Carbon monoxide enters the bloodstream through the lungs and reduces oxygen delivery to the body's organs and tissues. Early symptoms of carbon monoxide poisoning include drowsiness and headache, followed by unconsciousness, respiratory failure, and death. The health threat from lower levels of CO is most serious for those who suffer from cardiovascular diseases, such as angina pectoris. At much higher levels of exposure CO can be poisonous to the point where even healthy individuals may be seriously affected. 4-5 U.S. EPA Office of Air and Radiation.
Ozone can be good or bad, depending on where it is found.
Ozone, the main ingredient of smog, presents a serious air quality problem in many parts of the United States. Even at low levels, ozone can cause a number of respiratory effects such as acute respiratory problems, aggravation of existing asthma conditions, significant temporary decreases in lung capacity of 15 to over 20 percent, inflammation of lung tissue, impairment of the body's immune system defenses, making people more susceptible to respiratory illnesses, including bronchitis and pneumonia. Such groups of people include active children, active adults who exercise or work vigorously outdoors and people with asthma or other respiratory illnesses. United States Environmental Protection Agency. In the past, automotive sources were the major contributor of Pb emissions to the atmosphere.