Abstract
BackgroundWith an increasing proportion of the population living in cities, mass transportation has been rapidly expanding to facilitate the demand, yet there is a concern that mass transit has the potential to result in excessive exposure to noise, and subsequently noise-induced hearing loss.MethodsNoise dosimetry was used to measure time-integrated noise levels in a representative sample of the Toronto Mass Transit system (subway, streetcar, and buses) both aboard moving transit vehicles and on boarding platforms from April – August 2016. 210 measurements were conducted with multiple measurements approximating 2 min on platforms, 4 min within a vehicle in motion, and 10 min while in a car, on a bike or on foot. Descriptive statistics for each type of transportation, and measurement location (platform vs. vehicle) was computed, with measurement locations compared using 1-way analysis of variance.ResultsOn average, there are 1.69 million riders per day, who are serviced by 69 subway stations, and 154 streetcar or subway routes. Average noise level was greater in the subway and bus than in the streetcar (79.8 +/− 4.0 dBA, 78.1 +/− 4.9 dBA, vs 71.5 +/−1.8 dBA, p < 0.0001). Furthermore, average noise measured on subway platforms were higher than within vehicles (80.9 +/− 3.9 dBA vs 76.8 +/− 2.6 dBA, p < 0.0001). Peak noise exposures on subway, bus and streetcar routes had an average of 109.8 +/− 4.9 dBA and range of 90.4–123.4 dBA, 112.3 +/− 6.0 dBA and 89.4–128.1 dBA, and 108.6 +/− 8.1 dBA and 103.5–125.2 dBA respectively. Peak noise exposures exceeded 115 dBA on 19.9%, 85.0%, and 20.0% of measurements in the subway, bus and streetcar respectively.ConclusionsAlthough the mean average noise levels on the Toronto transit system are within the recommended level of safe noise exposure, cumulative intermittent bursts of impulse noise (peak noise exposures) particularly on bus routes have the potential to place individuals at risk for noise induced hearing loss.
Highlights
With an increasing proportion of the population living in cities, mass transportation has been rapidly expanding to facilitate the demand, yet there is a concern that mass transit has the potential to result in excessive exposure to noise, and subsequently noise-induced hearing loss
More conservative models were developed including the US National Institute for Occupational Safety and Health (NIOSH) and the US Environmental Protection Agency (EPA) limits, which aim to protect 92–98% of the population from noise-induced hearing loss (NIHL). Their main difference lies in that NIOSH limits were developed to protect against occupational noise exposure over an 8-h workday, whereas the EPA limits set to prevent NIHL from everyday noise over 24 h
When time weighted averages are compared, noise exposure was louder on combined measurements of subway and buses than streetcars (79.8 +/− 4.0 A-weighted decibels (dBA), 78.1 +/− 4.9 dBA vs 71.5 +/− 1.8 dBA, p < 0.0001)
Summary
With an increasing proportion of the population living in cities, mass transportation has been rapidly expanding to facilitate the demand, yet there is a concern that mass transit has the potential to result in excessive exposure to noise, and subsequently noise-induced hearing loss. Several organizations have set out to prevent noise-induced hearing loss, by establishing recommended noise exposure limits (Table 1) [13,14,15,16] Models based on these recommendations were derived to predict the amount of NIHL based on specific noise-exposure levels [17]. More conservative models were developed including the US National Institute for Occupational Safety and Health (NIOSH) and the US Environmental Protection Agency (EPA) limits, which aim to protect 92–98% of the population from NIHL Their main difference lies in that NIOSH limits were developed to protect against occupational noise exposure over an 8-h workday, whereas the EPA limits set to prevent NIHL from everyday noise over 24 h. This offers a guideline, it only accounts for chronic noise exposure at a static intensity, and does not capture the potential traumatic effects of impulse noise exposure [18]
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