India, Oct. 31 -- A day after record-breaking rain washed pollutants out of Delhi's air and brought Delhi its cleanest October day in four years, shallow fog enveloped the national capital on Saturday morning, even as air quality remained in the satisfactory category.

Delhi recorded an air quality index (AQI) of 95 at 6am on Saturday, compared with 60 in the Central Pollution Control Board's (CPCB) 4pm bulletin on Friday. The air quality remained in the satisfactory category, although the increase indicated a deterioration from the previous day's unusually clean conditions.

At 6am , CPCB data showed PM2.5 as the predominant pollutant at 17 of Delhi's 58 reporting stations and PM10 at four stations. At the same time on Friday, PM2.5 was ...