Something most folks may not be aware of is that standing behind a idling scooter is about 1000 times worse than standing behind a idling car breathing in fumes – that’s because common two-stroke scooters which make up a large portion of the vehicles in Asian countries especially Vietnam, Thailand, Malaysia, and India process fuel in a way that leaks fuel out of the exhaust port after each cycle.
These two-stroke engines have been banned in certain cities in China already, but are a cheap way to buy transportation in 3rd world countries and most likely will remain for years to come. This is something everyone should be cognizant about when going about their daily activities – avoid being around these scooters and hold your breath if they pass by you. The emissions from these vehicles in essence is attaching toxic benzine and organic aerosols to dust and dirt in the air just ready for unsuspecting victims to inhale. You can compound the problem if there is already pollutants suspended in the air.
For reference purposes below is a visual chart showing pollutants by vehicle type and running versus idling.