Meerut, Oct. 22 -- The city lit up with celebrations on Diwali night, but the joyous burst of fireworks came with a choking reminder of pollution. Despite restrictions, banned firecrackers were set off across Meerut, causing the Air Quality Index (AQI) to soar beyond 400 - a level classified as 'severe'. The dense smog that blanketed the city on Tuesday morning left residents struggling to breathe. According to the Central Pollution Control Board, AQI in severe category, "May cause respiratory impact even on healthy people, and serious health impacts on people with lung/heart disease. The health impacts may be experienced even during light physical activity." According to officials, while only green firecrackers were permitted, a large number of restricted ones were used openly. Pollution levels had started climbing before the festival, touching 300 by Sunday evening. As Diwali celebrations picked up, the AQI rose rapidly - reaching around 405 by midnight. From 8pm to nearly 1am, fireworks continued to light up the skyline, filling the air with smoke and particulate matter. Experts have warned that if pollution levels continue to rise unchecked, the administration may have to impose curbs on ongoing construction activities in the city. Early Tuesday morning, a thick layer of haze and reduced visibility confirmed the deteriorating air quality. In response to the pollution surge, the municipal corporation has activated teams to sprinkle water across city roads to control dust. Builders have been warned to cover construction materials, and strict action has been promised against those contributing to pollution. "Employees have been directed to intensify water sprinkling and ensure compliance at construction sites. Polluters will face penalties," said Lavi Tripathi, additional municipal commissioner....