TIME-WEIGHTED AVERAGE (TLV-TWA): 2 ppm - Carcinogenicity Designation A4

STEL: 5 ppm

TLV BASIS - CRITICAL EFFECT(S) : Irritation

CARCINOGENICITY DESIGNATION A4 - Not Classifiable as a Human Carcinogen: Inadequate data on which to classify the substance as a human and/or animal carcinogen.

NOTE: In many Canadian jurisdictions, exposure limits are similar to the ACGIH TLVs. Since the manner in which exposure limits are established, interpreted, and implemented can vary, obtain detailed information from the appropriate government agency in each jurisdiction.

Non-flammable gas. However, heat from a surrounding fire can rupture cylinders, causing a dangerous explosion and the release of toxic sulfur dioxide gas. Cylinders have fusible metal plugs which melt at 165 deg F, releasing SO₂.

SO₂ is extremely stable to heat, even up to 2000 deg C. Complex reactions of SO₂ occur in the atmosphere. SO₂ gas and its aqueous forms are oxidized to sulfuric and sulfates which contribute to air pollution.

Moisture.

3 to 5 ppm (detection); 1 to 3 ppm (detection)

Not reliable: odour threshold is about the same magnitude as TLV.

This material is a VERY TOXIC GAS. Before handling, it is very important that engineering controls are operating and that protective equipment requirements are being followed. People working with this chemical should be properly trained regarding its hazards and its safe use.

If sulfur dioxide is accidentally released, immediately put on a suitable respirator and leave the area until the severity of the release is determined. In case of leaks or spills, escape-type respiratory protective equipment should be available in the work area. Immediately report leaks, spills or ventilation failures. Be aware of typical signs and symptoms of poisoning and first aid procedures. Any signs of illness should be reported immediately to supervisory personnel.

Use in smallest possible amounts in a well-ventilated area, separate from the storage area. If possible, use closed handling systems for processes involving this material. Prevent the release of gas into workplace air.

Do not use with incompatible materials such as bases (e.g. sodium hydroxide) and powdered metals.

Do not heat compressed gas cylinders. Leave cylinder cap on cylinder until cylinder is secured and ready for use. Always secure cylinders to a wall, rack or other solid structure in an upright position. Do not handle cylinders with oily hands. Use the appropriate pressure regulator. Ensure equipment is compatible with cylinder pressure and contents. Follow supplier recommendations. Before connecting the cylinder for use, make sure that back feed from the system into the cylinder is prevented. Do not open cylinder if damaged. Never use excessive force when opening. Open cylinder valve slowly to prevent rapid decompression and damage to valve seat. Make sure valves on gas cylinders are fully opened when gas is used. Open and shut valves at least once a day, while cylinder is in use, to avoid valve 'freezing'. Make sure cylinders are labelled clearly. Avoid damaging cylinders. Move cylinders by hand truck or cart designed for that purpose. Do not drop cylinders or permit them to bang against each other. Do not lift cylinders by the cap or with a lifting magnet. Shut flow off at cylinder valve and not just at the regulator after use. Replace outlet caps or plugs and cylinder caps as soon as cylinder is disconnected from equipment. Keep empty cylinders under slightly positive pressure. Do not use cylinders as rollers or for any other purpose than to contain the gas as supplied. Regularly check cylinders for evidence of corrosion or leakage.

Follow handling precautions on Material Safety Data Sheet. Have suitable emergency equipment for fires, spills and leaks readily available. Practice good housekeeping. Maintain handling equipment. Comply with applicable regulations.

Engineering methods to control hazardous conditions are preferred. Methods include mechanical ventilation (dilution and local exhaust), process or personnel enclosure, control of process conditions, and process modification (e.g. substitution of a less hazardous material). Administrative controls and personal protective equipment may also be required.

Use a corrosion-resistant ventilation system separate from other exhaust ventilation systems. Exhaust directly to the outside. Treatment of exhaust gases to prevent environmental contamination may be required. Supply sufficient replacement air to make up for air removed by exhaust systems.