1910.1000(b): Table Z-2 Exposure Limits
Employee exposure to substances in Table Z-2 must not exceed the 8-hour time weighted average in any 8-hour shift of a 40-hour week, and must not exceed the acceptable ceiling at any time during a shift, except for the limited peak time and concentration listed in the table.
Key takeaways
- 1910.1000(b) is part of OSHA's general industry standards (29 CFR Part 1910).
- OSHA cited it 12 times in the last 3 years, in 12 inspections, with $395,268 in current penalties.
- 3 deaths are linked to inspections that cited this rule.
- Most citations: NM (1), SD (1), CO (1).
- Related part: 1910.1000(b)(2) Acceptable ceiling concentrations (9 citations).
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In this article
What this rule covers
29 CFR 1910.1000(b) ("Table Z-2") is one requirement inside 1910.1000 Air contaminants, an OSHA general industry standard (Part 1910). It includes 3 sub-paragraphs. The official text below is copied word for word from the Electronic Code of Federal Regulations (eCFR). The numbers, injury cases and training on this page show how OSHA enforces it on real job sites.
Official text
(b) Table Z-2. An employee's exposure to any substance listed in Table Z-2 shall not exceed the exposure limits specified as follows: 12 citations
(1) 8-hour time weighted averages. An employee's exposure to any substance listed in Table Z-2, in any 8-hour work shift of a 40-hour work week, shall not exceed the 8-hour time weighted average limit given for that substance in Table Z-2. Open (b)(1) 3 citations
(2) Acceptable ceiling concentrations. An employee's exposure to a substance listed in Table Z-2 shall not exceed at any time during an 8-hour shift the acceptable ceiling concentration limit given for the substance in the table, except for a time period, and up to a concentration not exceeding the maximum duration and concentration allowed in the column under “acceptable maximum peak above the acceptable ceiling concentration for an 8-hour shift.” Open (b)(2) 9 citations
(3) Example. During an 8-hour work shift, an employee may be exposed to a concentration of Substance A (with a 10 ppm TWA, 25 ppm ceiling and 50 ppm peak) above 25 ppm (but never above 50 ppm) only for a maximum period of 10 minutes. Such exposure must be compensated by exposures to concentrations less than 10 ppm so that the cumulative exposure for the entire 8-hour work shift does not exceed a weighted average of 10 ppm.
Source: eCFR, text current as of 2026-10-15. Read all of 1910.1000.
Export the list: 12 inspections cited 1910.1000(b) in the last 3 years, with employer, location, penalty and date.
Purple Belt, $59/moInjuries linked to this rule
3 deaths are linked to inspections where OSHA cited 1910.1000(b).
At 10:45 a.m. on August 1, 2024, an employee was found unconscious after pressure washing the inside of a walk-in cooler with a gas operated pressure washer. The employee was killed due to suspected carbon monoxide poisoning.
Full case list with employer, penalty, filters and download is part of OSHA Data (Purple Belt).
Unlock with Purple BeltWhere and how often it was cited
| Year | Citations |
|---|---|
| 2024 | 3 |
| 2025 | 7 |
| 2026 | 2 |
Top states: NM (1), SD (1), CO (1), MS (1), DC (1)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| DARLING INGREDIENTS INC. | GRAPELAND, TX | $165,514 |
| WOODLAND PULP, LLC | BAILEYVILLE, ME | $165,514 |
| CATALYST REFINERS, INC. | NITRO, WV | $16,550 |
| THE WESTERN SUGAR COOPERATIVE | FORT MORGAN, CO | $16,131 |
| OLDE TYME FARMERS MARKET LLC | HATTIESBURG, MS | $11,000 |
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OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1910.1000(b).
Related parts of this rule
- 1910.1000(b)(2) Acceptable ceiling concentrations 9 citations
- 1910.1000(b)(1) 8-hour time weighted averages 3 citations
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Frequently asked questions
What is the 8-hour TWA limit under Table Z-2?
Exposure in any 8-hour shift of a 40-hour week shall not exceed the TWA limit given for the substance.
Can exposure go above the ceiling?
Only for the time period and up to the concentration allowed in the maximum peak column.
What does the rule's example show?
For a substance with a 10 ppm TWA, 25 ppm ceiling and 50 ppm peak, exposure above 25 ppm (never above 50 ppm) is allowed for a maximum of 10 minutes, balanced to keep the shift average at or below 10 ppm.
About this page
Sources
- 29 CFR 1910.1000 (eCFR), text current as of 2026-10-15
- U.S. Department of Labor enforcement data: OSHA inspections, citations and accident records, copied nightly; data as of 2026-11-06
3-year window. Federal OSHA only; state-plan rules are not counted. Plain-language text is a summary, not legal advice; the official text controls. Black Belt Safety is not part of OSHA or the Department of Labor.