The deadline for submittal of such a plan for Clark County was May 3, 1999. Carbon monoxide is a colorless, odorless, poisonous byproduct of combustion. In urban areas, motor vehicles can cause more than 90 percent of the carbon monoxide pollution.
Carbon monoxide replaces the oxygen in the bloodstream, making the heart work harder.
It is especially detrimental for people with heart or respiratory diseases. It also affects concentration and learning ability. The EPA's finding starts a clock for mandatory application of sanctions under the Clean Air Act if Clark County does not submit a plan that the EPA can approve. If a plan is not approved after 18 months, offsets for emissions from new industrial sources would increase. After 24 months, the county s share of federal highway funds would be frozen.