Pilot survey of subway and bus stop noise levels

Health risks assessment and source admeasurement of potentially dangerous heavy metals (Cu, Fe, and Ni) in rapidly growing urban settlement

Environmental contamination is a global challenge that impacts every aspect of ecosystem. The contaminants from anthropogenic or industrial trash continually recirculate into the environment, agricultural land, plants, livestock, and ultimately into humans by way of the food chain. After an increase in human and farmland animal deaths from illnesses due to contaminated drinking water, toxic metal water poisoning has remained a global concern. Diverse environmental and enforcement organisations have attempted to regulate the activities that serve as precursors to these heavy metals which have been proven ineffective. These unnecessary metals have severely hampered most biological processes. The presence of hazardous metals, which are harmful at extremely high levels and have a negative effect on the health of living bodies generally degrades the nutritional value of water. In order to evaluate the heavy metals (Cu, Ni, and Fe) toxicity of groundwater in pri-urban areas, the current study was conducted that have been considered as advance solution to tackle climate change which influence coastal ecosystem. Additionally, the impacts of soil and plant (spinach and brassica) contamination from groundwater were evaluated. The heavy metals were examined in the soil and groundwater samples (Pb, Fe and Ni). While Fe concentrations in water samples were found to be high as 1.978 mg/L as compared to Ni and Cu values low. According to WHO guidelines, the mean value of Fe exceeds the limit value. Similarly, Cu had a higher mean value (0.7 mg/L) in soil samples than other metals (Ni and Fe). In comparison to Ni and Cu, the Fe concentrations in spinach and brassica plants samples are greater, at 17.2 mg/L and 3.22 mg/L, respectively. The possible effects of metal poisoning of groundwater and plants on human health have been assessed using the Hazard Quotient (HQ), Evaluated Daily Intake (EDI), and Incremental Life Time Cancer Risk formulas (ILTCR). When drinking Ni-contaminated water, humans are more at risk of developing cancer (0.0031) than Fe and Cu. Metal concentrations in water and brassica showed substantially more scattered behaviour on the plot and no meaningful relationship, although PCA and masked matrix correlation showed a fair association between Ni and Cu in brassica (r2: 0.46) and Fe and Ni in spinach (r2: 0.31). According to the study's findings, it is anticipated that special management and groundwater monitoring will be needed in the examined area to reduce the health risks related to drinking water that has been contaminated with metals.

Influence of the Noise-Canceling Technology on How We Hear Sounds

Purpose: This study explores the influence of the noise-canceling technology in commercial earphones on sound pressure levels and preferred listening levels in terms of hearing protection. Materials and Methods: Thirty individuals completed puretone audiometry and real-ear measurements to assess sound pressure levels at the level of the eardrum with and without the activation of the noise-canceling function. The Knowles Electronics Manikin for Acoustic Research was used to investigate the acoustic characteristics of two environmental sounds (bus and café). Two types of earphones (wireless and wired canal type) were utilized in the study. Results: For both bus and café noises, in the low-frequency range, sound pressure levels were significantly decreased for all types of earphones when the noise-canceling function was turned on. The same results were observed for the whole frequency range. In terms of preferred listening levels, the wireless canal type and wired canal type earphones showed significant reduction in volume levels. Conclusion: The findings of the study show that for both low- and whole frequency range, the use of noise-canceling function significantly decreases the sound pressure levels of the signal for all styles of earphones, suggesting a potential of the noise-canceling technology in hearing protection.

Use of Personal Listening Devices and Knowledge/Attitude for Greater Hearing Conservation in College Students: Data Analysis and Regression Model Based on 1009 Respondents

