The unprotected exploration of a local environment by a human is limited by a number of factors. One of these factors is exposure to chemical contaminants. The following is a list of substances toxic to humans:
Deuterium
Asbestos
Lead
Mercury
Vinyl chloride
Inorganic Arsenic compounds
Inorganic Cadmium compounds
Inorganic Fluoride compounds
Hexavalent Chromium compounds
Oxidic compounds
Sulfidic compounds
Soluble inorganic Nickel compounds
Polycyclic aromatic hydrocarbons
Chlorobiphenyls
Dodecachloropentacyclodecane
Polybrominated biphenyls
Chlorofluorocarbon
Polychlorinated Terphenyls
Bromochlorodifluoromethane
Bromotrifluoromethane
Dibromotetrafluoroethane
Dibenzo-para-dioxin
Dibenzofuran
Polychlorinated dibenzo-para-dioxins
Polychlorinated dibenzofurans
Tetrachloromethane
1,1,1-trichloroethane (methyl chloroform)
Bromofluorocarbons
Hydrobromofluorocarbons
Methyl bromide
Bis(chloromethyl) ether
Chloromethyl ether
Hydrochlorofluorocarbons
Benzene
(4-Chlorophenyl)cyclopropylmethanone,O-[94-nitrophenyl)methyl]oxime
Benzidine
benzidine dihydrochloride
3,3-Dichlorobenzidine
Bis(2-ethylhexyl)phthalate
Creosote waste
1,2-Dichloroethane
Dichloromethane
Hexachlorobenzene
Tetrachloroethylene
Trichloroethylene
Tributyltetradecylphosphonium chloride
Bromochloromethane
Acetaldehyde
1,3-Butadiene
Acrylonitrile
Arolein
Ammonia
Nonylphenol
Inorganic Chloramines
Ethylene oxide
N-Nitrosodimethylamine
Formaldehyde
Ozone
Nitric oxide
Nitrogen dioxide
Sulfur dioxide
Hexachlorobutadiene
| Compound | Limit (mg.m-3) |
| H2O2 | 1.4 |
| NH3 | 35 |
| H2Se | 0.2 |
| Cl2 | 3 |
| F2 | 0.2 |
| Br2 | 0.7 |
| HCN | 11 |
| HCl | 7 |
| HBr | 10 |
| SO2 | 13 |
| PH3 | 0.4 |
| CO2 | 9000 |
| CO | 55 |
| OF2 | 0.1 |
| O3 | 0.2 |
| NO2 | 9 |
| NF3 | 29 |
| CClF3 | 0.4 |
| CHCl3 | 240 |
| CHCl2F | 4200 |
| CH2ClBr | 1050 |
| CFCl3 | 5600 |
| CF2Br2 | 860 |
| C2Cl2F4 | 7000 |