Health Reports
Canadians vulnerable to workplace noise

by Pamela L. Ramage-Morin and Marc Gosselin

Release date: August 15, 2018

Excessive workplace noise can contribute to elevated blood pressure, sleep disturbance, stress, noise-induced hearing loss (NIHL), tinnitus and other negative health conditions.Note 1Note 2Note 3Note 4Note 5 An estimated 22.4 million U.S. workers (17%) reported that, in their current jobs, they had to speak in raised voices to be heard.Note 6 This is indicative of a hazardous noise level equivalent to at least 85 dB.Note 7Note 8 Over 11 million Canadians (42%) worked in noisy environments in 2012 and 2013, or had done so in the past.Note 9

Occupational health and safety legislation is designed to help protect workers from workplace hazards, including excessive noise.Note 10 Many workers in Canada are covered by provincial, territorial or federal legislation,Note 11 with each jurisdiction defining its own occupational exposure limits for loudness and duration of noise. For example, in most provinces, the daily limit is equivalent to 85 dB of continuous noise over an eight-hour period (Appendix A). The legislation specifies a hierarchy of employer and employee responsibilities to manage noise.Note 4Note 10Note 11Note 12 Employers are required to prevent the generation of unacceptable noise levels or, alternatively, to reduce workers' exposure to noise through measures such as shorter shifts. The final defence against potentially excessive noise is to provide hearing protection and education on its use.Note 4 Despite these measures, workplace noise remains a hazard. For example, it resulted in almost 30,000 NIHL claims accepted by the Workplace Safety and Insurance Board in Ontario from 2006 to 2015.Note 13

There is an information gap on Canadian workers exposed to hazardous workplace noise but for whom hearing protection is not mandatory.Note 9 Using data from cycles 3 (2012 to 2013) and 4 (2014 to 2015) of the Canadian Health Measures Survey (CHMS), this study describes Canadians aged 19 to 79 who, when working in noisy environments, were not required to wear hearing protection and only did so sometimes, rarely or never—henceforth referred to as "vulnerable" workers. Characteristics of these workers are examined, as well as sources of noise, years worked in noisy environments, and adverse outcomes—specifically, self-reported hearing difficulties and tinnitus.

Methods

Data source

The Canadian Health Measures Survey (CHMS) is an ongoing cross-sectional survey that samples households from five regions across Canada (Atlantic, Quebec, Ontario, Prairies and British Columbia). Participants provided demographic, socioeconomic, health and lifestyle information through an in­person, computer-assisted household interview, followed by direct physical measurements collected at a mobile examination centre (MEC). The CHMS excludes full-time members of the Canadian Armed Forces; residents of the three territories, First Nations reserves and other Aboriginal settlements, and certain remote regions; and residents of institutions such as nursing homes. Altogether, these exclusions represent approximately 4% of the target population. Proxy interviews were accepted in cases of physical or intellectual impairment.

This analysis used data from cycles 3 (2012 to 2013) and 4 (2014 to 2015). The combined cycle 3 and 4 response rate for the household and MEC components was 52.7%. Further details are available in the CHMS user guides and in the Instructions for Combining Multiple Cycles of Canadian Health Measures Survey (CHMS) Data.Note 14Note 15Note 16 Ethics approval for the CHMS was obtained from Health Canada's Research Ethics Board.Note 17

Study sample

This study was based on a sample of 6,571 respondents (3,250 men and 3,321 women) aged 19 to 79. The weighted sample from cycles 3 (n=3,288) and 4 (n=3,283) represented a population of 25.9 million Canadians.

Definitions

"Ever worked in a noisy environment" and "currently working in a noisy environment" were established with two questions: "At any time in your life, have you worked in a noisy environment? By noisy, I mean so loud that you and your co-workers had to speak in a raised voice to be understood by or communicate with someone standing an arm's length away." Respondents were instructed to include unpaid work. Those who responded "yes" were then asked "Are you currently working in a noisy environment?"

