Cars, trucks and other forms of transportation account for more than 70 percent of the ozone-forming emissions and air pollution in the Sacramento Metropolitan area. High air pollution levels can cause many health problems, including aggravated cardiovascular and respiratory illness, added stress to heart and lungs and damaged cells in the respiratory system. Air pollution is especially bad for people with heart disease, coronary artery disease or congestive heart failure, those with asthma, emphysema or chronic obstructive pulmonary disease, as well as pregnant women, children and the elderly.