In Ontario, the workplace noise exposure limit is 85 dBA Lex,8 — the A-weighted noise energy averaged over an 8-hour day (O. Reg. 381/15 s. 2(4)). It is a single limit, not 87 dBA — 87 dBA is the federal Canada Labour Code figure, which does not apply to Ontario provincial workplaces. Ontario uses a 3 dB exchange rate, so the safe time halves for every 3 dB: 8 hours at 85 dBA, 15 minutes at 100 dBA (a circular saw), under a minute at 112 dBA (a jackhammer). At 85 dBA the employer must control noise at source first (s. 2), post warning signs where noise regularly exceeds 85 dBA (s. 2(7)), and train workers on hearing protection (s. 3). Notably, O. Reg. 381/15 does not require audiometric testing — recommended, but not the law in Ontario.
Noise-induced hearing loss is the most common permanent occupational disability in Ontario. It is irreversible. Once the hair cells in the cochlea are destroyed by excessive noise, they do not regenerate. The damage is cumulative — a carpenter who runs a circular saw without hearing protection for 20 years will not notice gradual hearing loss until it is severe enough to affect daily conversation, and by then, most of the damage is decades old. The 85 dBA Lex,8h limit in O. Reg. 381/15 is based on the ISO 1999 standard and decades of epidemiological data showing that workers exposed to sound levels at or above 85 dBA averaged over an 8-hour day face a significant risk of material hearing impairment. At 85 dBA over a working lifetime (40 years), roughly 8% of the exposed population will develop hearing loss sufficient to impair conversation. At 90 dBA — only 5 dB higher — that number jumps to 25%. The 3 dB exchange rate is critical to understanding noise dose: because decibels are logarithmic, every 3 dB increase doubles the sound energy. This means 88 dBA carries the same daily dose as 85 dBA in half the time — 4 hours instead of 8. At 100 dBA, the level of a circular saw, the equivalent dose accumulates in just 15 minutes. A construction worker who uses a circular saw for 30 minutes without protection has already exceeded the daily limit.
The Lex,8h (equivalent continuous sound level for 8 hours) is not a simple average. It is an energy-weighted calculation that accounts for both the intensity and duration of each noise exposure during the workday. The formula is Lex,8h = 10 * log10(sum of (ti/8 * 10^(Li/10))), where ti is the duration of task i in hours and Li is the sound level in dBA. What makes this counterintuitive is that the loudest task dominates the total even if it is short. A worker who spends 7 hours in a quiet office (60 dBA) and 15 minutes using a chop saw (104 dBA) does not have an exposure anywhere near 60 dBA. The 15 minutes of saw use contributes far more noise energy than the 7 hours of quiet. In practice, this means that even brief exposure to very loud equipment — jackhammers (112 dBA), concrete saws (108 dBA), sandblasting (112 dBA) — can push a worker over the 85 dBA limit for the entire day. Workers and supervisors who think "I only used it for a few minutes" often do not understand that those few minutes may have constituted the majority of their daily noise dose.
O. Reg. 381/15 section 2 requires the employer to take all measures reasonably necessary to reduce noise exposure. Engineering controls — reducing the noise at the source — are the first choice, not hearing protection. This is not a suggestion; it is the legal hierarchy. Engineering controls include: substituting quieter equipment (a belt-driven saw instead of a direct-drive model), enclosing noise sources (generator enclosures, machine guards), using vibration dampening mounts, maintaining equipment properly (dull blades generate more noise), and modifying work processes (cutting in a separate area rather than in the occupied workspace). Administrative controls — rotating workers, scheduling loud tasks when fewer workers are present, limiting individual exposure time — are the second tier. Hearing protection is the last resort, to be used when engineering and administrative controls cannot reduce exposure below 85 dBA, or as an interim measure while controls are being implemented. The reason for this hierarchy is simple: engineering controls protect everyone in the area automatically, while hearing protection depends on every individual worker inserting earplugs correctly every time, which real-world compliance studies show happens less than half the time. A well-maintained equipment enclosure reduces noise exposure reliably for years. A pair of foam earplugs depends on a worker rolling them tight, inserting them deep enough, and not pulling them out when they want to hear a coworker talk.
