You must treat the existence of toxic gases in the workplace appropriately. Otherwise, a fatal work accident will occur.
The first thing you should do is to ensure that you know gases that are classified as toxic gases.
After that, you need to identify their existences in the workplace exactly, where the sources are located.
Finally, you must take appropriate countermeasures to these toxic gases in order to eliminate or reduce the releases, monitor them, and alert you when unsafe levels of the gases are detected in the atmosphere.
The Definition of Toxic Gas
For the toxic gas definition, I will use the definition of toxic gas by the NFPA.
According to NFPA, a toxic gas is defined as:
“A gas with a median lethal concentration (LC50) in air of more than 200 ppm but not more than 2000 ppm by volume of gas or vapor, or more than 2 mg/L but not more than 20 mg/L of mist, fume, or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 0.44 lb and 0.66 lb (200 g and 300 g) each.”
From the above definition, then I take several gases that have health hazard rating from 2 to 4 as the examples.
The health hazard rating by NFPA 704 is
- 4: deadly
- 3: extreme danger
- 2: hazardous
- 1: slightly hazardous
- 0: normal material
The examples of toxic gases that you will see in the section below are arranged based on their health hazard ratings.
28 Toxic Gases in the Workplace
After knowing the definition of toxic gas, now we will see some examples of toxic gases that can commonly be found in the workplace.
Be careful when you deal with one of the following toxic gas in the workplace since they are harmful to your health.
| Toxic Gas | Chemical Formula | NFPA Toxic Rating |
| Arsine | ASH3 | 4 |
| Diborane | B2H6 | 4 |
| Dichlorosilane | H2Cl2Si | 4 |
| Fluorine | F2 | 4 |
| Hydrogen Cyanide | HCN | 4 |
| Hydrogen Fluoride | HF | 4 |
| Hydrogen Sulfide | H2S | 4 |
| Ozone | O3 | 4 |
| Phosgene | COCL2 | 4 |
| Phosphine | PH3 | 4 |
| Sulfur Tetrafluoride | SF4 | 4 |
| Ammonia | NH3 | 3 |
| Boron Trichloride | BCl3 | 3 |
| Boron Trifluoride | BF3 | 3 |
| Carbon Monoxide | CO | 3 |
| Chlorine | Cl2 | 3 |
| Dimethylamine | (CH3)2NH | 3 |
| Ethylene Oxide | C2H4O | 3 |
| Hydrogen Bromide | HBr | 3 |
| Hydrogen Chloride | HCL | 3 |
| Monomethylamine | CH3NH2 | 3 |
| Nitric Oxide | NO | 3 |
| Nitrogen Dioxide | NO2 | 3 |
| Sulfur Dioxide | SO2 | 3 |
| Trimethylamine | C3H9N | 3 |
| Methyl Chloride | CH3Cl | 2 |
| Vinyl Chloride | C2H3Cl | 2 |
Toxic Gas Accidents in the Workplace
In this final section, I would like to show some work accident data in some countries that associated with toxic gases.
In the US, according to the U.S Bureau of Labor Statistics, there were 297 fatalities across the 7-year span, i.e. from the year 2011 to 2017, caused by toxic gas exposures.
Meanwhile, in Japan work accidents caused by harmful substances – including toxic gases – were responsible for 6% of the total fatalities in 2019, as published by Japan Industrial Safety & Health Association.
In China, gas or chemical exposure was responsible for 9% of the total work accident in 2019, as reported by China Labour Bulletin.
