New Delhi’s air quality plummeted again on Friday, and a thick haze of toxic smog hung over India’s capital due to a drop in temperature and wind speed, and a spike in the burning of crop waste in surrounding farmlands, writes Reuters.

The haze reduced visibility and the Air Quality Index (AQI) hit 461 on a scale of 500, according to the federal pollution control board. This level of pollution means the air will affect healthy people and seriously impact those with existing diseases.

The concentration of poisonous PM2.5 particulate matter averaged 329 micrograms per cubic meter of air. The government prescribes a “safe” PM2.5 reading at 60 micrograms per cubic meter of air over a period of 24 hours.

PM2.5 is small enough to travel deep into the lungs, enter the bloodstream and can cause severe respiratory diseases, including lung cancer.

“This is becoming a nightmare”, - said Gufran Beig, founder project director of air quality and weather monitor SAFAR that falls under the Ministry of Earth Science.