Ventilation for Airborne Hazards.

A good ventilation system at your work site is an effective method of keeping both toxic and nuisance materials out of the air and out of your lungs. Some toxic materials capable of causing chronic lung disease, if inhaled in large enough quantities, include asbestos fibers, chlorine, silica dust (silicon dioxide) and arsenic fumes. Examples of nuisance materials (those that don't usually have a bad effect on the lungs when exposures are kept under reasonable control) include cellulose fibers, glycerin mist, limestone, plaster of paris and tin oxide.

The first step in keeping the air clean is to prevent materials from escaping from their containers by using covers and lids. Solvent vapors can be kept out of the air by keeping solvent tanks covered when not in use. Furthermore, airborne dust levels can be reduced by keeping operations which generate dust, such as sandblasting operations, separated from other work areas.

However, when it is not possible to keep toxic materials contained, it is important to remove dirty or contaminated air from the work area and replace it with clean air.

How Should Dirty Air Be Removed From The Workplace?

The best way to remove contaminated air from the work area is with the use of what is called "local exhaust ventilation." Typical window or cooling fans were not designed to remove contaminated air from individual work areas and are not recommended for this purpose.

What Is Local Exhaust Ventilation?

Local exhaust ventilation is an effective method for removing airborne toxic or nuisance materials at their point of origin, thereby preventing them from entering your lungs. Examples of processes that use local exhaust ventilation include welding and grinding operations. To be effective, a local exhaust ventilation system should include: 1) a collector or hood, 2) ducts to carry the air, 3) the right choice of fan, 4) a device to clean the air if required, and 5) exhaust system.

What Should You Do To Use A Local Exhaust Ventilation System Correctly?

Simple but important points in working with a local exhaust ventilation system include:

Try not to put yourself between the source and the opening of the air exhaust hood. If you do this, you will breathe contaminants as they are drawn into the hood.

• Do not block fresh air supply for the workroom.
• Do not block or obstruct hoods.
• Protect ventilation ducts from damage and holes.
• Keep operation close to the hood to improve capture of vapors and fumes.
• Be aware of special precautions required when ventilating potentially explosive or corrosive vapors.
• Prevent recirculation of exhaust air back into the workplace.
• Evaluate the ventilation system periodically to ensure it is operating as designed.
  

What If You Have Problems With The System?

Problems can occur with ventilation equipment, like any other tool used at work. Contact your employer if you experience problems with a ventilation system. Most often a routine maintenance program of cleaning out ducts, replacing fan blades and repairing leaks will restore a system to full operation.