How LA County’s chronic noise pollution is hurting our health

The wail of emergency sirens. The roar of garbage trucks. The hum of gridlocked freeway traffic.

Living in a noisy neighborhood can be annoying. It can also be harmful to your health.

Chronic street noise — from sirens, traffic and construction — is more than just a nuisance, it’s a growing health hazard, health experts say. In recent years, research has shown that consistent exposure to noise may be linked to a host of conditions, including cardiovascular disease and stroke.

A study released in May in the journal Environmental Health found that long-term exposure to traffic noise has been linked to increased mortality rates in people with diabetes.

Los Angeles County — with its vast network of freeways and its notorious traffic — is one of the loudest in the U.S., according to the Department of Transportation. Areas close to major airports or highways are most impacted, according to the department’s interactive noise map.

Many of these areas also tend to have more lower-income residents, and more people of color, than other parts of the county.

“Loud noise produces a stress response, even you don’t notice it and it’s sort of this background hum,” said Charlie Roscoe, an environmental health researcher at Harvard University. “Over time when your body is flooded with stress hormones, that can lead to inflammation and, ultimately, disease.”

Further research shows a link between exposure to traffic noise over time and obesity.

“Noise pollution basically has the ability to negatively affect all of the mechanisms to do with your cardiometabolic health,” Roscoe said.

Who is most at risk?

The Department of Transportation map shows, in hues of dark blue, purple and red, that many of the noisiest places to live in L.A. County are clustered around airports, business and shopping hubs, and areas surrounded or transected by freeways, including downtown L.A., Inglewood and Glendale.

The health effects may be worse for people of color and those in lower income brackets who are more likely to live in heavy traffic areas, some researchers say.

“Especially in America, rail lines, highways and airports often border neighborhoods that tend to be where the most underserved communities live,” Roscoe said, nodding to the racist history of redlining and highway placement across many U.S. cities.

“People who are already probably experiencing some social risk factors and stressors on their health are the ones who are both experiencing the most noise pollution and most vulnerable to the negative health effects,” she added.

The same inequities apply to children. According to a 2019 study of more than 94,000 U.S. schools, those with a higher percentage of Black, Latino or Asian/Pacific Islander students, as well as students who qualified for free or reduced lunches, were significantly more exposed to street noise.

Noise exposure for children has been linked to lower reading scores, hyperactivity and heightened stress hormones.

How loud is too loud?

Highway traffic noise ranges from about 70 to 80 decibels at a distance of 50 feet, according to the Department of Transportation. A typical emergency siren measures roughly 124 decibels — louder than a jet takeoff.

Noise levels over 70 decibels can provoke a stress response in many people, spiking cortisol, adrenaline and other stress hormones, according to the National Institutes of Health. The agency also warns that two years of regular exposure to 90 dBs can produce hearing loss.

The World Health Organization found that average road traffic noise above 53 dB is associated with adverse health effects.

In L.A. County, neighborhoods around LAX and the Burbank airport experience average noise levels above 80 dBs, along with Commerce and much of Inglewood, according to the noise map.

A couple of weeks after Lily Niewald moved into her one-bedroom apartment in the Mid-City neighborhood of Los Angeles — two blocks from a fire station — she realized there would be a problem: the sound of sirens thundering from firetrucks and emergency vehicles roaring past her ground floor, street-facing apartment countless times a day.

“You not only hear the blaring sound, but you can also feel the vibration,” said Niewald, a 26-year-old student and barista who chose Mid-City for its relative affordability. “It’s stressful and upsetting, but it’s also distracting because I constantly have to stop whatever I’m doing.”

Nighttime noise is more problematic, experts say. The World Health Organization recommends less than 40dB as an annual average of nighttime noise outside the bedroom to prevent sleep disturbances and other health issues.

Niewald, said the constant sound of sirens outside her bedroom window takes a toll on her sleep. She described being jolted awake night after night.

“Your body thinks that there’s some intense danger or something serious happening,” she said. “Even if I’m able to go back to sleep, I feel extra fatigued and have more brain fog the next day.”

Niewald grew up in Manhattan, where there’s plenty of street noise, but she said she now places greater importance on living somewhere quieter.

“Now even when driving I get a whole wave of anxiety throughout my body when a siren starts,” she said. “It sort of makes me hate cities. I definitely value quiet spaces now more than ever.”

Compounding effects of noise

Traffic noise may be particularly harmful to those struggling with mental health conditions like post traumatic stress disorder, experts say.

“Loud noises especially in the night, you can imagine how that would be triggering for people with PTSD,” Roscoe said. “It's not that everyone is going to experience noise and develop a mental health issue, but if you already have that susceptibility the stress response has been shown to be even greater.”

Prior noise exposure may prime the body to overreact to sounds later, producing a compounding negative effect on the body, Roscoe said.

Studies show that emergency responders are 150% more likely to experience hearing loss over time than the average population, and roughly 26% of firefighters in the U.S. report suffering from tinnitus, or ringing in the ears.

But not all city noise is harmful.

Psychologist David Hindman, former president of the California Psychological Association, said noisiness can also point to a sense of togetherness and liveliness in a community that outweighs some of the negative effects. 

“It’s more complicated than just all noise is bad,” he said. “Often the nosiest areas also have elements of community and engagement that have been shown to be very important to mental and physical health.”

Urban areas are generally associated with higher depression risks than rural ones, many researchers say, but some studies have found higher rates of depression in sprawling suburbs versus more densely populated city centers. They cite more opportunities for social networking and interaction.

Hindman, who worked at a South Central LA health clinic for 15 years, said an abundance of street vendors, churches, holiday festivals and other community gatherings throughout the area created an overall sense of “aliveness.”

Fighting against urban noise

Local officials try to curb noise in neighborhoods through a variety of tactics. Residents can report excessive noise caused by individuals, businesses and construction sites, by calling the local police department or other designated complaint line.

The county Department of Public Health noted that each jurisdiction is responsible for enforcing its own noise rules.

Workplaces are required to adhere to state noise regulations. For problems with excess noise at work, employees can make complaints to the California Division of Occupational Safety and Health, known as Cal/OSHA.

Highway sound walls are also part of local efforts to dampen the impact of traffic noise.

Last year, Atwater Village secured $2.5 million to build a “living sound wall” made of dead plant matter, which is said to be an effective way to block out noise.

“As someone who lived in a city with a highway running through it, I’ve always been aware of the noise pollution that comes from freeways in this city,” said state Sen. Anthony Portantino (D-Glendale), who requested the funding from the state. “Folks that live near noise-generating situations have been very expressive to me throughout my tenure in public office."

Portantino authored a state bill, which became law in 2022, directing the California Highway Patrol to test noise-detecting cameras. The idea was that the technology would eventually allow for violators to be automatically ticketed, like a red light camera.

That's a sign of progress, Portantino said, but there is more to be done.

“California is having such a proliferation of freeways, general traffic and noise and impacts quality of life,” he said. “We need more sound barriers throughout the city, and also more parks and green spaces. Just an emphasis on a more tranquil life in L.A. County.”