Air pollution in Delhi drops from 'severe' to 'very poor'; stringent curbs revoked

New Delhi: The Centre on Saturday removed stringent curbs, including a ban on construction work related to linear projects and the entry of polluting trucks into Delhi, following an improvement in air quality due to an increase in the wind speed and a change in the wind direction.

These measures constitute the final stage, Stage IV, of the Centre's air pollution control plan called the Graded Response Action Plan (GRAP).

The Commission for Air Quality Management in National Capital Region and Adjoining Areas (CAQM), a statutory body responsible for formulating strategies to combat pollution in the region, asked Delhi and NCR states to revoke all emergency measures, under which only CNG, electric and BS VI-compliant vehicles from other states are allowed to enter Delhi, with exemptions granted to those involved in essential services.

All medium and heavy goods vehicles not engaged in essential services were also banned in the capital under Stage IV of GRAP, according to the latest CAQM order.

The pollution control body said all other curbs under stages I, II and III of GRAP, including a ban on non-essential construction work, mining, stone crushers and diesel generators will continue.  

The city's 24-hour average AQI, recorded at 4 pm every day, improved from 405 on Friday to 319 on Saturday. It was 419 on Thursday, 401 on Wednesday, 397 on Tuesday, 358 on Monday, 218 on Sunday, 220 on Saturday and 279 on Friday.

Neighbouring Ghaziabad (276), Gurugram (322), Greater Noida (228), Noida (265) and Faridabad (309) also recorded "very poor" air quality.

An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", 401 and 450 "severe" and above 450 "severe plus".

The air quality forecasts by the India Meteorological Department/Indian Institute of Tropical Meteorology do not indicate any steep degradation in the overall air quality of Delhi-NCR in the coming days, the CAQM said.

Recent findings from a joint project by the Delhi government and Indian Institute of Technology (IIT), Kanpur found out that vehicular emissions accounted for about 45 per cent of the capital's air pollution on Friday. This reduced to 33 per cent on Saturday.

Secondary inorganic aerosols -- particles such as sulfate and nitrate that are formed in the atmosphere due to the interaction of gases and particulate pollutants from sources like power plants, refineries and vehicles -- is the second major contributor to Delhi's foul air, accounting for 19 to 36 per cent of the air pollution in the city over the last few days.

Delhi's air quality dropped over the last few days despite the city government implementing stringent measures, including a ban on construction work and the entry of diesel-guzzling trucks into the national capital.

According to IQAir, a Swiss company that specialises in air-quality monitoring, Delhi was the second-most polluted city in the world on Saturday after Baghdad.

Doctors say breathing in the polluted air of Delhi is equivalent to the harmful effects of smoking approximately 10 cigarettes a day.  

Prolonged exposure to high levels of pollution can cause or exacerbate respiratory problems such as asthma, bronchitis and chronic obstructive pulmonary disease (COPD) and dramatically raise the risk of cardiovascular disease, they said.  

Unfavourable meteorological conditions, combined with vehicular emissions, paddy-straw burning, firecrackers and other local pollution sources, contribute to hazardous air quality levels in Delhi-NCR during winters.  

According to a report compiled by the Energy Policy Institute at the University of Chicago (EPIC) in August, air pollution is shortening lives by almost 12 years in Delhi.