Delhi remains India’s most polluted city for second day in a row; GRAP Stage IV restrictions kick in

Restrictions have been imposed on construction activities and the plying of older vehicles

For the second day on the trot, Delhi fared the worst in terms of air quality in the country with pollution continuing to soar prompting the Central Pollution Control Board (CPCB) to a sound a warning about its implications on people’s health.

Severe-level air pollution affects healthy people and seriously impacts those with existing diseases, said the CPCB.

The warning came a day after the city’s air quality nosedived sharply from a nearly two-week relief from hazardous levels of pollution that had encouraged the Commission for Air Quality Management in NCR and Adjoining Areas (CAQM) to roll back its most severe curbs on December 5.

The restrictions were lifted as the air quality improved in the Delhi-National Capital Region (NCR) following an over month-long battle with high pollution levels, mainly caused by stubble burning in neighbouring States, vehicular pollution and slower wind speed.  

However, the Central panel once again invoked the Stage IV of its Graded Response Action Plan (GRAP) imposing restrictions on construction activities and the plying of older vehicles as the city’s air quality index (AQI) reading touched 401 (severe) at 10 p.m. on Monday (December 6, 2024).

The AQI is a measurement of air pollution on a scale of 0-500. An AQI reading between 201 and 300 termed ‘poor’, 301 and 400 ‘very poor’, 401 and 450 ‘severe’, and 451 and 500 ‘severe plus’.

According to official data, the pollution levels are likely to stay high as the AQI reading scaled up to 433 (severe) at 4 p.m. on Tuesday (December 17, 2024), with the concentration of hazardous particulate matter rising over 16 times the permissible safe limit prescribed by the World Health Organization (WHO).

According to the CPCB, the level of PM2.5 — tiny particles that are 2.5 microns or less in diameter — was recorded at 251.5 micrograms per cubic meter at 7 p.m. on Tuesday, which is 16.7 times the WHO’s permissible limit of 15 micrograms per cubic meter for a 24-hour period.

PM2.5 are inhalable particles, invisible to naked eyes, that remain suspended in the air and lead to severe respiratory issues once they enter the body and cling to lungs.

The Central government’s Air Quality Early Warning System for Delhi too predicted ‘severe’ category pollution levels on Wednesday due to a significant drop in wind speed, a factor that causes sudden spike in pollution due to the non-dispersal of pollutants in air.

According to the Central agency, the pollution levels are likely to fall on December 19 and 20, with the AQI reading expected to remain in the ‘very poor’ zone.

Published - December 18, 2024 01:09 am IST