also_reported listlengths 1 8 ⌀ | cas_number stringlengths 5 46 ⌀ | disagreements listlengths 0 2 ⌀ | id stringlengths 3 80 | pel_mgm3 stringlengths 1 11 ⌀ | pel_ppm stringclasses 46
values | source stringlengths 39 79 | source_quote stringlengths 19 139 | substance stringlengths 3 110 | url stringlengths 58 135 | verified_fields listlengths 2 8 | rel_statement stringclasses 20
values | rel_mgm3 stringclasses 81
values | rel_ppm stringclasses 37
values | ceiling_notation stringclasses 2
values | stel_mgm3 stringclasses 31
values | stel_ppm stringclasses 18
values | ceiling stringclasses 4
values |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0338.html",
"source_quote": "NIOSH REL C 2 mg/m3 [15-minute]",
"value": "C 2"
}
] | 123-31-9 | [] | hydroquinone | 2 | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Hydroquinone | 123-31-9 | - | 2 | - | | Hydroquinone | https://referencesource.org/workplace-exposure-limits/hydroquinone/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0340.html",
"source_quote": "NIOSH REL TWA 10 ppm (45 mg/m3)",
"value": "TWA 10"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/n... | 95136 | [] | indene | 48 | 10 | https://www.dir.ca.gov/title8/5155.html | 95136 | | Indene | 10 | 48 | Indene | https://referencesource.org/workplace-exposure-limits/indene/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0341.html",
"source_quote": "NIOSH REL TWA 0.1 mg/m3",
"value": "TWA 0.1"
}
] | 7440746 | [] | indium | 0.1 | null | https://www.dir.ca.gov/title8/5155.html | 7440746 | | Indium | -- | 0.1 | Indium | https://referencesource.org/workplace-exposure-limits/indium/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | null | null | indium-compounds | 0.1 | null | https://www.dir.ca.gov/title8/5155.html | Indium compounds | -- | 0.1 | Indium compounds | https://referencesource.org/workplace-exposure-limits/indium-compounds/ | [
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-28T00:00:00",
"field": "ceiling_notation",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "7553562 | | Iodine | 0.1 | 1 | C",
"value": "the values given in the PEL columns are ceiling values"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel... | 7553-56-2 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Iodine | 7553-56-2 | (C)0.1 | (C)1 | - |",
"value": "(C)0.1"
},
{
"as_... | iodine | (C)1 | (C)0.1 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Iodine | 7553-56-2 | (C)0.1 | (C)1 | - | | Iodine | https://referencesource.org/workplace-exposure-limits/iodine/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0343.html",
"source_quote": "NIOSH REL TWA 0.6 ppm (10 mg/m3)",
"value": "TWA 0.6"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg... | 75478 | [] | iodoform | 10 | 0.6 | https://www.dir.ca.gov/title8/5155.html | 75478 | | Iodoform | 0.6 | 10 | Iodoform | https://referencesource.org/workplace-exposure-limits/iodoform/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Iron oxide fume | 1309-37-1 | - | 10 | - |",
"value": "10"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement... | 1309-37-1 | [] | iron-oxide-dust-and-fume-as-fe | null | null | https://www.cdc.gov/niosh/npg/npgd0344.html | NIOSH REL TWA 5 mg/m3 | Iron oxide dust and fume (as Fe) | https://referencesource.org/workplace-exposure-limits/iron-oxide-dust-and-fume-as-fe/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 5 | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0345.html",
"source_quote": "NIOSH REL TWA 0.1 ppm (0.23 mg/m³) ST 0.2 ppm (0.45 mg/m³)",
"value": "TWA 0.1"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "htt... | 13463406 | [] | iron-pentacarbonyl-as-fe | 0.8 | 0.1 | https://www.dir.ca.gov/title8/5155.html | 13463406 | | Iron pentacarbonyl, as Fe | 0.1 | 0.8 | | 0.2 | 1.6 | Iron pentacarbonyl, as Fe | https://referencesource.org/workplace-exposure-limits/iron-pentacarbonyl-as-fe/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"stel_mgm3",
"stel_ppm",
"substance"
] | null | null | null | null | 1.6 | 0.2 | null |
null | null | null | iron-salts-soluble-as-fe | 1 | null | https://www.dir.ca.gov/title8/5155.html | Iron salts, soluble, as Fe | -- | 1 | Iron salts, soluble, as Fe | https://referencesource.org/workplace-exposure-limits/iron-salts-soluble-as-fe/ | [
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0347.html",
"source_quote": "NIOSH REL TWA 100 ppm (525 mg/m3)",
"value": "TWA 100"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/np... | 123-92-2 | [] | isoamyl-acetate | 525 | 100 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isoamyl acetate | 123-92-2 | 100 | 525 | - | | Isoamyl acetate | https://referencesource.org/workplace-exposure-limits/isoamyl-acetate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0348.html",
"source_quote": "NIOSH REL TWA 100 ppm (360 mg/m3) ST 125 ppm (450 mg/m3)",
"value": "TWA 100"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https... | 123513 | [] | isoamyl-alcohol-3-methylbutanol | 360 | 100 | https://www.dir.ca.gov/title8/5155.html | 123513 | | Isoamyl alcohol; 3-methylbutanol | 100 | 360 | | 125 | 450 | Isoamyl alcohol; 3-methylbutanol | https://referencesource.org/workplace-exposure-limits/isoamyl-alcohol-3-methylbutanol/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"stel_mgm3",
"stel_ppm",
"substance"
] | null | null | null | null | 450 | 125 | null |
