The air pollution data collected by the System of Air Quality and Weather Forecasting and Research (SAFAR) is in sharp contrast to the data presented by the Delhi Government. SAFAR’s analysis report that compared day-to-day pollution levels between December 25 and January 9 registered a mass concentration of PM2.5: four times higher than the prescribed limit since the implementation of the scheme.
However, the concentration of PM 2.5 witnessed a sudden drop on Saturday. Whether the sudden drop was due to freak weather pattern (high wind speed) or fewer numbers of cars on Saturday is debatable. However, if fewer numbers of vehicles/cars is responsible for low concentration of PM 2.5, then why such a drop was not witnessed on any other day is anyone’s guess.
The values of eight station data of SAFAR, a unit of the Ministry of Earth Science (MoES), showed that there was major drop in mass concentration of primary pollutant.
It may be noted that on December 31, 2015, the concentration of PM 2.5 was 211 µg/m3 while on the next day, i.e January 1, the value reduced to 180 µg/m3 (a drop of 31 µg/m3). However, on January 2, the PM 2.5 level was recorded at 215 µg/m3, an increase by 35 µg/m3. After that, the mass concentration of PM 2.5 saw an upward trend and was recorded above 250 ug/m3 till Friday.
This further means that the value of PM 2.5 was four to five times higher during the first week of the implementation of odd-even scheme, whereas permissible limit in Delhi air is 60 µg/m3.
Ecologists and metrological scientists said Delhi weather is unpredictable. “Variations in temperature and wind speed are dependent on the Western Disturbance. Due to freak weather pattern and relatively high wind speed, levels of pollutants in air are less,” said an ecologist.
Meanwhile, the Delhi Government on Sunday claimed that 50 per cent pollution drop has been measured in Delhi air. However, the observations are based on a 20-minute pollution data collected through light scanner technology.
“Scientists have been consistently predicting that with improved weather conditions, the odd/even formula will show immediate results,” the Delhi Government claimed on Sunday.