Ozone can also hurt plants and crops. A gas that comes from the burning of fossil fuels, mostly in cars. It cannot be seen or smelled. Carbon monoxide is released when engines burn fossil fuels. Emissions are higher when engines are not tuned properly, and when fuel is not completely burned.
Cars emit a lot of the carbon monoxide found outdoors.
Furnaces and heaters in the home can emit high concentrations of carbon monoxide, too, if they are not properly maintained. Carbon monoxide makes it hard for body parts to get the oxygen they need to run correctly. Exposure to carbon monoxide makes people feel dizzy and tired, and gives them headaches. Elderly people with heart disease are hospitalized more often when they are exposed to higher amounts of carbon monoxide. A reddish-brown gas that comes from the burning of fossil fuels.