null | 6032-29-7 | null | isoamyl-alcohol-secondary | null | null | https://www.cdc.gov/niosh/npg/npgd0349.html | NIOSH REL TWA 100 ppm (360 mg/m3) ST 125 ppm (450 mg/m3) | Isoamyl alcohol (secondary) | https://referencesource.org/workplace-exposure-limits/isoamyl-alcohol-secondary/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 360 | TWA 100 | null | null | null | null |
null | 75-28-5 | null | isobutane | null | null | https://www.cdc.gov/niosh/npg/npgd0350.html | NIOSH REL TWA 800 ppm (1900 mg/m3) | Isobutane | https://referencesource.org/workplace-exposure-limits/isobutane/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 1900 | TWA 800 | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0351.html",
"source_quote": "NIOSH REL TWA 150 ppm (700 mg/m3)",
"value": "TWA 150"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/np... | 110-19-0 | [] | isobutyl-acetate | 700 | 150 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isobutyl acetate | 110-19-0 | 150 | 700 | - | | Isobutyl acetate | https://referencesource.org/workplace-exposure-limits/isobutyl-acetate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0352.html",
"source_quote": "NIOSH REL TWA 50 ppm (150 mg/m3)",
"value": "TWA 50"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/... | 78-83-1 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Isobutyl alcohol | 78-83-1 | 100 | 300 | - |",
"value": "100"
},
{
"as... | isobutyl-alcohol | 300 | 100 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isobutyl alcohol | 78-83-1 | 100 | 300 | - | | Isobutyl alcohol | https://referencesource.org/workplace-exposure-limits/isobutyl-alcohol/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
null | 78-82-0 | null | isobutyronitrile | null | null | https://www.cdc.gov/niosh/npg/npgd0353.html | NIOSH REL TWA 8 ppm (22 mg/m3) | Isobutyronitrile | https://referencesource.org/workplace-exposure-limits/isobutyronitrile/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 22 | TWA 8 | null | null | null | null |
null | 26675467 | null | isoflurane | 15 | 2 | https://www.dir.ca.gov/title8/5155.html | 26675467 | | Isoflurane | 2 | 15 | Isoflurane | https://referencesource.org/workplace-exposure-limits/isoflurane/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0354.html",
"source_quote": "NIOSH REL TWA 50 ppm (270 mg/m3) [skin]",
"value": "TWA 50"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/nio... | 26952216 | [] | isooctyl-alcohol | 270 | 50 | https://www.dir.ca.gov/title8/5155.html | 26952216 | S | Isooctyl alcohol | 50 | 270 | Isooctyl alcohol | https://referencesource.org/workplace-exposure-limits/isooctyl-alcohol/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0355.html",
"source_quote": "NIOSH REL TWA 4 ppm (23 mg/m3)",
"value": "TWA 4"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npg... | 78-59-1 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Isophorone | 78-59-1 | 25 | 140 | - |",
"value": "25"
},
{
"as_of": "2... | isophorone | 140 | 25 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isophorone | 78-59-1 | 25 | 140 | - | | Isophorone | https://referencesource.org/workplace-exposure-limits/isophorone/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "4098719 | S | Isophorone diisocyanate; IPDI | 0.005 | 0.045 | | 0.02 | --",
"value": "0.005"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"sour... | 4098-71-9 | [] | isophorone-diisocyanate | null | null | https://www.cdc.gov/niosh/npg/npgd0356.html | NIOSH REL TWA 0.005 ppm (0.045 mg/m3) ST 0.02 ppm (0.180 mg/m3) [skin] | Isophorone diisocyanate | https://referencesource.org/workplace-exposure-limits/isophorone-diisocyanate/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 0.045 | TWA 0.005 | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "108214 | | Isopropyl acetate | 250 | 950 | | 310 | 1185",
"value": "310"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_mgm3",
"source": "https://www.... | 108-21-4 | [] | isopropyl-acetate | 950 | 250 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isopropyl acetate | 108-21-4 | 250 | 950 | - | | Isopropyl acetate | https://referencesource.org/workplace-exposure-limits/isopropyl-acetate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "67630 | | Isopropyl alcohol | 400 | 980 | | 500 | 1225",
"value": "500"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_mgm3",
"source": "https://www.d... | 67-63-0 | [] | isopropyl-alcohol | 980 | 400 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isopropyl alcohol | 67-63-0 | 400 | 980 | - | | Isopropyl alcohol | https://referencesource.org/workplace-exposure-limits/isopropyl-alcohol/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0362.html",
"source_quote": "NIOSH REL TWA 500 ppm (2100 mg/m3)",
"value": "TWA 500"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/n... | 108-20-3 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Isopropyl ether | 108-20-3 | 500 | 2100 | - |",
"value": "500"
},
{
"a... | isopropyl-ether | 2100 | 500 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isopropyl ether | 108-20-3 | 500 | 2100 | - | | Isopropyl ether | https://referencesource.org/workplace-exposure-limits/isopropyl-ether/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Isopropyl glycidyl ether (IGE) | 4016-14-2 | 50 | 240 | - |",
"value": "50"
},
{
"as_of": "2026-08-05T00:00:00",
"field"... | 4016-14-2 | [] | isopropyl-glycidyl-ether | null | null | https://www.cdc.gov/niosh/npg/npgd0363.html | NIOSH REL C 50 ppm (240 mg/m3) [15-minute] | Isopropyl glycidyl ether | https://referencesource.org/workplace-exposure-limits/isopropyl-glycidyl-ether/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 240 | C 50 | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "75310 | | Isopropylamine | 5 | 12 | | 10 | 24",
