Delhi air quality drops to hazardous levels as smog shrouds Indian capital

Northern city has consistently been ranked as the world’s most polluted capital

People walk in smoggy conditions at India Gate in New Delhi on October 31, 2023. AFP

Residents of Delhi woke up to a blanket of smog and haze on Wednesday as the level of air pollution in India's capital reached hazardous levels.

Air Quality Index levels in the city were above 400, with the Anand Vihar station recording 442 AQI, according to the Central Pollution Control Board, the country’s leading environmental watchdog.

An AQI between zero and 50 is considered “good”, 51-100 is “satisfactory”, 101-200 “moderate”, 201-300 “poor”, 301-400 “very poor” and 401-500 “severe”, according to India's air quality standards, which are less stringent than those followed by the World Health Organisation.

Most of the pollution on Wednesday was from PM 2.5 – particulate matter 2.5 microns in diameter or less – and PM 10, according to IQAir, a Swiss company that tracks air quality data worldwide.

IQAir reported the concentration of PM 2.5 early in the day as 230 micrograms per cubic metre – more than 40 times the safe limit of five micrograms per cubic metre set by the WHO.

PM 2.5 particles penetrate deep into lungs and into the bloodstream and are blamed for chronic respiratory and cardiac diseases.

Delhi, home to 20 million people, suffers from air pollution throughout the year but the level surges in November with the onset of winter, when pollutants get trapped by the colder air. The city has repeatedly ranked as the world’s most polluted capital.

A study released this week by the All India Institute of Medical Sciences in Delhi showed that high PM 2.5 levels were responsible for a 19 per cent increase in visits to the hospital's emergency rooms between 2017 and 2019.

Out of 69,400 emergency visits recorded by doctors at AIIMS during that period, 2,669 were by adults with acute respiratory symptoms.

The doctors observed that an increase in ER visits by adults with acute respiratory symptoms was associated with an increase in PM 10 and PM 2.5 levels.

While the PM 10 increased the number of visits for cough – 74 per cent of the total patients recorded, PM2.5 increased the number visits for difficulty in breathing – 95 per cent, the study said.

The doctors suggested that a thorough study of pollution sources and regional meteorological factors responsible for variations in levels recorded in different areas would lead to better mitigation strategies.

The burning of crop stubble by farmers in the nearby states of Uttar Pradesh, Haryana, Punjab and Rajasthan, and the setting off of fireworks to celebrate religious festivals at this time, both of which continue despite being banned, add to Delhi's winter pollution spike.

India's Supreme Court on Tuesday asked the state governments of these states to report the steps they had taken to control the burning of fields.

It also asked the Commission for Air Quality to provide a report on action taken to reduce air pollution in and around the capital.

On the same day, the Bombay High Court expressed concern about the “deteriorating” air quality in Mumbai, India's financial capital, over the past two weeks.

The AQI readings in the western coastal city had hovered between “poor” and “very poor”, touching the 400-mark on October 18.

The Board of Control for Cricket in India has decided to not hold firework displays during matches played in Delhi and Mumbai in the Cricket World Cup to avoid adding to the pollution.