Is it safe to exercise outdoors post diwali, when fumes from crackers, agricultural fires and vehicular emissions get trapped low on the earth’s surface because of falling temperature and turn the city’s air into a toxic smog? Instead of stopping exercise

Avoid physical activity early mornings or late evenings. “When the temperature is low, pollutants get trapped closer to the ground so there is high concentration of pollutants in the air we breathe. Strenuous activity at this time leads to people inhaling greater volumes of minute pollutants, which get lodged in the lungs,” said Dr GC Khilnani, professor, department of pulmonary medicine, All India Institute of Medical Sciences (AIIMS). “Shift workout time to 11am to4pmwhentheairisabit clearer,” he added.

The ubiquitous green-coloured surgical masks provide zero protection against fine particles, which do maximum damage to the airway and lungs. “Surgical masks don’t have a high-grade filter and small particles can pass through them,” said Dr Vikas Maurya, senior chest specialist at west Delhi’s BLK Super-Speciality Hospital.

The most effective masks are N95, which are also called respirators. These are equipped to filter particles as minute as 2.5microns and do so 95% of the time.

The mask must cover your nose and mouth to avoid air leakage from the sides and must be changed frequently. “In a place like Delhi, one would need to change the mask every 2-3 days,” says Dr Maurya.

He has words of caution for those with breathing difficulty. “It can aggravate breathlessness symptoms as one needs to breathe hard through these masks.”