Gas leaf blowers' low frequency sound explains broad impact
The broad impact of gas leaf blower noise on communities may be explained by a strong low frequency component, according to a recently published pilot study co-authored by Erica Walker, a recent graduate of the doctoral program at the Harvard T.H. Chan School of Public Health and Executive Director, Jamie Banks. The study found low frequency noise from commercial gas leaf blowers persisted at high levels for 800 feet from the source. Low frequency sound travels over long distances and penetrates walls and windows.
“Our finding helps explain why so many people are complaining about the effects this noise is having on their health and quality of life,” said Banks. “At these levels, operating even one gas leaf blower can affect an entire neighborhood.”
Loud noise is known to harm hearing and non-hearing health, causing cardiovascular disturbances, psychological distress, and disruptions to learning and concentration. Vulnerable populations include landscape workers, children, senior, and people with hearing and neurological disorders, such as autism. More than 100 million people in the US are estimated to be exposed to harmful levels of environmental noise.
The study appears online Nov 3, 2017 in the Journal of Environmental and Toxicological Studies. It is the first in the U.S. to explore the characteristics of sound from gas-powered lawn and garden equipment.
Sound from leaf blowers and a hose vacuum—equipment commonly used in landscape maintenance—was over 100 dbA at the source and decreased over distance. However, the low frequency component persisted at high levels. “From a community perspective, the sound ratings supplied by manufacturers do not take frequency into consideration,” said Walker. “Our findings suggest that reporting more information on a sound’s character may be a step in the right direction,” she adds.
A Finnish study presented in 2004 also found strong tonal and low frequency components among various brands of commercial gas leaf blowers. These are the types of sound poorly tolerated by humans and which become amplified in indoor settings.
The dB(A) is the standard used by manufacturers to rate the sound of their equipment and is the metric communities use to set regulatory policy. “We now know that this metric breaks down in instances where there is a significant low frequency noise component,” said Walker. In fact, in the International Institute for Noise Control Engineering and the National Academy of Engineering have both indicated that the dB(A) is not sufficient for describing the impact of sound that contains a strong low frequency component.
Gas leaf blowers are identified as sources of harmful noise by the US Centers for Disease Control, US EPA as well as the national landscape industry association. “People need to recognize that this type of noise is not just an annoyance, it is a public health problem. We need think about prevention,” said Banks.