"value": "10"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_mgm3",
"source": "https://www.dir.ca.gov/... | 75-31-0 | [] | isopropylamine | 12 | 5 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Isopropylamine | 75-31-0 | 5 | 12 | - | | Isopropylamine | https://referencesource.org/workplace-exposure-limits/isopropylamine/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement",
"source": "https://www.cdc.gov/niosh/npg/npgd0364.html",
"source_quote": "NIOSH REL TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)",
"value": "TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "... | 1332-58-7 | [] | kaolin | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Kaolin | 1332-58-7 | - | - | - | | Kaolin | https://referencesource.org/workplace-exposure-limits/kaolin/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 143-50-0 | null | kepone | null | null | https://www.cdc.gov/niosh/npg/npgd0365.html | NIOSH REL Ca TWA 0.001 mg/m3 | Kepone | https://referencesource.org/workplace-exposure-limits/kepone/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 0.001 | null | null | null | null | null |
null | 8008-20-6 | null | kerosene | null | null | https://www.cdc.gov/niosh/npg/npgd0366.html | NIOSH REL TWA 100 mg/m3 | Kerosene | https://referencesource.org/workplace-exposure-limits/kerosene/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 100 | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0367.html",
"source_quote": "NIOSH REL TWA 0.5 ppm (0.9 mg/m3) ST 1.5 ppm (3 mg/m3)",
"value": "TWA 0.5"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https:/... | 463-51-4 | [] | ketene | 0.9 | 0.5 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Ketene | 463-51-4 | 0.5 | 0.9 | - | | Ketene | https://referencesource.org/workplace-exposure-limits/ketene/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "L.P.G. (Liquefied petroleum gas) | 68476-85-7 | 1000 | 1800 | - |",
"value": "1000"
},
{
"as_of": "2026-08-05T00:00:00",
... | 68476-85-7 | [] | l-p-g | null | null | https://www.cdc.gov/niosh/npg/npgd0679.html | NIOSH REL TWA 1000 ppm (1800 mg/m3) | L.P.G. | https://referencesource.org/workplace-exposure-limits/l-p-g/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 1800 | TWA 1000 | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "7439921 | | Lead (metallic) and inorganic compounds, dust and fume, as Pb | -- | 0.01",
"value": "0.01"
}
] | 7439-92-1 | [] | lead | null | null | https://www.cdc.gov/niosh/npg/npgd0368.html | NIOSH REL TWA (8-hour) 0.050 mg/m3 See Appendix C | Lead | https://referencesource.org/workplace-exposure-limits/lead/ | [
"cas_number",
"rel_statement",
"substance"
] | TWA (8-hour) 0.050 mg/m3 See Appendix C | null | null | null | null | null | null |
null | 7758976 | null | lead-chromate-as-pb | 0.01 | null | https://www.dir.ca.gov/title8/5155.html | 7758976 | | Lead chromate, as Pb | -- | 0.01 | Lead chromate, as Pb | https://referencesource.org/workplace-exposure-limits/lead-chromate-as-pb/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement",
"source": "https://www.cdc.gov/niosh/npg/npgd0369.html",
"source_quote": "NIOSH REL TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)",
"value": "TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)"
}
] | 1317-65-3 | [] | limestone | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Limestone | 1317-65-3 | - | - | - | | Limestone | https://referencesource.org/workplace-exposure-limits/limestone/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 1317653 | null | limestone-calcium-carbonate-see-particulates-not-otherwise-regulated | null | null | https://www.dir.ca.gov/title8/5155.html | 1317653 | | Limestone; calcium carbonate; see Particulates not otherwise regulated | Limestone; calcium carbonate; see Particulates not otherwise regulated | https://referencesource.org/workplace-exposure-limits/limestone-calcium-carbonate-see-particulates-not-otherwise-regulated/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0370.html",
"source_quote": "NIOSH REL TWA 0.5 mg/m3 [skin]",
"value": "TWA 0.5"
}
] | 58-89-9 | [] | lindane | 0.5 | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Lindane | 58-89-9 | - | 0.5 | X | | Lindane | https://referencesource.org/workplace-exposure-limits/lindane/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0371.html",
"source_quote": "NIOSH REL TWA 0.025 mg/m3",
"value": "TWA 0.025"
}
] | 7580-67-8 | [] | lithium-hydride | 0.025 | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Lithium hydride | 7580-67-8 | - | 0.025 | - | | Lithium hydride | https://referencesource.org/workplace-exposure-limits/lithium-hydride/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | 4485125 | null | lithium-stearate | 10 | null | https://www.dir.ca.gov/title8/5155.html | 4485125 | | Lithium stearate | -- | 10 | Lithium stearate | https://referencesource.org/workplace-exposure-limits/lithium-stearate/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | 108-39-4 | null | m-cresol | null | null | https://www.cdc.gov/niosh/npg/npgd0155.html | NIOSH REL TWA 2.3 ppm (10 mg/m3) | m-Cresol | https://referencesource.org/workplace-exposure-limits/m-cresol/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 10 | TWA 2.3 | null | null | null | null |
