Karnal, Oct. 23 -- Two days after Diwali celebrations, Haryana saw a marginal improvement in air quality, though six of its cities continued to feature among the country's 10 most polluted.

According to the Central Pollution Control Board (CPCB), Dharuhera in Rewari district recorded the worst air quality in India on Wednesday, with an Air Quality Index (AQI) of 379, placing it in the "very poor" category. The industrial town, which had ranked second a day earlier, was in the "severe" category then. In comparison, Delhi's AQI stood at 353.

The AQI measures air quality on a scale of 0 to 500, with six categories-good (0-50, dark green), satisfactory (51-100, green), moderate (101-200, yellow), poor (201-300, orange), very poor (301-400, ...