NEW DELHI: Several people in Delhi who stepped out of their houses on Saturday complained about their eyes stinging and watering. They also reported an uncomfortable feeling of “being choked”. This wasn’t surprising because air pollution levels in the city had reached alarming proportions. Experts said that heavy vehicular traffic in the run-up to Diwali compounded the problems caused by respirable particles that had accumulated in the past few days from the burning of crop stubble in the neighbouring states.

Already considered one of the global cities with the worst air to breathe, Delhi saw levels of PM2.5 (fine, respirable particles) reach an astounding 750 micrograms per cubic metres – 12 times the safety range for the pollutant in India and 30 times the World Health Organization’s global safety benchmark. This peak level was measured at Anand Vihar for a few hours around noon on Saturday. Even otherwise, the measured level of 350-450 micrograms per cubic metres there was way beyond the Indian safe level of 60 microgram per cubic metre. At RK Puram and Mandir Marg too, the PM2.5 levels hovered between 250 and 450 micrograms per cubic metre.

The levels of nitrogen dioxide (NO2) were also very high during the day, measuring between 200 and 250 micrograms per cubic metres at RK Puram and 100-150 micrograms per cubic metre at Anand Vihar and Mandir Marg against the safe limit of 80 micrograms per cubic metre.

“It was uncomfortable going to Connaught Place in the dense smog . The traffic fumes seemed more intense and my eyes started burning. I wanted to get back home as soon as possible,” said Pamela Chowdhury who lives in Greater Kailash. Nandita Chatterjee, who was driving from Defence Colony to Man Singh Road, said she started getting breathless and her cough worsened.

The Central Pollution Control Board air quality index categorised the pollution at Mandir Marg, Anand Vihar and RK Puram as “severe”. The health warning for such an occurrence is dire even for healthy individuals, and people are advised to minimize exposure to pollution by avoiding outdoor activities, especially heavy exercise outdoors.

According to the data provided by the System of Air Quality and Weather Forecasting and Research (SAFAR), the average PM10 (coarse particles) level on Saturday was 400-450 micrograms per cubic metre (safe limit is 100 microgram per cubic metre) and that of PM2.5 was 235 micrograms per cubic metres. Experts said these high levels could be partly accounted for by the moisture in the air that held together the accumulated pollutant particles.

“The Diwali traffic has played a major role in the increased air pollution levels as is evident from the high NO2 levels. Vehicular pollution is usually behind this problem,” said Anumita Roychowdhury, who heads the Centre for Science and Environment’s Clean Air programme. She also explained that since vertical wind was almost absent, whatever pollution was being generated lay trapped close to the surface.

An official from one of the air quality monitoring agencies added, “Despite the government’s directions, it is evident that the burning of crop stubble is continuing in places near the capital.” This year, the visible increase in Diwali traffic has added to the pollution caused by the annual burning, leading to people outside their homes complaining of eye and skin irritation.