LUCKNOW, Sept. 27 -- Lucknow is breathing unusually clean air for a city in the plains so clean that its latest air-quality reading is now almost at par with Rishikesh and lower than Srinagar, two cities typically associated with clean mountain air. After three days of rain, Lucknow's AQI, according to the Central Pollution Control Board 4 PM bulletin, dropped to 38 on Saturday, following an even lower reading of 37 on Friday. Rishikesh recorded an AQI of 37, while Srinagar stood at 68. Dehradun, another hill city, recorded 49, while Silchar and Kohima reported 52 and 65, respectively. The citywide AQI of 38 masks a striking variation across Lucknow's monitoring stations. Lalbagh, which has often recorded some of the city's highest pollution levels during bad-air episodes, was at just 24 on Saturday, lower even than Rishikesh's 37. Kendriya Vidyalaya recorded 28, BR Ambedkar University 38, while Talkatora District Industries Centre stood at 60, showing a 36-point gap between the lowest and highest readings among the four stations....