Stopping lasting health damage from the toxic winter smog

Do masks and air purifiers protect us from toxic air? Should children be allowed to play outdoors when pollution peaks? Who is at biggest risk of hospitalisations and emergency room visits? Can pollutants increase the risk of respiratory infections? What's the best time to exercise in winter? Dr Randeep Guleria, India's top pulmonologist and director of Delhi's All India Institute of Medical Sciences, tells us why and how we must protect ourselves from air pollution to prevent irreversible damage to health.