Photograph of a Drager hand pump used to measure carbon dioxide levels in the environment. Effects of Sulphur Dioxide Gas Exposure SO2

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What are the effects on humans of exposure to SO2 sulphur dioxide gas?

SO2 toxicity, exposure limits, sources, effects.

This article series gives basic information about exposure to and potential health hazards from a number of common toxic gases that may be found indoors or in or around buildings. We describe symptoms of exposure to these gases, industry recommendations for gas exposure limits, how gases may be measured, and how to track down and cure the sources of gas leaks in buildings.

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Sulfur Dioxide Gas Exposure Hazards & Effects

For sulfur dioxide (SO2 )the TLV had been 5.0 ppm for many years, but in 1978 ACGIH announced its intention to reduce that TLV to 2.0 ppm; that was done in 1980. The reason for this was recent information indicating that chronic (long term, repeated) exposure to sulfur dioxide concentrations near 5.0 ppm was found to have some minimal effects on working populations.

Sulfur dioxide is an upper respiratory tract irritant and acute (single or short-term) exposures cause nothing but irritation of the nose and throat. Long term exposures to sulfur dioxide concentrations in excess of 2.0 ppm can be expected in some cases to cause minor lung changes.

Potential Symptoms of sulfur dioxide gas exposure: Eye, nose, throat irritation; rhinorrhea, nosebleeds; choking, coughing, shortness of breath, chest pain, pulmonary edema, cyanosis; reflex bronchoconstriction; eye, skin burns; frostbite (on contact with liquid); asthma; chronic bronchitis. [12]

Affected organs: eyes, skin, respiratory system.

Health Effects of sulfur dioxide gas exposure: Irritation-Eye, Nose, Throat, Skin---Marked (HE14) Mutagen (HE2); Respiratory effects--- Bronchoconstriction, pulmonary edema, reactive airways dysfunction syndrome (HE9 and HE11); Suspect reproductive effects (HE5)

Affected Organs: Eyes, skin, respiratory system

OSHA Note:

Sulfur dioxide is listed by the FDA as generally recognized as safe when used in accordance with good manufacturing practice as a preservative of fruits or vegetables (21 CFR 182.3862). [12]

Sulfur Oxides Toxicity and Exposure Limits References:

Sulphur dioxide Sulfur dioxide SO2 exposure limits (PELS typically are at 5 ppm or less by some standards) are at

Watch out: NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 100 ppm

Sulfur dioxide & other Oxides: Air Quality Criteria for Particulate Matter and Sulfur Oxides, Vol. III, US EPA, Environmental Criteria and Assessment Office, Research Triangle Park NC 27711, Dec. 1982, EPA-600/8/2-029c. Web search 08/26/2010, original source: [large PDF]

OSHA citations for sulphur dioxide hazards & effects:[12]

At VOCs VOLATILE ORGANIC COMPOUNDS we discuss several chemicals and gases found indoors and offer advice for reducing indoor exposure.

Question: Sulphur dioxide SO2 exposure limits?

[This question originally appeared in reader comments at CARBON DIOXIDE - CO2] - Ed.]

This article is interesting. I think I understand the concept but I have an application that use an analyzer.
To calibrate this instrument, I need to use an 8% SO2 compress gas cylinder (cylinder capacity 5m3). This is located in a sealed 10x10x10 room, so my room is 1000m3 and unventilated.
Worst case scenario, the cylinder empties in this room. Is this an accute risk knowing that 3000 ppm is the LC50 (1/2hour) limit and the bottle contains 80000ppm? I have a bit of difficulties to put some math around this. Could you please explain?

I think 8% concentration x 5m3 cylinder = 0.4m3 of SO2 release in the room.
The gas will occupy 0.4m3/1000m3 = 0.04% of the room volume which is 400ppm.
400ppm < LC50 3000ppm = Low Risk?

- Syl


Syl, your question was a bit unclear and makes me worry that you are messing with gases without proper education or preparation. You are asking about Sulphur dioxide (SO2) in an article about Carbon dioxide (CO2) - in any event, if you are asking about recommended exposure limits for Sulphur dioxide SO2,

Sulphur dioxide exposure limits: OSHA PELs for SO2 and other recommended exposure limits are given at Sulfur Dioxide Gas in our article titled: GAS EXPOSURE LIMITS & STANDARDS. Depending on the standard, SO2 PELs range among 0.25 ppm, 2 ppm, or 5 ppm. - all significantly less than your 400 ppm.

Watch out: NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 100 ppm


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