null | 99-65-0 | [] | m-dinitrobenzene | null | null | https://www.cdc.gov/niosh/npg/npgd0232.html | NIOSH REL TWA 1 mg/m3 [skin] | m-Dinitrobenzene | https://referencesource.org/workplace-exposure-limits/m-dinitrobenzene/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 1 | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0463.html",
"source_quote": "NIOSH REL TWA 2 ppm (11 mg/m3) [skin]",
"value": "TWA 2"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/... | 99-08-1 | [] | m-isomer | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | m-isomer | 99-08-1 | - | - | - | | m-isomer | https://referencesource.org/workplace-exposure-limits/m-isomer/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0513.html",
"source_quote": "NIOSH REL TWA 5 mg/m3",
"value": "TWA 5"
}
] | 626175 | [] | m-phthalodinitrile | 5 | null | https://www.dir.ca.gov/title8/5155.html | 626175 | | m-Phthalodinitrile | -- | 5 | m-Phthalodinitrile | https://referencesource.org/workplace-exposure-limits/m-phthalodinitrile/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | 92-06-8 | null | m-terphenyl | null | null | https://www.cdc.gov/niosh/npg/npgd0592.html | NIOSH REL C 5 mg/m3 (0.5 ppm) | m-Terphenyl | https://referencesource.org/workplace-exposure-limits/m-terphenyl/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | C 5 | 0.5 | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement",
"source": "https://www.cdc.gov/niosh/npg/npgd0623.html",
"source_quote": "NIOSH REL See Appendix D",
"value": "See Appendix D"
}
] | 108441 | [] | m-toluidine | 9 | 2 | https://www.dir.ca.gov/title8/5155.html | 108441 | S | m-Toluidine | 2 | 9 | m-Toluidine | https://referencesource.org/workplace-exposure-limits/m-toluidine/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
null | 108-38-3 | null | m-xylene | null | null | https://www.cdc.gov/niosh/npg/npgd0669.html | NIOSH REL TWA 100 ppm (435 mg/m3) ST 150 ppm (655 mg/m3) | m-Xylene | https://referencesource.org/workplace-exposure-limits/m-xylene/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 435 | TWA 100 | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0671.html",
"source_quote": "NIOSH REL C 0.1 mg/m3 [skin]",
"value": "C 0.1"
}
] | 1477550 | [] | m-xylene-a-a-diamine | 0.1 | null | https://www.dir.ca.gov/title8/5155.html | 1477550 | S | m-Xylene-a,a′-diamine | -- | 0.1 | C | m-Xylene-a,a′-diamine | https://referencesource.org/workplace-exposure-limits/m-xylene-a-a-diamine/ | [
"cas_number",
"ceiling_notation",
"pel_mgm3",
"substance"
] | null | null | null | the values given in the PEL columns are ceiling values | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement",
"source": "https://www.cdc.gov/niosh/npg/npgd0373.html",
"source_quote": "NIOSH REL TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)",
"value": "TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)"
}
] | 546-93-0 | [] | magnesite | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Magnesite | 546-93-0 | - | - | - | | Magnesite | https://referencesource.org/workplace-exposure-limits/magnesite/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 13717005 | null | magnesite-magnesium-carbonate-see-particulates-not-otherwise-regulated | null | null | https://www.dir.ca.gov/title8/5155.html | 13717005 | | Magnesite; magnesium carbonate; see Particulates not otherwise regulated | Magnesite; magnesium carbonate; see Particulates not otherwise regulated | https://referencesource.org/workplace-exposure-limits/magnesite-magnesium-carbonate-see-particulates-not-otherwise-regulated/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement",
"source": "https://www.cdc.gov/niosh/npg/npgd0374.html",
"source_quote": "NIOSH REL See Appendix D",
"value": "See Appendix D"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir.ca.gov/t... | 1309-48-4 | [] | magnesium-oxide-fume | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Magnesium oxide fume | 1309-48-4 | - | - | - | | Magnesium oxide fume | https://referencesource.org/workplace-exposure-limits/magnesium-oxide-fume/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 557040 | null | magnesium-stearate | 10 | null | https://www.dir.ca.gov/title8/5155.html | 557040 | | Magnesium stearate | -- | 10 | Magnesium stearate | https://referencesource.org/workplace-exposure-limits/magnesium-stearate/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0375.html",
"source_quote": "NIOSH REL TWA 10 mg/m3 [skin]",
"value": "TWA 10"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir.ca.gov/title8/51... | 121-75-5 | [] | malathion | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Malathion | 121-75-5 | - | - | - | | Malathion | https://referencesource.org/workplace-exposure-limits/malathion/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0376.html",
"source_quote": "NIOSH REL TWA 1 mg/m3 (0.25 ppm)",
"value": "0.25"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/np... | 108-31-6 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Maleic anhydride | 108-31-6 | 0.25 | 1 | - |",
"value": "0.25"
},
{
"a... | maleic-anhydride | 1 | 0.25 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Maleic anhydride | 108-31-6 | 0.25 | 1 | - | | Maleic anhydride | https://referencesource.org/workplace-exposure-limits/maleic-anhydride/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
null | 542-78-9 | null | malonaldehyde | null | null | https://www.cdc.gov/niosh/npg/npgd0377.html | NIOSH REL Ca See Appendix A See Appendix C (Aldehydes) | Malonaldehyde | https://referencesource.org/workplace-exposure-limits/malonaldehyde/ | [
"cas_number",
"rel_statement",
"substance"
