Province of Saskatchewan, Canada --- Air Quality

SOURCE: "Guide For Evaluating Indoor Air Quality," Occupational Health and Safety Branch, Human Resources, Labor and Employment, Saskatchewan, Canada. (Undated. Obtained 1992 from Canadian authorities).

CARBON DIOXIDE

Guidelines

INDOOR AIR QUALITY . . . FRESH AIR SUPPLY

Complaints of "poor air quality" are often directly related to an inadequate supply of fresh outdoor air. Perhaps as many as 80 percent of indoor air quality complaints in Canada are solved by increasing the supply of fresh outdoor air to a space. The source of a complaint may be strictly due to an insufficient supply of fresh air or it may be due to odours or emissions from building materials, office supplies, photocopiers, occupant activities, etc. An increase in fresh air will dilute these airborne contaminants thus creating a more acceptable indoor environment.

Occupants of a space exhale cabon dioxide. The extent of air exchange within an enclosed occupied space can be determined by measuring airborne carbon dioxide. Many studies and surveys have demonstrated a direct relationship between occupant complaint rates and carbon dioxide concentration.

CARBON DIOXIDE (parts per million)	EFFECTIVE VENTILATION RATE (cubic feet per minute [cfm] of fresh outdoor air)	SIGNIFICANCE -
350 to 400	-	typical outdoor level
less than 600	greater than 35 cfm/occupant	few complaints
600 to 800	20 to 35 cfm/occupant	occasional complaints
800 to 1000	15 to 20 cfm/occupant	complaints increase
above 1000	less than 15 cfm/occupant	complaints common Insufficient fresh air supply

Section 47 of the Saskatchewan Occupational Health and Safety Regulations states, "Every employer shall make effective and suitable provision for securing and maintaining the circulation of an adequate supply of clean and wholesome air throughout the place of employment to ensure the adequate ventilation of the place of employment and, so far as is reasonably practicable, to render harmless and inoffensive any impurities in the air."

To comply with the minimum requirements of Section 47, in an enclosed indoor space where worker complaints are prevalent the occupant generated carbon dioxide concentrations must not exceed 1000 parts per million. In a space which is supplied with air by a mechanical ventilation system only (no openable windows or other air source) it is generally necessary to supply fresh outdoor air at a rate no less than 15 cubic feet per minute (15 cfm) per occupant.

In order to ensure that the air supplied is of adequate quality (clean) it is necessary to comply with Section 51 of The Occupational Health and Safety Regulations which states,

"Every employer shall ensure that:

1. all parts of a ventilation system are maintained;
2. louvers are regularly cleaned; and
3. ventilation openings are always free of any obstruction or source of contamination."