Every pair of earplugs and earmuffs sold in North America carries a Noise Reduction Rating (NRR) tested under ANSI S3.19 or S12.6 laboratory conditions. A box of foam earplugs might read NRR 33. In theory, that means 33 dB of noise reduction. In practice, real-world studies consistently show that workers achieve 30-50% of the lab-rated NRR. NIOSH (the U.S. National Institute for Occupational Safety and Health) developed a derating formula that Canada and CSA Z94.2 recognize: effective NRR = (rated NRR - 7) * 50%. So those NRR 33 earplugs provide about 13 dB of effective reduction. NRR 25 earmuffs provide about 9 dB. The gap between lab and reality comes from three factors: improper insertion (the number-one cause of protection failure — most workers do not insert foam plugs deep enough), poor fit (ear canal geometry varies widely), and removal during the shift (even removing earplugs for 5 minutes in an 8-hour shift can increase effective exposure by 5-10 dB because noise energy accumulates exponentially). This is why CSA Z94.2 recommends fit testing for hearing protection, similar to fit testing for respirators — verifying that a specific worker achieves adequate attenuation with a specific product.
Here is where Ontario differs from most of Canada: O. Reg. 381/15 does not require audiometric (hearing) testing. There is no section mandating baseline or annual audiograms — unlike the federal Canada Labour Code and most other provinces, which build testing into their hearing-conservation programs. The Ontario regulation's actual duties are noise control (s. 2), warning signs where noise regularly exceeds 85 dBA (s. 2(7)), and worker training on the care and use of hearing protection (s. 3). That gap is real, not a loophole to lean on. Audiometric testing is the only way to catch noise-induced hearing loss early — while it is still just a threshold shift on a chart, not something the worker notices in conversation. Best practice, and what a defensible employer does, is a baseline audiogram within 6 months of first exposure and annual re-tests compared to that baseline. A standard threshold shift (STS) — an average shift of 10 dB or more at 2000, 3000, and 4000 Hz in either ear — is the early warning: refit protection, review the noise controls, and retest. As a rough order of magnitude, audiometric testing is commonly quoted at around $30 to $60 per worker per year, while the lifetime cost of a permanent noise-induced hearing-loss claim is often cited in the tens to low hundreds of thousands of dollars plus any experience-rating impact. These are illustrative industry estimates, not published WSIB figures — but WSIB can accept a hearing-loss claim whether or not you ever tested.
Most construction workers underestimate how loud their equipment actually is. A circular saw at 100 dBA exceeds the 85 dBA limit in 15 minutes of cumulative use. A hammer drill at 105 dBA does it in under 5 minutes. A jackhammer at 112 dBA reaches the daily limit in 56 seconds. Even tools that seem moderate — a table saw at 93 dBA, a router at 95 dBA — exceed the limit in 2 hours or less. On a typical residential framing site, the ambient noise from multiple tools running simultaneously often exceeds 90 dBA across the entire area, meaning every worker on site — not just the one running the saw — is accumulating noise dose. Workers near a generator running at 96 dBA for the full shift are over the limit by noon. The widespread attitude that hearing protection is only needed for "really loud" tools like jackhammers ignores the reality that many common tools exceed the limit after brief use. A carpenter who frames walls all day with a pneumatic nail gun (97 dBA), cuts plates and studs with a circular saw (100 dBA), and uses a router for trim work (95 dBA) can easily accumulate a daily Lex,8h of 95-100 dBA — well into the range where hearing damage is guaranteed without protection.
Browse the full WSIB & OHSA toolkit for PPE, JHSC, first-aid, fall-protection and site-signage requirements. If you run crews, keeping a record of who was exposed to what — and for how long — is part of your OHSA paper trail; ToolFluency's Ontario contractor tools keep timesheets, jobs and exposure notes in one place so the paperwork is ready when a Ministry inspector shows up. Always confirm current requirements against the official regulation on Ontario e-Laws (O. Reg. 381/15).
Under O. Reg. 381/15 s. 2(4), no worker may be exposed to a sound level greater than 85 dBA Lex,8 — the A-weighted noise energy averaged over an 8-hour day. Ontario uses a single 85 dBA limit with a 3 dB exchange rate, meaning the allowed exposure time halves for every 3 dB increase.
By the ToolFluency team · Updated September 2026
Free Ontario noise exposure calculator. Add tasks and durations to calculate Lex,8h daily noise dose. See hearing protection requirements, employer obligations, and maximum exposure durations under O. Reg. 381/15.
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