] | Ca See Appendix A See Appendix C (Aldehydes) | null | null | null | null | null | null |
null | 109-77-3 | null | malononitrile | null | null | https://www.cdc.gov/niosh/npg/npgd0378.html | NIOSH REL TWA 3 ppm (8 mg/m3) | Malononitrile | https://referencesource.org/workplace-exposure-limits/malononitrile/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 8 | TWA 3 | null | null | null | null |
null | null | null | manganese-and-compounds-as-mn | 0.2 | null | https://www.dir.ca.gov/title8/5155.html | Manganese and compounds, as Mn | -- | 0.2 | Manganese and compounds, as Mn | https://referencesource.org/workplace-exposure-limits/manganese-and-compounds-as-mn/ | [
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | 7439-96-5 (metal) | null | manganese-compounds-and-fume-as-mn | null | null | https://www.cdc.gov/niosh/npg/npgd0379.html | NIOSH REL TWA 1 mg/m3 ST 3 mg/m3 | Manganese compounds and fume (as Mn) | https://referencesource.org/workplace-exposure-limits/manganese-compounds-and-fume-as-mn/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 1 | null | null | null | null | null |
null | 7439-96-5 | null | manganese-compounds-as-mn | (C)5 | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Manganese compounds (as Mn) | 7439-96-5 | - | (C)5 | - | | Manganese compounds (as Mn) | https://referencesource.org/workplace-exposure-limits/manganese-compounds-as-mn/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0380.html",
"source_quote": "NIOSH REL TWA 0.1 mg/m3 [skin]",
"value": "TWA 0.1"
}
] | 12079651 | [] | manganese-cyclopentadienyl-tricarbonyl-as-mn | 0.1 | null | https://www.dir.ca.gov/title8/5155.html | 12079651 | S | Manganese, cyclopentadienyl-tricarbonyl, as Mn | -- | 0.1 | Manganese, cyclopentadienyl-tricarbonyl, as Mn | https://referencesource.org/workplace-exposure-limits/manganese-cyclopentadienyl-tricarbonyl-as-mn/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_mgm3",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "7439965 | | Manganese fume, as Mn | -- | 0.2 | | -- | 3",
"value": "3"
}
] | 7439-96-5 | [
{
"field": "pel_mgm3",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Manganese fume (as Mn) | 7439-96-5 | - | (C)5 | - |",
"value": "(C)5"
},
{
... | manganese-fume-as-mn | (C)5 | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Manganese fume (as Mn) | 7439-96-5 | - | (C)5 | - | | Manganese fume (as Mn) | https://referencesource.org/workplace-exposure-limits/manganese-fume-as-mn/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | null | null | manganese-tetroxide | 0.2 | null | https://www.dir.ca.gov/title8/5155.html | Manganese tetroxide | -- | 0.2 | Manganese tetroxide | https://referencesource.org/workplace-exposure-limits/manganese-tetroxide/ | [
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
null | 1317-35-7 | null | manganese-tetroxide-as-mn | null | null | https://www.cdc.gov/niosh/npg/npgd0381.html | NIOSH REL See Appendix D | Manganese tetroxide (as Mn) | https://referencesource.org/workplace-exposure-limits/manganese-tetroxide-as-mn/ | [
"cas_number",
"rel_statement",
"substance"
] | See Appendix D | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement",
"source": "https://www.cdc.gov/niosh/npg/npgd0382.html",
"source_quote": "NIOSH REL TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)",
"value": "TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)"
}
] | 1317-65-3 | [] | marble | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Marble | 1317-65-3 | - | - | - | | Marble | https://referencesource.org/workplace-exposure-limits/marble/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 7439976 | null | mercury-alkyls-as-hg | 0.01 | null | https://www.dir.ca.gov/title8/5155.html | 7439976 | S | Mercury alkyls, as Hg | -- | 0.01 | 0.04 mg/M3 | -- | 0.03 | Mercury alkyls, as Hg | https://referencesource.org/workplace-exposure-limits/mercury-alkyls-as-hg/ | [
"cas_number",
"ceiling",
"ceiling_notation",
"pel_mgm3",
"stel_mgm3",
"substance"
] | null | null | null | a ceiling value in addition to the TWA values | 0.03 | null | 0.04 mg/M3 |
null | 7439-97-6 | null | mercury-aryl-and-inorganic-as-hg | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Mercury (aryl and inorganic) (as Hg) | 7439-97-6 | - | (2) | - | | Mercury (aryl and inorganic) (as Hg) | https://referencesource.org/workplace-exposure-limits/mercury-aryl-and-inorganic-as-hg/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 7439976 | null | mercury-aryl-compounds-as-hg | 0.1 | null | https://www.dir.ca.gov/title8/5155.html | 7439976 | S | Mercury aryl compounds as Hg | | 0.1 | C | Mercury aryl compounds as Hg | https://referencesource.org/workplace-exposure-limits/mercury-aryl-compounds-as-hg/ | [
"cas_number",
"ceiling_notation",
"pel_mgm3",
"substance"
] | null | null | null | the values given in the PEL columns are ceiling values | null | null | null |
null | 7439-97-6 (metal) | null | mercury-compounds-except-organo-alkyls-as-hg | null | null | https://www.cdc.gov/niosh/npg/npgd0383.html | NIOSH REL NIOSH REL: Hg Vapor: TWA 0.05 mg/m3 [skin] Other: C 0.1 mg/m3 [skin] | Mercury compounds [except (organo) alkyls] (as Hg) | https://referencesource.org/workplace-exposure-limits/mercury-compounds-except-organo-alkyls-as-hg/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 0.05 | null | null | null | null | null |
