,957 farm fires have been reported in Punjab and 4,592 fires in Haryana between March 1 and May this year. For Punjab, this is the highest corresponding count in at least five years, with 6,392 fires recorded last year and 5,585 fires in 2018. For Haryana too, this figure is the highest in at least five years and is close to last year’s count of 4,461 fires during the same period.
“The magnitude of rabi fires usually pales in comparison to the kharif ones. This is because unlike paddy residue, wheat residue is widely used as animal fodder,” said LS Kurinji, Programme Associate at CEEW, adding that while favourable meteorological conditions are at play during the summers, this can still impact air quality to an extent. “The higher mixing height and faster wind speed during summers can provide adequate ventilation, but it is still harmful and shows it is critical to act now to have a safer winter,” she added.
A Delhi Pollution Control Committee (DPCC) official said the Delhi government has launched a 14-point summer action plan from April 12 to focus on different sources of pollution, including anti-dust and anti-open burning campaigns. “The real-time source apportionment study for Delhi is also on track and we can expect data on the various sources of pollution from the end of July onwards,” said the official.