Among the given pollutants, Methane is not included in the National Air Quality Index (AQI). The measurement of air quality is based on eight pollutants, viz.: → Particulate Matter (size less than 10 µm) or (PM10) → Particulate Matter (size less than 2.5 µm) or (PM2.5) → Nitrogen Dioxide (NO2) → Sulphur Dioxide (SO2) → Carbon Monoxide (CO) → Ozone (O3) → Ammonia (NH3) → Lead (Pb) for which short-term (up to 24- hourly averaging period) National Ambient Air Quality Standards are prescribed. AQI has six categories of air quality. These are: Good, Satisfactory, Moderately Polluted, Poor, Very Poor and Severe.