Circular No. 09/2025/TT-BYT dated April 28, 2025 on National Technical Regulation on Permissible Exposure Limit Value of 70 Chemicals at the Workplace

CIRCULAR

ON NATIONAL TECHNICAL REGULATION ON PERMISSIBLE EXPOSURE LIMIT VALUE OF 70 CHEMICALS AT THE WORKPLACE

Pursuant to the Law on Occupational Safety and Hygiene in 2015;

Pursuant to the Law on Standards and Technical Regulations in 2006;

Pursuant to Decree No. 42/2025/ND-CP dated February 27, 2025 of the Government on functions, tasks, powers and organizational structure of the Ministry of Health of Vietnam;

Pursuant to Decree No. 127/2007/ND-CP dated August 01, 2007 of the Government detailing the implementation of a number of articles of the Law on Standards and Technical Regulations; Decree No. 78/2018/ND-CP dated June 15, 2018 of the Government amending a number of Articles of the Government's Decree No. 127/2007/ND-CP dated August 01, 2007, detailing the implementation of a number of Articles of the Law on Standards and Technical Regulations;

At the request of the Director General of the Vietnam Administration of Disease Prevention;

The Ministry of Health promulgates the Circular on National Technical Regulation on Permissible Exposure Limit Value of 70 Chemicals at the Workplace.

Article 1. National technical regulation on chemicals

The QCVN 01:2025/BYT - National Technical Regulation on Permissible Exposure Limit Value of 70 Chemicals at the Workplace is promulgated together with this Circular.

Article 2. Effect

1. This Circular comes into force from October 01, 2025.

2. The occupational hygiene standards for the following chemicals: Acrolein, Acrylamide, Acrylonitrile, Amyl acetate, Phthalic anhydride, Antimony, ANTU, Asphalt (fume), Acetone cyanohydrin, Acetonitrile, Formic acid, Methacrylic acid, Nitric acid, Trihydroxy phosphate, Picric acid, Trichloroacetic acid, Azinphos-methyl, Silver and compounds, Benomyl, Benzidine, Benzoyl peroxide, Benzyl chloride, Beryllium and compounds, Bromine, 1,3-Butadiene, n-Butyl acetate, Carbofuran, Calcium carbonate, Calcium hydroxide, Calcium oxide, Calcium silicate, Calcium Sulfate dihydrate, Calcium cyanamide, 1,6- Hexanolactam (dust), 1,6- Hexanolactam (vapor), Captan, Carbaryl, Catechol, Tetraethyl lead, Lead and inorganic compounds, Chloroacetaldehyde, Chlorine dioxide, Chloroacetophenone, Chlorobenzene, 2-Chlorobuta-1,3-dien, Cresol, Crotonaldehyde, Cumene, Mineral (mist), Petroleum distillates (naphta), Turpentine, Vegetable oil (mist), Stoddard solvent, Soapstone (respirable dust), Soapstone (inhalable dust), Demeton, Diazinon, Diborane, Dibutyl phthalate, 1,1-Dichloroethane, 1,1-Dichloroethylene, Dichlorvos, Dicrotophos, Dimethylamine, Dimethylformamide, 1,1-Dimethylhydrazine, Dimethyl sulfate, Dinitrotoluene (DNT), Dinitrobenzenes in the occupational hygiene standards attached to Decision No. 3733/2002/QD-BYT dated October 10, 2002 of the Minister of Health shall cease to be effective from the effective date of this Circular.

Article 3. Implementation

The Chief of the Ministry Office, Chief of the Ministry Inspectorate, Director General of the Vietnam Administration of Disease Prevention, Director Generals of the Ministry of Health, heads of units affiliated to the Ministry of Health, Directors of the Departments of Health of provinces and central-affiliated cities, heads of health units of Ministries and central authorities, relevant organizations and individuals are responsible for implementing this Circular.

Authorities, organizations, individuals shall report any issues arise during the implementation to the Ministry of Health (Vietnam Administration of Disease Prevention) for research and resolution./.

QCVN 01:2025/BYT

NATIONAL TECHNICAL REGULATION ON PERMISSIBLE EXPOSURE LIMIT VALUE OF 70 CHEMICALS AT THE WORKPLACE

Foreword

The QCVN 01:2025/BYT is compiled by the Drafting Board for the National Technical Regulation on occupational hygiene, approved by the Vietnam Administration of Disease Prevention, appraised by the Ministry of Science and Technology, and promulgated by the Ministry of Health under Circular No. 09/2025/TT-BYT dated April 28, 2025.

NATIONAL TECHNICAL REGULATION ON PERMISSIBLE EXPOSURE LIMIT VALUE OF 70 CHEMICALS AT THE WORKPLACE

1. GENERAL REGULATIONS

1.1. Scope

This Regulation regulates the permissible exposure limit value of 70 chemicals at the workplace including: Acrolein, Acrylamide, Acrylonitrile, Amyl acetate, Phthalic anhydride, Antimony, ANTU, Asphalt (fume), Acetone cyanohydrin, Acetonitrile, Formic acid, Methacrylic acid, Nitric acid, Trihydroxy phosphate, Picric acid, Trichloroacetic acid, Azinphos-methyl, Silver and compounds, Benomyl (inhalable dust), Benzidine, Benzoyl peroxide, Benzyl chloride, Beryllium and compounds, Bromine, 1,3-Butadiene, n-Butyl acetate, Butyl acrylate, Carbofuran, Calcium carbonate (inhalable dust), Calcium hydroxide (inhalable dust), Calcium oxide, Calcium silicate (inhalable dust), Calcium Sulfate dihydrate (inhalable dust), Calcium cyanamide, 1,6- Hexanolactam (dust), 1,6- Hexanolactam (vapor), Captan, Carbaryl, Catechol, Tetraethyl lead, Lead and inorganic compounds, Chloroacetaldehyde, Chlorine dioxide, Chloroacetophenone, Chlorobenzene, 2-Chlorobuta-1,3-dien, Cresol, Crotonaldehyde, Cumene, Mineral (mist), Petroleum distillates (naphta), Turpentine, Vegetable oil (mist-inhalable dust), Stoddard solvent, Soapstone (respirable dust), Soapstone (inhalable dust), Demeton, Diazinon, Diborane, Dibutyl phthalate, 1,1-Dichloroethane, 1,1-Dichloroethylene, Dichlorvos, Dicrotophos, Dimethylamine, Dimethylformamide, 1,1-Dimethylhydrazine, Dimethyl sulfate, Dinitrobenzenes, Dinitrotoluene (DNT)

1.2. Regulated entities

This Regulation applies to state management authorities on occupational environment; authorities and organizations involved in occupational environmental monitoring; authorities and individuals conducting activities involving chemical substances in the workplace.