null | 7439976 | null | mercury-metallic-and-inorganic-compounds-as-hg | 0.025 | null | https://www.dir.ca.gov/title8/5155.html | 7439976 | S | Mercury, metallic and inorganic compounds as Hg | -- | 0.025 | 0.1 mg/M3 | Mercury, metallic and inorganic compounds as Hg | https://referencesource.org/workplace-exposure-limits/mercury-metallic-and-inorganic-compounds-as-hg/ | [
"cas_number",
"ceiling",
"ceiling_notation",
"pel_mgm3",
"substance"
] | null | null | null | a ceiling value in addition to the TWA values | null | null | 0.1 mg/M3 |
null | 7439-97-6 | null | mercury-organo-alkyl-compounds-as-hg | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Mercury (organo) alkyl compounds (as Hg) | 7439-97-6 | - | (2) | - | | Mercury (organo) alkyl compounds (as Hg) | https://referencesource.org/workplace-exposure-limits/mercury-organo-alkyl-compounds-as-hg/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
null | 7439-97-6 | null | mercury-vapor-as-hg | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Mercury (vapor) (as Hg) | 7439-97-6 | - | (2) | - | | Mercury (vapor) (as Hg) | https://referencesource.org/workplace-exposure-limits/mercury-vapor-as-hg/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0385.html",
"source_quote": "NIOSH REL TWA 10 ppm (40 mg/m3)",
"value": "TWA 10"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/n... | 141-79-7 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Mesityl oxide | 141-79-7 | 25 | 100 | - |",
"value": "25"
},
{
"as_of"... | mesityl-oxide | 100 | 25 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Mesityl oxide | 141-79-7 | 25 | 100 | - | | Mesityl oxide | https://referencesource.org/workplace-exposure-limits/mesityl-oxide/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0386.html",
"source_quote": "NIOSH REL TWA 20 ppm (70 mg/m3) [skin]",
"value": "TWA 20"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/nios... | 79414 | [] | methacrylic-acid | 70 | 20 | https://www.dir.ca.gov/title8/5155.html | 79414 | S | Methacrylic acid | 20 | 70 | Methacrylic acid | https://referencesource.org/workplace-exposure-limits/methacrylic-acid/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
null | 74828 | null | methane | null | null | https://www.dir.ca.gov/title8/5155.html | 74828 | | Methane | (h) | -- | Methane | https://referencesource.org/workplace-exposure-limits/methane/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/npgd0387.html",
"source_quote": "NIOSH REL TWA 2.5 mg/m3",
"value": "TWA 2.5"
}
] | 16752775 | [] | methomyl | 2.5 | null | https://www.dir.ca.gov/title8/5155.html | 16752775 | S | Methomyl | -- | 2.5 | Methomyl | https://referencesource.org/workplace-exposure-limits/methomyl/ | [
"cas_number",
"pel_mgm3",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "72435 | | Methoxychlor; 1,1,1-trichloro-2, 2-bis(p-methoxyphenyl)ethane | -- | 10",
"value": "10"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_statement"... | 72-43-5 | [] | methoxychlor | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methoxychlor | 72-43-5 | - | - | - | | Methoxychlor | https://referencesource.org/workplace-exposure-limits/methoxychlor/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0389.html",
"source_quote": "NIOSH REL C 2 ppm (13.5 mg/m3) [60-minute]",
"value": "C 2"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/nio... | 76380 | [] | methoxyflurane | 13 | 2 | https://www.dir.ca.gov/title8/5155.html | 76380 | | Methoxyflurane | 2 | 13 | Methoxyflurane | https://referencesource.org/workplace-exposure-limits/methoxyflurane/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0405.html",
"source_quote": "NIOSH REL TWA 2 ppm (8 mg/m3) ST 4 ppm (16 mg/m3)",
"value": "TWA 2"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cd... | 137053 | [] | methyl-2-cyanoacrylate | 0.908 | 0.2 | https://www.dir.ca.gov/title8/5155.html | 137053 | | Methyl 2-cyanoacrylate | 0.2 | 0.908 | Methyl 2-cyanoacrylate | https://referencesource.org/workplace-exposure-limits/methyl-2-cyanoacrylate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "79209 | | Methyl acetate | 200 | 610 | | 250 | 760",
"value": "250"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_mgm3",
"source": "https://www.dir.c... | 79-20-9 | [] | methyl-acetate | 610 | 200 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl acetate | 79-20-9 | 200 | 610 | - | | Methyl acetate | https://referencesource.org/workplace-exposure-limits/methyl-acetate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl acetylene (Propyne) | 74-99-7 | 1000 | 1650 | - |",
"value": "1000"
},
{
"as_of": "2026-08-05T00:00:00",
"field":... | 74-99-7 | [] | methyl-acetylene | null | null | https://www.cdc.gov/niosh/npg/npgd0392.html | NIOSH REL TWA 1000 ppm (1650 mg/m3) | Methyl acetylene | https://referencesource.org/workplace-exposure-limits/methyl-acetylene/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 1650 | TWA 1000 | null | null | null | null |
null | 59355-75-8 | null | methyl-acetylene-propadiene-mixture | null | null | https://www.cdc.gov/niosh/npg/npgd0393.html | NIOSH REL TWA 1000 ppm (1800 mg/m3) ST 1250 ppm (2250 mg/m3) | Methyl acetylene-propadiene mixture | https://referencesource.org/workplace-exposure-limits/methyl-acetylene-propadiene-mixture/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 1800 | TWA 1000 | null | null | null | null |
null | null | null | methyl-acetylene-propadiene-mixture-mapp | 1,800 | 1,000 | https://www.dir.ca.gov/title8/5155.html | Methyl acetylene-propadiene mixture; MAPP | 1,000 | 1,800 | | 1250 | 2250 | Methyl acetylene-propadiene mixture; MAPP | https://referencesource.org/workplace-exposure-limits/methyl-acetylene-propadiene-mixture-mapp/ | [
