The PM10 level (presence of particles with diameter less than 10 mm) was recorded at 626 in Delhi-NCR and 650 in Delhi, leading to hazy conditions.
The PM2.5 level (presence of particles with diameter less than 2.5 mm) that deteriorated from "very poor" to "severe" showed improvement today at 164 in Delhi region and 162 in Delhi-NCR, the CPCB data said.
Yesterday, the PM2.5 level in Delhi-NCR was at 268 and Delhi at 277.
According to the CPCB, the air quality index (AQI), a measurement of the concentration of toxic particulate matter in air, at several places in Delhi remained over 500.
An AQI between 0-50 is considered "Good", 51-100 "Satisfactory", 101-200 "Moderate", 201-300 "Poor", 301-400 "Very Poor", and 401-500 "Severe".
The India Meteorological Department (IMD) said that strong dust raising winds of the order of 2,535 kmph is likely to continue over Rajasthan, Punjab, Haryana, Chandigarh and Delhi during the next 24 hours.
It also forecast thunderstorms at isolated places over the city in the coming days, bringing relief from the dusty air.
Lieutenant Governor Anil Baijal had on Thursday ordered stoppage of all civil construction activities across the city till Sunday as part of the emergency measures which also include intensifying mechanical road sweeping.