New research shows unhealthy noise in Portland

(JULY 28, 2025) A new study by scientists at Oregon State University shows that many neighborhoods in Portland have unhealthy levels of noise. This is the first study of its kind in the United States and can help other U.S. cities understand noise pollution better. European countries are ahead in studying how noise affects health.

The research team, led by professor Matthew Bozigar and graduate student Carson Mowrer, found that the loudest areas of Portland are also the ones where people have lower incomes and where more residents are people of color.

The scientists used special equipment to measure sound in different parts of the city and created computer models to understand the patterns. They published their results in a science journal.

Professor Bozigar explained that many people in the U.S. still think noise is just annoying. But in Europe, noise is seen as a serious health risk. Studies there show that noise can cause sleep problems, stress, heart disease, high blood pressure, and other health issues. There is not as much research like this in the U.S., and cities here are very different from European ones, so the same risks may not apply.

To better understand Portland’s noise problem, the researchers worked with the Multnomah County Health Department. They used low-cost digital monitors to record sound 24 hours a day for a full year, starting in August 2023. They paid special attention to nighttime noise, which can affect sleep the most.

The study showed that most parts of Portland are louder than the safe levels suggested by the U.S. government and the World Health Organization. They found several types of noise areas, including quiet places, places with sudden loud sounds, and areas with constant noise. The biggest reason for high noise levels was being close to busy roads.

The results give local leaders better information to help make the city quieter, especially in neighborhoods that need it most. This could help improve public health in the long term.

The study is part of a larger project. A second report will come out soon and include a detailed noise map of Portland. Multnomah County is also working on an online map so people can see the data for themselves.