Air pollution these days has become a real challenge in India, especially in North India. Breathing clean air has become a luxury in megacities such as Delhi, Ghaziabad and Noida. These places are frequently recording hazardous Air Quality Index (AQI) levels these days. To give you an idea, AQI below 50 is the threshold for the “Good” category on the AQI scale. But these cities have surpassed this...