The NIOSH rule: 85 dBA, 8 hours, 3 dB exchange — with numbers you can use
The US National Institute for Occupational Safety and Health (NIOSH) recommends a Recommended Exposure Limit (REL) of 85 dBA as an 8-hour time-weighted average, with a 3 dB exchange rate: every 3 dB increase halves allowable time. That gives 4 hours at 88 dBA, 2 hours at 91, 1 hour at 94, 30 minutes at 97, about 15 minutes at 100 dBA, and only minutes above 103 dBA. The rule comes from studies of permanent noise-induced hearing loss across working lifetimes — it is a damage threshold, not a comfort target.
Two common confusions: OSHA's Permissible Exposure Limit in the US is 90 dBA over 8 hours with a 5 dB exchange — less protective and widely regarded as outdated — while the EU Physical Agents Directive (2003/10/EC) sets lower action values at 80 dBA (offer protection, inform workers) and 85 dBA (mandatory protection, health surveillance) plus peak limits of 135–140 dBC. If you work under EU/UK rules, 80 dBA is already the trigger to act. Use our exposure calculator and noise exposure guide to turn your measured Leq plus duration into a dose percentage.
How to apply it at home: measure the activity's Leq — blender 88 dBA for 5 minutes is negligible; a 97 dBA home workshop for an hour without protection exceeds a full day's dose. Sensitive people, children, and those with existing loss should protect earlier, and impulse noise (gunshots, fireworks) follows separate peak rules where even single events matter.
Underestimated leisure: concerts, clubs, headphones, DIY
Leisure, not work, delivers most people's loudest doses. Front-of-house concert levels of 95–105 dBA give safe times from under an hour to minutes; clubs hold 95–110 dBA for hours; sports crowds peak 105–115 dBA on goals. Headphones at maximum reach 100–105 dB at the eardrum — the 60-60 rule helps: at most 60% volume, at most 60 minutes straight, then a quiet break. For DIY, a circular saw (95–105 dBA), angle grinder (95–110) and lawnmower (85–95) all demand earmuffs or plugs; even a hair dryer at close range hits 80–90 dBA.
Regulars should own musician's earplugs with 15–25 dB of even attenuation — foam plugs muffle music, filtered plugs preserve it. Keep a pair on your keyring and a pair of earmuffs on the workbench so protection is closer than the excuse. Parents: volume-limit kids' headphones to 85 dB max, keep portable speakers at arm's length, and seat children away from PA stacks at events — small ear canals get higher doses from the same sound.
Take the ear's warning signs seriously — and know when to get help
Tinnitus after noise (ringing, hissing, buzzing), muffled hearing, needing to lip-read in a pub you handled easily before — these are overload, not trifles. Ears still ringing the next morning means it was too loud; repeated overloads sum over years toward permanent high-frequency loss that first steals consonants (s, f, th) and birdsong. A simple test: if you must raise your voice to be heard at arm's length (about 70+ dBA background), the environment is already loud enough to plan protection.
Seek prompt medical assessment for persistent ringing beyond 24 hours, sudden one-sided loss, severe dizziness, or hearing loss after a blast or blow — early audiometry documents the baseline and guides treatment. This article is educational and cannot diagnose; for personal advice see an audiologist or ENT physician. For day-to-day awareness, our meter's Leq plus the exposure calculator show where you stand before symptoms do.
Work: what applies in the US, UK and EU — and what employers must do
Under OSHA (US), employers must run a hearing-conservation programme from 85 dBA 8-hour TWA (action level), with audiometry, protection and training; the PEL is 90 dBA. Under the EU directive and UK Control of Noise at Work Regulations, duties start at 80 dBA (assess, offer protection, inform) and tighten at 85 dBA (enforce use, designate zones, health surveillance), with an exposure limit of 87 dBA accounting for protection. Control follows the hierarchy: first eliminate or quiet the source (buy quieter tools — compare dB in datasheets, where 3 dB less is half the energy), then engineering (enclosures, damping, maintenance), then organisation (rotation, quiet breaks, signage), and only last personal protection.
Phone and browser readings never replace a normed assessment with calibrated kit — but they find suspect areas fast. Walk the floor with 60-second Leq per workstation, note peaks and dBC for bass-heavy machines, export CSV, and hand the log to the safety officer. That screening conversation, with data, is exactly what our methodology and validation notes are written to support.
Practical everyday protection: measure, quiet, protect
Measure instead of guessing: bedroom at night (target under 35 dB, WHO suggests below 45 dB with peaks controlled), children's room, home-office desk (concentration drops measurably above 55 dBA), favourite café seat, rehearsal spot. Quiet the source: pick appliances by datasheet dB, service rattles, seal window and door gaps (leaks cost 5–15 dB), add rugs, curtains and bookshelves against reverberation (2–5 dB less tail, far calmer feel), decouple washers and speakers with rubber/Felt. Protect the ear: foam plugs (NRR 25–33 dB if fitted well), filtered music plugs for venues, earmuffs for DIY — fit matters more than rating; a poorly fitted 33 dB plug protects less than a well-fitted 20 dB one.
For babies and small children: keep white-noise machines under 50 dB at the crib and off all night if possible, never place them inside the cot, and measure with the meter at crib position — adult “quiet” at the door can be loud at the pillow. For sleep, a steady fan near 40 dB often masks peaks better than silence; for study, steady 45–55 dBA beats fluctuating 60+ with spikes.
Your one-sentence rule — and what to measure this week
Below 70 dBA stay relaxed; 70–85 dBA design consciously (distance, duration, layout); above 85 dBA protect consistently and track dose with Leq. This week: log bedroom night Leq, desk day Leq, and one leisure peak (commute, gym, venue) — three 60-second measurements that reveal where your personal dose actually comes from. Then read everyday sounds with levels, the measuring workflow, and quieting your home step by step.
Educational reference only — not medical or legal advice. For hearing concerns consult a qualified professional; for workplace compliance use certified measurements.