1.3. Definitions

For the purposes of this Regulation, the terms below shall be construed as follows:

(Vietnamese names of chemicals shall comply with regulations in Vietnamese Standards TCVN 5529:2010 Chemical terms - Basic principle and Vietnamese Standards TCVN 5530:2010 Chemical terms - Nomenclature of chemical elements and compounds).

1.3.1. Acrolein is a colorless, highly flammable liquid compound with a foul odor. Its chemical formula is CH₂CHCHO, and its IUPAC name is 2-propenal. Other names of Acrolein include acraldehyde, acrylic aldehyde, allyl aldehyde, ethylene aldehyde, and acrylaldehyde.

1.3.2. Acrylamide is a white, odorless, crystalline solid compound that is soluble in water. Its chemical formula is CH₂CHCONH₂, and its IUPAC name is 2-propenamide. Other names of Acrylamide include acrylamide monomer and propenamide.

1.3.3. Acrylonitrile is a colorless or yellow, highly volatile liquid compound with a pungent odor. Its chemical formula is CH₂CHCN, and its IUPAC name is 2-propenenitrile. Other names of Acrylonitrile include acrylonitrile monomer, AN, cyanoethylene, propenenitrile, and VCN.

1.3.4. Amyl acetate is a liquid organic compound with a banana and apple-like scent. Its chemical formula is CH₃COOC₅H₁₁, and its IUPAC name is Pentyl ethanoate. Other names of Amyl acetate include acetic acid n-amyl ester, acetic acid pentyl ester, n-amyl acetate, amyl ethanoate, and apple seed oil.

1.3.5. Phthalic anhydride is a colorless solid organic compound. Its chemical formula is C₆H₄(CO)₂O, and its IUPAC name is 2-benzofuran-1,3-dione. Another name for anhydrid phthalic is isobenzofuran-1,3-dione.

1.3.6. Antimony is a hard, silver-white metalloid that exists in solid crystalline form, melts easily. It has poor electrical and thermal conductivity. It has a low vaporization temperature. Its chemical symbol is Sb, and its IUPAC name is Antimony. Other names of Antimony include antimony metal, antimony powder, and stibium.

1.3.7. ANTU is a crystalline, powdery, odorless, white or gray organic compound,. Its chemical formula is C₁₀H₇NHC(NH₂)S. Its IUPAC name is Naphthalen-1-ylthiourea. Other names of ANTU include 1-(1-naphthyl)-2-thiourea, dirax, 1-naphthylthiourea, anturat, rattrack, smeesana, alrato, alpha-naphthylthiourea, and 1-naphthyl thiourea.

1.3.8. Asphalt (fume) is a mixture of heavy hydrocarbons with a complex composition, tar-like dark brown color, and waterproof. It is softened and melted when being heated. Until now, the exact and complete composition and structure of Asphalt have not been fully determined. Asphalt mixtures with sand, gravel, and crushed stone are used for road paving (Asphalt is also known as road tar). Other names of Asphalt include asphaltum, bitumen, petroleum asphalt, petroleum bitumen, road asphalt, roofing asphalt, and road tar.

1.3.9. Acetone cyanohydrin is a colorless, liquid organic compound with an almond-like odor. Its chemical formula is CH₃C(OH)CNCH₃. Its IUPAC name is 2-hydroxy-2-methylpropanenitrile. Other names of Aceton cyanohydrin include Cyanohydrin-2-propanone, α-hydroxyisobutyronitrile, and 2-hydroxy-2-methyl-propionitrile.

1.3.10. Acetonitrile is a colorless, liquid organic compound with a aromatic odor. Its chemical formula is CH₃CN. Its IUPAC name is Acetonitrile. Other names of Acetonitrile include Cyanomethane, ethyl nitrile, methanecarbonitrile, methyl cyanide, and MeCN.

1.3.11. Formic acid is a colorless, liquid compound, a weak acid. Its chemical formula is HCOOH. Its IUPAC name is Formic acid. Other names of Formic acid include Carbonous acid, formylic acid, hydrogen carboxylic acid, hydroxy(oxo)methane, metacarbonoic acid, oxocarbinic acid, and oxomethanol.

1.3.12. Methacrylic acid is a viscous, colorless, organic compound with an unaromatic odor, soluble in warm water and can be mixed with most organic solvents. Its chemical formula is CH₂=C(CH₃)COOH. Its IUPAC name is 2-methylprop-2-enoic acid. Other names of Methacrylic acid include Methacrylic acid, 2-methyl-2-propenoic acid, α-methacrylic acid, 2-methylacrylic acid, and 2-methylpropenoic acid.

1.3.13. Nitric acid is a colorless, liquid inorganic compound that emits strong fumes in moist air. Its chemical formula is HNO3. Its IUPAC name is Nitric acid. Other names of Nitric acid include Aqua fortis, spirit of niter, eau forte, hydrogen nitrate, and acidum nitricum.