Given the concern regarding increased hearing loss in young people who use personal listening devices (PLDs), the present study analyzes the experience of PLDs among college students to identify their knowledge of and attitude toward hearing conservation. It also explains their relationship between knowledge of hearing loss and attitude-related hearing conservation as a questionnaire response using a regression model. A total of 1009 Korean college students responded to an online questionnaire. As a survey tool, the Personal Listening Device and Hearing Questionnaire was adapted as a Korean version with 78 modified items under 9 categories. Using principal component analysis, specific factors were extracted, and their relationships and paths were confirmed using multiple regression analysis. The results of the knowledge category of the questionnaire indicate that most respondents knew how to maintain healthy hearing and understood the signs of hearing loss. Regardless, many college students habitually use PLDs at high levels in noisy environments; they do not recognize how to prevent hearing loss. Even though they continue their current use pattern for PLDs, they also had a positive attitude toward receiving more information about hearing conservation. According to the regression model, the students' self-reported hearing deficits were due to the volume rather than the frequent use. Interestingly, knowledge about hearing loss may encourage students to develop a positive attitude toward reasonable restriction of PLD use. When PLD users have detailed knowledge about the hearing loss provided by professionals, we believe that most will avoid serious hearing problems and its risks and maintain a judicious attitude toward their own conservation.

Environmental and Health Effects of Ventilation in Subway Stations: A Literature Review

Environmental health in subway stations, a typical type of urban underground space, is becoming increasingly important. Ventilation is the principal measure for optimizing the complex physical environment in a subway station. This paper narratively reviews the environmental and health effects of subway ventilation and discusses the relevant engineering, environmental, and medical aspects in combination. Ventilation exerts a notable dual effect on environmental health in a subway station. On the one hand, ventilation controls temperature, humidity, and indoor air quality to ensure human comfort and health. On the other hand, ventilation also carries the potential risks of spreading air pollutants or fire smoke through the complex wind environment as well as produces continuous noise. Assessment and management of health risks associated with subway ventilation is essential to attain a healthy subway environment. This, however, requires exposure, threshold data, and thereby necessitates more research into long-term effects, and toxicity as well as epidemiological studies. Additionally, more research is needed to further examine the design and maintenance of ventilation systems. An understanding of the pathogenic mechanisms and aerodynamic characteristics of various pollutants can help formulate ventilation strategies to reduce pollutant concentrations. Moreover, current comprehensive underground space development affords a possibility for creating flexible spaces that optimize ventilation efficiency, acoustic comfort, and space perception.

Noise Exposure on the London Underground, an Observational Study over a Decade

OBJECTIVES

There are no hearing protection regulations in place for passengers using public transport, such as the London Underground. In light of this, we sought to examine sound pressure levels experienced by regular users of the London Underground.

METHODS

Sound pressure levels (A-weighted decibels: dBA) were taken on moving London Underground carriages between Euston and South Wimbledon on the Northern Line, and between Euston and Vauxhall on the Victoria Line, during 2006 and 2018. In addition, carriage sound pressure levels travelling within Zone 1 of the London Underground were tested in 2019. Three experimental and three technical repeats were undertaken using a hand-held calibrated multi-function sound level meter.

RESULTS

Passengers are routinely and consistently subjected to sound pressure levels exceeding 80 dBA, with levels sometimes reaching over 100 dBA.

CONCLUSION

This study is unique within the literature, with no published studies outlining exposure levels for London Underground passengers. It provides evidence of elevated noise exposure to passengers, consistently along large stretches of the London Underground, over a prolonged study period (2006-2019).

KEY WORDS

Sensorineural hearing losssound pressureexposureLondonundergroundtube.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2020.

Speech, movement, and gaze behaviours during dyadic conversation in noise

How do people have conversations in noise and make themselves understood? While many previous studies have investigated speaking and listening in isolation, this study focuses on the behaviour of pairs of individuals in an ecologically valid context. Specifically, we report the fine-grained dynamics of natural conversation between interlocutors of varying hearing ability (n = 30), addressing how different levels of background noise affect speech, movement, and gaze behaviours. We found that as noise increased, people spoke louder and moved closer together, although these behaviours provided relatively small acoustic benefit (0.32 dB speech level increase per 1 dB noise increase). We also found that increased noise led to shorter utterances and increased gaze to the speaker's mouth. Surprisingly, interlocutors did not make use of potentially beneficial head orientations. While participants were able to sustain conversation in noise of up to 72 dB, changes in conversation structure suggested increased difficulty at 78 dB, with a significant decrease in turn-taking success. Understanding these natural conversation behaviours could inform broader models of interpersonal communication, and be applied to the development of new communication technologies. Furthermore, comparing these findings with those from isolation paradigms demonstrates the importance of investigating social processes in ecologically valid multi-person situations.

