Label abbreviations descriptions

SULFUR DIOXIDE†

Chemical Identification
CAS # 7446-09-5
Formula

SO₂
Synonyms

sulfurous acid anhydride; sulfurous oxide; sulfur oxide
Physical Properties
Physical description Colorless gas with a characteristic, irritating, pungent odor.
Boiling point 14°F Molecular weight 64.1
Freezing point/melting point -104°F Vapor pressure 3.2 atm
Flash point Vapor density 2.26
Specific gravity 1.434 Ionization potential 12.30 eV
Lower explosive limit (LEL) Upper explosive limit (UEL)
NFPA health rating 3 NFPA fire rating 0
NFPA reactivity rating 0 NFPA special instruction
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs
Monitoring Methods Used by OSHA
Analyte code (IMIS no.) 2290
Sampling group
Sampler/Sampling media Silica gel coated with silver nitrate and a glass fiber filter treated with sodium carbonate/glycerol, 2, (200/200 mg) [SKC 226-177]
Sampling time*

240 min
Sampling volume (TWA)*

12 L
Sampling flow rate (TWA)*

0.05 L/min
Sampling volume (STEL/Peak/C)*

7.5 L
Sampling flow rate (STEL/Peak/C)*

0.5 L/min
Analytical method instruments IC
Method reference OSHA 1011 (fully validated)
Notes

Use this method when sampling for both hydrogen sulfide and sulfur dioxide. Sulfur trioxide and gaseous elemental sulfur can cause a positive interference. The sampling pump must be capable of maintaining a constant flow of 0.5 L/min with a back pressure of approximately 20 inches of water. 
Special requirements

* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Wipe Method
Sampler/Sampling media
Bulk Method
Bulk Method
On-Site Screening Techniques
Device CMS Chip CMS Chip
Model/Type Sulfur dioxide, 0.4-10 ppm range Sulfur dioxide, 5-150 ppm range
Sampling information
(see manufacturer instructions)
Exposure Limits
OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA

5 ppm (13 mg/m³)

 REL-TWA

2 ppm (5 mg/m³)

 TLV-TWA PEL-TWA

2 ppm (5 mg/m³)
PEL-STEL REL-STEL

5 ppm (13 mg/m³)

 TLV-STEL

0.25 ppm [2008]

 PEL-STEL

5 ppm (10 mg/m³)
PEL-C REL-C TLV-C PEL-C
Skin notation

N

 Skin notation

N

 Skin notation

N

 Skin notation

N
Notes:

See 29 CFR 1910.1000 Table Z-1.

 Notes: Notes: Notes:
Health factors:  See NIH-NLM PubChem. IDLH

100 ppm
Carcinogenic classifications: TLV-A4, IARC-3 Notes:
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:

0.3 ppm/3 ppm/25 ppm

Last Updated Date : 01/12/2021