Where we live, work, and play impacts our health. Air pollution and traffic noise from nearby roads and highways can increase residents’ risk of chronic health conditions, but living in areas with more local infrastructure means residents have easier access to health care, healthy food, and recreational facilities. New transportation options such as light rail can increase the physical activity levels of people living nearby.
New research supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) is exploring the role that the constructed or built environment plays in public health to guide policymaking and community planning:
- In Sacramento, research underscores the importance of considering not only pollution but also traffic noise when evaluating the impact of roadways.
- Analysis of Google Street View data highlights the role proximity to health care, healthy food, and recreational facilities plays in community health.
- A new light rail line in suburban Washington, D.C., offers an important opportunity to identify the health benefits of new transportation infrastructure for racial and ethnic groups who face high levels of health risks.
Traffic-Related Air Pollution and Noise Linked to Debilitating and Costly Health Conditions
Exposure to high levels of vehicle pollution and traffic noise increases the risk of health conditions related to heart disease, stroke, and diabetes for nearby residents. Yu Yu of the University of California, Los Angeles (UCLA) and her colleagues identified these patterns using data from the Sacramento Area Latino Study on Aging (SALSA Study), which interviewed more than 1,500 older Mexican Americans—a rapidly growing group of area residents with a high prevalence of health problems.1
The researchers examined metabolic syndrome, a cluster of conditions that increase the risk of heart disease, stroke, and type 2 diabetes. The conditions include high blood pressure, high blood sugar, abnormal cholesterol levels, and excess body fat around the waist. Estimates suggest that metabolic syndrome increases U.S. health care costs annually by more than $220 billion.
The research team measured exposure to traffic-related pollution by linking participants’ home addresses to complex models of air pollution developed by the California Department of Transportation. They did the same for noise exposure using data such as vehicle speed and different vehicle types.
Researchers found that participants with higher exposure to traffic-related air pollution and noise had higher levels of all conditions of metabolic syndrome except abdominal obesity. Pollution and noise had a particularly negative impact on levels of HDL cholesterol—the “good” cholesterol that is linked to reduced risk of heart disease.
These findings document the public health benefits of stricter emission controls and programs to reduce traffic noise. Encouraging the use of public transit, car-sharing, walking, and biking could help reduce metabolic syndrome and its associated health care costs, the researchers suggest.
“We often blame people with conditions like metabolic syndrome for not having a healthier lifestyle related to diet and exercise,” says co-author Beate Ritz of UCLA. “But members of these communities often do not have an option of moving away from high traffic impacted neighborhoods.”
“This is also an environmental justice issue,” she points out. “The communities most impacted by these pollutants do not have a choice about it.”
Local Infrastructure’s Impact on Public Health—Measured by Google Street Views
While traffic pollution and noise have negative health consequences, highways and roads can improve residents’ access to places that positively impact their health—from public parks and gyms to health clinics and grocery stores selling fresh produce. Local infrastructure also enhances access to stores and family and friends, all of which may benefit health.
To explore connections between highways and roads and community health, Quynh Nguyen of the University of Maryland Population Research Center and her research team examined more than 16 million Google Street View images of intersections in over 2,000 counties across the United States.2 Using the images, they measured the built environment by the level of infrastructure, including main roads, unpaved roads, and commercial and residential buildings.
They linked local infrastructure information to health data from the Behavioral Risk Factor Surveillance System of the U.S. Centers for Disease Control and Prevention, focusing on adult obesity, diabetes, physical distress, mental health, excessive drinking, and teen birth rates.
The results suggest that counties with more infrastructure have lower levels of chronic diseases such as diabetes and lower levels of physical distress, inactivity, and teen birth rates. Counties with less infrastructure had higher levels of the negative health factors except excessive drinking. The researchers found similar patterns when they focused on 500 cities.
The greater abundance of services and facilities found in areas with more roads may offer residents of these areas greater access to places and resources that promote health, Nguyen and colleagues suggest. Rural areas with few buildings, unpaved roads, and grasslands may have fewer primary care physicians, less access to healthy foods, and fewer recreational facilities than more urban areas, all of which can have a negative impact on health.
Promoting community health may involve advocating for road improvements and community resources such as parks and sidewalks in under-resourced areas, which could potentially reduce health inequalities between urban and rural America, the researchers suggest.
Measuring the Impact of New Transportation Options on Residents’ Physical Activity
Research in predominantly white communities has shown that new transportation options are related to increases in physical activity.3 A research team at the University of Maryland has designed a way to document the impact of a new light rail line—projected to open in December 2022—on walking, biking, and public transportation use among African American and Hispanic adults, two groups who have historically been underrepresented in public health research.4
Jennifer Roberts leads the Purple Line Impact on Neighborhood, Health, and Transit (PLIGHT) Study, which is examining transit use and physical activity among adults living in Prince George’s County, Maryland, an area bordering Washington, D.C. The first study of its kind, the PLIGHT Study will enable the research team to measure a new transportation option’s impact on the health of African American and Hispanic residents, the largest racial and ethnic groups in the county.
The PLIGHT Study will use focus groups, questionnaires, accelerometry (devices that capture intensity of physical activity), and travel diaries to assess the new rail line’s impact. Natural experiments such as this introduction of a new public transportation option offer policymakers real-world evidence on how the built environment affects physical activity and health, informing future policies nationwide, Roberts notes.
This article was produced under a grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). The work of researchers from the following NICHD-funded population dynamics research centers was highlighted in this article: University of California, Los Angeles (grant 5P2CHD041022-19) and University of Maryland (grant 5P2CHD041041-18).