The Relationship between Sound and Amenities of Transit-Oriented Developments

Experts in diverse fields have investigated sound in cities throughout the United States. This research aims to examine sound levels and determine its contributors at the transit-oriented development (TOD) station and neighborhood levels by studying selected Dallas Area Rapid Transit (DART) light rail stations. A multilevel analysis was performed to model the likelihood of TOD stations and neighborhoods affecting sound levels, controlling for station amenities, socio-demographics and built environment characteristics. Sound measurements were sampled in three time intervals with 15 min sampling over weekdays and weekends at TOD and non-TOD stations by a type II SPL meter that was mounted on a small camera tripod at a height of 1.5 m, at a distance of 1.5 m from rails and curbs. The research team found that amenities, built environmental characteristics, and neighborhood features have significant implications on sound levels at both the TOD station and the neighborhood level, which affects quality of life (QoL). TOD stations that include more amenities have a greater level of significance on sound levels. Additionally, neighborhoods with a pervasive street grid configuration, public facilities, and built environment densities are significantly associated with a likelihood of high sound levels. Conversely, higher population densities and intersection densities decrease the likelihood of a high sound level environment. These patterns provide an arena for transportation, urban, and environmental planning and policymaking to generate transformative solutions and policies.

The effect of brief subway station noise exposure on commuter hearing

Objective

To demonstrate that brief exposure to subway noise causes temporary threshold shift and is preventable with noise protection.

Methods

The study was conducted as a randomized crossover trial. Twenty subjects were randomly assigned to two groups, one with hearing protection and one without. Subjects were exposed to subway platform noise for 15 minutes. Pre‐ and post‐exposure pure tone audiometry (PTA) and otoacoustic emissions were compared. After a washout period, subjects switched hearing protection groups and repeated the process.

Results

A statistically significant reduction in PTA thresholds after subway noise exposure was identified, for subjects with and without hearing protection (P < .001). For exposure without hearing protection, the mean threshold was 5.19 dB pre‐exposure and 3.91 dB post‐exposure (decrease of 1.28 dB; 95% confidence interval, 0.82–1.74). For exposure with hearing protection, the mean threshold was 4.81 dB pre‐exposure and 3.47 dB post‐exposure (decrease of 1.34 dB; 95% confidence interval, 0.89–1.79).

Conclusion

Brief exposure to subway noise did not cause hearing loss with or without noise protection. Though clinically insignificant, the unexpected finding of reduction in PTA suggests that there are complex heterogeneous short‐ and long‐term cochlear responses to noise exposure that should be further explored.

Level of Evidence

1b

Cardiovascular benefits of reducing personal exposure to traffic-related noise and particulate air pollution: A randomized crossover study in the Beijing subway system

To assess the cardiovascular benefits of protecting against particulate air pollution and noise, we conducted a randomized crossover study with 40 young healthy college students from March to May 2017 in the underground subway, Beijing. Participants each received 4 treatments (no intervention phase [NIP], respirator intervention phase [RIP], headphone intervention phase [HIP], respirator plus headphone intervention phase [RHIP]) in a randomized order during 4 different study periods with 2-week washout intervals. We measured personal exposure to particulate matter (PM), noise and electrocardiogram (ECG) parameters (heart rate variability (HRV), heart rate (HR) and ST segment changes), ambulatory blood pressure (BP) continuously for 4 hours to investigate the cardiovascular effects. Compared with NIP, most of the HRV parameters increased, especially high frequency (HF) [21.1% (95% CI: 15.7%, 26.9%), 18.2% (95% CI: 12.8%, 23.9%), and 35.5% (95% CI: 29.3%, 42.0%) in RIP, HIP, and RHIP, respectively], whereas ST segment elevation and HR decreased for all 3 modes of interventions. However, no significant differences were observed in BP among the 4 treatments. In summary, short-term wearing of a respirator and/or headphone may be an effective way to minimize cardiovascular risk induced by air pollution in the subway by improving autonomic nervous function.

Analysis of Subway Interior Noise at Peak Commuter Time

Background and Objectives

Although mass transit systems are convenient and efficient for urban people, little attention has been paid to the potential hearing hazard from their noise. The purpose of the current study was to measure and analyze levels of subway interior noise at peak commuter times and to provide information about commuters’ daily dose of noise exposure.