1.3.14. Trihydroxy phosphate is a colorless crystalline solid compound that is soluble in ethanol and water in any proportion. Its chemical formula is H₃PO₄. Its IUPAC name is Phosphoric acid; trihydroxidooxidophosphorus. Other names include Orthophosphoric acid and trihydroxylphosphine oxide.

1.3.15. Picric acid is a yellow crystalline compound with a bitter taste, known as one of the strongest acidic compounds of phenol. Similar to other nitrate-containing compounds (such as TNT), Picric acid is an explosive. Its chemical formula is HOC₆H₂(NO₂)₃. Its IUPAC name is 2,4,6-Trinitrophenol. Other names of Picric acid include Acid carbasetic, phenoltrinitrateacid, picronitric, trinitrophenol, 2,4,6-trinitro-1-phenol, 2-hydroxy-1,3,5-trinitrobenzene, tnp, and melinite.

1.3.16. Trichloroacetic acid is a white solid compound with a pungent odor. Its chemical formula is C₂HCl₃O₂. Its IUPAC name is Trichloroacetic acid.

1.3.17. Azinphos-methyl is a dark orange crystalline compound used as an insecticide. Its chemical formula is (CH₃O)₂P(S)SCH₂(N₃C₇H₄O). Its IUPAC name is O,O-dimethyl S-[(4-oxo-1,2,3-benzotriazin-3(4H)yl)methyl] phosphorodithioate. Other names of Azinphos-methyl include Guthion, azinphosmethyl, and azinphos.

1.3.18. Silver and soluble compounds: Silver is a transition metal that is white in color, soft, and has high electrical and thermal conductivity. Its chemical symbol is Ag, and its IUPAC name is Silver. Some soluble compounds of silver include Silver acetate, silver bromate, silver bromide, silver carbonate, silver chloride, silver chromate, silver cyanide, silver dichromate, silver hydroxide, silver iodate, silver iodide, silver nitrite, silver oxalate, silver sulfate, silver sulfide, and silver thiocyanate.

1.3.19. Benomyl (inhalable dust) is a white crystalline compound. Its chemical formula is C₁₄H₁₈N₄O₃. Its IUPAC name is 1-(butylcarbamoyl)-1H-1,3-benzimidazol-2-yl methylcarbamate.

1.3.20. Benzidine is a crystalline powdery compound that can be yellow-gray, gray-red, or white in color. Its chemical formula is NH₂C₆H₄C₆H₄NH₂. Its IUPAC name is 1,1'-biphenyl]-4,4'-diamine. Other names of Benzidine include Di-phenylamine, diphenylamine, 4,4'-bianiline, 4,4'-biphenyldiamine, 1,1'-biphenyl-4,4'-diamine, 4,4'-diaminobiphenyl, p-diaminodiphenyl, and p-benzidine.

1.3.21. Benzoyl peroxide is a white granular compound with the odor of benzaldehyde. It is poorly soluble in water but soluble in acetone. Its chemical formula is (C₆H₅CO)₂O₂. Its IUPAC name is Benzoic peroxyanhydride. Other names of Benzoyl peroxide include Benzoperoxide and dibenzoyl peroxide (DBPO).

1.3.22. Benzyl chloride is a colorless liquid compound. Its chemical formula is C₆H₅CH₂Cl. Its IUPAC name is (chloromethyl)benzene. Other name for Benzyl chloride is α-chlorotoluene.

1.3.23. Beryllium and compounds: Beryllium is an alkaline earth metal that is gray, lightweight, and brittle. Its chemical symbol is Be. Some compounds of Beryllium include beryllium-aluminum alloy, beryllium chloride, beryllium fluoride, beryllium hydroxide, beryllium sulfate, beryllium sulfate tetrahydrate, beryllium oxide, beryllium carbonate, beryllium nitrate, beryllium nitrate trihydrate, beryllium nitrate tetrahydrate, beryllium phosphate, beryllium silicate, and zinc beryllium silicate.

1.3.24. Bromine is a red-brown liquid that emits fumes at room temperature and easily vaporizes. Its chemical formula is Br₂.

1.3.25. 1,3-Butadiene is a colorless gas organic and easily condenses into the liquid state. Its chemical formula is CH₂CHCHCH₂. Its IUPAC name is Buta-1,3-diene. Other names of 1,3-Butadiene include Biethylene, erythrene, divinyl, vinylethylene, bivinyl, and butadiene.

1.3.26. n-Butyl acetate is a compound that exists in the form of yellow-gray, gray-red, or white crystalline powder. Its chemical formula is CH₃COO(CH₂)₃CH₃. Its IUPAC name is 1,1'-biphenyl]-4,4'-diamine. Other names of n-Butyl acetate include Benzidine, diphenylamine, 4,4'-bianiline, 4,4'-biphenyldiamine, 1,1'-biphenyl-4,4'-diamine, 4,4'-diaminobiphenyl, p-diaminodiphenyl, and p-benzidine.

1.3.27. Butyl acrylate is a colorless liquid organic compound. Its chemical formula is CH₂=CHCOOC₄H₉. Its IUPAC name is Butyl prop-2-enoate. Other names of Butyl acrylate include Butyl ester of acrylic acid and butyl-2-propenoate.

1.3.28. Carbofuran is an odorless solid crystalline compound with a white or slightly gray color. Its chemical formula is C₁₂H₁₅NO₃. Its IUPAC name is 2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl methylcarbamate. Other names of Carbofuran include Furadan, curater, and furacarb.

1.3.29. Calcium carbonate (inhalable dust) is a white odorless powdery compound. Its chemical formula is CaCO₃. Its IUPAC name is Calcium carbonate. Other names of Calcium carbonate include Calcite, aragonite, chalk, lime (material), limestone, marble, oyster, pearl, whiting, and atomite.

1.3.30. Calcium hydroxide (inhalable dust) is a white or gray-white, odorless, powdery compound. Its chemical formula is Ca(OH)₂. Its IUPAC name is Calcium hydroxide. Other names of Calcium hydroxide include Slaked lime, milk of lime, calcium(II) hydroxide, pickling lime, hydrated lime, portlandite, calcium hydrate, and calcium dihydroxide.