Respondents who had worked in a noisy environment reported on the duration (less than 5 years, 5 to less than 10 years, 10 years or more); whether they were required to wear hearing protection at work (yes, no); and how often they used hearing protection at work when in a noisy area, dichotomized as "used" (always, often) or "not used" (sometimes, rarely, never). The last two variables were combined to group respondents as: required and used, required but not used, not required but used, and not required and not used. Workers in the "not required and not used" category are referred to as "vulnerable" in this study.

Sources of loud workplace noise were identified from a predefined list. Machinery such as bulldozers, backhoes and sawmill equipment was grouped with modes of transportation, which included trains, airplanes, cars and trucks. Loud noise from people was combined with that from music at concerts or other amplified music. The "Other" noise source category was combined with munitions such as guns or cannons, as the sample size for the latter was too small to present separately.

Self-reported "hearing difficulty" was based on the hearing attribute of the Health Utilities Index Mark 3.Note 18Note 19 Respondents were asked "Are you usually able to hear what is said in a group conversation with at least three other people without a hearing aid?" Those who responded "no" were asked follow-up questions: "Are you usually able to hear what is said in a group conversation with at least three other people with a hearing aid?," "Are you able to hear at all?," "Are you usually able to hear what is said in a conversation with one other person in a quiet room without a hearing aid?" and "Are you usually able to hear what is said in a conversation with one other person in a quiet room with a hearing aid?" Responses were scored according to an established algorithm and classified from level 1 (no hearing problems) to level 6 (unable to hear at all). A dichotomous variable identified individuals with hearing problems (levels 2 to 6) versus no hearing problems (level 1).

Respondents were asked whether they had ever experienced tinnitus (yes, no), described as "the presence of hissing, buzzing, ringing, rushing or roaring sounds in your ears when there is no other sound around you."

In addition to sex and age group, respondents aged 25 or older were grouped by level of education: less than postsecondary graduation versus postsecondary graduation or more. Employment status was determined for people who had worked at a job or business in the past 12 months. This was established with the question "Were you an employee or self-employed?" Those working in a family business without pay were grouped with the self-employed. Job category was derived from a variant of the 2011 National Occupational Classification.Note 20 Categories A to F (management, professional, technical and paraprofessional, administration and administrative support, sales, and personal and customer information services) comprised "white-collar" workers, and categories G to J (industrial, construction and equipment operation trades; workers and labourers in transport and construction; natural resources, agriculture and related production occupations; and occupations in manufacturing and utilities) comprised "blue-collar" workers. The terms "blue-collar" and "white-collar" are used to make broad distinctions between the work environments of different occupational groups. It is acknowledged that these terms may not reflect the current reality of the Canadian workforce. They have been used in the absence of better alternatives and because they still provide a useful, albeit very general, distinction in work environments.

Analytical techniques

Data from cycles 3 and 4 were pooled and weighted with combined survey weights generated by Statistics Canada.Note 16 To account for the complex survey design variance estimation, coefficients of variation and significance testing (95% confidence intervals [CIs]) were completed using the bootstrap technique with 22 degrees of freedom.Note 21 Estimates represent the average Canadian household population during the survey timeframe (2012 to 2015). Analyses were conducted using SAS 9.3 and SAS-Callable SUDAAN 11.0 software.

Weighted frequencies and cross-tabulations were calculated to examine the percentage of people who worked in noisy environments by selected characteristics, with a focus on those considered vulnerable (hearing protection not required and not used). Estimates of self-reported hearing difficulties and tinnitus are presented. Logistic regression models adjusted for age (continuous) were used to examine whether bivariate results for hearing difficulties and tinnitus were confounded by age.

