Living near major roadways has been linked with increased risk of cardiovascular events and worse prognosis. Residential proximity to major roadways may also be associated with increased risk of hypertension, but few studies have evaluated this hypothesis.
Researchers from Brown University examined the association between residential proximity to major roadways and prevalent hypertension.
In this cross-sectional analysis researchers examined data from 5,401 postmenopausal women enrolled into the San Diego cohort of the Women’s Health Initiative. The study collected information on demographics, medical history, indicators of individual and neighborhood socioeconomic status, and for local supermarket/grocery and fast food/convenience store density.
Gregory Wellenius, ScD, Department of Epidemiology, Brown University School of Public Health, and corresponding author and graduate student Kipruto Kirwa, MPH along with their co-authors took this dataset and used mapping software to measure the distance from each woman’s home to a major roadway.
The researchers then examined the association between the prevalence of high blood pressure and distance from the highway in ranges of; less than 100 or exactly 100 meters, between 100 and 200 meters, 200 to 1,000 meters and more than 1,000 meters.
After adjusting for confounding factors they can controlled for age, ethnicity, smoking status, education, household income, cholesterol, body-mass index, diabetes history, physical activity level, and local food quality.
The adjusted prevalence ratios for hypertension were 1.22 for women living less than 100 meters from roadway, 1.13for those living 100 to 200 meters from roadway and 1.05 for women living over 200 to 1,000 meters from roadway compared to women who lived over 1,000 meters from a major roadway who had a risk of 0.006.
Women who lived within 100 meters of a highway or major arterial road had a 22 percent higher risk of hypertension than women who lived at least 1,000 meters away. In a range of intermediate distances, hypertension risk rose with proximity to the roadways.
Hypertension is an underlying factor for some cardiovascular diseases. For that reason, the increased likelihood of hypertension reported in the new study may help explain prior findings of associations between proximity to major roadways and cardiovascular diseases such as stroke. A few studies, mostly in Europe, have also tested the association between roadway proximity and hypertension, but results have been mixed.
According to assistant professor Wellenius “I think in the United States this study does tip the scale in favor of being concerned about the urban environment and how we develop our cities and our transportation systems.” “There are a lot of new developments going up right near highways. One has to start thinking about what are the associated health effects with that.”
He had acknowledged that because the study only measured who had hypertension and where they lived at one moment in time, it does not necessarily show a causal link. The study also does not shed light on what specifically about proximity to the road could cause hypertension. It could be airborne pollutants or noise or both — or something else. But prior studies have shown specific physiological effects from pollution and noise that could have direct causal relevance to cardiovascular disease.
Assistant professor Wellenius cautions that hypertension, even when treated, still carries an elevated risk of cardiovascular disease. The best policy, he said, is therefore prevention.
“The public health message is that we need to take into consideration the health of the population when planning neighborhoods, when planning transportation systems, and when deciding where new highways are going to go, and how we might be able to mitigate traffic or its effects,” Wellenius said.