"pel_mgm3",
"pel_ppm",
"stel_mgm3",
"stel_ppm",
"substance"
] | null | null | null | null | 2250 | 1250 | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0394.html",
"source_quote": "NIOSH REL TWA 10 ppm (35 mg/m3) [skin]",
"value": "TWA 10"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/nios... | 96-33-3 | [] | methyl-acrylate | 35 | 10 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl acrylate | 96-33-3 | 10 | 35 | X | | Methyl acrylate | https://referencesource.org/workplace-exposure-limits/methyl-acrylate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0397.html",
"source_quote": "NIOSH REL TWA 200 ppm (260 mg/m3) ST 250 ppm (325 mg/m3) [skin]",
"value": "TWA 200"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source":... | 67-56-1 | [] | methyl-alcohol | 260 | 200 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl alcohol | 67-56-1 | 200 | 260 | - | | Methyl alcohol | https://referencesource.org/workplace-exposure-limits/methyl-alcohol/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-28T00:00:00",
"field": "ceiling",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "74839 | S | Methyl bromide | 1 | 3.88 | 20 ppm",
"value": "20 ppm"
},
{
"as_of": "2026-09-28T00:00:00",
"field": "ceiling_notation",
"source": "https://www.... | 74-83-9 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl bromide | 74-83-9 | (C)20 | (C)80 | X |",
"value": "(C)20"
},
{
... | methyl-bromide | (C)80 | (C)20 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl bromide | 74-83-9 | (C)20 | (C)80 | X | | Methyl bromide | https://referencesource.org/workplace-exposure-limits/methyl-bromide/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-28T00:00:00",
"field": "pel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "74873 | | Methyl chloride | 50 | 105 | 300 ppm | 100 | 210",
"value": "50"
},
{
"as_of": "2026-09-28T00:00:00",
"field": "pel_mgm3",
"source": "https://www.... | 74-87-3 | [] | methyl-chloride | null | null | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl chloride | 74-87-3 | - | (2) | - | | Methyl chloride | https://referencesource.org/workplace-exposure-limits/methyl-chloride/ | [
"cas_number",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl chloroform (1,1,1-Trichloroethane) | 71-55-6 | 350 | 1900 | - |",
"value": "350"
},
{
"as_of": "2026-08-05T00:00:00",... | 71-55-6 | [] | methyl-chloroform | null | null | https://www.cdc.gov/niosh/npg/npgd0404.html | NIOSH REL C 350 ppm (1900 mg/m3) [15-minute] | Methyl chloroform | https://referencesource.org/workplace-exposure-limits/methyl-chloroform/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 1900 | C 350 | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "8022002 | S | Methyl demeton; a mixture of o,o-dimethyl o-(2-(ethylthio)ethyl) phosphorothioate and o,o-dimethyl S-(2-(ethylthio)-ethyl) phosphorothioate | -- | 0.5",
"val... | 8022-00-2 | [] | methyl-demeton | null | null | https://www.cdc.gov/niosh/npg/npgd0410.html | NIOSH REL TWA 0.5 mg/m3 [skin] | Methyl demeton | https://referencesource.org/workplace-exposure-limits/methyl-demeton/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 0.5 | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0416.html",
"source_quote": "NIOSH REL C 0.2 ppm (1.5 mg/m3)",
"value": "C 0.2"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/np... | 1338234 | [] | methyl-ethyl-ketone-peroxide | 1.5 | 0.2 | https://www.dir.ca.gov/title8/5155.html | 1338234 | | Methyl ethyl ketone peroxide | 0.2 | 1.5 | C | Methyl ethyl ketone peroxide | https://referencesource.org/workplace-exposure-limits/methyl-ethyl-ketone-peroxide/ | [
"cas_number",
"ceiling_notation",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | the values given in the PEL columns are ceiling values | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "107313 | | Methyl formate | 100 | 250 | | 150 | 375",
"value": "150"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "stel_mgm3",
"source": "https://www.dir.... | 107-31-3 | [] | methyl-formate | 250 | 100 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl formate | 107-31-3 | 100 | 250 | - | | Methyl formate | https://referencesource.org/workplace-exposure-limits/methyl-formate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl hydrazine (Monomethyl hydrazine) | 60-34-4 | (C)0.2 | (C)0.35 | X |",
"value": "(C)0.2"
},
{
"as_of": "2026-08-05T00:... | 60-34-4 | [] | methyl-hydrazine | null | null | https://www.cdc.gov/niosh/npg/npgd0419.html | NIOSH REL Ca C 0.04 ppm (0.08 mg/m3) [2-hr] | Methyl hydrazine | https://referencesource.org/workplace-exposure-limits/methyl-hydrazine/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 0.08 | C 0.04 | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0420.html",
"source_quote": "NIOSH REL Ca TWA 2 ppm (10 mg/m3) [skin]",
"value": "TWA 2"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/nio... | 74-88-4 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl iodide | 74-88-4 | 5 | 28 | X |",
"value": "5"
},
{
"as_of": "2... | methyl-iodide | 28 | 5 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl iodide | 74-88-4 | 5 | 28 | X | | Methyl iodide | https://referencesource.org/workplace-exposure-limits/methyl-iodide/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0421.html",
"source_quote": "NIOSH REL TWA 50 ppm (240 mg/m3)",
"value": "TWA 50"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/npg/... | 110-12-3 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl isoamyl ketone | 110-12-3 | 100 | 475 | - |",
