OSHA medical surveillance trigger thresholds by substance
The airborne exposure level that triggers mandatory medical surveillance under each OSHA substance-specific standard (29 CFR 1910 Subpart Z), compared across all regulated substances. Each record is one substance, carrying its action level, PEL, the exposure duration that triggers surveillance, the medical exam scope and frequency, biological monitoring requirements if any, and the record retention period. Answers 'what is the action level for lead', 'at what exposure must I provide medical exams for benzene workers', 'how often does cadmium biological monitoring need to happen', and 'which OSHA substances require 40-year record retention'. The action level is typically half the PEL but not always, and the surveillance trigger conditions vary wildly: lead uses blood lead levels, cadmium uses urine cadmium, and most others use airborne concentration plus days-per-year thresholds.
Records23
Sources23
Verified
Review by
LicenceUS federal regulation — 17 USC 105, no copyright
The data
| Substance | CFR section | PEL | Surveillance trigger | Exam frequency | Record retention | Action level |
|---|---|---|---|---|---|---|
| 1,2-dibromo-3-chloropropane | 1910.1044 | 1 part DBCP per billion parts of air (ppb) as an 8-hour time-weighted average | employees who work in regulated areas and employees who are subjected to DBCP exposures in an emergency situation | At the time of initial assignment, and annually thereafter, the employer shall provide a medical examination for employees who work in regulated areas | The employer shall maintain this record for at least 40 years or the duration of employment plus 20 years, whichever is longer | |
| 1,3-Butadiene | 1910.1051 | one (1) part BD per million parts of air (ppm) measured as an eight (8)-hour time-weighted average | each employee with exposure to BD at concentrations at or above the action level on 30 or more days or for employees who have or may have exposure to BD at or above the PELs on 10 or more days a year | Every 3 years after the initial physical examination | Medical screening and surveillance records shall be maintained for each employee for the duration of employment plus 30 years | 0.5 ppm calculated as an eight (8)-hour time-weighted average |
| 13 Carcinogens (4-Nitrobiphenyl, etc.) | 1910.1003 | employees considered for assignment to enter regulated areas, and for authorized employees | Authorized employees shall be provided periodic physical examinations, not less often than annually, following the preassignment examination | |||
| Acrylonitrile | 1910.1045 | two (2) parts acrylonitrile per million parts of air (2 ppm) as an eight (8)-hour time-weighted average | each employee who is or will be exposed to AN at or above the action level, without regard to the use of respirators | at least annually for all employees specified in paragraph (n)(1) of this section | The employer shall assure that this record be maintained for at least forty (40) years, or for the duration of employment plus twenty (20) years, whichever is longer | 1 ppm as an eight (8)-hour time-weighted average |
| Asbestos | 1910.1001 | 0.1 fiber per cubic centimeter of air as an eight (8)-hour time-weighted average (TWA) | exposed to airborne concentrations of fibers of asbestos at or above the TWA and/or excursion limit | Periodic medical examinations shall be made available annually | this record is maintained for the duration of employment plus thirty (30) years | |
| Benzene | 1910.1028 | one part of benzene per million parts of air (1 ppm) as an 8-hour time-weighted average | employees who are or may be exposed to benzene at or above the action level 30 or more days per year | a medical examination annually following the previous examination | The employer shall maintain this record for at least the duration of employment plus 30 years | an airborne concentration of benzene of 0.5 ppm calculated as an 8-hour time-weighted average |
| Beryllium | 1910.1024 | an airborne concentration of beryllium in excess of 0.2 µg/m 3 calculated as an 8-hour TWA | Who is or is reasonably expected to be exposed at or above the action level for more than 30 days per year | At least every two years thereafter | The employer must ensure that medical records are maintained and made available in accordance with the Records Access standard | a concentration of airborne beryllium of 0.1 micrograms per cubic meter of air (µg/m 3) calculated as an 8-hour time-weighted average (TWA) |
| Bloodborne pathogens | 1910.1030 | The employer shall make available the hepatitis B vaccine and vaccination series to all employees who have occupational exposure, and post-exposure evaluation and follow-up to all employees who have had an exposure incident | The employer shall maintain the records required by paragraph (h) for at least the duration of employment plus 30 years | |||
| Cadmium | 1910.1027 | five micrograms per cubic meter of air (5 µg/m 3), calculated as an eight-hour time-weighted average | all employees who are or may be exposed to cadmium at or above the action level | thereafter at least biennially. Biological sampling shall be provided at least annually | The employer shall assure that this record is maintained for the duration of employment plus thirty (30) years | an airborne concentration of cadmium of 2.5 micrograms per cubic meter of air (2.5 µg/m 3), calculated as an 8-hour time-weighted average (TWA) |
