Low wind speed in and around Delhi has started impacting the city’s air, with the air quality index (AQI) reading 133 at 7am on Sunday.

After a month of the cleanest air in five years, Delhi’s air quality has started worsening. With monsoon almost drawing to a close and little possibility of more rainfall this month, Delhi’s air quality may deteriorate further by the end of September, scientists at India Meteorological Department (IMD) said.

On Saturday, the AQI reading as recorded by the Central Pollution Control Board (CPCB) was 118 at 4pm.

An AQI reading of 0-50 is considered ‘good’ (minimal health risk), 51-100 is ‘satisfactory’ (minor discomfort to sensitive people), and 100-200 is ‘moderate’ (breathing discomfort to people with lungs and heart disease).

“Clean air days may almost be over now, as meteorological conditions change. The monsoon is set to withdraw by September-end, after which calm winds will blow across the northwestern region, which are not favourable for the dispersion of pollutants. The pollutants suspended in the air, which were till last month being blown away by the rain and winds are likely to hang in over the city in the absence of any such weather activity,” said Kuldeep Srivastava, the head of regional weather forecasting centre, IMD.