In the Classroom

Outdoor Dining, Ambient Noise, and Health

PhD students Laura Buckley and Stephanie Grady used a sound level meter mobile app to compare noise levels on streets open and closed to traffic in two cities during the pandemic.

Remote learning has undoubtedly presented challenges for students and educators alike in the era of COVID-19—but it also has created opportunities for inspiration and innovation inside and outside of the (virtual) classroom.

Students learning remotely in the Field Methods in Exposure Science course (EH804) at the School of Public Health experienced the latter while completing a project on noise exposure during the fall 2020 class taught by Diana Ceballos, professor of environmental health.

Stephanie Grady and Laura Buckley, PhD students in the Department of Environmental Health, attended classes remotely last semester from Boston and Ithaca, New York, respectively, and did not have access to professional sound level meters or other specialized tools that would enable them to capture acoustic measurements.

No sound level meter? No problem. Thanks to the National Institute for Occupational Safety and Health (NIOSH), there are several apps for that.

Buckley and Grady simply downloaded three NIOSH-designed mobile apps—the Sound Level Meter, the Heat Safety Tool, and a Noise Mapper app in beta form—and they had the necessary tools to begin a semester-long project comparing noise levels on streets in their respective cities that are open to traffic, versus streets that are closed to traffic and open for outdoor dining.

Measured in decibels and defined as “unwanted or harmful sound,” noise is an annoyance—and that matters, said Grady during a final class presentation on Zoom with Buckley on December 15. It especially matters because 80 percent of the US population lives in cities, and is exposed to higher noise levels, she said.

“Noise is related to sleep disturbance, hearing loss, cardiovascular diseases, communication disruption, and cognitive impairment, as well as anxiety and depression and behavioral changes,” Grady said. “Understanding this complex nature of the effect of noise on health is already difficult, but what complicates this even more is that people do not live in a vacuum in which they’re exposed to only one harmful exposure at a time.”

The students’ project took place as COVID-19 cases, hospitalizations, and deaths were rising sharply again prior to the winter season, and many restaurants were continuing to offer outdoor seating as a safety precaution for employees and customers.

“Open street initiatives have been around for some time in cities across the world,” said Buckley during the presentation. These initiatives are often designed as public health measures to encourage climate mitigation, physical activity, access to open spaces, and social cohesion, but there is little research on how these measures actually impact environmental noise, she said.

Furthermore, “cities implement these systems in a lot of different ways,” Buckley said. “So with this uptick in outdoor dining due to COVID, we thought it would be a good opportunity to learn about the impact on ambient noise levels when you reduce traffic noise exposure, but increase the number of pedestrians, bicyclists, and outdoor dining areas on closed streets.”

Using the Sound Level Meter app, which NIOSH developed to provide tools for people to assess their exposure to occupational and environmental noise and make informed decisions, the students collected and recorded three, 10-minute noise samplings independently in their city on one street open to traffic, and one street closed to traffic and open for outdoor diners.

They also utilized the Heat Safety Tool app, co-designed by NIOSH and the Occupational Safety and Health Administration (OSHA) to inform and provide workers with information to prevent heat stress. The students used this app to characterize temperature and its relationship to ambient noise on the streets.

In their noise exposure assessment, they analyzed factors such as average noise, loudest noise, temperature, relative humidity, traffic count, and pedestrian count, noting that the most common sources of noise were outdoor diners, dogs, car traffic, street performers, and other outdoor music.

Cautioning that their findings were exploratory because of the small sample size, the students found that, on average, Boston streets are 1.5 decibels louder than the streets in Ithaca, and streets that are open to traffic are 4.2 decibels louder than streets closed to traffic. Noise levels also differ by source, Grady said.

“We noticed that the number of samples we collected [of a noise source] did not account for intensity of a single source,” she said. “Even though we heard more outdoor diners in our samples, the street performers were the loudest to us, perception-wise.”

Further analysis showed a negative correlation between noise levels and relative humidity—a function of weather—which could be an indication of lower noise levels when it rains because there are likely fewer people outside. The beta Noise Mapper app that Buckley and Grady used was designed by NIOSH to provide a snapshot of noise on a street during any given measurement period—such as wind, barking dogs, or honking horns—and it can indicate a noise level estimate for a particular area.

“There was a dog that was very upset with my presence on the street one day,” said Buckley, referencing a high-noise indicator displayed in a screenshot from the app.  

Much more research is needed on outdoor noise measurements, but such data can inform policies and interventions to keep noise levels in control and prevent adverse health outcomes, the students said.

Ceballos, who studies hazard exposures and health disparities and previously served as an industrial hygienist for NIOSH, says that the class project was a “wonderful opportunity and win-win situation” for the students to adapt to remote teaching during a pandemic, learn new skills with technology, and provide valuable feedback to NIOSH and to the CDC about the Noise Mapper app.

“As a field methods class, we were faced with a challenge that is not typical of other classes,” Ceballos says. Shipping instruments to students was not feasible, she adds, particularly for international students. The mobile apps, which were well designed and reliable replacements to traditional noise measurement devices, enabled students to complete the full project remotely. NIOSH representatives in Washington, DC and Cincinnati also served as guest speakers during the virtual class sessions, which likely would not have happened if the sessions were in-person only, she says.

Grady, Buckley, and other EH804 students also had the opportunity to translate their knowledge to the broader public, by contributing content from their class research to Wikipedia pages about various environmental health topics. Some of the class-generated Wikipedia content by other students includes information about blue space (waterbodies) in urban planning by doctoral student Pilar Botana (who will also translate the page into Spanish), incineration by PhD student Alina McIntyre, PFAS by PhD student Greylin Nielsen, pesticides by doctoral student Emily Hammel (SPH’20), environmental hazards by MPH student Caredwen Foley, and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT)—a computer model that is used to compute air parcel trajectories, by PhD student Sean Mueller.

“The implications of all of the students’ work are huge, and the impact on public health is immeasurable,” says Ceballos.