МакедонскиCO is a colorless, odorless and tasteless poisonous gas. It has been estimated that, on a global level, 80% of the carbon monoxide in the atmosphere comes from natural sources. Nature is capable of preventing the increase of CO concentrations in the atmosphere, since soil bacteria turn it into CO2.
The remaining 20% come from human activities such as incomplete combustion of carbon based fuels such as oil, diesel and wood. Primary sources of outdoor exposure are the vehicle exhaust gases, industrial processes (as metal processing and chemical production), incomplete incineration of solid waste and the natural sources such as forest fires. Sources of indoor exposure are the household fireboxes and cigarette smoke. CO changes atmospheric photochemistry which has a share in the creation of smog (ground level ozone О3).
Carbon monoxide is an issue for local pollution and poses the biggest threat for urban areas with heavy traffic flow. Million of tones of this invisible, but lethal gas are released in the atmosphere each year, 75% of it deriving from vehicle exhaust gases. The levels of danger have been exceeded at streets and parking places for most of the time.
