Dehradun witnessed a sharp spike in air pollution after Diwali celebrations, with PM2.5 concentrations touching 829.8 micrograms per cubic metre around 2 am on November 9, as firecracker emissions worsened air quality across several Uttarakhand cities.The pollution spike raised concerns over its potential health impact, particularly on children, the elderly and people with pre-existing respiratory conditions.Dehradun recorded an AQI of 359 in the 24 hours ending at 8 am on November 9, placing it in the 'very poor' category. The city's average PM10 and PM2.5 concentrations during the period stood at 262.5 and 196.5 micrograms per cubic metre, respectively.ALSO READ | Diwali Turns Tragic In Delhi: 10-Year-Old Boy Dies After Firecracker Hits His ChestHowever, particulate matter concentrations rose sharply in the early hours of Monday following hours of firecracker bursting. Around 2 am, PM2.5 levels touched 829.8 micrograms per cubic metre, while PM10 concentrations exceeded 1,000 micrograms per cubic metre.The deterioration in air quality was not limited to Dehradun. Several other Uttarakhand cities, including Haridwar, Rishikesh, Kashipur and Rudrapur, also reported elevated pollution levels.Haridwar recorded an AQI of 310, placing it in the 'very poor' category, with PM2.5 and PM10 concentrations at 133 and 169 micrograms per cubic metre, respectively.At 8 am, PM2.5 concentrations stood at 199 micrograms per cubic metre in Kashipur and 90 micrograms per cubic metre in Rishikesh.Haldwani, however, fared relatively better, recording an AQI of 78, with PM2.5 and PM10 concentrations at 47 and 57 micrograms per cubic metre, respectively.Dehradun Records Unprecedented Pollution SpikeProfessor Vijay Shridhar of Doon University said firecracker bursting was considerably more extensive this Diwali than in previous years, contributing to a substantial increase in particulate matter concentrations.According to NDTV, he said pollution levels remained in the 'severe' category for several hours, with PM2.5 and PM10 concentrations registering exceptionally high levels between 12:30 am and 6 am.According to Shridhar, this was the first time they had observed peak concentrations of both PM2.5 and PM10 crossing the 1,000-microgram-per-cubic-metre mark.He added that the city's AQI crossed 400 during the early morning hours, with air quality fluctuating between the 'very poor' and 'severe' categories.ALSO READ | Delhi's Diwali Pollution Worst In 5 Years, AQI Stays 'Very Poor' Next MorningExpert Flags Health Risks, Urges RestraintShridhar said the intensity and duration of firecracker bursting were particularly concerning this year, with firecracker sounds continuing until around 3 am.He warned that exposure to high concentrations of particulate matter could pose serious health risks, particularly for vulnerable groups, the report added.Children, elderly people and individuals with pre-existing respiratory conditions are especially susceptible to the adverse effects of deteriorating air quality, he said.The professor urged people to exercise restraint during celebrations, cautioning against the prolonged and uncontrolled use of firecrackers.He also stressed the need for greater public awareness and responsible celebrations, saying the health risks associated with extreme short-term pollution spikes should not be overlooked.