Transportation and public health interact in several ways, such as in the areas of public safety and exposure of the public to air pollution. Chapters 6 and 7 indicate improvement in some critical indicators of transportation’s health impacts over the last several decades, but challenges remain.
As discussed in chapter 6, transportation fatalities and injuries have declined in recent decades, yet every day in 2014, on average, about 95 people die and nearly 6,500 people are injured in transportation accidents— primarily on the highway. Air pollution from transportation also adversely affects health, as discussed in chapter 7. Here, too, there has been a reduction in transportation emissions over the last few decades, resulting in corresponding reductions in public health impacts.
Perhaps the most dramatic improvement has been the virtual elimination of lead from gasoline. U.S. air quality has improved as lead concentrations have decreased from a mean of 1.84 µg/m3 (micrograms, or one-millionth of a gram, per cubic meter of air) in 1980 to 0.02 in 2015 [USEPA]. This phase out brought major public health benefits, particularly for children and populations living near major highways who were no longer exposed to unhealthy levels of lead from gasoline emitted into the air. Lead when inhaled or ingested from soil was shown to produce elevated lead levels in the blood, with multiple health effects such as lowering IQs for exposed children, and cardiovascular problems for adults [WORLD BANK 1998].
The mode of transportation people use also impacts health. Americans increasingly have an obesity problem, in part because of diet and sedentary lifestyles, and in many cases lack of exercise. During the last half century, people as a whole spend less time each day walking and bicycling to workplaces or other places, while spending more time sitting in vehicles [AJPH 2011]. Census Bureau reports show that in 1960, 10.3 percent of people walked to work, compared to 3.9 percent in 1990 and 2.7 percent in 2014. People also are less likely today than in the 1960s to use public transit, which generally involves walking a block or so to and from a bus stop or transit station.
The interactions between transportation and public health are increasingly recognized as an aspect of transportation planning. The Federal Government and several states and communities are explicitly addressing these connections in their statewide transportation plans. At the Federal level, in November 2015, the USDOT and the Centers for Disease Control launched an online tool to promote health through transportation. This site provides a variety of health-related transportation indicators to measure progress states are making and how states rank with each other. Examples of indicators include, among others, how much people walk or bike in their daily trips; traffic fatalities per 100,000 residents; seat belt use; alcohol-related traffic fatalities; and percentage of population residing within 200 meters of a road that carries, at least, 125,000 vehicles per day (thus exposing nearby people to pollution and noise). The site also identifies strategies that could be used to improve performance on transportation health issues [USDOT 2016].