Results

An estimated 11.0 million Canadians (43%) aged 19 to 79 have worked in noisy environments, defined as the need to speak in a raised voice to communicate with co-workers at arm's length. More men (7.7 million) than women (3.3 million) had experienced noisy workplaces (Table 1). For women, younger ages (19 to 39 years) and a lower level of education were associated with a history of work in noisy environments.

Among people who had experienced noisy work environments, 6.1 million (56%) were classified as "vulnerable" to noise—they were not required to use hearing protection and only did so sometimes, rarely or never. Although the percentage of vulnerable women (72%) was greater than that of men (48%) (Figure 1), men outnumbered women in these circumstances at 3.7 million, compared with 2.4 million.

Over the 2012-to-2015 period, 3.6 million Canadians (14%) were currently working in noisy environments (Table 2). Of these workers, half were vulnerable to loud noise. Similar proportions of employees and the self-employed worked in noisy environments, but the latter were significantly more likely to be vulnerable—72%, compared with 47% of employees. People in blue-collar occupations were more likely than those in white-collar occupations to work in noisy environments, but were less likely to be vulnerable to excessive noise—39%, compared with 66%.

Sources and duration of occupational noise

Among vulnerable workers, men were more likely than women—81% versus 51%—to identify machinery (such as bulldozers and sawmill equipment) and modes of transportation (trains, airplanes, cars, trucks, etc.) as the sources of loud workplace noise (Table 3). Women were more likely than men to experience loud workplace noise caused by amplified music and noise from people—43%, compared with 20%. No difference was evident between men and women for other sources of noise. Most vulnerable women (61%) had worked in noisy environments for less than five years, compared with 45% of men. Vulnerable men were more likely than women to have worked in noisy environments for 10 years or more—38%, compared with 23%.

Tinnitus and self-reported hearing difficulties

An estimated 54% of men and 49% of women who were vulnerable to workplace noise had experienced tinnitus, significantly more than the 39% of men and women who had never worked in noisy environments (Figure 2). Those who were vulnerable were also more likely than those in the comparison group to report hearing difficulties. Logistic regression models taking age (continuous) into account revealed that men who were vulnerable to noise had higher odds than those who had never experienced noisy work environments of having tinnitus (odds ratio [OR] 1.9; 95% CI: 1.4 to 2.5) and hearing difficulties (OR 2.0; 95% CI: 1.1 to 3.8). For vulnerable women, the age-adjusted odds of having hearing difficulties were significant (OR 5.0; 95% CI: 2.7 to 9.5), while the association with tinnitus lost significance once age was taken into account (OR 1.5; 95% CI: 1.0 to 2.3).

Discussion

Key findings of this study relate to differences between men and women exposed to noisy workplaces. The likelihood of having worked in a noisy environment was no different for men of different ages, whereas younger women were more likely than women of older ages to have experienced a noisy workplace, despite having fewer potential years of exposure. Women's growing participation in the labour force over the past decades likely contributes to the higher exposure to noisy environments among younger women.Note 22 This may also reflect the movement of younger women into trades and other traditionally male-dominated sectors, such as construction and manufacturing.Note 23 Additionally, workplaces may be becoming noisier, particularly with the proliferation of electronic devices.Note 3 Even if the work itself is relatively quiet, there may be an abundance of second-hand noise—noise that surrounds people, but is not produced by them. For example, the constant noise of pagers in hospitals has been identified as a source of excessive noise for hospital workersNote 3Note 5, as has noise from restaurant-related activities for staff from cooks to servers.Note 6Note 24

Although fewer women than men worked in noisy environments, women were proportionately more likely to be vulnerable. To some extent, this difference could be attributed to the industrial roots of workplace health and safety legislation, which evolved in response to the hazards associated with the factories and manufacturing activities characteristic of male-dominated occupations.Note 25 Legislation built around these industries may not be so easily applied to non-industrial, female-dominated settings such as the health, education and service sectors, even though hazardous noise may be present.Note 3Note 24Note 26Note 27 Also, volunteer positions and occupations in non-profit organizations are not necessarily covered by health and safety legislation in all Canadian jurisdictions, and women are more likely than men to work in these sectors.Note 25Note 28