1.3.31. Calcium oxide is an odorless, white, crystalline, solid compound at room temperature. Its chemical formula is CaO. Its IUPAC name is Calcium oxide. Other names of Calcium oxide include Quicklime, burnt lime, unslaked lime, pebble lime, and calcia.

1.3.32. Calcium silicate (inhalable dust) is a white, ordorless, crystalline, solid compound at room temperature. Its chemical formula is CaSiO₃. Its IUPAC name is Calcium silicate. Other names of Calcium silicate include Dicalcium silicate, calcium orthosilicate, belite, calcium monosilicate, calcium hydrosilicate, calcium metasilicate, grammite, micro-cell, silene, and silicic acid calcium salt.

1.3.33. Calcium Sulfate dihydrate (inhalable dust) is a white or nearly white, odorless, crystalline, solid compound. Its chemical formula is CaSO₄.2H₂O. Its IUPAC name is Calcium(II) sulfate dihydrate. Other names of Calcium Sulfate dihydrate include Gypsum, gypsum stone, hydrated calcium sulfate, and mineral white.

1.3.34. Calcium cyanamide is a colorless solid compound in the form of powder or crystals. It may turn gray or black when contaminated. Its chemical formula is CaCN₂. Its IUPAC name is Calcium cyanamide. Other names of Calcium cyanamide include Calcium carbimide, cyanamide, cyanamide calcium salt, lime nitrogen, nitrogen lime, and nitrolime.

1.3.35. 1,6- Hexanolactam is a compound in the form of powder or vapor with an unaromatic odor. Its chemical formula is C₆H₁₁NO. Its IUPAC name is Azepan-2-one. Other names of 1,6- Hexanolactam include 1-Aza-2-cycloheptanone, 2-azacycloheptanone, ε-1,6- Hexanolactam, capron PK4, cyclohexanone iso-oxime, extrom 6N, hexahydro-2-azepinone, hexahydro-2H-azepin-2-one, hexanolactam, hexano-6-lactam, and aminocaproic lactam.

1.3.36. Captan is a white solid compound and easily combustible. Its chemical formula is C₉H₈Cl₃NO₂S. Its IUPAC name is 2-(trichloromethylsulfanyl)-3a,4,7,7a-tetrahydroisoindole-1,3-dione. Other names of it include n-trichloromethylmercapto-4-cyclohexene-1,2-dicarboximide.

1.3.37. Carbaryl is a solid, white, odorless, crystalline compound, and slightly soluble in water. Its chemical formula is CH₃NHCOOC₁₀H₇. Its IUPAC name is Naphthalen-1-yl methylcarbamate. Other names of Carbaryl include Sevin, α-naphthyl n-methylcarbamate, and 1-naphthyl methylcarbamate.

1.3.38. Catechol is a white or colorless, crystalline compound with a slight phenol odor. Its chemical formula is C₆H₆O₂. Its IUPAC name is Benzene-1,2-diol. Other names of Catechol include Pyrocatechol, 1,2-benzenediol, 2-hydroxyphenol, 1,2-dihydroxybenzene, o-benzenediol, and o-dihydroxybenzene.

1.3.39. Tetraethyl lead is a colorless, liquid compound and has a aromatic odor. Its chemical formula is Pb(C₂H₅)₄. Its IUPAC name is Tetraethylplumbane. Other names of Tetraethyl lead include Lead tetraethyl, tetraethyl lead, and tetra-ethyl lead.

1.3.40. Lead and inorganic compounds: Lead is a odorless, gray, powdery or lump-like soft substance. Its chemical formula is Pb. Its IUPAC name is Lead. Other names of Lead include Lead metal, lead element, lead flake, and plumbumlead. Inorganic compounds of lead include lead oxides and lead salts.

1.3.41. Chloroacetaldehyde is a colorless, liquid organic compound with a pungent odor. Its chemical formula is ClCH₂CHO. Its IUPAC name is Chloroacetaldehyde. Other names of Chloroacetaldehyde include 2-Chloroacetaldehyde and 2-chloroethanal.

1.3.42. Chlorine dioxide is a yellow, liquid inorganic compound. Its chemical formula is ClO₂. Its IUPAC name is Chlorine dioxide. Other names of Chlorine dioxide include Chlorine oxide and chlorine peroxide.

1.3.43. Chloroacetophenone is a white, crystalline compound, and insoluble in water at room temperature. Its chemical formula is C₆H₅COCH₂Cl. Its IUPAC name is 2-chloro-1-phenylethan-1-one. Other names of Chloroacetophenone include 2-Chloro-1-phenylethanone, α-chloroacetophenone, 2-chloroacetophenone, chloromethyl phenyl ketone, and chenyl chloromethyl ketone.

1.3.44. Chlorobenzene is an aromatic solvent compound. Its chemical formula is C₆H₅Cl. Its IUPAC name is Chlorobenzene. Other names of Chlorobenzene include Benzene chloride, monochlorobenzene, phenyl chloride, and chlorobenzol.

1.3.45. 2-Chlorobuta-1,3-dien is a colorless, liquid compound. Its chemical formula is C₄H₅Cl. Its IUPAC name is 2-Chlorobuta-1,3-dien. Other names of 2-Chlorobuta-1,3-dien include 2-Chlorobuta-1,3-diene and 2-chloro-1,3-butadiene.

1.3.46. Cresol is a group of aromatic organic compounds. Its chemical formula is CH₃C₆H₄OH. Its IUPAC name is Cresol. Other name of Cresol is Sesone.

1.3.47. Crotonaldehyde is an organic compound. Its chemical formula is CH₃CH=CHCHO. Its IUPAC name is Crotonaldehyde. Other names of Crotonaldehyde include 2-Butenal, β-methyl acrolein, and propylene aldehyde.

