Air pollution levels about 3.5 times higher at bus stops: Study

Alice Chia Channel NewsAsia 20 Sep 16;

SINGAPORE: Commuters waiting at bus stops in Singapore could be breathing in three-and-a-half times more toxic gases and particles than at ambient levels, and with prolonged exposure this may lead to health problems.

These are the findings of a research team led by Dr Erik Velasco, an air pollution expert from the Singapore-MIT Alliance for Research and Technology. The team also comprises students from the National University of Singapore.

After the measurements of their study were validated and the findings published in August, they found that bus stops are hotspots of exposure to tiny particles from vehicle exhaust fumes. These particles permeate the bloodstream and can cause or exacerbate existing pulmonary and cardiovascular diseases such as lung cancer and asthma, the researchers said.

The study started in 2011 and measurements were taken using state-of-the-art portable sensors over a period of two years at five bus stops across VivoCity, Little India, Bugis, One Raffles Quay and the National University of Singapore.

While all five were found to be polluted, the frequency of pollutant spikes were highest at the Bugis bus stop, followed by the one at VivoCity as there were more commuters and traffic in those areas.

According to the Land Transport Authority, about 63 per cent of all journeys in Singapore during peak hours are undertaken on public transport and of the 7.7 million daily trips, 49 per cent are by bus.

To reduce commuters' exposure to the pollutants, the research team suggests installing fans at bus stops to disperse the toxic particles and fumes. It also advises commuters to reduce waiting times at bus stops by checking bus arrival schedules.

In the long term, having electric trams and buses could also help to reduce the level of air pollution, researchers said.

- CNA/am

Vehicle emissions more toxic than PM2.5 pollutants
Audrey Tan, The Straits Times AsiaOne 21 Sep 16;

Even without the haze shrouding Singapore, commuters waiting for a bus could still be polluting their lungs.

The tiny particles from vehicle emissions are smaller - and more toxic - than the PM2.5 pollutants dominant during periods of haze, a new study has shown.

"Waiting at the bus stop for only 10 minutes each time may seem innocuous. But these short exposures all add up," said researcher Erik Velasco who helmed the study.

"A commuter who takes a two-way trip by bus to work for five days per week is actually exposed to these participles for nearly seven hours per month and over three full days per year. This exposure can affect people with existing pulmonary and cardiovascular diseases, among others."

PM2.5 are pollutant particles measuring less than 2.5 microns in diameter - about one-30th the diameter of a strand of human hair.

They are hazardous because they are small enough to be breathed into the lungs and absorbed into the bloodstream.

Dr Velasco, a research scientist from the Singapore-MIT Alliance for Research and Technology, has found that the particles commuters breathe in while waiting at a bus stop are even smaller - by about 100 times.

At a media briefing yesterday, he said a commuter who makes a two-way bus journey five days a week could be inhaling about 3.5 times more tiny pollutant particles than at an ambient level, which researchers measured at Fort Canning Park.

The findings were significant considering that travel on buses made up almost half the 7.7 million public transport trips every day in 2014, said Dr Velasco, citing Land Transport Authority data.

Steve Yang, specialist in respiratory medicine and consultant at the Raffles Internal Medicine Centre in Raffles Hospital, said the human body has no efficient way to remove particles smaller than 2.5 microns in diameter.

People should not stand near idling buses, he added.

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