| Coke oven emissions | 1910.1029 | 150 micrograms per cubic meter of air (150 µg/m 3), averaged over any 8-hour period | all employees who are employed in a regulated area at least 30 days per year | at least annually | The employer shall maintain medical records required under paragraph (m)(2) of this section for at least 40 years, or for the duration of employment plus 20 years, whichever is longer | |
| Cotton dust | 1910.1043 | lint-free respirable cotton dust greater than 200 µg/m 3 mean concentration, averaged over an eight-hour period | Each employer covered by the standard shall institute a program of medical surveillance for all employees exposed to cotton dust | The employer shall provide at least annual medical surveillance for all employees exposed to cotton dust above the action level | The employer shall maintain this record for at least 20 years | The action level for yarn manufacturing and cotton washing operations is an airborne concentration of lint-free respirable cotton dust of 100 µg/m 3 mean concentration, averaged over an eight-hour period |
| Ethylene oxide | 1910.1047 | one (1) part EtO per million parts of air (1 ppm) as an 8-hour time-weighted average (8-hour TWA) | all employees who are or may be exposed to EtO at or above the action level, without regard to the use of respirators, for at least 30 days a year | At least annually each employee exposed at or above the action level for at least 30 days in the past year | The employer shall ensure that this record is maintained for the duration of employment plus thirty (30) years | 0.5 ppm calculated as an eight (8)-hour time-weighted average |
| Formaldehyde | 1910.1048 | 0.75 parts formaldehyde per million parts of air (0.75 ppm) as an 8-hour TWA | all employees exposed to formaldehyde at concentrations at or exceeding the action level or exceeding the STEL | prior to assignment to a job where formaldehyde exposure is at or above the action level or above the STEL and annually thereafter | Medical records shall be kept for the duration of employment plus 30 years | 0.5 part formaldehyde per million parts of air (0.5 ppm) calculated as an eight (8)-hour time-weighted average (TWA) concentration |
| Hazardous waste operations and emergency response | 1910.120 | All employees who are or may be exposed to hazardous substances or health hazards at or above the permissible exposure limits | At least once every twelve months for each employee covered unless the attending physician believes a longer interval (not greater than biennially) is appropriate | This record shall be retained for the period specified and meet the criteria of | ||
| Hexavalent chromium | 1910.1026 | 5 micrograms per cubic meter of air (5 µgm/m 3), calculated as an 8-hour time-weighted average (TWA) | Who are or may be occupationally exposed to chromium (VI) at or above the action level for 30 or more days a year | The employer shall provide a medical examination: (i) Within 30 days after initial assignment, unless the employee has received a chromium (VI) related medical examination that meets the requirements of this paragraph within the last twelve months; (ii) Annually | The employer shall ensure that medical records are maintained and made available in accordance with | a concentration of airborne chromium (VI) of 2.5 micrograms per cubic meter of air (2.5 µgm/m 3) calculated as an 8-hour time-weighted average (TWA) |
| Inorganic arsenic | 1910.1018 | 10 micrograms per cubic meter of air (10 µg/m 3), averaged over any 8-hour period | All employees who are or will be exposed above the action level, without regard to the use of respirators, at least 30 days per year | Examinations must be provided in accordance with paragraphs (n)(2)(i) and (n)(2)(ii)(B) and (C) of this section at least annually | The employer shall maintain or assure that the physician maintains those medical records for at least 40 years, or for the duration of employment plus 20 years whichever is longer | a concentration of inorganic arsenic of 5 micrograms per cubic meter of air (5 µg/m 3) averaged over any eight (8) hour period |
| Lead | 1910.1025 | fifty micrograms per cubic meter of air (50 µg/m 3) averaged over an 8-hour period | all employees who are or may be exposed at or above the action level for more than 30 days per year | At least annually for each employee for whom a blood sampling test conducted at any time during the preceding 12 months indicated a blood lead level at or above 40 µg/100 g | The employer shall maintain or assure that the physician maintains those medical records for at least 40 years, or for the duration of employment plus 20 years, whichever is longer | an airborne concentration of lead of 30 micrograms per cubic meter of air (30 µg/m 3) averaged over an 8-hour period |
| Methylene chloride | 1910.1052 | twenty-five parts of MC per million parts of air (25 ppm) as an 8-hour TWA | at or above the action level on 30 or more days per year, or above the 8-hour TWA PEL or the STEL on 10 or more days per year | The employer shall update the medical and work history for each affected employee annually | The employer shall ensure that this record is maintained for the duration of employment plus thirty (30) years | 12.5 parts per million (ppm) calculated as an eight (8)-hour time-weighted average (TWA) |
| Methylenedianiline | 1910.1050 | an airborne concentration of MDA in excess of ten parts per billion (10 ppb) as an 8-hour time-weighted average | Employees exposed at or above the action level for 30 or more days per year | a medical examination at least annually following the initial examination | The employer shall maintain this record for at least the duration of employment plus 30 years | 5 ppb as an eight (8)-hour time-weighted average |