1.3.48. Cumene is a hydrocarbon consisting of an aromatic ring and a propyl group, and is a component of crude oil and refined fuels. Its chemical formula is C₆H₅CH(CH₃)₂. Its IUPAC name is Cumene. Other names of Cumeme include Cumol, isopropyl cumene, and 2-phenyl propane.

1.3.49. Mineral (mist): Mineral or paraffin oil is a colorless, odorless, light mixture of high alkanes derived from mineral sources, particularly the distillation fraction of crude oil. Other names include Heavy mineral oil mist, paraffin oil mist, and white mineral oil mist.

1.3.50. Petroleum distillates (naphta) are a dense liquid mixture of organic chemicals. They primarily consist of hydrocarbon compounds, mainly alkane-based, with a diverse range of components. Other names include Aliphatic petroleum naphtha, petroleum naphtha, and rubber solvent.

1.3.51. Turpentine is a colorless liquid with a characteristic odor. Its chemical formula is C₁₀H₁₆. Its IUPAC name is Turpentine. Other names of Turpentine include Gumspirits, gum turpentine, spirits of turpentine, steam distilled turpentine, sulfate wood turpentine, turps, and wood turpentine.

1.3.52. Vegetable oil (mist - inhalable dust) is oil extracted from plants. It is also known as vegetable mist.

1.3.53. Stoddard solvent is a colorless liquid with an aromatic scent similar to kerosene. Other names of Stoddard solvent include dry cleaning safety solvent, mineral spirits, petroleum solvent, and spotting naphtha.

1.3.54. Soapstone is a bright gray, odorless crystal. Its chemical formula is 3MgO.4SiO2.H2O. Other names of Soapstone include massive talc, Soapstone silicate, and steatite.

1.3.55. Demeton is a light brown, liquid compound with a sulfur-like odor. It is insoluble in water, and a type of phosphorothioate insecticides. Its chemical formula is (C₂H₅O)₂PSOC₂H₄SC₂H₅. Its IUPAC name is 0,0-diethyl S-[2-(ethylsulfanyl)ethyl] phosphorothioate. Other names of Demeton include Demeton thiol, izosystox, bay 10756, bayer 10756, bayer 8169, demetona (Spanish), demeton-O, demeton-S, demox, denox, diethoxy thiophosphoric acid ester of 2-ethylmercaptoethanol, O,O-diethyl-2-ethylmercaptoethyl thiophosphate, diethoxythiophosphoric acid, O,O-diethyl S-2-(ethylthio)ethyl phosphorothioate mixed with phosphorothioic acid, O,O-diethyl O-2-(ethylthio)ethyl ester, E-1059, ENT 17295, mercaptophos (USSR), phosphorothioic acid, O,O-diethyl O-2-(ethylthio)ethyl ester mixed with O,O-diethyl S-2-(ethylthio)ethyl phosphorothioate, systemox, systox, UL demeton-S, bay 18436, bayer 18436, bayer 25/154.

1.3.56. Diazinon is a viscous, colorless or dark brown, liquid compound with a slight amine odor. It is insoluble in water, and an insecticide. Its chemical formula is C₁₂H₂₁N₂O₃PS. Its IUPAC name is O,O-diethyl O-[4-methyl-6-(propan-2-yl)pyrimidin-2-yl] phosphorothioate. Other names of Diazinon include Diethoxy-[(2-isopropyl-6-methyl-4-pyrimidinyl)oxy]-thioxophosphorane, basudin, diazide, spectracide, dazzel, dimpylate, dipofene, diziktol, dizinon, dyzol, ENT 19,507, EPA pesticide chemical code 057801, exodin, G-24480, G 301, gardentox.

1.3.57. Diborane is a colorless gas compound with a characteristic sweet odor. It is highly flammable. Its chemical formula is B₂H₆. Its IUPAC name is Diborane. Other names of Diborane include Boroethane, boron hydride, diborane hexanhydride, diborano (Spanish), and diboron hexahydride.

1.3.58. Dibutyl phthalate is a colorless or yellow, viscous, organic compound with a light aromatic odor. Its chemical formula is C₆H₄(COOC₄H₉)₂. Its IUPAC name is Dibutyl benzene-1,2-dicarboxylate. Other names of Dibutyl phthalate include Di-n-butyl phthalate; butyl phthalate; n-butyl phthalate; 1,2-benzenedicarboxylic acid dibutyl ester; o-benzenedicarboxylic acid dibutyl ester; DBP; palatinol C; elaol; dibutyl 1,2-benzene-dicarboxylate; benzene-o-dicarboxylic acid di-n-butyl ester; bis-n-butyl phthalate; BUFA; genoplast B; hexaplas M/B; kodaflex dibutyl phthalate (DBP); morflex-240; NLA-10.

1.3.59. 1,1-Dichloroethane is a colorless, viscous, organic compound with a chloroform-like odor. It is slightly soluble in water but miscible with most organic solvents. Its chemical formula is CH₃CHCl₂. Its IUPAC name is 1,1-dichloroethane. Other names include Ethylidene dichloride; ethylidene chloride; CFC-150a; 1,1-DCA; asymmetrical dichloroethane; 1,1-ethylidene dichloride; geminal dichloroethane; aethylidenchlorid (German); asym- dichloroethane; chlorinated hydrochloric ether; chlorure d’ethylidene (French); dichloromethylethane.

1.3.60. 1,1-Dichloroethylene is a liquid or gas, organic compound with a chloroform-like odor. It is poorly soluble in water but easily soluble in organic solvents. Its chemical formula is CH₂=CCl₂. Its IUPAC name is 1,1-dichloroethene. Other names include 1,1-DCE; vinylidene chloride; vinylidene dichloride; asymmetrical dichloroethane; VDC; vinylidene chloride(II); vinylidine chloride(II); ethene; 1,1-dichloro-; ethylene; 1,1- dichloro-; NCl- 054262; sconatex; asym-dichloroethylene.

