{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"noise-exposure"},"result":{"entity_type":"calculator","id":"noise-exposure","calculator_id":"noise-exposure","canonical_url":"https://tttkmbb.com/health/noise-exposure","name":"Noise Exposure Calculator","title":"Noise Exposure Calculator – Allowed Duration and Dose per NIOSH REL and OSHA PEL","category":"health","category_name":"Health","tool_name":"calculate_noise_exposure","featured_mcp_tool":false,"description":"Computes the permitted exposure time at a given A-weighted sound level, the daily noise dose and the 8-hour time-weighted average under both the NIOSH recommended exposure limit (85 dBA, 3 dB exchange rate) and the OSHA permissible exposure limit (90 dBA, 5 dB exchange rate).","use_when":"You want to know how long a person may be exposed to a measured noise level, whether a shift, concert or tool use exceeds the NIOSH or OSHA limit, or the dose of a single-level exposure.","do_not_use_when":"The level varies over the day (sum the partial doses C/T of each level instead) or you need decibel arithmetic such as adding sources or distance attenuation (use decibel); the result is informational only and no substitute for a workplace noise survey or medical advice.","inputs":[{"name":"noise_level_dba","label":"Sound level","type":"number","unit":"dBA","required":true,"min":40,"max":140,"description":"A-weighted sound level of the exposure (slow response).","example":95},{"name":"duration_hours","label":"Exposure duration","type":"number","unit":"h","required":true,"max":24,"exclusive_min":0,"description":"Length of the exposure at that level.","example":2},{"name":"standard","label":"Standard","type":"enum","required":false,"default":"niosh","values":[{"value":"niosh","label":"NIOSH REL (85 dBA, 3 dB exchange rate)"},{"value":"osha","label":"OSHA PEL (90 dBA, 5 dB exchange rate)"}],"description":"Criterion used for exceeds_limit, time_weighted_average_dba and hearing_protection_recommended; both standards are always computed.","example":"niosh"}],"outputs":[{"name":"allowed_duration_hours_niosh","label":"Allowed duration (NIOSH)","type":"number","unit":"h","decimals":2,"description":"8 / 2^((L − 85) / 3): time at this level that reaches 100 % of the NIOSH REL."},{"name":"allowed_duration_hours_osha","label":"Allowed duration (OSHA)","type":"number","unit":"h","decimals":2,"description":"8 / 2^((L − 90) / 5): time at this level that reaches 100 % of the OSHA PEL (Table G-16)."},{"name":"dose_percent_niosh","label":"Dose (NIOSH)","type":"number","unit":"%","decimals":1,"description":"100 × duration_hours / allowed_duration_hours_niosh."},{"name":"dose_percent_osha","label":"Dose (OSHA)","type":"number","unit":"%","decimals":1,"description":"100 × duration_hours / allowed_duration_hours_osha."},{"name":"exceeds_limit","label":"Exceeds limit","type":"boolean","decimals":4,"description":"true when the dose under the selected standard is above 100 %."},{"name":"time_weighted_average_dba","label":"8-hour TWA","type":"number","unit":"dBA","decimals":1,"description":"Equivalent 8-hour time-weighted average for the selected standard: 10·log10(D/100) + 85 (NIOSH) or 16.61·log10(D/100) + 90 (OSHA)."},{"name":"hearing_protection_recommended","label":"Hearing protection recommended","type":"boolean","decimals":4,"description":"true when the TWA reaches 85 dBA: dose ≥ 50 % under OSHA (action level, hearing conservation program) or ≥ 100 % under NIOSH (REL)."},{"name":"comparison_table","label":"NIOSH allowed minutes by level","type":"object","decimals":1,"description":"NIOSH allowed exposure in minutes keyed by sound level in dBA (85, 88, 91, 94, 97, 100)."}],"input_schema":{"type":"object","properties":{"noise_level_dba":{"description":"A-weighted sound level of the exposure (slow response). Unit: dBA.","type":"number","minimum":40,"maximum":140,"examples":[95],"x-unit":"dBA"},"duration_hours":{"description":"Length of the exposure at that level. Unit: h.","type":"number","maximum":24,"exclusiveMinimum":0,"examples":[2],"x-unit":"h"},"standard":{"description":"Criterion used for exceeds_limit, time_weighted_average_dba and hearing_protection_recommended; both standards are always computed.","type":"string","enum":["niosh","osha"],"default":"niosh","examples":["niosh"]}},"additionalProperties":false,"required":["noise_level_dba","duration_hours"]},"output_schema":{"type":"object","properties":{"allowed_duration_hours_niosh":{"description":"8 / 2^((L − 85) / 3): time at this level that reaches 100 % of the NIOSH REL. Unit: h.","type":"number","x-unit":"h"},"allowed_duration_hours_osha":{"description":"8 / 2^((L − 90) / 5): time at this level that reaches 100 % of the OSHA PEL (Table G-16). Unit: h.","type":"number","x-unit":"h"},"dose_percent_niosh":{"description":"100 × duration_hours / allowed_duration_hours_niosh. Unit: %.","type":"number","x-unit":"%"},"dose_percent_osha":{"description":"100 × duration_hours / allowed_duration_hours_osha. Unit: %.","type":"number","x-unit":"%"},"exceeds_limit":{"description":"true when the dose under the selected standard is above 100 %.","type":"boolean"},"time_weighted_average_dba":{"description":"Equivalent 8-hour time-weighted average for the selected standard: 10·log10(D/100) + 85 (NIOSH) or 16.61·log10(D/100) + 90 (OSHA). Unit: dBA.","type":"number","x-unit":"dBA"},"hearing_protection_recommended":{"description":"true when the TWA reaches 85 dBA: dose ≥ 50 % under OSHA (action level, hearing conservation program) or ≥ 100 % under NIOSH (REL).","type":"boolean"},"comparison_table":{"description":"NIOSH allowed exposure in minutes keyed by sound level in dBA (85, 88, 91, 94, 97, 100).","type":"object"}}},"formula":"NIOSH: T = 8 / 2^((noise_level_dba − 85) / 3) h; OSHA: T = 8 / 2^((noise_level_dba − 90) / 5) h; dose D = 100 × duration_hours / T; TWA = 10 × log10(D / 100) + 85 (NIOSH) or 16.61 × log10(D / 100) + 90 (OSHA)","method":"NIOSH (1998) recommends an 85 dBA 8-hour TWA with a 3 dB exchange rate (equal energy); OSHA 29 CFR 1910.95 enforces a 90 dBA PEL with a 5 dB exchange rate and an 85 dBA action level (dose 50 %). Neither integrates levels below 80 dBA, and no exposure above 115 dBA continuous or 140 dB peak is permitted. Informational only.","sources":[{"name":"NIOSH (1998) Criteria for a Recommended Standard: Occupational Noise Exposure, DHHS (NIOSH) Publication 98-126","url":"https://www.cdc.gov/niosh/docs/98-126/","type":"government","retrieved_at":"2026-09-24"},{"name":"OSHA 29 CFR 1910.95 – Occupational noise exposure","url":"https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.95","type":"standard","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"95 dBA for 2 hours (NIOSH)","inputs":{"noise_level_dba":95,"duration_hours":2,"standard":"niosh"},"expected":{"allowed_duration_hours_niosh":0.79,"allowed_duration_hours_osha":4,"dose_percent_niosh":252,"dose_percent_osha":50,"exceeds_limit":true,"time_weighted_average_dba":89,"hearing_protection_recommended":true,"comparison_table":{"85":480,"88":240,"91":120,"94":60,"97":30,"100":15}},"url":"https://tttkmbb.com/api/v1/calculate/noise-exposure?noise_level_dba=95&duration_hours=2&standard=niosh"},{"name":"100 dBA for 30 minutes (OSHA)","inputs":{"noise_level_dba":100,"duration_hours":0.5,"standard":"osha"},"expected":{"allowed_duration_hours_niosh":0.25,"allowed_duration_hours_osha":2,"dose_percent_niosh":200,"dose_percent_osha":25,"exceeds_limit":false,"time_weighted_average_dba":80,"hearing_protection_recommended":false},"url":"https://tttkmbb.com/api/v1/calculate/noise-exposure?noise_level_dba=100&duration_hours=0.5&standard=osha"}],"faq":[{"q":"Why do NIOSH and OSHA differ so much?","a":"NIOSH halves the allowed time for every 3 dB increase (equal energy rule) starting from 85 dBA, OSHA for every 5 dB starting from 90 dBA. At 95 dBA that is 47.6 minutes versus 4 hours; NIOSH's limit is the health-based recommendation, OSHA's the enforceable minimum in the US."},{"q":"How do I handle several noise levels in one day?","a":"Compute the dose of each period separately (100 × C/T) and add them; the total must stay at or below 100 %. Run this calculator once per level and sum the dose outputs."},{"q":"What about the EU?","a":"EU Directive 2003/10/EC uses a 3 dB exchange rate like NIOSH with an exposure limit of 87 dBA and action values of 80 and 85 dBA (8-hour Lex), so the NIOSH allowed duration is the closer comparison."}],"tags":["noise exposure","noise dose","niosh rel","osha pel","permissible exposure time","hearing protection"],"related":[{"calculator_id":"decibel","reason":"Add sound sources or convert between sound level and intensity."}],"links":{"html":"https://tttkmbb.com/health/noise-exposure","markdown":"https://tttkmbb.com/health/noise-exposure.md","json":"https://tttkmbb.com/health/noise-exposure.json","api":"https://tttkmbb.com/api/v1/calculate/noise-exposure","schema":"https://tttkmbb.com/api/v1/calculators/noise-exposure","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:48:18Z","next_actions":[{"tool":"run_calculator","calculator_id":"noise-exposure","reason":"Run Noise Exposure Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/health/noise-exposure.md"}}