Delhi's air quality improved Friday after rainfall lashed parts of the national capital, according to authorities.
The overall Air Quality Index (AQI) of Delhi was recorded at 266 which falls in the poor category, according to the Centre-run System of Air Quality Forecasting and Research.
On Wednesday and Thursday, the air quality had deteriorated to the very poor category, alarming authorities who were planning to roll out more stringent measures to combat pollution.
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".
A senior official said the reason for improvement of air quality was the rainfall Thursday which lashed parts of the national capital, cleansing the air of the pollutants.
The PM10 level (presence of particles in the air with a diameter of less than 10 micrometres) in Delhi stood at 253 and the PM 2.5 level was recorded at 110, according to the SAFAR data.
On Thursday, the PM2.5 (presence of particles in the air with a diameter of less than 2.5 micrometres) touched a new high at 158. The PM2.5, also called "fine particulates," can be a matter of more serious health concern than PM10.
A Central Pollution Control Board official said a number of factors were responsible for the deteriorating air quality, including vehicular pollution and construction activities.