1.3.61. Dichlorvos is a colorless or amber, liquid, organic compound with a light aromatic odor. It is flammable, and slightly soluble in water. Dichlorvos is an organophosphate widely used as an insecticide. Its chemical formula is (CH₃O)₂P(O)OCH=CCl₂. Its IUPAC name is 2,2-dichlorovinyl dimethyl phosphate. Other names include DDVP; vapona; apavap; astrobot; atgard; atgard V; bay 19149; bayer 19149; benfos; bibesol; brevinyl; brevinyl E 50; canogard; cekusan; chlorvinphos; cyanophos; cypona; DDVF; DDVP (Insecticide); dedevap; deriban; derribante; DES; devikol; dichlofos; dichlorman; 2,2-dichloroethenol dimethyl phosphate; 2,2-dichloroethenyl dimethyl phosphate.

1.3.62. Dicrotophos is an amber, liquid, organic compound with an ester-like odor. It is flammable, and soluble in water. Dicrotophos is an organophosphate acetylcholinesterase inhibitor used as an insecticide. Its chemical formula is C₈H₁₆NO₅P. Its IUPAC name is (2E)-4-(dimethylamino)-4-oxobut-2-en-2-yl dimethyl phosphate. Other names include Bidrin; bidirl; carbicron; carbicrin; 2-dimethyl-cis-2-dimethylcarbamoyl-1-methylvinylphosphate; diapadrin; dicron; ektafos; carbomicron; ciba 709; dicroptophos; didrin; 3-(dimethoxyphosphinyloxy)-N; N-dimetyl [e] crotonamit.

1.3.63. Dimethylamine is a liquid or gas, organic compound with a strong fishy or ammonia-like odor. It is soluble in water. Its chemical formula is (CH₃)₂NH. Its IUPAC name is N-methylmethanamine. Other names include Al3-15638-X; N,N-dimethylamine; dimethylamine; anhydrous; DMA; methanamine; n-methyl-.

1.3.64. Dimethylformamide is a colorless, liquid, organic compound with amines-like odor. It is flammable and soluble in water. Its chemical formula is O=CHN(CH₃)₂. Its IUPAC name is N,N-dimethylformamide. Other names include DMF; Al3-03311; N-dimethylformamide; N,N-dimethylmethanamide; dimetilformamida (Spanish); DMFA; dynasolve 100; formamide; N,N-dimethyl-; formic acid; amide; N,N-dimethyl-; N-formyldimethylamine; NCl-060913; NSC-5356; U-4224; weld-on P-70 primer.

1.3.65. 1,1-Dimethylhydrazine is a colorless, liquid, organic compound with amines-like odor. It will turn yellow upon exposure to air. It is soluble in water, miscible with ethanol and petroleum ether, and flammable in vapor form. Its chemical formula is (CH₃)₂NNH₂. Its IUPAC name is 1,1-dimethylhydrazine. Other names include Dimazine; dimazin; dimethylhydrazine; asym-dimethylhydrazine; N,N-dimethylhydrazine; U-dimethylhydrazine; hydrazine; 1,1-dimethyl.

1.3.66. Dimethyl sulfate is a colorless, liquid, organic compound with an onion-like odor. It is poorly soluble in water. Its chemical formula is (CH₃O)₂SO₂. Its IUPAC name is Dimethyl sulfate. Other names include Sulfuric acid dimethyl ester; dimethyl ester of sulfuric acid; methyl sulfate; dimethyl monosulfate; DMS; methyle (sulfate de) (French); methyl sulfate: sulfate dimethylique (French); sulfate de methyle (French); sulfato de dimetilo (Spanish).

1.3.67. Dinitrobenzenes are organic compounds that exist in three isomers (o-, m-, and p-). They are white or yellow, crystalline, solid, organic compounds with a characteristic odor. It is soluble in organic solvents. The chemical formula is C₆H₄(NO₂)₂. IUPAC names include 1,2-dinitrobenzene; 1,3-dinitrobenzene; 1,4-dinitrobenzene. Other names: o-isonaer benzene; o-dinitro-; benzene; 1,2-dinitro; o-dinitrobenceno (Spanish); 1,2-dinitrobenzene; 1,2-dinitrobenzol; 1,2-DNB. m-isomer: Benzene; m-dinitro-; benzene; 1,3-dinitro-; m-dinitrobenceno (Spanish); 1,3-dinitrobenzene; 1,3-dinitrobenzol; 1,3-DNB. p-isomer: Benzene; p-dinitro-; benzene; 1,4-dinitro-; p-dinitrobenceno (Spanish); 1,4-dinitrobenzene; 1,4-dinitrobenzol; dithaneA-4; 1,4-DNB.

1.3.68. Dinitrotoluene (DNT) is a light yellow, solid, organic compound. It is soluble in alcohol, ether, benzene, and acetone. Its chemical formula CH₃C₆H₃(NO₂)₂. Other name of DNT is Methyldinitrobenzene.

1.3.69. TWA - Time Weighted Average is the average concentration of a substance in the workplace air. It is determined based on exposure duration of 8 hours per shift or 40 hours per workweek, which employees must not be exposed to beyond this threshold.

The limit value for TWA is also applied when a substance has no specified Short Term Exposure Limit (STEL). If the concentration at any point during a work shift exceeds 3 times the TWA value, the exposure duration to this concentration must not exceed 30 minutes. Throughout the work shift, the exposure concentration at any point must not exceed 5 times the TWA value even if the average 8-hour exposure does not exceed the TWA limit.

1.3.70. STEL - Short Term Exposure Limit is the concentration value of a substance in the workplace air. It is the average value over a 15-minute period, which employees must not be exposed to beyond this threshold. If the concentration of the substance in the workplace environment is between the TWA and STEL limits, employees must not be exposed for more than 15 minutes per instance and no more than 4 times during a work shift with at least 60 minutes between each instance.

