What Respirator Is Required for Acid?

This article is a complete guide to the types of respirators required for all commonly used acids.

Acids are incredibly dangerous if handled improperly or inhaled. Inhaling acid fumes can cause serious respiratory problems, so it is important to know what respirator is required for the acid you’re working with before starting.

There are three main types of respirators: air-purifying (AP), supplied-air (SA), and self-contained breathing apparatus (SCBA). Each acid is paired with the right respirator type and rating below.

NOTE: AFP means Assigned Protection Factor, PPM means parts per million, IDLH means Immediately Dangerous to Life or Health (for large chemical spills or chemical attacks). The minimum respirators required are established by NIOSH and OSHA and published in the NIOSH Pocket Guide to Chemicals

Acetic Acid (CH₃COOH)

Description & uses: Colorless crystal or liquid with a sour smell, and often found in vinegar at 5-8% concentration level. Used to manufacture cellulose, plastic, dye, photography chemicals, synthetic rubber, insecticides. Acetic acid is potent and exposure can lead to significant irritation or burning of the eyes, skin, nose and throat. It can also erode teeth and cause black skin, conjunctivitis of the eyes, edemas and bronchitis from long-term exposure.

Respirators Required for Acetic Acid:

50 ppm or less: Supplied-air respirator (AFP 25) in continuous flow mode, or air-purifying respirator with organic vapor cartridge (AFP 50), or full-face cartridge respirator with organic vapor cartridge (AFP 50)
Escape situations: Any full-face air-purifying respirator or escape respirator with organic vapor cartridge (AFP 50)
IDLH: SCBA respirator (AFP 10,000)

Acetoxybenzoic Acid / Aspirin (CH₃COOC₆H₄COOH)

Description & uses: Commonly known as Aspirin, Acetoxybenzoic acid can mildly irritate the eyes, skin and respiratory tract. When ingested in very high concentrations over prolonged periods it can lead to blood clotting, nausea, liver disease and kidney disease. It is odorless and colorless and is typically in a white powder form. It can smell like vinegar when it is exposed to water. This acid is combustible, as well.

Respirators Required for Acetoxybenzoic Acid / Aspirin: none

Acrylic Acid / Acroleic Acid (CH₂=CHCOOH)

Description & uses: Colorless solid or liquid with an acrid distinct smell. Used to manufacture adhesives, coatings, esters, resins, chemicals for treating oil, water treatment chemicals, detergents and various polymers. Acrylic acid is a class II combustible liquid that must be stored and handled with care. It is a mild irritant to humans that primarily affects the eyes, skin and respiratory system. For skin and eye exposure washing with water is sufficient. If inhaled, acrylic acid can cause respiratory problems and medical care should be sought.

Respirators Required for Acrylic Acid / Acreolic Acid: none

Carbolic Acid / Phenol (C₆H₅OH)

Description & uses: Carbolic acid (aka Phenol) is a clear or light pink solid crystal with a sweet and acrid smell that is combustible. It is used to manufacture plastic, nylon, pharmaceuticals, epoxies and other products. It is also used to kill germs in disinfectants and sanitizers. Carbonic acid can impact multiple parts of the body, including eyes, nose, throat, lungs, skin, liver, kidneys and muscles. Skin or eye contact requires washing with water. Breathing or swallowing phenol requires immediate medical attention.

Respirators Required for Carbolic Acid / Phenol:

50 ppm or less: Air-purifying half mask respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 10), or supplied air respirator (APF 10).
50-125 ppm: Supplied air respirator with continuous flow (AFP 25), or a powered air-purifying respirator with organic vapor canister plus particulate filter (APF 25)
125-250 ppm: Full-face air-purifying respirator with organic vapor cartridge or canister with N100/R100/P100 filter (APF 50), or full-face SCBA mask (APF 50), or full-face supplied-air respirator (APF 50)

Escape situations: Any full-face air-purifying respirator or escape respirator with organic gas canister and N100/R100/P100 filter (APF = 50)
IDLH: SCBA respirator (AFP 10,000) or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)

Carbonic Acid / Dry Ice (CO₂)

Description & uses: Carbonic acid (aka Dry Ice) is simply liquified or frozen carbon dioxide that turns into colorless and odorless CO2 gas when warmed. Carbonic acid is used to make soft drinks and sparkling wines, and as a coolant in its liquid or solid (Dry Ice) forms. It becomes combustible in the presence of some metals (magnesium, titanium, aluminum, chromium, manganese). Carbonic acid’s primary danger is its extreme cold in liquid and solid form which quickly causes frostbite if touched. The CO2 gases released are also very cold and breathing them can rapidly cool the moist surfaces of the respiratory system, leading to frostbite. Breathing carbonic acid gases can cause headaches, dizziness, difficult breathing and rapid heart rate. Prolonged high exposure can lead to asphyxia, convulsions and death.

