Would Bangkokians tolerate a vehicle ban to ease toxic haze?
A vehicle ban is needed to tamp down Bangkok's growing haze problem as the health of city residents is being put at risk, a local expert on pollution said Tuesday.
The authorities are urged to introduce measures to reduce the number of vehicles on the capital's congested roads to bring down levels of PM 2.5 and other dangerous particulate matter than can lodge itself deep inside people's lungs, according to Supat Wangwongwattana, former chief of the Pollution Control Department (PCD).
"Although the air in Bangkok has been unhealthy and slightly worse than the [WHO's] general standard for what is safe, it remains within an acceptable safety standard for our health," he said at a pollution-themed seminar run by Thammasat University.
When higher levels of PM2.5 are recorded the city should roll out special measures like a 90-day ban on certain vehicles, added Mr Supat, who lectures on public health at the same university.
He said heavy lorries could be barred from entering the city during rush hour. Other measures seek to outlaw parking on roadsides between the hours of 9am and 1pm to ease congestion, or to allow them to drive only on alternating days.
It's also time for the authorities to regulate people's vehicle usage by only allowing cars to operate on even or odd days of the calendar month.
"Such measures should be put in place between January and the end of March, when air pollution is expected to reach a new high," Mr Supat said.
"It should be done every day as there is no effective advanced weather-forecasting system in the country, so no one knows when the heavy pollution is going to happen," he added.
PM2.5 levels in Bangkok spiked this month, tearing past 50 µcg per cubic metre and peaking at nearly 100 µcg on some days.
The major source of the problem is the number of vehicles on Bangkok's roads, having grown from 6 million in 2005 to nearly 10 million now. The situation is exacerbated by the proliferation of high rises obstructing air flow.
Moreover, stagnant weather conditions since last month have stopped polluted air from being dispersed.
Information supplied by the PCD shows Bangkok has faced high levels of PM2.5 for a considerable period, with the average daily level ranging from 26-35 µcg per cu m over the last seven years.
Negative side effects of this kind of particulate matter may include cardiovascular problems, cardiac arrhythmia or strokes, and respiratory effects including asthma attacks and bronchitis.
Mr Supat said the air quality may improve based on tightened fuel regulations to control emissions in line with European Union guidelines. He suggested Euro 5 as a good target for 2023 and Euro 6 for 2029.
Euro 5 introduced particulate filters (DPFs) for diesel vehicles, which capture 99% of particulate matter, along with lower limits across the board. Euro 6 cut the permitted level of NOx for diesels from 0.18g/km in Euro 5 to 0.08g/km, among other changes.
Mr Supat said the study found cleaner fuel and vehicles could slash the PM2.5 level by 5% in 2025 and by up to 86% by 2050. Thailand has reduced air pollution in the past by using more environmental friendly fuel specifications.
In 2012, the level of sulphur in the air reportedly plummeted from 10,000 parts per million (PPM) to just 50 PPM after the government decided to improve gasoline quality to fit Euro 4-compatible engines.
Nantavarn Vichit-Vadakan, dean of the School of Global Studies at Thammasat University, cited the black smoke that is regularly seen billowing from the exhausts of public buses as a major source of PM2.5.
The Bangkok Mass Transit Authority has been ordered to deal with this problem but critics say that little if anything has been done.
Air-pollution-induced respiratory disease is more prevalent in northern Thailand due to seasonal haze produced by burning farm waste, said Orapan Poachnukoon from Thammasat's Faculty of Medicine.