Industrial Hygiene


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Inorganic Acids

The most common inorganic acids are hydrochloric, nitric, sulphuric, and phosphoric acids, which contain hydrogen atoms that dissociate in water or other solvents. Inorganic acids may be present in industrial environments as vapours, mists, or gases. The main hazard associated with inorganic acids is that they are highly corrosive and can cause severe irritation and burns to skin, eyes, respiratory tract, and mucous membranes.

Occupational Exposure

Inorganic acids are used in a broad range of industries, including metal manufacturing and finishing, fertilizer production, battery manufacturing, chemical and petrochemical sectors. The amount of vapour or mist that is generated varies on the process and the application method. Human exposure depends on several factors, such as proximity to the chemical source, particle size, and ventilation.

Health Effects

Inorganic acids are corrosive and cause chemical burns to eyes, skin, and mucous membranes. According to the International Agency for Research on Cancer (IARC, 1992), occupational exposure to strong inorganic acid mists containing sulphuric acid is known to be a human carcinogen, based on studies in humans that indicate a causal relationship between exposure to strong inorganic acid mists containing sulphuric acid and human cancer. Mists or vapours of inorganic acids can cause irritation to the respiratory tract and mucous membranes, discolouration or erosion of teeth.

Inorganic Acids Analytical Services

ChemicalAnalytical MethodEstimated LOD (μg per sample)NIOSH Recommended Exposure Limits (mg/m3)
Hydrobromic acidNIOSH 79032.010
Hydrochloric acidNIOSH 79030.67
Hydrofluoric acidNIOSH 79030.4TWA 2.5 (15 min)
Nitric acidNIOSH 79032.0TWA 5
Perchloric acidNIOSH 790345-
Phosphoric acidNIOSH 79033.0TWA 1
Sulfuric acidNIOSH 79033.0TWA 1

CASSEN Testing Labs Services

  • Individual Compound Analysis and Analysis Packages – CASSEN provides a range of options to match your analytical needs with competitive pricing for larger sample batches.
  • Technical Consultation – CASSEN Testing Labs offers technical consultations for selecting an appropriate analytical method and sampling procedure. Support and information is available by phone, online videos, and detailed instruction manuals provided with sampling media.
  • Quality Control and Accreditation – CASSEN Testing Labs is accredited by the American Industrial Hygiene Association Laboratory Accreditation Programs, LLC (AIHA-LAP, LLC) and operates strictly according to ISO17025 Quality Standard. CASSEN participates in the United Kingdom’s Workplace Analysis Scheme for Proficiency (WASP) program as well as AIHA’s Industrial Hygiene Proficiency Analytical Testing (IHPAT) Program.
  • Rapid Turnaround Time Options – Rush analysis (8 hrs, 24 hrs, 48 hrs) is available by request in order to help resolve pressing issues that can endanger health and safety or incur high downtime costs at industrial facilities.


IARC (1992). Occupational exposures to mists and vapours from strong inorganic acids and other industrial chemicals. IARC Monogr. Eval. Carcinog. Risks Hum., 54: 1–310.

NTP (1997). NTP Report on Carcinogens. Background Document for Strong Inorganic Acid Mists Containing Sulfuric Acid.