Respirators Required for Carbonic Acid / Dry Ice:

40,000 ppm or less: Supplied-air respirator (APF 10), or full-face SCBA mask (APF 50)
Escape situations: Escape-type SCBA mask

IDLH: SCBA respirator (AFP 10,000) or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)

Chromic Acid / Chromium Trioxide (CrO3)

Description & uses: Chromic acid is used to chrome plate metal, preserve wood products, manufacture plastics and clean industrial and laboratory items. It forms in flakes or power and is dark red in color with no odor. It is combustible and reacts to metals, wood, paper and sulfur. Chromic acid exposure through the skin, eyes and breathing can lead to intense irritation and perforations in the respiratory system, eye damage, skin ulcers, liver and kidney damage, and possibly cancer. No amount of exposure is safe for humans.

Respirators Required for Chromic Acid:

Any concentrations or IDLH: SCBA respirator (AFP 10,000) or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)
Escape situations: Escape-type SCBA mask, or full-face air-purifying respirator with N100/R100/P100 filter (APF = 50)

Citric Acid (C₂H₈O₇)

Description & uses: Citric acid is produced naturally in oranges, lemons, limes, grapefruit, pineapple and other fruits and vegetables. It is also manufactured from black mold (Aspergillus niger). Citric acid is added to packaged foods, drinks, candy and vitamin supplements for flavor and as a preservative. It is a component in manufacturing soaps, disinfectants, cosmetics, hair products, pharmaceuticals and forestry products. It is also used in water treatment. Citric acid is white or colorless, has a crystalline solid form, and is odorless. Citric acid is relatively mild for humans. Skin exposure typically causes mild irritation, and ingesting citric acid in normal food-level quantities may only cause mild effects (unless there are other factors like allergy or ulcers). However, Citric acid causes significant irritation and burning of the eyes — long-term exposure can cause conjunctivitis, ulceration and cornea damage.

Respirators Required for Citric Acid:

15 mg/m3 or less: none
15 to 150 mg/m3: Half-face air-purifying respirator with acid gas cartridge (AFP 25)

150 to 750 mg/m3: Full-face air-purifying respirator with acid gas cartridge (AFP 50)
750 to Up to 1500 mg/m3: Full-face piece PAPR (Powered Air Purifying Respirator) with acid gas canister and N100/R100/P100 filter
IDLH: SCBA respirator (AFP 10,000) or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)

Escape situations: Any full-face air-purifying respirator or escape respirator with acid gas canister having an N100, R100 or P100 filter (APF = 50)

Cresylic Acid (CH₃C₆H₄OH)

Description & uses: Cresylic acid is a white crystal solid under 88 degrees F, that liquifies above 88 degrees F. It has a sweet odor. It is used to manufacture disinfectants, coatings, pesticides and chemicals such as cresols, xylenols, and phenols. Other uses include thermoset resins, paint strippers and road surfacing. Cresylic acid is dangerous to the eyes, skin, respiratory system, liver, kidneys, pancreas, central nervous system and cardiovascular system. It produces irritation and/or burns in the eyes, skin and mucous membranes. Impacts on the central nervous and cardiovascular systems are more serious, including respiratory failure, weak pulse and potential brain damage. Finally, cresylic acid can damage the lungs, liver, kidney and pancreas. A protective respirator is essential when working around cresylic acid.

Respirators Required for Cresylic Acid:

23 ppm or less: Air-purifying half mask respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 10), or supplied air respirator (APF 10).
23 to 57.5 ppm: Supplied air respirator in continuous-flow (APF 25), or powered air-purifying respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 25)
57.5 to 115 ppm: Air-purifying full-face respirator with organic vapor cartridge/canister and N100/R100/P100 filter (APF 50), or supplied-air respirator with tight-fitting face seal in continuous-flow mode (APF 50), or SCBA full-face apparatus (APF 50), or supplied-air full-face respirator (APF 50)

115 to 250 ppm: Supplied-air full-face respirator operated in positive pressure mode (APF 2000), or SCBA full-face apparatus (APF 2000)
Escape situations: Escape-type SCBA mask, or air-purifying full-face respirator with organic vapor canister and N100/R100/P100 filter (APF = 50)
IDLH: Full-face SCBA respirator (AFP 10,000) or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)

Dibutyl Acid / Dibutyl Phosphate ((C₄H₉O)₂(OH)PO)

Description & uses: Dibutyl acid (dibutyl phosphate) is an odorless liquid or oil with an amber coloration that is combustible. It is used in manufacturing, as a catalyst for other chemicals, in recycling to separate different metals, and as an additive to prevent foaming. Exposure leads to irritation of the eyes, skin and respiratory system, and headaches. Breathing or ingesting Dibutyl acid requires immediate medical assistance.

