It is worrying to know that even waiting for buses at bus stops over a short duration each day could pose a health hazard in the longer term ("Air-quality study throws spotlight on bus stops"; yesterday).
Some studies have shown that exposure to traffic pollutants known as PM 2.5 can push up the risk of dying by 7 per cent, compared with being away from vehicular traffic.
Microscopic particles largely produced by diesel exhaust have been shown to cause lung damage and harmful changes in blood vessels and clotting.
I notice that some makes of public buses, such as Volvo (double deck) and Mercedes-Benz (single deck), emit fumes from the rear left of the bus, directly at commuters waiting at bus stops.
This causes commuters to move away from the spot, to avoid breathing in the fumes.
This is also common in the Central Business District (CBD) when several buses enter the bus bays during peak hours. Because of the more built-up environment in the CBD, it is harder for these fumes to dissipate, and harder for commuters to avoid them.
Buses should be modified such that their exhaust pipes face the road, away from commuters at bus stops.
At a time when motorists are being encouraged to travel by public transport, the problem of air quality at bus stops needs urgent attention.
Andrew Seow Chwee Guan