The Capital will be able to breathe some clean air over the coming days as Wednesday evening could bring a spell of rain which will improve the air quality. Delhi recorded “very poor” Air Quality Index at 313 on Tuesday, according to Safar. This will improve by Wednesday and reach at 283, though still in “poor” category.
“We expect a spell of rains or showers on Wednesday evening,” a MeT department official said. On Tuesday, the 24-hour rolling average of PM10 and PM2.5 was at 242µgm-3 and 152µgm-3 respectively, in moderate and very poor categories, respectively. This will take a dip on Wednesday and touch 218µgm-3 and 115µgm-3, respectively.
PM2.5 and PM10 are ultra-fine particles that are the dominant pollutants in Delhi. The acceptable levels of PM 2.5 and PM10 are 60μg/m3 and 100μg/m3, respectively. According to the recently notified and enforced graded response system, when pollution levels are between “poor” and “moderate”, the measures to be enforced are — strict ban on garbage burning, closing brick kilns, mechanised sweeping of roads and ban on fire-crackers, among others. When the pollution levels fall in very poor category, the measures to be implemented are — hiking parking fees by up to 4%, banning diesel generator sets and increasing frequency of metro trains.
Wind speed, another key factor in Delhi’s air quality, is also expected to pick up over the coming days. “By Thursday, the wind speed will be around 15-20 kmph,” the official said. Low wind speed in winters accounts for the typically poor air quality in the season. With weathermen predicting stronger winds and rain spells over the coming days, particulate matter will be dissipated and washed out, improving the air quality. However, it will get colder, as the minimum temperature is expected to drop to 5-6 degrees Celsius.