STEL applies to chemicals that may cause skin or mucous membrane irritation, suppression or stimulation of the central nervous system, or irreversible tissue damage.

1.3.71. Measurement duration is the period of time for a single measurement or sampling of a chemical during a work shift.

1.3.72. Exposure duration is the period of time during which an employee is exposed to a chemical during a work shift.

1.3.73. Discrete sampling is a measurement or sample taken at a specific point of time, over a short period with a minimum duration of 15 minutes.

1.3.74. CAS (Chemical Abstracts Service): Chemical Abstracts Service Registry Number of the American Chemical Society.

1.3.75. IUPAC: International Union of Pure and Applied Chemistry

1.3.76. IARC: International Agency for Research on Cancer. Based on carcinogenicity, IARC classify chemicals into the following 05 types:

Group 1: Carcinogenic to humans.

Group 2A: Probably carcinogenic to humans.

Group 2B: Possibly carcinogenic to humans.

Group 3: Not classifiable as to its carcinogenicity to humans.

Group 4: Probably not carcinogenic to humans.

1.3.77. NIOSH: National Institute for Occupational Saferty and Health.

1.3.78. OSHA: Occupational Safety and Health Administration.

2. TECNICAL REGULATIONS

2.1. Permissible exposure limit value of 70 chemicals at the workplace

Table 1. Permissible exposure limit value of 70 chemicals at the workplace

Unit of calculation: mg/m³

Note: (-) means unidentified or not specified

2.2. The formula for converting the concentration of a chemical (in the form of vapor, gas) in the air from ppm (parts per million) to mg/m³

Where:

- C (mg/m³): The concentration of the chemical in the air measured in mg/m³.

- ppm: The concentration of the chemical in the air measured in parts per million (ppm).

- Wm: Molecular weight of the chemical.

- 24,45: The volume of a gas molecule measured in liters under standard conditions (25°C, 1 atm).

2.3. The adjusted permissible exposure limit for prolonged exposure exceeding 8 hours per day.

The following formula shall be used:

Where:

- TWA_n : The adjusted permissible exposure limit for prolonged exposure exceeding 8 hours per day (mg/m³).

- TWA: The permissible exposure limit based on an 8-hour daily exposure (mg/m³) as prescribed in Table 1 (Section 2.1, Part II) corresponding to each type of chemical.

- h: The actual number of hours of exposure in one day (h > 8).

2.4. The adjusted permissible exposure limit for prolonged exposure exceeding 40 hours per week.

The following formula shall be used:

Where:

- TWA_t : The adjusted permissible exposure limit for prolonged exposure exceeding 40 hours per week (mg/m³).

- TWA: The permissible exposure limit based on an 8-hour daily and 40-hour weekly exposure (mg/m³) as regulated in Table 1 (Section 2.1, Part II) corresponding to each type of chemical.

- H: The actual number of hours of exposure (H>40) in one workweek.

2.5. Calculation method for actual exposure

2.5.1. The exposure value during the work shift when the total measurement duration is equivalent to the total exposure duration

The actual exposure shall be calculated as follows:

TWA_tt = (C1 .T1 + C2.T2 +...+ Cn.Tn):T

Where:

- TWA_tt: The actual exposure (mg/m³).

- C1, C2, ..., Cn: The actual concentration (mg/m³) corresponding to the measurement durations T1, T2, ..., Tn (minutes).

+ Sampling and measurement may be done once with the duration equal to the exposure duration in the work shift if the chemical concentration is low.

+ Sampling and measurement may be divided into multiple times (2, 3, 4,..., n times), with the duration of each measurement varying depending on the chemical concentration to avoid overloading on the filter paper or sampling tool. The total measurement duration is equal to the total exposure duration.

- T: The total exposure duration (minutes).

+ If the total exposure duration is less than or equal to 8 hours per day, the exposure value is calculated as for 8-hour and T equals 480 (in minutes).

+ If the total exposure duration is over 8 hours per day, T is the actual exposure duration.

Sampling and measurement shall be conducted with minimum total measurement duration equal to 80% of the exposure duration. In this case, T is the total measurement duration (in minutes). During the remaining time, the exposure level will be considered equivalent to the level during the measured and sampled time.

Example: One (or a group of) worker(s) works for 6 hours in a day with exposure to formaldehyde. The average measured concentration of formaldehyde during the 6 hours is 0.8 mg/m3; the remaining 2 hours are either resting or working in a location without exposure to formaldehyde. In this case, TWA_tt is calculated as follows:

TWA_tt = (0,8mg/m³ x 6x60 minutes + 0mg/m³ x 2x60 minutes) : 480 minutes = 0,6mg/m³

2.5.2. The exposure value during the work shift when the total measurement duration is less than the total exposure duration

In cases where the working conditions or technical requirements do not allow for convenient sampling, discrete sampling shall be carried out for assessment of exposure during the work shift:

Based on the production process, predict each time interval during which the generation and dispersion of the chemical are relatively stable, and then randomly take representative samples for each of these time intervals. The number and duration of the time intervals depend on the fluctuation level of the generation and dispersion of the chemical during the work shift. In cases where the generation and dispersion causing contamination of the chemical are predicted to be relatively uniform throughout the work shift, the number of time intervals can be 2 (n = 2) with each interval having the same length, which is equal to half of the total exposure time.

The exposure value during the work shift shall be calculated as follows:

TWA_tt = (C1 .T1 + C2.T2 +...+ Cn.Tn):T

Where:

- TWA_tt: The actual exposure (mg/m3).

- C1; C2; ...; Cn: The average concentration (mg/m3) over the time intervals K1; K2; ...; Kn (minutes).

- K1; K2; ...; Kn: The time intervals within the work shift (minutes). The sum of the time intervals K1 + K2 + ... + Kn equals the total duration of the work shift.

