Traffic exhaust is a major source of air pollution in California, especially in urban areas, and is a major contributor to greenhouse gases. Traffic exhaust pollutants include compounds such as carbon monoxide, nitrogen oxides, particulates (fine dust and soot), also called "criteria" air pollutants, and a wide range of toxic air pollutants such as benzene or PAHs. Potential health effects from being exposed to traffic exhaust pollutants include respiratory illnesses, such as asthma, heart disease, adverse reproductive or pregnancy outcomes, cancer, and shortening of the life span.
EHIB has examined health effects as well as issues of environmental justice in terms of who lives near busy roads.