CARBON MONOXIDE IN THE WORKPLACE
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365-BSA-01-IMOT © 2024, Workplace Safety & Prevention Services (WSPS)
1 877 494 WSPS (9777) | 905 614 1400 | WSPS.CA
There are two types of ventilation:
1) General or dilution ventilation supplies clean air
to the workplace to dilute the concentration of the
contaminated air after it has been released into the
workplace. The contaminants are still present in
the workroom air, although diluted. For this reason
such ventilation is not acceptable for controlling
moderately or highly toxic materials (see figure 2).
2) Local exhaust or extraction ventilation collects
and removes the contaminated air at its source
before it is released into the workplace. The air is
then filtered, using either a particulate filter,
activated carbon, or scrubber system. After
removing the contaminant, the air is then exhausted
out of the workplace or is recirculated (see figure 3).
Rules for good ventilation:
Direct air flow away from the worker's breathing
zone.
Do not position a worker in the path of contaminant
discharge.
Exhaust contaminated air from the workplace.
Place the exhaust hood opening of the ventilation
system as close as possible to the source of the
contamination.
Avoid cross drafts.
Supply clean, fresh make-up air to replace the air exhausted by the system.
Discharge the contaminated air away from openings which draw air into the facility.
Ensure all contaminates exiting the facility are in compliance with local regulations.
The chart on the next page compares dilution and local exhaust ventilation, and lists the advantages and
disadvantages of each.
Figure 3: Local Exhaust Ventilation
Figure 2: Dilution Ventilation
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