Delhi witnesses cleanest August air in 4 years: CPCB data

In fact, as per the data, till August 23, available with the Central Pollution Control Board (CPCB), this month has had only ‘satisfactory’ and ‘good’ air days, as per the air quality index (AQI).

The air in the Capital this August has so far been the cleanest for four years, thanks to repeated spells of intense rain and persistent drizzles, data from the apex pollution control body shows

Monsoon clouds looming in the sky over Connaught Place in New Delhi. (Amal KS/HT PHOTO)

In fact, as per the data, till August 23, available with the Central Pollution Control Board (CPCB), this month has had only ‘satisfactory’ and ‘good’ air days, as per the air quality index (AQI).

An AQI between 0 and 50 is considered ‘good’, 51 and 100 ‘satisfactory’, 101 and 200 ‘moderate’, 201 and 300 ‘poor’, 301 and 400 ‘very poor’, and 401 and 500 ‘severe’.

As per data analysed by HT, while August 2019 had two consecutive ‘good’ air days and 20 ‘satisfactory’ days, it also recorded nine ‘moderate’ days. However, the same month in 2018, 2017 and 2016 did not record a single ‘good’ air day.

According to CPCB officials, with a forecast of more rainfall over the next week in Delhi and the national capital region (NCR), air quality is likely to remain in the satisfactory category and may even improve.

On Sunday, as per the CPCB’s daily 4pm bulletin, Delhi’s 24-hour AQI was 53 (satisfactory).

Delhi received a spell of ‘heavy to very heavy’ rainfall between August 20 and 21. On August 20, the city experienced a good air day with an AQI of 50. This was the second good air day this month, and third for the year so far. Previously, on August 13, after a period of heavy rain, Delhi’s AQI dropped to 50. The first ‘good’ air day this year was recorded on March 28, days after the nationwide lockdown was imposed, with an AQI reading of 45.

“Since August 20, the AQI has been below 60, in the lower range of the ‘satisfactory’ zone, which is a good sign,” the above quoted CPCB official added.

Anumita Roychowdhury, executive director (research and advocacy) at the Centre for Science and Environment (CSE), said, “Generally, monsoon months are cleaner than the rest of the year. Higher number of clean air days this August is a combination of good rainfall and the overall reduction in pollution levels in the months preceding August (during the lockdown). Pollutants did not accumulate as much, and were washed away by heavy rainfall. It is crucial to keep this trend through the coming winter months with aggressive implementation of pollution control measures.”

Scientists at the IMD said that with another week of rain forecast, this August is likely to become among the wettest compared to at least the last five years. IMD’s data between June 1 and August 22 shows that Delhi received a cumulative rainfall of 414.2mm. In August alone, Delhi received 217.5mm rainfall, which was a surplus of 32%.

“Light rain will continue in many parts, but a ‘moderate’ spell of rain will hit Delhi on the night of August 25, and will continue on August 26 and 27,” said Kuldeep Srivastava, head of the regional weather forecasting centre.

The System of Air Quality and Weather Forecasting and Research (Safar), the Central government’s air quality monitoring and forecasting wing, too has forecast that with more rains likely, the air quality over next week is expected to remain in the ‘satisfactory’ zone.