Materials and Methods

To measure the subway interior noise, nine subway lines inside Seoul (i.e., lines 1-9) and six lines surrounding the capital city area (i.e., Central, Bundang, Sinbundang, Incheon, Gyeongui, and Gyeongchun) were chosen. The noise was measured and recorded by a sound level meter for two-hour periods in the morning and evening.

Results

1) In the LZeq analysis, the average noise level of all 15 lines was 72.78 dB; the maximum and minimum noise levels were 78.34 and 62.46 dB, respectively. The average noise level of the nine lines inside Seoul was 73.45 dB, which was 1.68-dB louder than that of the six lines surrounding the capital city area. 2) Based on the LZeq analysis of 33 measured frequencies, 12.5 Hz was the highest frequency and 20,000 Hz was the lowest. 3) There was no remarkable difference in the level of subway interior noise between morning and evening peak commuter times.

Conclusions

We concluded that the level of subway interior noise was not loud enough for commuters to incur noise-induced hearing loss. Regardless, environmental noise control efforts in the subway system might be needed for commuters who take a subway every day.

A preliminary investigation of noise impact within metro stations in the urban city of Guangzhou, China

The noise in the metro station is synthesized from a variety of different noise sources. Excessive noise exposure will bring serious impacts on humans' health. To alleviate the shortage of the urban land, most metro stations are planning to develop convenience stores and shopping malls. In order to evaluate the potential noise impact on humans' comfort in the metro stations, this study selected four representative stations of Guangzhou Metro Line 1 to carry out a preliminary questionnaire survey of 226 respondents for the perception and perform a noise measurement. Additionally, platform screen doors as a potential method for noise mitigation were examined. The results show that the noise caused by trains was dominant in the metro stations; however, the noise impact by public broadcast and passengers cannot be ignored. The noise levels of the transfer stations were obviously greater than the normal stations, especially during the peak hours. In addition, people in the metro stations have potential exposure to noise that the noise levels exceed the criteria limit of China, which would bring discomfort for humans; however, the normal activities of people would not be impacted. The platform screen doors should be further improved or relevant noise mitigation methods should be taken into account to reduce the noise level within the criteria limit.

The influence of subway station design on noise levels

OBJECTIVES/HYPOTHESIS

To investigate the impact of subway station design on platform noise levels.

STUDY DESIGN

Observational.

METHODS

Continuous A-weighted decibel (dBA) sound levels were recorded in 20 New York City subway stations, where trains entered on either a straight track or curved track in 10 stations each. Equivalent continuous noise levels (L_eq ) at various locations on the boarding platform (inbound end, midplatform, and outbound end) during train entry and exit were compared between the straight and curved stations in broadband as well as narrow one-third octave bands.

RESULTS

Overall, curved stations trended louder than straight stations, although the difference in broadband L_eq did not reach statistical significance (curve, 83.4 dBA; straight, 82.6 dBA; P = .054). Noise levels were significantly louder at the inbound end of the platform during train entry (inbound, 89.7 dBA; mid, 85.5 dBA; outbound, 78.7 dBA; P < .001) and at the outbound end during train exit (inbound, 79.7 dBA; mid, 85.3 dBA; outbound, 89.1 dBA; P < .001). Narrow band analysis showed that curved stations were significantly louder than straight stations at 100 Hz and high frequencies from 8 to 20 kHz. Peak impact levels ranged from 104 to 121 dBA.

CONCLUSIONS

Curved stations have a different noise profile compared to straight stations and are significantly louder than straight stations at high frequencies. Designing stations with straight tracks within the platform can help reduce commuter noise exposure.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:1169-1174, 2017.

Preferred listening levels of mobile phone programs when considering subway interior noise

Today, people listen to music loud using personal listening devices. Although a majority of studies have reported that the high volume played on these listening devices produces a latent risk of hearing problems, there is a lack of studies on “double noise exposures” such as environmental noise plus recreational noise. The present study measures the preferred listening levels of a mobile phone program with subway interior noise for 74 normal-hearing participants in five age groups (ranging from 20s to 60s). The speakers presented the subway interior noise at 73.45 dB, while each subject listened to three application programs [Digital Multimedia Broadcasting (DMB), music, game] for 30 min using a tablet personal computer with an earphone. The participants’ earphone volume levels were analyzed using a sound level meter and a 2cc coupler. Overall, the results showed that those in their 20s listened to the three programs significantly louder with DMB set at significantly higher volume levels than for the other programs. Higher volume levels were needed for middle frequency compared to the lower and higher frequencies. We concluded that any potential risk of noise-induced hearing loss for mobile phone users should be communicated when users listen regularly, although the volume level was not high enough that the users felt uncomfortable. When considering individual listening habits on mobile phones, further study to predict total accumulated environmental noise is still needed.

