Complete data could've raised average Diwali pollution level 49%

NEW DELHI: Missing PM2.5 data from monitoring stations could have raised the city's average pollution level by 49% on Diwali, according to an analysis by Centre for Research on Energy and Clean Air (CREA).Had the missing readings been recorded at 1,000 micrograms per cubic metre (g/m³), the city's average PM2.5 level would have increased from 269 to 400(g/m³), it revealed. The daily national ambient air quality standard for PM2.5 is 60 g/m³ and WHO's safe guideline is 15 g/m³.The analysis was done a day after Central Pollution Control Board (CPCB) said its stations' analysers were calibrated to measure particulate matter concentrations only up to 1,000g/m³ and could not display readings beyond it on Diwali night for several hours.Nor were these readings considered for calculating the average AQI, it said.CREA said if 400g/m³ had been considered, city's AQI on Monday would have risen from 344 (very poor) to near severe.