Respirators Required for Dibutyl Acid / Dibutyl Phosphate:

10 ppm or less: Air-purifying half mask respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 10), or supplied air respirator (APF 10).

10 to 25 ppm: Supplied air respirator in continuous-flow (APF 25), or powered air-purifying respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 25)
25 to 30 ppm: Air-purifying full-face respirator with organic vapor cartridge/canister and N100/R100/P100 filter (APF 50), or supplied-air respirator with tight-fitting face seal in continuous-flow mode (APF 50), or SCBA full-face apparatus (APF 50), or supplied-air full-face respirator (APF 50)
30+ or IDLH: Full-face SCBA respirator (AFP 10,000), or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)

Escape situations: Escape-type SCBA mask, or air-purifying full-face respirator with organic vapor canister and N100/R100/P100 filter (APF = 50)

Dichloropropionic Acid / Dalapon (CH₃CCl₂COOH)

Description & uses: Dichloropropionic Acid (aka Dalapon) is liquid that has an acrid smell and no coloration that is not combustible. It is generally used as an herbicide against perennial grasses. Dalapon is highly reactive / corrosive to copper and aluminum, along with organic tissues and aquatic organisms. Exposure to Dichloropropionic Acid causes irritation of the eyes and skin, trachea and lungs. I can burn the skin, as well. Serious internal effects include diarrhea, vomiting, slow pulse and impacts on the central nervous system and brain function.

Respirators Required for Dichloropropionic Acid / Dalapon:

NOTE: NIOSH does not have specific respirator requirements for Dichloropropionic Acid. However, above 5 mg/m3 is considered an occupational exposure limit, and this acid has significant proven negative health effects. Therefore, we believe the appropriate respirators by concentration level based on other similar acids should likely be:

5 mg/m³ or less: Air-purifying half mask respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 10), or supplied air respirator (APF 10).
Above 5 mg/m³ or IDLH: Full-face SCBA respirator (AFP 10,000), or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)

Escape situations: Escape-type SCBA mask, or air-purifying full-face respirator with organic vapor canister and N100/R100/P100 filter (APF = 50)

Dichlorophenoxyacetic Acid / 2,4-D (Cl₂C₆H₃OCH₂COOH)

Description & uses: Dichlorophenoxyacetic Acid (aka 2,4-D) is the most widely used herbicide on Earth. It targest broad-leaf weeds around crops, roadsides, etc. and also helps old rubber trees produce more rubber. It is formed as a white or yellowish-white crystalline powder with no odor, and is non-combustible. Exposure to Dichlorophenoxyacetic Acid negatively impacts the skin, central nervous system, liver and kidneys. Significant exposure can lead to weakness, exhaustion, muscle twitches, convulsons and skin conditions. It will also cause liver and kidney damage. Breathing or swallowing 2,4-D in high concentration requires immediate medical help.

Respirators Required for Dichlorophenoxyacetic Acid / 2,4-D:

100 mg/m³ or less: Air-purifying full-face or half-face respirator with organic vapor cartridge and N95/R95/P95/N99/R99/P99/N100/R100/P100 filter (AFP 25 or 50), supplied-air respirator (APF 10), SCBA apparatus with full-face coverage (APF 50)
IDLH: Full-face SCBA respirator (AFP 10,000), or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)
Escape situations: Escape-type SCBA mask, or air-purifying full-face respirator with organic vapor canister and N100/R100/P100 filter (APF = 50)

Ethanecarboxylic Acid / Propionic Acid (CH₃CH₂COOH)

Ethanedioic Acid

Ethanoic Acid

Ethylenecarboxylic Acid

Ethylformic Acid

Formic Acid

Hydroacrylic Acid

Hydrochloric Acid

Do you need a respirator for hydrochloric acid?

Yes. Hydrochloric acid is regulated by the EPA as a dangerous material, and it should be handled accordingly. When working with hydrochloric acid of any concentration, you must use a respirator designed for vapor, a face shield and gloves made of rubber.