| Occupational noise exposure | 1910.95 | whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent | At least annually after obtaining the baseline audiogram, the employer shall obtain a new audiogram for each employee exposed at or above an 8-hour time-weighted average of 85 decibels | an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent | ||
| Respirable crystalline silica | 1910.1053 | an airborne concentration of respirable crystalline silica in excess of 50 µg/m 3, calculated as an 8-hour TWA | each employee who will be occupationally exposed to respirable crystalline silica at or above the action level for 30 or more days per year | at least every three years, or more frequently if recommended by the PLHCP | The employer shall ensure that medical records are maintained and made available in accordance with | a concentration of airborne respirable crystalline silica of 25 µg/m 3, calculated as an 8-hour TWA |
| Respiratory protection | 1910.134 | Before the employee is fit tested or required to use the respirator in the workplace | Records of medical evaluations required by this section must be retained and made available in accordance with | |||
| Vinyl chloride | 1910.1017 | No employee may be exposed to vinyl chloride at concentrations greater than 1 ppm averaged over any 8-hour period | exposed, without regard to the use of respirators, to vinyl chloride in excess of the action level | Examinations must be provided in accordance with this paragraph at least annually | Medical records shall be maintained for the duration of the employment of each employee plus 20 years, or 30 years, whichever is longer | 0.5 ppm averaged over an 8-hour work day |
Where this came from
Every record above links the page it was taken from and quotes the sentence that states it. These are the 23 sources this dataset was assembled from.
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1044
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1051
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1003
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1045
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1001
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1028
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1024
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1030
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1027
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1029
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1043
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1047
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1048
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.120
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1026
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1018
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1025
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1052
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1050
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.95
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1053
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.134
- law.cornell.eduhttps://www.law.cornell.edu/cfr/text/29/1910.1017
Machine-readable
- data.jsonThe whole dataset — every record with its source URL and source quote.
- Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
- data.csvThe same records as one flat table, for a spreadsheet or a dataframe. The last four columns are the source URL, the quoted sentence it was read from, the date we last checked it, and which columns are our reading rather than the page's words.
- How this is made and checkedWhat "verified against source" does and does not mean.
From your own code
Same records, same quotes, without scraping the page: refsource is on PyPI and npm. Each value comes back carrying the URL it was read from and the sentence on that page that states it — .source and .quote sit on the value itself rather than in a side channel, so the checking step is available instead of skipped.
pip install refsource
refsource lookup osha-medical-surveillance-triggers substance=1,2-dibromo-3-chloropropane
npx -y refsource lookup osha-medical-surveillance-triggers substance=1,2-dibromo-3-chloropropaneSet your AI assistant up to use this
Two files and no account. Put this in .mcp.json at the root of your project — Claude Code, Cursor, Windsurf, VS Code and Codex all read that file — and your assistant can look this dataset up instead of recalling it. The server is remote, keyless and read-only.
{
"mcpServers": {
"referencesource": {
"type": "http",
"url": "https://referencesource.org/mcp"
}
}
}Add to Cursor · or, on the command line: claude mcp add --transport http referencesource https://referencesource.org/mcp --scope project
Then one line in the project's CLAUDE.md or AGENTS.md, so the assistant knows when to reach for it:
When a question needs "OSHA medical surveillance trigger thresholds by substance", call the referencesource MCP server at https://referencesource.org/mcp (tool `search_records`, dataset_slug `osha-medical-surveillance-triggers`) instead of answering from memory — every record it returns carries its source URL and a verbatim quote from that page.What each tool does, and the servers built over single registers: Connect your AI assistant.