Sleep as a mediator in the pathway linking environmental factors to hypertension: a review of the literature

Environmental factors, such as noise exposure and air pollution, are associated with hypertension. These environmental factors also affect sleep quality. Given the growing evidence linking sleep quality with hypertension, the purpose of this review is to investigate the role of sleep as a key mediator in the association between hypertension and environmental factors. Through this narrative review of the extant literature, we highlight that poor sleep quality mediates the relationship between environmental factors and hypertension. The conceptual model proposed in this review offers opportunities to address healthcare disparities in hypertension among African Americans by highlighting the disparate impact that the predictors (environmental factors) and mediator (sleep) have on the African-American community. Understanding the impact of these factors is crucial since the main outcome variable (hypertension) severely burdens the African-American community.

Street-level noise in an urban setting: assessment and contribution to personal exposure

BACKGROUND

The urban soundscape, which represents the totality of noise in the urban setting, is formed from a wide range of sources. One of the most ubiquitous and least studied of these is street-level (i.e., sidewalk) noise. Mainly associated with vehicular traffic, street level noise is hard to ignore and hard to escape. It is also potentially dangerous, as excessive noise from any source is an important risk factor for adverse health effects. This study was conducted to better characterize the urban soundscape and the role of street level noise on overall personal noise exposure in an urban setting.

METHODS

Street-level noise measures were obtained at 99 street sites located throughout New York City (NYC), along with data on time, location, and sources of environmental noise. The relationship between street-level noise measures and potential predictors of noise was analyzed using linear and logistic regression models, and geospatial modeling was used to evaluate spatial trends in noise. Daily durations of street-level activities (time spent standing, sitting, walking and running on streets) were estimated via survey from a sample of NYC community members recruited at NYC street fairs. Street-level noise measurements were then combined with daily exposure durations for each member of the sample to estimate exposure to street noise, as well as exposure to other sources of noise.

RESULTS

The mean street noise level was 73.4 dBA, with substantial spatial variation (range 55.8-95.0 dBA). Density of vehicular (road) traffic was significantly associated with excessive street level noise levels. Exposure duration data for street-level noise and other common sources of noise were collected from 1894 NYC community members. Based on individual street-level exposure estimates, and in consideration of all other sources of noise exposure in an urban population, we estimated that street noise exposure contributes approximately 4% to an average individual's annual noise dose.

CONCLUSIONS

Street-level noise exposure is a potentially important source of overall noise exposure, and the reduction of environmental sources of excessive street- level noise should be a priority for public health and urban planning.

Cultural and demographic factors influencing noise exposure estimates from use of portable listening devices in an urban environment

PURPOSE

This study examined listening levels and duration of portable listening devices (PLDs) used by people with diversity of ethnicity, education, music genre, and PLD manufacturer. The goal was to estimate participants' PLD noise exposure and identify factors influencing user behavior.

METHOD

This study measured listening levels of 160 adults in 2 New York City locations: (a) a quiet college campus and (b) Union Square, a busy interchange. Participants completed a questionnaire regarding demographics and PLD use. Ordinary least squares regression was used to explore the significance of demographic and behavioral factors.

RESULTS

Average listening level was 94.1 dBA, with 99 of 160 (61.9%) and 92 of 159 (57.5%) exceeding daily (L A8hn) and weekly (L Awkn) recommended exposure limit, respectively. African American participants listened at the highest average levels (99.8 dBA).

CONCLUSIONS

A majority of PLD users exceeded recommended exposure levels. Factors significant for higher exposure were ethnicity and age; factors not significantly associated with exposure were gender, education, location, awareness of possible association between PLD use and noise-induced hearing loss, mode of transportation, device manufacturer, and music genre. Efforts to effect behavior changes to lessen noise-induced hearing loss risk from PLD use should be sensitive to the cultural differences within the targeted population.

