Air Pollution and Health: Bridging the Gap from Sources to Health Outcomes

EPA has established National Ambient Air Quality Standards (NAAQS) for six principal air pollutants or "criteria pollutants" that include carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), particulate matter in two size ranges [less than 2.5 μm (PM2.5) and less than 10 μm (PM10)], ozone, and sulfur dioxide (http://www.epa.gov/air/criteria.html). While associations have been identified between these pollutants and adverse health effects, considerable uncertainty remains with regards to the methods and approaches to understanding relationships between air pollution and health effects, such as, which components (gas and or aerosol) and/or sources are most toxic, the mechanisms of actions of the pollutants and causal relationships, effect of confounding factors, and who are susceptible populations, especially for particulate matter since it is composed of many individual species (EPA 2006a (ozone), EPA 2006b (Pb), EPA 2008a (NOx), 2008b (SOx), EPA 2009 (PM), EPA 2010 (CO)). Air pollution and health research continues to reduce these uncertainties across the source-to-health effects paradigm as indicated by the National Research Council (NRC 1998, 1999, 2001, 2004) and EPA (EPA 2006a, 2006b, 2008a, 2008b, 2009, 2010).