Blue-collar workers—more noise, less vulnerable

Although blue-collar workers were more likely than white-collar workers to work in noisy environments, the latter were more likely to be vulnerable. The workplaces of many blue-collar workers likely expose employees to noise that exceeds the occupational exposure limits and therefore require the use of hearing protection. Rabinowitz et al.Note 29 found that, in noisier environments, workers were more likely to require and use hearing protection and less likely to experience hearing loss than workers exposed to lower ambient noise. Many factories and industrial workplaces have hearing conservation programs with trained personnel to test and monitor employees' hearing acuity and to educate employees on noise-induced hearing loss and preventative measures, including the use of hearing protection. By the nature of their occupations, white-collar workers may have less exposure to noise—in level or duration—and therefore face no requirement to use hearing protection. Ironically, this may place them at greater risk of hazardous noise than workers in blue-collar occupations. That said, many blue-collar workers have the added workplace risk of exposure to ototoxic substances, such as heavy metals and carbon monoxide, which can have a negative impact on hearing acuity.Note 4Note 30

At one time, unionization may have explained the greater protection and lower vulnerability of blue-collar workers compared with people in white-collar occupations. However, unionization of industrial workers has been in decline over the past few decades, while more female-dominated workplaces such as offices, schools and hospitals have seen an increase in union membership.Note 31 A more feasible explanation may be that of Tak, Davis and Calvert,Note 6 who found that in sectors where the proportion of workers exposed to loud noise is high, non-use of hearing protection is low. This was the case for the mining industry, whereas the opposite was true for health care and social services. This suggests that a culture of hearing protection use has developed in industries that typically have noisy work environments. It is also possible that noise exposure is more constant for blue-collar workers and more intermittent for people in white-collar occupations. When loud noise is of a shorter duration, the need for hearing protection may be less obvious—during shift changes in a hospital setting, for example. Noise that peaks at excessive levels has been recorded in these situations.Note 32

Self-employed more vulnerable to noise than employees

Employers have a duty to ensure the safety of their employees under health and safety regulations, including protection from hazardous noise. Many employees benefit from workplace occupational health and safety committees with associated policies and practices. For example, in Ontario, workplaces that regularly employ 20 or more workers are required to have a health and safety committee.Note 33 Smaller workplaces, which may not have a committee or even a safety representative, have been associated with a greater likelihood of exposure to occupational hazards and inadequate policies and procedures.Note 34 The self-employed are exempt from health and safety regulations and therefore are not required to use hearing protection. This includes farmers, who have been identified as a group at risk of hearing difficulties and loss from work-related noise exposure.Note 35Note 36

Source of occupational noise

Noise from machinery and transportation—identified as a source of workplace noise by men more often than by women—is an undesirable and unintentional by-product of work. Some female-dominated work environments, such as many classrooms and hospitals, also have unintentional and excessive levels of noise.Note 5Note 26 Workers in these sectors are among the least likely to use hearing protection,Note 6 perhaps because of the necessity for verbal communication in health care and teaching environments, because of a lack of awareness, or because of work cultures that do not include the use of hearing protection.

Women were more likely than men to identify loud music and people as a source of workplace noise. In some circumstances, this workplace noise is not only intentional, but also desirable. Marketers, retailers, restaurateurs and other service providers have long been aware that they can attract or repel particular types of clientele and influence their behaviour through the volume, tempo and selection of music.Note 37 Venues that wish to attract a young clientele likely also want to hire younger workers, who may then be exposed to hazardous noise without the benefit of hearing protection. Wait staff, for example, often do not use hearing protection in noisy work environments.Note 6