Estimation of permanent noise-induced hearing loss in an urban setting

The potential burden of noise-induced permanent threshold shift (NIPTS) in U.S. urban settings is not well-characterized. We used ANSI S3.44-1996 to estimate NIPTS for a sample of 4585 individuals from New York City (NYC) and performed a forward stepwise logistic regression analysis to identify predictors of NIPTS >10 dB. The average individual is projected to develop a small NIPTS when averaged across 1000-4000 Hz for 1- to 20-year durations. For some individuals, NIPTS is expected to be substantial (>25 dB). At 4000 Hz, a greater number of individuals are at risk of NIPTS from MP3 players and stereos, but risk for the greatest NIPTS is for those with high occupational and episodic nonoccupational (e.g., power tool use) exposures. Employment sector and time spent listening to MP3 players and stereos and participating in episodic nonoccupational activities associated with excessive noise levels increased the odds of NIPTS >10 dB at 4000 Hz for 20-year durations. Our results indicate that the risk of NIPTS may be substantial for NYC and perhaps other urban settings. Noise exposures from "noisy" occupational and episodic nonoccupational activities and MP3 players and stereos are important risk factors and should be a priority for public health interventions.

Mass transit ridership and self-reported hearing health in an urban population

Information on prevalence and risk factors associated with self-reported hearing health among mass transit riders is extremely limited, even though evidence suggests mass transit may be a source of excessive exposure to noise. Data on mass transit ridership were collected from 756 study participants using a self-administered questionnaire. Hearing health was measured using two symptom items (tinnitus and temporary audiometric threshold shift), two subjective measures (self-rated hearing and hearing ability), and two medical-related questions (hearing testing and physician-diagnosed hearing loss). In logistic regression analyses that controlled for possible confounders, including demographic variables, occupational noise exposure, nonoccupational noise exposure (including MP3 player use) and use of hearing protection, frequent and lengthy mass transit (all forms) ridership (1,100 min or more per week vs. 350 min or less per week) was the strongest predictor of temporary threshold shift symptoms. Noise abatement strategies, such as engineering controls, and the promotion of hearing protection use should be encouraged to reduce the risk of adverse impacts on the hearing health of mass transit users.

Listening level of music through headphones in train car noise environments

Although portable music devices are useful for passing time on trains, exposure to music using headphones for long periods carries the risk of damaging hearing acuity. The aim of this study is to examine the listening level of music through headphones in the noisy environment of a train car. Eight subjects adjusted the volume to an optimum level (L(music)) in a simulated noisy train car environment. In Experiment I, the effects of noise level (L(train)) and type of train noise (rolling, squealing, impact, and resonance) were examined. Spectral and temporal characteristics were found to be different according to the train noise type. In Experiment II, the effects of L(train) and type of music (five vocal and five instrumental music) were examined. Each music type had a different pitch strength and spectral centroid, and each was evaluated by φ(1) and W(φ(0)), respectively. These were classified as factors of the autocorrelation function (ACF) of the music. Results showed that L(music) increased as L(train) increased in both experiments, while the type of music greatly influenced L(music). The type of train noise, however, only slightly influenced L(music). L(music) can be estimated using L(train) and the ACF factors φ(1) and W(φ(0)).

Characteristics of noise-canceling headphones to reduce the hearing hazard for MP3 users

Three pairs of headphones [standard iPod ear buds and two noise-canceling headphones (NCHs)] were chosen to investigate frequency characteristics of noise reduction, together with their attenuation effects on preferred listening levels (PLLs) in the presence of various types of background noise. Twenty-six subjects with normal hearing chose their PLLs in quiet, street noise, and subway noise using the three headphones and with the noise-canceling system on/off. Both sets of NCHs reduced noise levels at mid- and high-frequencies. Further noise reductions occurred in low frequencies with the noise canceling system switched on. In street noise, both NCHs had similar noise reduction effects. In subway noise, better noise reduction effects were found in the expensive NCH and with noise-canceling on. A two way repeated measures analysis of variance showed that both listening conditions and headphone styles were significant influencing factors on the PLLs. Subjects tended to increase their PLLs as the background noise level increased. Compared with ear buds, PLLs obtained from NCHs-on in the presence of background noise were reduced up to 4 dB. Therefore, proper selection and use of NCHs appears beneficial in reducing the risk of hearing damage caused by high music listening levels in the presence of background noise.

