Blog Post #1437 – Improving Indoor Air Quality – Part 2

Article from the OH&S Canada magazine – (Fall – 2022)

Written by the Canadian Centre for Occupational Health and Safety (CCOHS)

“Maximize Indoor Ventilation”

There are two types of ventilation, natural and mechanical, and both should be maximized in indoor workspaces.

Natural ventilation allows air to move freely in and out of a space by opening exterior windows and doors. Mechanical ventilation is most often provided by heating, ventilation and air conditioning (HVAC) systems.

HVAC systems circulate conditioned air within a space with moto-driven fans or blowers through ducts. Recirculating stale air within a space using pedestal fans, ceiling fans or ductless air conditioners moves the air, but does not exchange or replace the air which may lead to a build-up of contaminants.

Improving ventilation is one layer of protection for the occupants of a space. HVAC systems are complex so it’s important to  consult with an HVAC professional before making any changes or improvements.

Questions to ask your HVAC professional:

  • Is the HVAC system operating optimally?
  • Is the HVAC system suitable for the type of setting and the number of workers?
  • Can the ventilation system be adjusted to bring more outdoor air into the building?
  • Is it possible to upgrade the air filters?

Consider installing ventilation system upgrades such as ultraviolet germicidal irradiation (UVGI), heat or energy recovery ventilation (HRV or ERV), or an air economizer. This should only be done by an HVAC professional.

Other questions to consider include:

  • Is the ventilation system inspected and maintained regularly?
  • Have filters been replaced as recommended?
  • Do the filters have the highest possible minimum efficiency reporting value (MERV) ratings recommended for use with the system?
  • Has the system been set to the maximum air changes per hour?

In general, the higher the MERV rating, the better it is at removing small particles from the air. To maintain an effective HVAC system, use HVAC system filters with the highest rated MERV filters that are compatible with your ventilation system.

A ventilation system can also improve the thermal comfort of occupants by maintaining a relative humidity between 30 per cent and 50 per cent. Relative humidity level below 20 per cent can cause discomfort through drying of the eyes and mucous membranes and skin, whereas a relative humidity level above 60 per cent may make the area stuffy and lead to the development of condensation on surfaces, which in turn can lead to mould growth.

Part #3 of 4 should be delivered over the next few days.

HRS Group Inc. has a great team that can help you with all your health and safety needs. Contact Deborah toll free at 1-877-907-7744 or locally at 705-749-1259.

We can also be reached at 

Ensure your workplace is a safe place.

Remember – In Canada, “ALL Accidents are Preventable”

‘Work’ and ‘Play’ safe.

Daniel L. Beal

CHSEP – Advanced Level
CEO & Senior Trainer
HRS Group Inc.


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