Karnal, Oct. 22 -- Haryana woke up to a thick blanket of smog on Tuesday, a day after Diwali , with Jind topping the national Air Quality Index (AQI) chart in the 'severe' category - recording the worst air in the country. According to the Central Pollution Control Board (CPCB), the 24-hour average AQI for Jind stood at 421, followed by Dharuhera (412), Narnaul (390), Rohtak (376) and Gurugram (370) - all from Haryana. These cities occupied the top five spots in the CPCB bulletin. Overall, eight towns from Haryana ranked among the top ten most polluted cities in India, surpassing even Delhi's AQI of 351. These included Bahadurgarh (368), Charkhi Dadri (353) and Sirsa (353) in addition to the top five. The AQI acts as a measure of overall air quality on a scale of 0 to 500, with six categories: good (0-50), satisfactory (51-100), moderate (101-200), poor (201-300), very poor (301-400), and severe (above 401). The CPCB calculates AQI based on at least three pollutants, one of which must be either PM2.5 or PM10. P4...