Unlike the smog-laden air hovering over the congested streets of large cities, Bermuda's air is generally of a good quality, the constant ocean breezes preventing the build-up of air pollution. However, there are pockets of high pollution, especially at rush hour, and Bermudians should still be concerned about their contributions to greenhouse gases; driving a private car is probably a typical resident of Bermuda's most polluting daily activity.
As explained by the US Environmental Protection Agency, "The power to move a car comes from burning fuel in an engine. Pollution from cars comes from by-products of this combustion (exhaust) and from evaporation of the fuel itself.
"Gasolines and diesel fuels are mixtures of hydrocarbons, compounds which contain hydrogen and carbon atoms. In a 'perfect' engine, oxygen in the air would convert all the hydrogen in the fuel to water and all the carbon in the fuel to carbon dioxide. Nitrogen in the air would remain unaffected. In reality, automotive engines emit several types of pollutants: hydrocarbons (HC), nitrogen oxides (NOX), carbon monoxide (CO), carbon dioxide (CO2) and soot (particulates). Depending on the source and make-up of the fuel, there may also be sulphur oxides (SOX) and lead (Pb)."
Exhaust emissions are measured by inserting a probe into the exhaust pipe of the vehicle while the engine (already warm) is running. The exhaust gas analyser takes a sample of the exhaust and measures, in gasoline engines, the HC and CO, and in diesel engines, the particulates. The results are then expressed in parts per million (PPM) for gasoline, and percentage opacity for diesel engines. The result is compared to a given standard and the result, pass or fail is displayed.
The level of evaporative emissions from the fuel tank will be tested by checking the fuel tank cap (known as the gas cap test) to ensure the cap is an effective seal.
A well-maintained vehicle, serviced according to manufacturers' recommendations, is highly unlikely to fail an emissions test. Regular changing of the engine oil and of the fuel, air and oil filters is the most effective way of ensuring missions are kept to a minimum.
* Citation for image and quote in text: US Environmental Protection Agency Office of Mobile Sources Fact Sheet OMS-5, August 1994
By Jennifer Hind