- T: The total exposure duration (minutes).

+ If the total exposure duration is less than or equal to 8 hours per day, the exposure value is calculated as for 8-hour and T equals 480 (in minutes).

+ If the total exposure duration is over 8 hours per day, T is the actual exposure duration.

The average concentration (C1; C2; ...; Cn) within the time intervals of the work shift is calculated based on the following formula:

Cx = (N1 + N2 +...+ Nn) : n

Where:

- Cx: The average concentration within a time interval of the work shift, interval x (mg/m³).

- N1; N2; ...; Nn: The measured concentrations at time points 1, 2, ..., n within the time interval x (mg/m³).

- n: The total number of randomly samples within the time interval X. (n≥2).

The duration of each discrete sampling must be equal.

Example: Based on the initial survey in a workshop, the dispersion of ammonia is relatively uniform throughout an 8-hour work shift. It divided into two measurement intervals of 4 hours each. Two random measurements representing the first 4 hours yielded values of 14 mg/m³ and 13 mg/m³, while two random measurements representing the last 4 hours yielded values of 17 mg/m³ and 18 mg/m³.

In this case, TWA_tt is calculated as follows:

TWA_tt = {[(14+13)mg/m³: 2] x 4x60 minutes + [(17+18)mg/m³: 2] x 4x60 minutes} : 480 minutes = 15,5mg/m³.

3. METHOD FOR DETERMINATION

3.1. The concentration of chemicals shall be determined by selecting and complying with the methods prescribed in Table 2 below:

Article 2. Methods for determination

Note:

1) (-):  Not determined

2) For chemicals with prescribed conversion rates:

The concentration of the chemical (column 2) = The analysis result according to the prescribed method (column 3) x Conversion rate (column 4).

3.2. In cases where sampling cannot be taken or the concentration of chemicals is low due to safety or technical reasons of production conditions, the concentration of the chemicals shall be determined by using digital measuring devices according to Appendix 1 attached to this Regulation and in conformity with the assessment requirements in Section 2.5, Part II of this Regulation and other relevant regulations.

4. MANAGEMENT REGULATION

4.1. The periodic monitoring of occupational environment with chemicals listed in Table 1 of this Regulation shall be carried out by organizations that meet the requirements and conditions for the capacity of occupational environment monitoring prescribed in Government’s Decree No. 44/2016/ND-CP dated May 15, 2016 detailing some articles of the law on occupational safety and sanitation, technical inspection of occupational safety, training of occupational safety and sanitation and monitoring of occupational environment; Decree No. 140/2018/ND-CP dated October 8, 2018 of the Government on amendments to Decrees related to business conditions and administrative procedures under the management of the Ministry of Labor, War Invalids and Social Affairs.

4.2. Based on the characteristics and conditions of the workplace, the generation and dispersion of pollutants at each working location require monitoring to select appropriate monitoring parameters.

5. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

5.1. Facilities where employees are exposed to the chemicals listed in Table 1 of this Regulation shall periodically monitor these chemicals in the occupational environment, implement control measures for harmful chemicals, and protect the health of employees in accordance with the law.

5.2. Organizations conducting occupational environment monitoring of chemicals are responsible for the monitoring results, ensuring integrity in monitoring activities, and carrying out monitoring in accordance with principles and procedures as prescribed by law.

6. IMPLEMENTATION

6.1. The Vietnam Administration of Disease Prevention, Ministry of Health shall take charge and cooperate with relevant competent authorities to implement this Regulation.

6.2. In cases where national standards, international standards, and legislative documents referenced in this Regulation are amended or replaced, the new documents shall prevail..

APPENDIX 1

DETERMINATION OF THE CONCENTRATION OF CHEMICALS IN THE AIR USING DIGITAL MEASURING DEVICES
(Attached to QCVN 01:2025/BYT dated April 28, 2025 of the Minister of Health)

1. Principle

The concentration of chemicals is determined based on the detection of various types of sensors (infrared, electrochemical, ionization optical sensors, etc.) of the measuring device when interacting with the chemicals present in the air. The results are displayed in mg/m³ or ppm.

2. Method for determination

2.1. Device, equipment

- Digital measuring device.

+ The sensitivity of the device is at least 10% of permissible exposure limit value.

+ The device is able to measure the average concentration of chemicals over time.

- The measuring device must be calibrated periodically at least once a year.

2.2. Procedures

a. Prepare the device in the laboratory before going to the field site

- Check the battery of the device to ensure it is fully charged, prepare backup batteries.

- Check the operational status of the device.

- Calibrate the device following the manufacturer's instructions for each type of device.

b. Carry out measuring at the field site

- Determine the measurement location: The area where the employees are working.

- Insert the battery into the device (if necessary). Turn on the device to check its operational status, then turn it off.

+ Place the device or the suction tube at the breathing zone height of the employees, typically between 1.5 to 1.8 meters above the floor, perpendicular to the source of chemical generation. The device can be handheld or placed on a tripod.

- Turn on the device: Measure continuously for the predetermined time or following the manufacturer's instructions.

+ At the end of the measurement time, read and record the average value displayed on the device screen, then turn off the device. Record the occupational and production conditions during the measurement period.

* Note: Do not use digital measuring devices in high humidity environments (above 95%); spray adhesives such as paint, grease, glue, etc. as they can damage the electronic circuits and soil the sensors in the measurement chamber.

2.3. Result

The result of the concentration of chemicals is the average value displayed on the screen of the device after the measurement.

3. Device protection

- After each on-site measurement, clean the inside and outside of the device using the specialized cleaning tools provided by the manufacturer.

- Remove the battery from the device (if using a removable battery) when storing it in a room.

- Store the device in a room with humidity levels between 40-80% and room temperature ranging from 20-30°C.

If the device is not used for an extended period, turn it on and run it for 5-10 minutes every two weeks to check its operation.