Eyes, skin, and mucous membranes are all vulnerable to hydrochloric acid’s corrosive nature. You must wear a respirator at all times when handling or being in close proximity to hydrochloric acid.

Hydrochloric acid is a type of strong, corrosive acid that can cause serious injury if it comes into contact with the skin or eyes. Hydrochloric acid respirators are designed to protect against these risks.

What type of respirator is used for hydrochloric acid?

For hydrochorlic acid you need to wear a minimum of a full-face air-purifying respirator. Respirators that cleanse the air and have acid gas canisters attached to the front or rear of the facepieces are required. The Assigned Protection Factor (APF) of the respirator should be 50+.

What is hydrochloric acid used for?

There are various applications for hydrochloric acid:

Producing fertilizers and dyes
Electroplating
Photography

Textile manufacturing
Rubber manufacturing
Producing chlorides

Can you survive inhaling hydrochloric acid?

If you inhale or ingest hydrochloric acid fumes or gas your lips, mouth, throat and stomach may all be seriously injured. Hydrochloric acid can cause holes (perforations) in the esophagus and stomach, and may lead to life-threatening infections in the lungs and abdomen.

Why is hydrochloric acid called muriatic acid?

Marine acid air was the name given to HCl gas in its gaseous form. Names like muriatic acid and hydrochloric acid are derived from the same source (muriatic means “pertaining to brine or salt,” therefore muriate denotes hydrochloride).

Hydrocyanic Acid

Hydrofluoric Acid

Hydrosulfuric Acid

Hydroxy-Propionic Acid

Mercaptoacetic Acid

Metacetonic Acid

Methacrylic Acid

Methanecarboxylic Acid

Methanoic Acid

Methylacrylic Acid

Methylpropenoic Acid

Muriatic Acid

Do you need a respirator for muriatic acid?

Yes. Safety precautions with muriatic acid are essential, and the same as hydrochloric acid. You need to use acid-resistant gloves and a respirator in addition to thick, full-coverage garments and a full-face mask.

Muriatic acid is highly toxic and should be diluted with water whenever possible to reduce its potency and make it safer to work with.

What type of respirator is used for muriatic acid?

For muriatic acid you need to wear a full-face air-purifying (AP) respirator. The Assigned Protection Factor (APF) of the respirator should be 50+.

What will happen if you inhale muriatic acid?

A wide variety of reactions may occur when typical pool chemicals like chlorine and muriatic acid come into close contact with biological tissue. Coughing, choking, chest pain, and shortness of breath may all occur if you breathe in the chemical dust or odor.

Nitric Acid / Engravers Acid

Orthophosphoric Acid

Oxalic Acid

Phosphoric Acid

Picric Acid

Propenoic Acid

Prussic Acid

Silicic Acid

Sulfuric Acid / Battery Acid (H₂SO₄)

Description & uses: Sulfuric acid (aka Battery Acid or Oil of Vitriol) is an oily, odorless liquid with a dark brown color. Sulfuric acid is used in lead acid batteries where it helps release ions from lead to generate electricity. It has a wide variety of uses, including breaking down organic materials and the manufacture of explosives, detergents, dyes, petroleum refining chemicals, pigments, pharmaceuticals, and more. Sulfuric acid is very dangerous and highly reactive to organic materials and water. Exposure in liquid or gaseous form can extensively damage the eyes, skin, nose, mouth, throat and teeth. It can cause pulmonary edemas, bronchitis, emphysema, conjunctivitis of the eyes and burns. High exposure can be deadly.

Respirators Required for Sulfuric Acid:

15 mg/m3 or less: Supplied-air respirator (AFP 25) in continuous flow mode, or powered air-purifying respirator with acid gas cartridge (AFP 25), or full-face cartridge respirator (AFP50) with acid gas cartridge and an N100, R100 or P100 filter, or air-purifying full-face respirator (AFP 50) with acid gas canister and N100, R100, or P100 filter.

Above 15 mg/m3 or IDLH: SCBA respirator (AFP 10,000) or self-contained full-face breathing apparatus in a pressure-demand or positive-pressure mode (AFP 10,000)
Escape situations: Any full-face air-purifying respirator or escape respirator with acid gas canister having an N100, R100 or P100 filter (APF = 50)

Trichlorophenoxyacetic Acid

Thioglycolic Acid

Thiovanic Acid

Trichloroacetic Acid

Trichloroethanoic Acid

References

NIOSH Pocket Guide to Chemicals

NIOSH Index of Chemical Names, Synonyms and Trade Names

NIH PubChem

InChem

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