[sustran] Delhi catches its breath after car free day yesterday

[Vinay Baindur]

drastic drop is possible in PM 10, and PM 2.5 also? more so on public
holidays + car free days perfect for "Ayudha pooja" day

http://www.thehindu.com/news/cities/Delhi/delhi-catches-its-breath/article7793911.ece?homepage=true



Delhi catches its breath


   - RUKMINI S <http://www.thehindu.com/profile/author/rukmini-s/>



   - [image: Bahadur Shah Zafar Marg wears a deserted look in view of
   car-free day in Delhi on Thursday; cars line up at the ITO junction in the
   evening.— Photos: V. Sudershan and Sandeep Saxena]
   Bahadur Shah Zafar Marg wears a deserted look in view of car-free day in
   Delhi on Thursday; cars line up at the ITO junction in the evening.—
   Photos: V. Sudershan and Sandeep Saxena
   -


[image: Inline image 1]

CSE and Greenpeace India observed lower levels of air pollution on Thursday
morning.

Did Delhi’s attempt at a car-free day on Thursday improve its air quality?
Probably, but not by as much as the government is claiming, a close reading
of the data shows.

On Thursday, cars were asked to remain off the roads from Red Fort to India
Gate, over a 6-8 km stretch of the city, from 7 a.m. to 12 noon. Thursday
was also a public holiday on account of Dussehra. Using hand-held exposure
monitors, two environmental groups, the Centre for Science and Environment
(CSE) and the Greenpeace India, separately observed lower levels of air
pollution on Thursday morning as compared to Wednesday morning.

The CSE found that the concentration of particulate matter of less than 10
micrometres in diameter (PM 10) was 310 microgramme per cubic metre on
average for the five hours for that stretch of road, or 59 per cent less
than on Wednesday. The PM 2.5 level, or the concentration of fine particles
particularly dangerous for respiratory health, was 265, or 62 per cent less
than the previous day.

Even with the reduction, the PM10 levels recorded by the CSE would classify
the air quality of the stretch as ‘poor’, according to India’s Air Quality
Index, and the PM2.5 levels would qualify as ‘severe’. The Greenpeace
monitored PM 2.5 levels over a four-hour period on the same stretch on
Wednesday and Thursday and found that the concentration on Thursday was 172
microgramme per cubic metre, as compared to 428 on Wednesday, or an air
quality of ‘very poor’ as compared to ‘severe’.

However, the CSE and the Greenpeace’s observations were from exposure
monitoring, or the air quality experienced by an individual, while the AQI
is with reference to ambient air quality. The AQI values are also for
24-hour averages.

Across the four functioning air quality monitoring stations in the city,
the PM 2.5 level for Thursday was half that of Wednesday. But a comparison
between Thursday and Wednesday is for a number of reasons unfair. “It will
not be fair to compare the difference in particulate matter of today’s 5
hours average with yesterday’s 5 hours average because yesterday was a bad
day due to higher winds and mild dust storm during morning hours and the
level of PM10 and PM2.5 during these hours were quite high,” Dr. Gufran
Beig, project director of the Pune-based Indian Institute of Tropical
Meteorology’s System of Air Quality and Weather Forecasting And Research
(SAFAR), told *The Hindu*. At SAFAR’s Lodhi road monitoring station closest
to the car-free zone, Thursday morning saw a 14 per cent reduction in PM10
levels compared to the previous six days’ morning average, and a 19.5 per
cent reduction in PM2.5 levels, Dr. Beig said. Additionally, Thursday
morning’s air quality was better than on Sunday (October 18).

Given that Thursday was a public holiday, traffic volumes were expectedly
lower. “We’ve been finding that traffic volumes do not really reduce on
weekends, but come down substantially on public holidays,” Anumita
Roychowdhury, CSE’s executive director (research and advocacy) and an air
pollution expert, told *The Hindu*.

“We also observed that roads were being cleaned on Wednesday morning which
would have raised the particulate matter levels,” Sunil Dahiya, Greenpeace
campaigner, told *The Hindu*. Thursday’s findings simply demonstrated that
days when there are fewer cars on the street see an improvement in air
quality, the CSE said.
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