"value": "100"
},
{
... | methyl-isoamyl-ketone | 475 | 100 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl isoamyl ketone | 110-12-3 | 100 | 475 | - | | Methyl isoamyl ketone | https://referencesource.org/workplace-exposure-limits/methyl-isoamyl-ketone/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0422.html",
"source_quote": "NIOSH REL TWA 25 ppm (100 mg/m3) ST 40 ppm (165 mg/m3) [skin]",
"value": "TWA 25"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "h... | 108-11-2 | [] | methyl-isobutyl-carbinol | 100 | 25 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl isobutyl carbinol | 108-11-2 | 25 | 100 | X | | Methyl isobutyl carbinol | https://referencesource.org/workplace-exposure-limits/methyl-isobutyl-carbinol/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0423.html",
"source_quote": "NIOSH REL TWA 0.02 ppm (0.05 mg/m³) [skin]",
"value": "TWA 0.02"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.go... | 624-83-9 | [] | methyl-isocyanate | 0.05 | 0.02 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl isocyanate | 624-83-9 | 0.02 | 0.05 | X | | Methyl isocyanate | https://referencesource.org/workplace-exposure-limits/methyl-isocyanate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0424.html",
"source_quote": "NIOSH REL TWA 200 ppm (705 mg/m3)",
"value": "TWA 200"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/np... | 563804 | [] | methyl-isopropyl-ketone | 705 | 200 | https://www.dir.ca.gov/title8/5155.html | 563804 | | Methyl isopropyl ketone | 200 | 705 | Methyl isopropyl ketone | https://referencesource.org/workplace-exposure-limits/methyl-isopropyl-ketone/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0425.html",
"source_quote": "NIOSH REL C 0.5 ppm (1 mg/m3) [15-minute]",
"value": "C 0.5"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/ni... | 74-93-1 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl mercaptan | 74-93-1 | (C)10 | (C)20 | - |",
"value": "(C)10"
},
{
... | methyl-mercaptan | (C)20 | (C)10 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl mercaptan | 74-93-1 | (C)10 | (C)20 | - | | Methyl mercaptan | https://referencesource.org/workplace-exposure-limits/methyl-mercaptan/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0426.html",
"source_quote": "NIOSH REL TWA 100 ppm (410 mg/m3)",
"value": "TWA 100"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/np... | 80-62-6 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl methacrylate | 80-62-6 | 100 | 410 | - |",
"value": "100"
},
{
... | methyl-methacrylate | 410 | 100 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl methacrylate | 80-62-6 | 100 | 410 | - | | Methyl methacrylate | https://referencesource.org/workplace-exposure-limits/methyl-methacrylate/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_ppm",
"source": "https://www.cdc.gov/niosh/npg/npgd0399.html",
"source_quote": "NIOSH REL TWA 100 ppm (465 mg/m3)",
"value": "TWA 100"
},
{
"as_of": "2026-09-08T00:00:00",
"field": "rel_mgm3",
"source": "https://www.cdc.gov/niosh/np... | 110-43-0 | [
{
"field": "pel_ppm",
"versions": [
{
"as_of": "2026-08-05T00:00:00",
"source": "https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1",
"source_quote": "Methyl n-amyl ketone | 110-43-0 | 100 | 465 | - |",
"value": "100"
},
{
... | methyl-n-amyl-ketone | 465 | 100 | https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1 | Methyl n-amyl ketone | 110-43-0 | 100 | 465 | - | | Methyl n-amyl ketone | https://referencesource.org/workplace-exposure-limits/methyl-n-amyl-ketone/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "298000 | S | Methyl parathion; o,o-dimethyl o-(p-nitrophenyl) phosphorothioate | -- | 0.2",
"value": "0.2"
}
] | 298-00-0 | [] | methyl-parathion | null | null | https://www.cdc.gov/niosh/npg/npgd0427.html | NIOSH REL TWA 0.2 mg/m3 [skin] | Methyl parathion | https://referencesource.org/workplace-exposure-limits/methyl-parathion/ | [
"cas_number",
"rel_mgm3",
"substance"
] | null | TWA 0.2 | null | null | null | null | null |
[
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_ppm",
"source": "https://www.dir.ca.gov/title8/5155.html",
"source_quote": "681845 | | Methyl silicate; tetramethyl silicate | 1 | 6",
"value": "1"
},
{
"as_of": "2026-08-05T00:00:00",
"field": "pel_mgm3",
"source": "https://www.dir... | 681-84-5 | [] | methyl-silicate | null | null | https://www.cdc.gov/niosh/npg/npgd0428.html | NIOSH REL TWA 1 ppm (6 mg/m3) | Methyl silicate | https://referencesource.org/workplace-exposure-limits/methyl-silicate/ | [
"cas_number",
"rel_mgm3",
"rel_ppm",
"substance"
] | null | 6 | TWA 1 | null | null | null | null |
null | 1634044 | null | methyl-tert-butyl-ether-mtbe | 144 | 40 | https://www.dir.ca.gov/title8/5155.html | 1634044 | | Methyl tert-butyl ether; MTBE | 40 | 144 | Methyl tert-butyl ether; MTBE | https://referencesource.org/workplace-exposure-limits/methyl-tert-butyl-ether-mtbe/ | [
"cas_number",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | null | null | null | null |
null | 78944 | null | methyl-vinyl-ketone | 0.14 | 0.05 | https://www.dir.ca.gov/title8/5155.html | 78944 | S | Methyl vinyl ketone | 0.05 | 0.14 | C | Methyl vinyl ketone | https://referencesource.org/workplace-exposure-limits/methyl-vinyl-ketone/ | [
"cas_number",
"ceiling_notation",
"pel_mgm3",
"pel_ppm",
"substance"
] | null | null | null | the values given in the PEL columns are ceiling values | null | null | null |
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