Hesperian Health Guides


Acids come in liquid form and are used to clean electronic parts and metals, added to fabric dyes, and used in leather treatment.

Acids release fumes that can be toxic when inhaled, sometimes causing lung problems immediately. Absorbing acids through the skin is also a common and dangerous form of exposure. As a group, acids are very reactive chemicals and can be extremely harmful when they touch your body. Even small amounts or very diluted acids can cause severe burns and penetrate your skin.

The charts include only some of the acids that exist. See Learn about chemicals used in your factory and how to find information about other acids. See the Index of chemical names to find alternative names for acids.

Prevent or reduce exposure:

  • Have ventilation systems that extract fumes and replace or dilute dirty air with clean air (see Chapter 17: Ventilation).
  • Enclose operations where possible.
  • Do not mix or pour acids by hand.
  • Wear acid-resistant gloves, acid-resistant long aprons, eye-protective glasses and a face shield. Wear correct respirators that fit you. All protective clothing should be clean, available each day, put on before work, and never taken home with you (see Chapter 18: Personal protective equipment).
  • Have an emergency plan for spills, splashes, and accidental exposures. The plan should include first aid treatment and protective equipment. Keep necessary supplies at the worksite, well stocked, and accessible to workers. See First aid for HF burns.
  • Work areas where acids are used, stored, and mixed need to be controlled for heat and monitored for concentration of fumes and vapors. They should also have alarms, fire extinguishers, and a fire emergency plan (see Chapter 11: Fire).

Acetic acid (methane carboxylic acid, ethanoic acid ) CAS No. 64-19-7

fire or explosive

Formic acid (formylic acid, aminic acid) CAS No. 64-18-6

fire or explosive

Hydrochloric acid (HCl, muriatic acid, hydrogen chloride) CAS No. 7647-01-0

Hydrofluoric acid (HF, fluoric acid, hydrofluoride) CAS No. 7664-39-3

immediate death

Nitric acid (hydrogen nitrate, nitrogen hydroxide oxide, aqua fortis) CAS No. 7697-37-2

Acids are colorless liquids with strong smells. Acetic acid has a vinegar-like smell. Formic, hydrochloric, hydrofluoric, and nitric acid have pungent, irritating odors. Acids release fumes. Nitric acid in fume form is red in color.
Acids are used in electronics and garment industries. Formic acid is used in dyeing and finishing textiles and treating leather. Hydrochloric and hydrofluoric acid are used to clean wafers, chips, and printed circuit boards. Nitric acid in fume form is used to dissolve, etch, and clean metals in the electronics industry.
They can severely irritate, burn the skin and cause a rash, pain, redness, ulceration and permanent scarring. When hydrochloric acid touches your skin, it will burn quickly, but the skin will feel cold and numb. Treat it quickly as a chemical burn. When hydrofluoric acid touches your skin it will burn quickly and deeply. However, hydrofluoric burns do not show right away, so it is important to immediately wash off any area that comes into contact with it. If it is absorbed through the skin it can be fatal. See First aid.

They severely irritate and burn the eyes and can lead to permanent eye damage, corneal scarring and blindness. See First aid.


The fumes can irritate your nose, throat, and lungs, causing coughing, wheezing and difficulty breathing. Inhaling fumes can cause dizziness and headaches. It can also create a buildup of fluid in the lungs, called lung edema. Hydrofluoric acid may be fatal because it can cause irregular heartbeat. See First aid for HF burns and First aid for chemicals.


They can lead to injury of the gastrointestinal tract and stomach causing loss of appetite, nausea, vomiting, diarrhea and abdominal pain. Hydrofluoric acid can burn your mouth and throat and lower your heart rate and blood pressure. See First Aid for HF burns and First aid for chemicals and seek medical attention right away.


Acids can harm your liver, kidneys, and lungs. They can cause chronic bronchitis and pneumonia.

Nitric acid can cause yellowing and erosion of the teeth.

Hydrochloric acid can cause yellowing and erosion of the teeth.

Hydrofluoric acid can cause digestive imbalance, irregular heartbeat, and affect your nervous system leading to seizures. It can also weaken or destroy your bones and cause skin problems.

Use butyl gloves, an apron, and eye/face protection to keep acids off your skin (see Chapter 18: Personal protective equipment).

For HCl, use Tychem or Teflon gloves.

For HF, use double nitrile gloves.

Wear a respirator that can filter acid fumes (see respirator with filter).