Adverse outcomes for workers who were vulnerable to noise

Associations between occupational noise and hearing difficulties and tinnitus found in this study are consistent with earlier research.Note 1Note 4Note 36Note 38Note 39 Tinnitus frequently coexists in individuals with hearing loss, serves as a warning sign of potential hearing damage and can have a negative impact on individuals' quality of life.Note 2Note 40Note 41Note 42Note 43 The World Health Organization estimates annual global costs of $105 billion from loss of productivity, premature retirement and unemployment among people with hearing loss.Note 38 These costs do not take into account those from other adverse effects, such as stress and fatigue. Workplace safety is a concern for people with hearing difficulties and tinnitus, as these conditions can increase the risk of harmful incidents.Note 4Note 13Note 44 Limiting workplace noise becomes even more important when the addition of non-occupational exposure is considered. Noise from electronic devices, commuting and recreational activities all add to daily exposure and cumulatively threaten to exceed the recommended daily limits.Note 4Note 44Note 45Note 46

Strengths and limitations

A major strength of this study is the large sample size achieved by combining two CHMS cycles. This facilitates the analysis of a subgroup of workers who were not required to use hearing protection and generally did not do so. Additionally, the sample size permitted most analyses to be stratified by sex, which revealed key differences between men and women exposed to loud occupational noise. The study is representative of the Canadian population aged 19 to 79 over the study period.

Nevertheless, this study has some limitations. Occupational noise levels were not measured or verified; they were based on the self-reported need to raise one's voice to converse at arm's length. Data on employment status (employee or self-employed) and job category (white-collar or blue-collar) referred to respondents' circumstances at the time of the survey. Analyses with these variables were limited to those currently working in a noisy environment and were not stratified by sex because of insufficient sample. The use of occupational codes does not take into account industry- and workplace-specific factors that are associated with noise exposure.Note 2 Requirements on the use of hearing protection could not be verified; workers could be misclassified if they were not aware of the health and safety regulations. Information is available on whether people worked in noisy environments and over what period of time, but it is not possible to establish whether exposures met or exceeded accepted health and safety thresholds. This study does not account for exposure to recreational or other non-occupational noise exposure, such as commuting,Note 45Note 46 or other potential contributing factors, such as exposure to ototoxic substances and head trauma.Note 4

Conclusion

A unique aspect of this study is the focus on a large subgroup of workers who are vulnerable to loud workplace noise because hearing protection was neither required nor routinely used. These men and women were more likely to have hearing difficulties and tinnitus than those who had never worked in a noisy environment. Future work to assess the effectiveness and gaps of occupational health and safety legislation could help enhance protection against the adverse effects of excessive noise. There may be a need for increased awareness, training and enforcement. That said, workplace-related legislation cannot account for the cumulative noise exposure experienced during leisure, commuting and other non-workplace activities. Protection against excessive noise is not only a workplace issue, but also a broader public health concern.

Appendix A

Occupational exposure limits

Occupational exposure limits specify the maximum duration and loudness of noise to which workers can be exposed over the course of their work day without the use of hearing protection.

A criterion level indicates a maximum exposure equivalent to x dB (decibels) of continuous noise for 8 hours.

The exchange rate specifies the relationship between sound levels and duration of exposure.

For example, a criterion level of 85 dB(A) and an exchange rate of 3 dB(A) indicate that a worker can be exposed on a daily basis to 85 dB(A) for 8 hours or 97 dB(A) for 30 minutes (Table A). For context: normal conversation is around 55 dB with increasingly loud noise generated from vacuum cleaners (70 dB), diesel trucks (85 dB, 20 metres away at 50 km/hour) and power mowers (96 dB at 1 metre away).Note 10Note 47

In most Canadian provinces, the criterion level is 85 dB(A) with a 3 dB(A) exchange rate. This is more stringent than federally regulated workplaces, which have a criterion level of 87 dB(A) and a 3 dB(A) exchange rate. Quebec has the least stringent standards, with a criterion level of 90 dB(A) and a 5 dB(A) exchange rate.

References
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