One suggestion to reduce the potential health hazard of breathing in tiny particles while waiting for buses was to minimise the waiting time at bus stops ("Air-quality study throws spotlight on bus stops"; last Wednesday).

Surely a better way is to reduce the pollution from bus exhaust.

More stringent checks should be done to ensure that buses leaving the depots do not emit black fumes.

I have seen many buses, vans and heavy vehicles plying our roads and emitting vast amounts of black fumes every day.

These vehicles should be subject to six-monthly inspections so as to keep our air pollutant-free.

Heavy vehicles from Malaysia should not be allowed to enter if they are emitting black fumes.

Heavier fines should also be imposed on all public or commercial vehicles that emit black fumes.

Koh Lian Chye