An Invisible Threat

Noise represents an environmental stressor that impacts sleep, relaxation and concentration. Photo: Borodin/Bigstock

By Alex Piazza
apiazza@umich.edu

At work, crews use jackhammers to repair the concrete sidewalk outside your office.

On your way home, drivers honk their horns as they pass by an accident along the highway.

And as you get ready for bed, a Boeing 737 takes flight within miles of your home.

You chalk it up as background noise, but these environmental exposures could have a profound impact on your health. And it goes well beyond just hearing loss.

For the past 20 years, Richard Neitzel has studied noise pollution. His research explores not only the health consequences associated with noise, but also its impact on the economy.

“It’s not news to anyone that noise exposure can cause hearing loss,” said Neitzel, associate professor of environmental health sciences and associate professor of global public health at the University of Michigan School of Public Health. “What many people don’t understand is that noise exposure can lead to a number of other health problems, like heart disease and mental illness.”

Neitzel has worked with everyone from farmers and dental hygienists to firefighters and soldiers to quantify common sources of noise exposure. Neitzel then links those noise exposures to certain health outcomes—connections that could help increase awareness and drive policy related to noise pollution.

“Noise is something that we’ve understood for hundreds of years is not good for us, and yet in America and around the world today, we have exposures that might actually be getting worse over time,” he said. “This issue is global in nature, and it’s going to take a global effort to really reduce the impact of noise on health.”

Heart Health

Noise is odorless and invisible, and because of that, policymakers often overlook its negative health implications.

Sure, it can cause permanent, irreversible hearing loss, which can have a very severe impact on sufferers, but researchers still struggle to get the public and policymakers to recognize noise as a serious public health threat.

Heart disease, on the other hand, remains a leading public health threat. About 610,000 Americans die from heart disease each year, according to the U.S. Centers for Disease Control and Prevention.

Common risk factors include diabetes, obesity and excessive alcohol consumption, but what about noise?

Noise represents an environmental stressor that impacts sleep, relaxation and concentration, which can contribute to hypertension and coronary heart disease.

Neitzel traveled to a gold mining village in Ghana to explore the connection between elevated noise levels and workers’ heart health.

The 22 gold miners who participated in the study provided saliva samples and wore heart rate monitors to measure changes in stress and noise exposure.

Neitzel, along with Allyson Green, Andrew Jones and Kan Sun, found that 21 of the 22 gold miners were exposed to sound levels that exceed the World Health Organization’s exposure guideline of 70 decibels over 24 hours. And based on saliva samples and other health data, those 21 individuals also showed elevated heart rate and levels of the stress hormone cortisol. Neitzel, along with Katrina Burns, Julius Fobil and Kan Sun, found a similar relationship between noise exposure and heart rate among 57 electronic waste recycling workers in Ghana.

“By documenting stress and noise in these communities, we now have a snapshot of the potential conditions faced by the estimated 15 million people worldwide that work in the gold mining industry, and the millions more who recycle electronic waste,” said Neitzel, whose project was funded by various U-M research units. “Our findings can inform policies and practices to begin immediately addressing these issues in similar vulnerable communities.”

Economic Impact

Neitzel is among a small cohort of environmental health researchers who work to connect noise exposure to serious health ailments beyond hearing loss.

But so far, there has been little activity regarding policy changes that protect people against noise pollution. That understanding is what inspired Neitzel to partner with Tracy Swinburn and Monica Hammer to measure how environmental noise impacts the economy.

They estimated the impact of environmental noise on the prevalence and cost of key components of heart disease, and their findings show that lowering the volume nationwide could reap big savings.

Just a five-decibel reduction in excess noise could reduce hypertension cases by an estimated 1.2 million and coronary heart disease cases by 279,000, research shows. That equates to an annual economic benefit of $3.9 billion, with $2.4 billion coming from direct health care costs and $1.5 billion from productivity gains.

“This demonstrates that environmental noise has significant negative economic ramifications,” he said.

Neitzel again partnered with Swinburn, Hammer and Daniel Eisenberg to study the economic impact of environmental noise, but instead of heart disease, they focused on lost productivity due to hearing loss.

They first estimated that hearing loss affects 23 million people of working age (18-64) in the United States. And research shows workers with hearing loss earn 25 percent less than their colleagues with typical hearing.

So what if the 20 percent of those hearing loss cases caused by excessive noise could be prevented? The United States would experience an economic benefit of about $123 billion, according to findings from Neitzel and his colleagues.

“Hearing loss is common, and the associated economic costs are significant,” Neitzel said. “These findings could help drive policy that focuses on controlling noise exposures at their source. This could involve designing consumer products, transportation and civil infrastructure, and buildings with the goal of reducing human exposures to noise. This is a long-term effort that will result in improved health and decreased noise annoyance, both of which have substantial benefits to society.”

Richard Neitzel received research funding from the National Institute for Occupational Safety and Health and the Robert Wood Johnson Foundation, as well as the University of Michigan's Graham Sustainability Institute, Office of Research and School of Public Health.