The particulate matter (PM) 2.5 was six times higher than the prescribed standard. It was 376 micrograms per cubic metre (µg/m³) on Thursday and 259 (µg/m³) on Wednesday. The permissible limit of PM 2.5 is 60 µg/m³.

Carbon Monoxide was 24.20 mg/m³ on Thursday compared to a permissible limit of 4.00 mg/m³.

According to the data from the Haryana State Pollution Control Board (HSPCB), the pollution level has remained above permissible limits since Diwali.

“As the wind speed has reduced from 18 km/hour on Wednesday to 6.3 km/hour on Thursday, the pollutants are trapped in the atmosphere,” Bhupender Singh, regional officer, HSPCB, said.

As the temperature dips, wood burning also increase in the region and it is one of the reasons for the rise in the level of PM 2.5, Singh said.

PM2.5 is suspended particulate matter 2.5 micrometres or less in diameter and a major component of air pollution. As it is very fine, it can settle in the lungs and worsen asthma and other respiratory problems.

Doctors have advised residents, especially children, elderly and asthma patients to stay indoors as the pollutants in the air have rose to levels dangerous to them. The condition has led to a significant rise in respiratory illnesses among residents.

“We have seen a significant increase in people reporting respiratory problems this week. In fact, our figures suggest a 50% rise in people reporting breathing related illnesses since the first week of January. Common complaints include cough, runny nose, wheezing and breathlessness. While common cold and flu are frequent in winter, vulnerable people -- children, the elderly and those with existing respiratory conditions such as asthma and bronchitis -- are reporting major problems,” Dr Piyush Goel, MD, consultant pulmonology, Columbia Asia Hospital, Gurgaon, said.

It has been noticed that people living in areas near congested traffic zones and highways are the most badly affected, doctors said.

“Apart from respiratory illnesses, a few cases of stroke, angina and heart attack that we believe were triggered by exposure to extreme cold and polluted air have been reported,” Goel said.

Dr. Neeraj Gupta, senior consultant , Pulmonology, Paras hospitals Gurgaon, said, “Long term exposure to fine particulate matter may be associated with increased rate of chronic bronchitis, reduced lung function and increased mortality from lung cancer and heart disease. People with breathing difficulty and heart problem, and children and the elderly may be particularly sensitive to the rise in PM2.5 level that damages pulmonary macrophage which are helpful in both innate and adoptive immunity.”

BOX--- Preventive measures

--- Remain indoors, close all windows and doors and if going outside, wear a qualified mask and minimize the duration or intensity of outdoor activities.

---- Sensitive populations (the elderly and those with pre-existing cardiopulmonary problems) should be more cautious of PM2.5 pollution and minimize outdoor PM2.5 exposure.

---- Patients with chronic cardiopulmonary problems should increase their medication dosage and pay close attention to their health to prevent severity of their symptoms during an increase in smog.

---- As oxidative stress is one of the main pathogenic mechanisms of PM2.5, taking antioxidant supplements or nutritious food (for example, w-3 fatty acids in fish oil).