• CO reduces the ability of the blood to carry oxygen, and is particularly dangerous to smokers, people with heart disease, and those with anemia or heart disease. CO can also cause permanent damage to the nervous system.
• VOC’s react in the presence of nitrogen oxides (NOx) and sunlight to form ground-level ozone, a major component of smog. Ozone irritates the eyes, damages the lungs, and aggravates respiratory problems. Ozone also reduces agricultural production and the growth rate of trees. A number of exhaust VOC’s are also toxic, with the potential to cause cancer, nerve damage, and other health effects. Benzene, a known human carcinogen, is an example of a toxic VOC found in vehicle exhaust.

Source - www.idontcareaboutair.com