The second phase of Delhi’s odd-even road-rationing scheme started on a bad note on Friday with particulate pollution far beyond permissible limits but the levels decreased as the day progressed.
Real-time data from monitoring stations of the Delhi Pollution Control Committee revealed poor readings on Friday morning . The levels of PM2.5 – the tiniest and deadliest particulate matter that affects lungs and enters the blood stream, and PM10 – slightly bigger in size -- were far beyond permissible limits .
This was despite the significant dip in vehicles on roads due to the odd-even scheme and a public holiday (Ram Navmi).
Air quality experts blamed the pollution on low wind speed.
The wind speed on Friday 8 am at RK Puram was 1 m/s. At noon, it went up to 2.8 m/s. Air pollution levels corresponded accordingly. According to Hindustan Times’ air pollution monitoring index PM 2.5 was 298 microgrammes per cubic metre at 8am but dropped to 62 microgrammes per cubic metre at noon. It further decreased to 48 microgrammes per cubic metre at 2 pm.
The permissible level of PM 2.5 is 60 per cubic metre while for PM10 it is 100 micrograms per cubic metre.
According to System of Air Pollution Monitoring and Forecasting (Safar) under the ministry of earth sciences, the Air Quality Index (AQI) of Delhi on Friday was 269 – a “poor” rating that comes with the advisory that sensitive people may experience health effects.
On Thursday though, the AQI scaled a moderate rating of 101-200; the health advisory deems this “acceptable for general public”. The portal, however, had not updated its readings after 10 am.
The air quality for the past week has been in the moderate and satisfactory range- unusual for Delhi. Met officials have attributed this to high wind speed, in the range of 5 m/s and 8 m/s .
Delhi last year overtook Beijing as the city with the worst air in the world as per WHO rankings, in which 13 of the 20 most polluted cities were in India. The Delhi government brought in the odd-even scheme to tackle air pollution but the fickle weather made it difficult to understand its impact on air pollution.
Scientists are hoping the second phase of the scheme will help them understand the impact better as weather is more stable in April .