E2648-SO2
Rev 11.03.2021
Sulfur Dioxide
A colorless, non-flammable gas with a pungent odor like struck matches that is soluble in
water.
Synonyms: Sulfurous anhydride, Sulfur(IV) oxide.
Conversion of ppm to mg/m
3
is calculated for 25°C and 1 atm.
3
Chemical formula
SO
2
Molar weight
64
Conversion
1 ppm = 2.62 mg/m
3
Relative gas density (to air)
2.21
Boiling point
−10 °C
Flammability
Nonflammable
Odor
A characteristic pungent irritant odor similar to a
just-struck match
Odor threshold
From 0.266 mg/m
3
(0.1 ppm) to 12.5 mg/m
3
(4.7 ppm)
according to different studies
Hazards
Inhaling sulfur dioxide is associated with increased
respiratory symptoms and disease, difficulty in breathing,
and premature death.
Exposure
limits (NIOSH)
TWA
5 mg/mm
3
/ 2 ppm
STEL
13 mg/mm
3
/ 5 ppm
IDLH (NIOSH)
262 mg/mm
3
/ 100 ppm
