Gurgaon: The city’s overall Air Quality Index (AQI) dropped to 174 on Saturday, bringing it into the moderate category from 215 on Friday. However, high particulate matter concentrations at individual monitoring stations and changing weather conditions could reverse the improvement in the coming days, experts warned.Of the city’s four monitoring stations, Gwal Pahari recorded the lowest AQI at 144, followed by Sector 51 at 162 and Teri Gram at 169, all in the moderate category. Vikas Sadan, however, continued to record poor air quality, with an AQI of 232, highlighting variations in pollution levels across the city.Despite the improvement in the overall AQI, PM2.5 concentrations remained high at all four stations. Sector 51 recorded 329 micrograms per cubic metre (µg/m³), followed by Vikas Sadan at 326 µg/m³, Gwal Pahari at 309 µg/m³ and Teri Gram at 206 µg/m³. At Sector 51, the concentration was nearly 22 times World Health Organization’s (WHO) recommended 24-hour guideline of 15 µg/m³.PM10 levels were also elevated, with Teri Gram recording 418 µg/m³, followed by Vikas Sadan at 269 µg/m³, Gwal Pahari at 199 µg/m³ and Sector 51 at 191 µg/m³. WHO’s recommended 24-hour guideline for PM10 is 45 µg/m³.PM2.5 consists of fine particles that can penetrate deep into the lungs and enter the bloodstream, while PM10 includes larger inhalable particles that can affect the respiratory system.The improvement followed a spike in pollution after Dussehra celebrations on Oct 20. Firecrackers and effigy burning added to the pollution load, while calm winds restricted the dispersal of pollutants, contributing to the rise in AQI the following day.Independent air quality expert Sachin Panwar attributed Saturday’s improvement to changes in weather conditions, particularly wind speed and direction, which helped disperse pollutants. Slightly warmer daytime temperatures and lower moisture levels also aided dispersion.“Wind speeds improved, which helped flush out pollutants. The daytime temperature was also slightly warmer, and changes in moisture levels helped improve dispersion. However, this improvement may not last. As northeasterly winds gradually strengthen and conditions become less favourable for dispersion, pollutants could begin to accumulate again,” Panwar said.He added that changing wind patterns would play a crucial role in determining pollution levels over the next few days. When wind speeds fall, pollutants tend to remain trapped closer to the ground, potentially worsening air quality.Meanwhile, the city recorded a maximum temperature of 30.4°C and a minimum of 16.8°C on Saturday, with both remaining close to the seasonal normal.