Exposures to transit and other sources of noise among New York City residents

To evaluate the contributions of common noise sources to total annual noise exposures among urban residents and workers, we estimated exposures associated with five common sources (use of mass transit, occupational and nonoccupational activities, MP3 player and stereo use, and time at home and doing other miscellaneous activities) among a sample of over 4500 individuals in New York City (NYC). We then evaluated the contributions of each source to total noise exposure and also compared our estimated exposures to the recommended 70 dBA annual exposure limit. We found that one in ten transit users had noise exposures in excess of the recommended exposure limit from their transit use alone. When we estimated total annual exposures, 90% of NYC transit users and 87% of nonusers exceeded the recommended limit. MP3 player and stereo use, which represented a small fraction of the total annual hours for each subject on average, was the primary source of exposure among the majority of urban dwellers we evaluated. Our results suggest that the vast majority of urban mass transit riders may be at risk of permanent, irreversible noise-induced hearing loss and that, for many individuals, this risk is driven primarily by exposures other than occupational noise.

Noise pollution survey of a two-storey intersection station in Tehran metropolitan subway system

According to the world population increase and demand on transportation in mega cities, modern and low-cost technologies are remarkably considered. Meanwhile, subway system, as a means to transfer a large population of people, is extremely welcomed due to its particular advantages including time and cost savings, traffic jam avoidance, and unaffected by weather. Nevertheless, despite the benefits of these technologies, such devices also have been associated with disadvantages for human. In many subway systems, noisy environments are clearly observed; therefore, workers and even the passengers are exposed to higher noise levels than permissible limit. In this research, noise measurements were performed at Imam Khomeini Station as the most crowded intersection subway station in Tehran. In this descriptive-sectional survey, the amount of noise pollution was investigated at both stories of Imam Khomeini Intersection Station. A variety of noise pollution indicators such as L(eq) 10 min were separately measured at each storey through five measurement points from 7 A.M. to 10 P.M. It was shown that the equivalent sound level range at Imam Khomeini station towards Elmo Sanat and Imam Khomeini towards Mirdamad were between 70.56-79.54 and 68.35-79.12 dB (A), respectively. It was indicated that except for the entrance stairs to the subway waiting platform and the first section of the platform on both stories, other measurement stations have the same equivalent sound levels.

Assessment of noise exposure during commuting in the Madrid subway

Because noise-induced hearing impairment is the result not only of occupational noise exposure but also of total daily noise exposure, it is important to take the non-occupational exposure of individuals (during commuting to and from their jobs, at home, and during recreational activities) into account. Mass transit is one of the main contributors to non-occupational noise exposure. We developed a new methodology to estimate a representative commuting noise exposure. The methodology was put into practice for the Madrid subway because of all Spanish subway systems it covers the highest percentage of worker journeys (22.6%). The results of the application highlight that, for Madrid subway passengers, noise exposure level normalized to a nominal 8 hr (L(Ex,8h-cj) ) depends strongly on the type of train, the presence of squealing noise, and the public address audio system, ranging from 68.6 dBA to 72.8 dBA. These values play an important role in a more complete evaluation of a relationship between noise dose and worker health response.

A study of riders' noise exposure on Bay Area Rapid Transit trains

Excessive noise exposure may present a hazard to hearing, cardiovascular, and psychosomatic health. Mass transit systems, such as the Bay Area Rapid Transit (BART) system, are potential sources of excessive noise. The purpose of this study was to characterize transit noise and riders' exposure to noise on the BART system using three dosimetry metrics. We made 268 dosimetry measurements on a convenience sample of 51 line segments. Dosimetry measures were modeled using linear and nonlinear multiple regression as functions of average velocity, tunnel enclosure, flooring, and wet weather conditions and presented visually on a map of the BART system. This study provides evidence of levels of hazardous levels of noise exposure in all three dosimetry metrics. L(eq) and L(max) measures indicate exposures well above ranges associated with increased cardiovascular and psychosomatic health risks in the published literature. L(peak) indicate acute exposures hazardous to adult hearing on about 1% of line segment rides and acute exposures hazardous to child hearing on about 2% of such rides. The noise to which passengers are exposed may be due to train-specific conditions (velocity and flooring), but also to rail conditions (velocity and tunnels). These findings may point at possible remediation (revised speed limits on longer segments and those segments enclosed by tunnels). The findings also suggest that specific rail segments could be improved for noise.

