Sulfur Dioxide

⚠ Danger ☠
Sulfur dioxide is deemed a particularly hazardous substance (PHS) by EH&S and you need approval before using it. Throughout this SOP, you will see PHS where steps specific to particularly hazardous substances exist.__]

This chemical standard operating procedure (SOP) and the associated Safety Data Sheet (SDS) are for our safety. Read and understand both documents. If this is a paper copy, check for updated versions on the IsoLab website.


Sulfur dioxide is used as an isotope reference gas for a mass spectrometer in our solid sulfur isotope analysis SOP.

Hazards - SDS

GHS Compressed Gas Hazard Pictogram GHS Corrosive Hazard Pictogram GHS Toxic Substance Hazard Pictogram

Contains gas under pressure; may explode if heated. Causes severe skin burns and eye damage. Toxic if inhaled.

Protection - SDS

Hierarchy of Controls
The Hierarchy of Hazard Controls. While you should consider Elimination and Substitution, this SOP assumes the bottom three are directly applicable and described in this section.

Engineering Controls

Before opening the SO2 cylinder, ensure the fume hood has proper air flow by checking the flow rate on the control panel and / or using a smoke match or wipe to visualize flow.

PHS - Before opening the SO2 cylinder, ensure the two detectors are on and have working batteries.

Administrative Controls

PHS - No specific administrative controls required.

Personal Protective Equipment (PPE)

PHS - Since the compressed SO2 cylinder is stored in a fume hood, only gloves (nitrile with extended cuff or similar) are required to open and close the cylinder.

Handling - SDS

Keep the valve tightly closed when not in use.

PHS - Decontamination - If removing the regulator for any purpose, keep it in the fume hood until the SO2 gas has had a chance to dissipate. Any tubing that is to be reused for another purpose or discarded, must first be flushed with an insert gas such as nitrogen, where the effluent is vented to a fume hood.

Storage - SDS

Sulfur dioxide must be stored in the 302A fume hood. Use MyChem, the UW EH&S chemical inventory database, to find additional information on chemical storage.

Spills - SDS

Do not breath gas.

PHS - Exposure:

If SO2 is released into the fume hood via leak, try to close the cylinder valve if safe to do so. Close the fume hood sash.

If SO2 has been released into the room, the SO2 detectors should be alarming. SO2 odor is pungent; similar to a just-struck match.

Immediately evacuate all personnel from danger area. Use self-contained breathing apparatus and protective clothing where needed. Reduce vapors with fog or fine water spray. Shut off flow if without risk. Ventilate area or move cylinder to a well ventilated area. Prevent runoff from contaminating surrounding environment. Toxic, corrosive vapors may spread from spill. Before entering area, especially a confined area, check atmosphere with an appropriate device.

If the release of SO2 endangers anyone outside the lab, pull the nearest fire alarm and call 911.

If you need assistance or advice, use the IsoLab Emergency Contacts sheet.

Consult the EH&S Spill Poster and Exposure Poster

PHSDo not dispose of unused quantities. Return cylinder to supplier. Contact Praxair or Airgas and make arrangements for pickup.

Consult our generalized Chemical Waste Disposal SOP.

Chemical SOP Signature Required Sticker
This sticker is placed on all chemical containers that are deemed particularly hazardous and require approval before use.

Training - PHS

Sulfur dioxide is deemed a particularly hazardous substance - PHS by EH&S and you need approval before using it. Complete the list of requirements below before using this chemical.


  1. You must have completed Managing Laboratory Chemicals in the last three years. Login to check.
  2. You also need to complete the EH&S compressed gas training.
  3. Read and understand the SDS for Sulfur dioxide.
  4. Read, understand, and digitally sign this SOP.
  5. Contact your Principal Investigator (PI) AND the Chemical Hygiene Officer (CHO) indicating that you have completed all prerequisites and await approval.


I have read and understood the present SOP and, before starting work outlined in the present SOP, I will complete all required training.

Last updated: 2021-06-15 13:53:11