New Delhi, Nov 13 (PTI) Delhi's annual average PM10 and PM2.5 levels were higher by 5 per cent and 7 per cent, respectively, between January 1 and November 12 against the year-ago period, the latest CPCB data showed on Wednesday.
Between January 1 and November 12, the national capital recorded 116 days with the Air Quality Index (AQI) in the 'poor', 'very poor', or 'severe' categories. The AQI on 201 days was 'good', 'satisfactory' or 'moderate', the Central Pollution Control Board (CPCB) data showed.
In comparison, Delhi recorded 110 'poor' air quality days last year and 206 days with air quality in the 'good', 'satisfactory' and 'moderate' categories.
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'.
Delhi witnessed 156 'poor' air quality days in 2022, 119 in 2021, and 93 in 2020. The figure for 2020, however, was attributed to lockdown measures that reduced pollution levels.
The air quality in the National Capital Region (NCR), including Ghaziabad, Noida, Gurugram, and Greater Noida, was also 'poor' on Tuesday.
However, Faridabad recorded an AQI in the 'moderate' category.
On Tuesday, Delhi's AQI hit 334 -- a sharp rise from 218 on the same day last year.
Delhi recorded the country's worst air quality on Wednesday as it turned 'severe' for the first time this season, with the AQI soaring to 418.
Of Delhi's 36 monitoring stations, 30 reported air quality in the 'severe' category, the CPCB said.
The running average for PM10 this year is 193.25 micrograms per cubic metre, higher than last year's 184.25 micrograms per cubic metre.
The average PM2.5 level this year has risen to 88.22 micrograms per cubic metre from 82.75 micrograms per cubic metre in 2023.
Particulate matter or PM2.5 and PM10 refer to fine particulate matter in the air, with the numbers indicating their size in micrometres.
PM2.5 are fine particles with a diameter of 2.5 micrometres or less, about the width of a human hair. These are so small that these can penetrate deep into the lungs and even enter the bloodstream, posing significant health risks.
PM10 are coarser particles with a diameter of 10 micrometres or less, about the width of 10 human hairs. While not as concerning as PM2.5, these can still irritate the airways and worsen respiratory problems.
On Wednesday, vehicular emission was the top contributor to Delhi's pollution, with an estimated share of approximately 13.3 per cent, according to the Centre's Decision Support System for Air Quality Management.
The other prominent pollutants were PM2.5 and PM10.
LM Darlong, the head of thoracic oncosurgery at Rajiv Gandhi Cancer Institute and Research Centre, told PTI that long-term exposure to PM2.5 posed a significant risk factor for lung cancer.
These fine particles can trigger mutations in lung cells, leading to uncontrolled cell growth. Over a decade of exposure, these mutations are often linked to genes that play a key role in regulating cell division, he said.
Early detection of lung cancer is critical as symptoms such as persistent cough or blood in sputum often appear only at later stages, making treatment more challenging, he added.