Particularly important for assessing the adverse health impacts of emissions from highways located near school buildings and residential areas are recent research reports that have focused on the links between motor vehicle emissions and adverse health effects suffered by children.

A new study designed to determine whether the proximity of 10 middle schools to major freeways in California’s East Bay caused adverse health effects among school children aged 10 to 12 found a statistically significant greater prevalence of diagnosed asthma and bronchitis among students at the four schools most affected by motor vehicle emissions. At each school, the study monitored concentrations of a number of motor vehicle-related pollutants, showing that PM_2.5 was 25% higher in a school yard 60 meters from a freeway than at monitors located a mile from the freeways. Black carbon, a component of diesel exhaust measured at the schools, was also shown to increase with proximity of the school to a major highway. Carbons levels were 55% higher at the school closest to a freeway compared to schools that were more than a mile distant from a freeway. Air quality at every school complied with national ambient air quality standards (NAAQS).

A study in the Bronx, New York, investigated truck traffic, particulate matter and carbon concentrations in the neighborhood around the Hunts Point terminal where one in three children have asthma (compared to one-in-five nationally), and the hospitalization rate for asthma is 12 times the national average. The reported carbon levels used as a surrogate for diesel emissions ranged at six sites from more than two to nearly seven times greater than the levels reported at the school site in the East Bay Children’s Respiratory Health Study with the highest levels. Carbon concentrations were found to correlate strongly with daily diesel truck traffic on the streets nearest the monitor.

The data from both the East Bay and the Hunts Point studies strongly suggest that carbon levels associated with diesel emissions may be directly responsible for inducing the allergic response that is asthma, or they are a surrogate measure of the mix of chemicals in diesel exhaust that initiate asthma. According to the President's Task Force on Environmental Health Risks and Safety Risks to Children, America is in the midst of an asthma epidemic.

EPA has observed that once asthma is induced in a child, “asthma cannot be cured, only controlled.” Asthma impairs health and the quality of life for the remainder of a lifetime. Since the East Bay study suggests that the numbers of children diagnosed with asthma appear to increase during the few years children are in middle schools located near highways, the greater number of years that younger children may be exposed during the elementary years threatens to impair the health of children who attend schools located near highways.

Another study assessed the impact of pollution levels on lung development from the ages of 10 to 18. Measurements of lung function in large cohorts of school children who were followed for eight years in 12 California communities demonstrate large deficits in three measures of lung function among students living in the communities with the highest pollutant concentrations compared with comparably aged students in communities with the lowest pollutant concentrations. Nearly 5 times more students suffered significantly reduced lung development in the most polluted community compared to the cleanest community. Since most lung development has been completed by age 18,  these reductions in lung function were expected to remain throughout the lifetime and contribute to future health complications and possible pre-mature death in adulthood.

The motor vehicle-related pollutants elemental carbon and NO2 were two of the three pollutants most strongly correlated with impaired lung development and increased prevalence of asthma and bronchitis. In the most polluted community in the lung development study, the eight-year elemental carbon concentration was comparable to the carbon level reported in the school yard closest to a freeway in the East Bay Children’s Respiratory Health study, and more than five times lower than the highest carbon levels measured in the Hunts Point neighborhoods adjacent to truck routes. These studies demonstrate that children in neighborhoods exposed to the pollutants emitted from freeways and major truck routes are at significantly greater risk of life-long health impairment from reduced lung function as well as asthma.

New research aimed at attempting to find an explanation for cancer deaths among children before age 16 found that mothers who lived less than one kilometer from a highway during pregnancy and the first months following birth were much more likely to lose a child to cancer. Another study identified increased chromosome aberrations in newborns who were exposed to polycyclic aromatic hydrocarbons (PAHs) during pregnancy as a result of the mother living in neighborhoods in Upper Manhattan and the South Bronx.  PAHs are found in diesel exhaust, and these neighborhoods are located near diesel bus and truck terminals. These chromosome aberrations are often a precursor to the development of cancer. This provides a plausible mechanism to explain why children die of cancer before age 16. Exposure to diesel exhaust in the womb may be one of the most harmful effects of vehicle-related emissions. Together, these studies suggest that fetuses may be the population most vulnerable to the adverse health effects of motor vehicle-related pollutants.