Noise exposure estimates of urban MP3 player users

PURPOSE

To examine the sound level and duration of use of personal listening devices (PLDs) by 189 college students, ages 18-53 years, as they entered a New York City college campus, to determine whether noise exposure from PLDs was in excess of recommended exposure limits and what factors might influence exposure.

METHOD

Free-field equivalent sound levels from PLD headphones were measured on a mannequin with a calibrated sound level meter. Participants reported demographic information, whether they had just come off the subway, the type of PLD and earphones used, and duration per day and days per week they used their PLDs.

RESULTS

Based on measured free-field equivalent sound levels from PLD headphones and the reported PLD use, per day 58.2% of participants exceeded 85 dB A-weighted 8-hr equivalent sound levels (L(Aeq)), and per week 51.9% exceeded 85 dB A-weighted 40-hr equivalent continuous sound levels (L(Awkn)).

CONCLUSIONS

The majority of PLD users exceeded recommended sound exposure limits, suggesting that they were at increased risk for noise-induced hearing loss. Analyses of the demographics of these participants and mode of transportation to campus failed to indicate any particular gender differences in PLD use or in mode of transportation influencing sound exposure.

Noise levels associated with New York City's mass transit systems

OBJECTIVES

We measured noise levels associated with various forms of mass transit and compared them to exposure guidelines designed to protect against noise-induced hearing loss.

METHODS

We used noise dosimetry to measure time-integrated noise levels in a representative sample of New York City mass transit systems (subways, buses, ferries, tramway, and commuter railways) aboard transit vehicles and at vehicle boarding platforms or terminals during June and July 2007.

RESULTS

Of the transit types evaluated, subway cars and platforms had the highest associated equivalent continuous average (L(eq)) and maximum noise levels. All transit types had L(eq) levels appreciably above 70 A-weighted decibels, the threshold at which noise-induced hearing loss is considered possible.

CONCLUSIONS

Mass transit noise exposure has the potential to exceed limits recommended by the World Health Organization and the US Environmental Protection Agency and thus cause noise-induced hearing loss among riders of all forms of mass transit given sufficient exposure durations. Environmental noise-control efforts in mass transit and, in cases in which controls are infeasible, the use of personal hearing protection would benefit the ridership's hearing health.

[Urban health: "the city is a strange lady, smiling today, devouring you tomorrow"]

More than half of the world's population is living in cities and the world is turning more and more urbanized. This literature review explores the ramifications of urban transformation, showing how cities take shape and impact human health in our times. While cities can offer positive opportunities, their negative impacts related to the lack of social organization, precarious urban living and working conditions, lack of governance and opportunities as well as the lack of strategies for promoting social equity tend to increase the adverse effects on the health of the urban communities. The article also advocates the study of urban health as a branch of knowledge related to public health, proposing a common conceptual model and taxonomy for urban health. Future directions for research and practice are discussed in the light of some examples from the Brazilian scientific literature.

Noise Pollution: A Modern Plague

Noise is defined as unwanted sound. Environmental noise consists of all the unwanted sounds in our communities except that which originates in the workplace. Environmental noise pollution, a form of air pollution, is a threat to health and well-being. It is more severe and widespread than ever before, and it will continue to increase in magnitude and severity because of population growth, urbanization, and the associated growth in the use of increasingly powerful, varied, and highly mobile sources of noise. It will also continue to grow because of sustained growth in highway, rail, and air traffic, which remain major sources of environmental noise. The potential health effects of noise pollution are numerous, pervasive, persistent, and medically and socially significant. Noise produces direct and cumulative adverse effects that impair health and that degrade residential, social, working, and learning environments with corresponding real (economic) and intangible (well-being) losses. It interferes with sleep, concentration, communication, and recreation. The aim of enlightened governmental controls should be to protect citizens from the adverse effects of airborne pollution, including those produced by noise. People have the right to choose the nature of their acoustical environment; it should not be imposed by others.