Traffic exposure associated with decreased lung function in asthma

A growing body of scientific literature supports the concept that exposure to roadways with high traffic density is associated with adverse general health and asthma effects. Heavy-duty diesel-powered vehicles like trucks and buses are often driven more frequently on roadways with high traffic density and, as such, diesel exhaust has been suspected to be a major cause of traffic-associated asthma morbidity.

Diesel exhaust is similar to tobacco smoke in that it is a mixture of particles and gases with many chemical constituents. Diesel exhaust particulate (DEP) is mostly carbon with 20–40% adsorbed organic compounds, but sulfates, nitrates and metals are also present.

In a cohort of adults with asthma or rhinitis (176 adults; 145 with asthma), the study authors assessed exposures to traffic by geocoding subjects' residential addresses and assigning distance to roadways.

FEV1% predicted was positively associated with distance from both nearest roadway and nearest major roadway.

Quality of life (QoL) was not significantly associated with either traffic variable.

Traffic exposure was associated with decreased lung function in adults with asthma.

References:
Exposure to traffic: Lung function and health status in adults with asthma. Balmes JR, Earnest G, Katz PP, Yelin EH, Eisner MD, Chen H, Trupin L, Lurmann F, Blanc PD. J Allergy Clin Immunol. 2009 Jan 17.
Fetal Exposure to Traffic Pollution May Affect Asthma Risk. Todd Neale, Staff Writer, MedPage Today.

How does diesel exhaust impact asthma? Thorax, 2010.
Image source: Interstate 80, seen here in Berkeley, California, is a freeway with many lanes and heavy traffic, Wikipedia, GNU Free Documentation License.