Sulfuric acid in the yard and garden
High risk for your yardSulfuric acid (H₂SO₄; oil of vitriol) is the world's most produced industrial chemical (~265 million tons/year) and one of the most hazardous corrosive substances encountered in occupational and consumer settings. Physical properties relevant to hazard: pure H₂SO₄ is a colorless, viscous, hygroscopic liquid (specific gravity 1.84); it generates intense heat upon dilution with water (exothermic hydration) — adding water to concentrated H₂SO₄ causes violent spattering. Mechanism of injury: H₂SO₄ causes immediate severe corrosive injury by dehydration (water extraction from tissues) and proton donation — unlike HF, there is no systemic ionic toxicity, but the physical corrosion is extreme. Concentrated H₂SO₄ (>51%) causes deep, penetrating burns with coagulative necrosis producing eschar; the exothermic reaction with tissue water amplifies thermal injury. Industrial uses: fertilizer production (phosphate processing), metal refining (pickling), battery manufacturing (lead-acid batteries — 38% H₂SO₄), chemical synthesis, petroleum refining. Consumer and criminal use: H₂SO₄ in drain cleaners (up to 95% concentration), battery acid, and acid attack assaults (deliberate throwing of concentrated acid — a documented form of violence in multiple countries). IARC Group 1: occupational exposure to strong inorganic acid mists (including H₂SO₄ mist) is carcinogenic to humans — specifically laryngeal and lung cancer; this relates to aerosolized acid mist in industrial settings, not single-incident skin burns. OSHA PEL: 1 mg/m³; NIOSH IDLH: 15 mg/m³.
What is sulfuric acid?
Also known as: Sulphuric acid, Dihydrogen sulfate, Dipping acid, Mattling acid.
- IUPAC name
- sulfuric acid
- CAS number
- 7664-93-9
- Molecular formula
- H2O4S
- Molecular weight
- 98.08 g/mol
- SMILES
- OS(=O)(=O)O
- PubChem CID
- 1118
Risk for people, pets,
High riskSulfuric acid (H₂SO₄; oil of vitriol) is the world's most produced industrial chemical (~265 million tons/year) and one of the most hazardous corrosive substances encountered in occupational and consumer settings. Physical properties relevant to hazard: pure H₂SO₄ is a colorless, viscous, hygroscopic liquid (specific gravity 1.84); it generates intense heat upon dilution with water (exothermic hydration) — adding water to concentrated H₂SO₄ causes violent spattering. Mechanism of injury: H₂SO₄ causes immediate severe corrosive injury by dehydration (water extraction from tissues) and proton donation — unlike HF, there is no systemic ionic toxicity, but the physical corrosion is extreme. Concentrated H₂SO₄ (>51%) causes deep, penetrating burns with coagulative necrosis producing eschar; the exothermic reaction with tissue water amplifies thermal injury. Industrial uses: fertilizer production (phosphate processing), metal refining (pickling), battery manufacturing (lead-acid batteries — 38% H₂SO₄), chemical synthesis, petroleum refining. Consumer and criminal use: H₂SO₄ in drain cleaners (up to 95% concentration), battery acid, and acid attack assaults (deliberate throwing of concentrated acid — a documented form of violence in multiple countries). IARC Group 1: occupational exposure to strong inorganic acid mists (including H₂SO₄ mist) is carcinogenic to humans — specifically laryngeal and lung cancer; this relates to aerosolized acid mist in industrial settings, not single-incident skin burns. OSHA PEL: 1 mg/m³; NIOSH IDLH: 15 mg/m³.
Regulatory consensus
3 regulatory and scientific bodies have classified Sulfuric acid. The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| IARC | — | Group 1 | |
| OSHA | — | Occupational exposure limit | |
| EPA CTX / NTP RoC | — | Known Human Carcinogen |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where your yard encounter sulfuric acid
- Outdoor Air — Vehicle exhaust, Industrial emissions, Power plant discharge
- Indoor Air — Combustion byproducts, Office buildings, Parking garages
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Sulfuric acid:
-
Fragrance-free formulations
Trade-offs: Consumer preference for scented productsRelative cost: 1.2-2×
-
Essential oil-based fragrances (with disclosure)
Trade-offs: Natural does not mean safe — many essential oils are skin sensitizersRelative cost: 2-5×
Frequently asked questions
Is sulfuric acid safe for your yard?
Sulfuric acid (H₂SO₄; oil of vitriol) is the world's most produced industrial chemical (~265 million tons/year) and one of the most hazardous corrosive substances encountered in occupational and consumer settings. Physical properties relevant to hazard: pure H₂SO₄ is a colorless, viscous, hygroscopic liquid (specific gravity 1.84); it generates intense heat upon dilution with water (exothermic hydration) — adding water to concentrated H₂SO₄ causes violent spattering. Mechanism of injury: H₂SO₄ causes immediate severe corrosive injury by dehydration (water extraction from tissues) and proton donation — unlike HF, there is no systemic ionic toxicity, but the physical corrosion is extreme. Concentrated H₂SO₄ (>51%) causes deep, penetrating burns with coagulative necrosis producing eschar; the exothermic reaction with tissue water amplifies thermal injury. Industrial uses: fertilizer production (phosphate processing), metal refining (pickling), battery manufacturing (lead-acid batteries — 38% H₂SO₄), chemical synthesis, petroleum refining. Consumer and criminal use: H₂SO₄ in drain cleaners (up to 95% concentration), battery acid, and acid attack assaults (deliberate throwing of concentrated acid — a documented form of violence in multiple countries). IARC Group 1: occupational exposure to strong inorganic acid mists (including H₂SO₄ mist) is carcinogenic to humans — specifically laryngeal and lung cancer; this relates to aerosolized acid mist in industrial settings, not single-incident skin burns. OSHA PEL: 1 mg/m³; NIOSH IDLH: 15 mg/m³.
What products contain sulfuric acid?
Sulfuric acid appears in: Vehicle exhaust (Outdoor air); Industrial emissions (Outdoor air); Combustion byproducts (Indoor air); Office buildings (Indoor air).
Why do regulators disagree about sulfuric acid?
Sulfuric acid has been classified by 3 agencies including IARC, OSHA, EPA CTX / NTP RoC, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.
See Sulfuric acid in the outdoor app
Look up products containing sulfuric acid, compare to alternatives, and explore the full data record.
Open in outdoor View raw API dataSources (2)
- NIOSH Pocket Guide: Sulfuric Acid — IDLH 15 mg/m³; corrosive burns; battery acid; drain cleaner; dehydration mechanism; industrial production; PPE requirements (2019) (2019) — regulatory
- IARC Monograph Vol 54: Occupational Exposures to Mists and Vapours from Strong Inorganic Acids — Group 1 carcinogen (acid mist); laryngeal/lung cancer; H₂SO₄ occupational exposure; industrial settings (1992) (1992) — regulatory
Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →