Delhi has witnessed a consistent air quality index (AQI) falling between the “moderate” and “poor” categories over the past few weeks. A positive change occurred after a night of light rain graced the national capital. Following the rain, the air quality has improved, shifting from ‘poor’ to ‘moderate.’

The overall AQI currently stands at 169, as reported by the System of Air Quality and Weather Forecasting and Research (SAFAR-India).

What is AQI?

The Air Quality Index (AQI) serves as a vital tool for conveying air quality conditions in a comprehensible manner. It simplifies complex data on various pollutants into a single numerical value, a name, and a color. Six AQI categories exist: Good + Satisfactory, Moderately Polluted, Poor, Very Poor, and Severe. These categories are determined based on the concentration values of air pollutants in the environment and their potential health effects, known as health breakpoints.

The AQ sub-index and health breakpoints are developed for eight pollutants, including PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb, for which short-term (up to 24 hours) National Ambient Air Quality Standards are established. The sub-index is calculated based on the measured ambient concentrations of a pollutant, following a linear function of concentration. For example, the sub-index for PM2.5 will be 51 at a concentration of 31 µg/m³, 100 at 60 µg/m³, and 75 at 45 µg/m³. The overall AQI is determined by the worst sub-index among these pollutants.

Air Quality of Delhi:

Late Monday night brought light rainfall to various parts of Delhi, resulting in a notable 6-degree drop in temperature. Over the past 24 hours, the city’s temperature decreased from 29 degrees Celsius to 23 degrees Celsius. Rainfall, accompanied by thunder and lightning, was observed in areas such as Noida, Indirapuram, south Delhi, and east Delhi.

For the day ahead, the weather department has forecasted a generally cloudy sky for Tuesday, with the possibility of light rain or thundershowers. Maximum and minimum temperatures are expected to be around 31 and 20 degrees Celsius, respectively. The Regional Met Centre in New Delhi predicts the likelihood of thunderstorms and lightning at isolated locations.

As per the latest update from RWFC Delhi, thunderstorms with light to moderate intensity rain are anticipated in areas including Tundla, Agra, Firozabad (U.P.), Chandpur, Sambhal, Bilari, Milak, Chandausi, Anupshahar, and Bahajoi (U.P.) over the next two hours.