If you have been battling a nagging cough/cold or worse an upper respiratory tract infection this season, the city’s poor air quality could be the culprit.

Official data has revealed that since the onset of winter, the city has not managed to keep down the level of its cancer-causing particulate matter 2.5 (or PM 2.5) within the safe limits of 60 micrograms per cubic metre. The lowest figure of PM 2.5 this season was recorded at 157 micrograms per cubic metre on November 1.

After battling a choking Diwali week, with the PM 2.5 recorded at 732 micrograms per cubic metre, the levels have remained anywhere between 473 and 213 micrograms per cubic metre.

Urging the Delhi Government to take immediate action to inform people about the air quality on a daily basis and issue health alerts — especially for children, elderly, and those suffering from respiratory and cardiac problems to take precaution — Centre for Science and Environment’s (CSE) Anumita Roychowdhury said: “High levels of PM 2.5 is a serious cause of concern.”

“Air pollution kills and at immediate risk are those with lung and cardiac problems. The tiny PM 2.5 particles go deep into the lungs and get trapped there. This on a short-term basis aggravates lung and cardiac conditions and in long term is known to cause lung cancer,” added Ms. Roychowdhury.

“Half of these million deaths have been caused by ischemic heart disease triggered by exposure to air pollution,” it noted.

Stating that world-over cities issue smog and haze alerts almost instantly when pollution reaches alarming levels, Ms. Roychowdhury added: “With the wind gone and high pollution from crackers and vehicles building up quickly very close to the ground level, Delhi is enveloped in a thick blanket of pollution. Every winter, the calm and cool weather makes pollution hang heavy, but the severity of the smog depends on the actual pollution level that is already unacceptably high and rising in the city.’’

“While the serious concern over very high levels of tiny particles persists, elevated levels of other pollutants have been now added to the toxic cocktail,’’ she cautioned.

The city has also recorded high levels of nitrogen dioxide, carbon monoxide and PM 10. Said Dr. Anil Bansal of the Delhi Medical Council said: “Calm weather conditions, increased crop burning by nearby States and spike in local pollution levels has left the Capital choked. The city hospitals are reporting large number of lung, eye and skin-related complications and one of the reasons could be the bad quality of air in the Capital.”

Dr. Neeraj Jain, senior consultant chest medicine, Sir Ganga Ram Hospital, said: “Post-Diwali, the number of patients we are getting with compromised lung function has definitely gone up. Worst hit are those with asthma and other breathing problems. Even healthy persons have reported upper respiratory tract infection and cough. What is worrying, however, is the fact that city dwellers are losing lung function, which adversely hits the quality of life.’’