Noise is part of the urban contract. If you want all the benefits of living with density, then you’ve got to accept a certain level of baby-screaming, train-screeching, neighbor-humping aural pollution.
But a new map from the Bureau of Transportation Statistics shows that nearly all of the U.S. population—urban, suburban, and rural—risks exposure to potentially harmful levels of vehicular and aviation noise. From the hills of Ventura County, to the streets of Chicago, to the heart of Appalachia, the hum of trucks, cars, and planes meets the ears of 97 percent of Americans, at roughly 35 to 50 decibels. That’s comparable to the noise of a humming refrigerator, according to the BTS.
As you might expect, the map is essentially a national Interstate highway map, painted mostly in warning-sign-orange (indicating 35-50 decibel-level noise) with bursts of pink and red (50-80), and the occasionally horrible purple and blue (80 and up: like a garbage disposal!) in places where cars and planes concatenate in high concentrations (i.e., cities).
BTS reports that “one-tenth of a percent of the population could potentially experience noise levels of 80 decibels or more.” About three percent of the population is exposed to the ear-pollutants at decibel levels between 50 and 80. These estimates reflect a weighted, average sound level for a 24-hour period from aviation and highway road noise data collected in 2014.
So, you may think, most Americans go about their lives amid some mild background din, and the few who live close to airports deal with a lot. Who cares?
Well, noise doesn’t have to be particularly penetrating to be a public health menace. The World Health Organization’s 2009 Night Noise Guidelines set a benchmark of recommended exposure to night sounds for Europeans, which was a surprisingly low annual average of 40 decibels (think: dishwasher murmur).
Above that level, negative health effects abound: Research shows that at 42 decibels and up, sleep schedules are interrupted. Exposure to road noise above 50 decibels (comparable to a quiet office) has been associated with higher risks of heart attack. And with every 10 decibel increase, that risk has been found to rise by 12 percent. Transportation noise also seems to be linked to obesity and depression. The map could be useful for policymakers looking “to prioritize noise-related transportation investments,” perhaps especially with an eye to health. The EPA, for one, has begun research aimed at making noise reduction part of the federal public health agenda. (We’ll see if that can advance in the Trump era.)
Future versions of the map may include sounds related to maritime or train travel, the BTS says in a statement. Curiously, though, humans find some transpo-noises more disruptive than others. As the former CityLab staff writer Emily Badger wrote in 2012:
At a given sound level, for instance, people generally get more upset about helicopters than we do fixed-wing aircraft. And we tend to get more upset—at the same decibel level—about fixed-wing aircraft than auto traffic. We like trains, though, and we’d typically prefer the sound of one to the equivalent in passing cars.
These psychological preferences don’t necessarily parallel our bodies’ reactions, though, and there are myriad other factors in the health risks associated with noise pollution—income, education, and eating habits, to start. But the research is loud and clear: Policymakers should put an ear to the ground.