Air Quality

Air quality involves many components, including ventilation, temperature, relative humidity and air contaminants. Ventilation systems used to control air quality can be achieved through the introduction of large quantities of air (dilution ventilation) or at the source where the contaminants are generated (local exhaust). Ventilation requirements during construction, renovation and building maintenance are also critical in ensuring the health of employees and occupants and may require specialized equipment to mitigate air quality problems.

Note: This section of the regulation does not apply to:

  • Underground mines
  • Confined spaces (under Part XVII)
  • A firefighter engaged in structural firefighting

As an employer you must ensure that:

  • Your employees do not generally work in an area that is less then 8.5 m3 (300 ft3) for each employee in the area.
    • When calculating the air space requirement above, heights above 3 m are excluded from the calculation. This means that if a work space is 2 m wide, 3 m long and 3.5 m in height, the work space for that employee is calculated as 2x3x3=18m3 and not 2x3x3.5=21 m3.
  • A work area is adequately ventilated by either:
    • Natural ventilation which brings in outside air through openings (doors, windows, louvres) that have a combined area equal to at least 5% of the floor area.
    • Louver
    • Mechanical ventilation (HVAC) that meets the ASHRAE standard 62-1989, "Ventilation for Acceptable Indoor Air Quality".
  • Where mechanical ventilation is used and the ASHRAE standard referred to does not specify supply rates of acceptable outside air required, an employer must ensure that the minimum amount of outside air introduced shall be 8 litres/second/person.
  • A ventilation system prevents the return of exhausted air through the outside air intake.
  • Exhausted air is replaced by air that:
    • Does not constitute a hazard to employee health
    • Does not contain air contaminants in concentrations that exceed 10% of the threshold limit value (TLV)
    • Is at a minimum temperature, when necessary (see temperature below)
    • Is properly distributed to not cause undue drafts or disturbance of conditions in the workplace

Air quality control during construction, renovation, and building maintenance is also critical to protect the health of occupants and employees. While current regulations do not specifically address this issue, standards and other sources can be used to assist you as an employer protect your employees and building occupants during such work.

One such standard is CSA Z317.13, "Infection Control During Construction, Renovation and Maintenance of Healthcare Facilities" . Temporary systems such as exhaust fans and ducts accessories may also be appropriate to control air quality during construction.

Exhaust fan

Regarding temperature, as an employer you must ensure that:

  • The temperature where an employee works in an enclosed work area is maintained as follows:
    • Where light work is performed while sitting, the minimum temperature required is 20°C
    • Where light physical work is performed while sitting, the minimum temperature is 18°C
    • Where light or moderate physical work is performed while standing, the minimum temperature required is 16°C
    • Where heavy physical work is performed while standing, the minimum temperature required is 12°C.
  • Ensure that when it is impractical to heat an area to the required minimum temperature, that a suitable area is provided where employees can go to get warm.

Regarding air contaminants, as an employer you must ensure that:

  • Any air contaminant is kept at a level that does not pose a hazard to an employee and, where a TLV exists, that the exposure of an employee at no time exceeds the TLV.
    • Where practical install engineering controls to comply with above.
  • Where practical air contaminants are removed at the source.
  • If you or your employee has reason to believe that the level of concentration of an air contaminant may be approaching 50% of the TLV, the air is tested to determine the contaminant’s concentration level.
  • When employee exposure to an air contaminant occurs in a timeframe other than an eight-hour work day within a 40-hour work week, that the Brief and Scala model (ACGIH publication "1997 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices", page 10) is used to adjust the TLV.
  • Employee exposure to an air contaminant does not exceed the adjusted TLV.
  • There is appropriate medical surveillance of employees exposed to the air contaminants for at least 12 months after the TLVs for the air contaminants have been adjusted. While you as an employer must provide for a medical surveillance program, your employees have the option to participate.
  • Adequate respiratory protective equipment is provided to each employee where:
    • The level of concentration of an air contaminant could exceed 50% of the TLV under normal working conditions
    • There is the possibility of accidental exposure to concentration exceeding the TLV
    • The oxygen content is less than or may be less than 19.5%
  • When work is completed in an area where dust may create a hazard to employees, controls are in place to protect employees.
  • Note re: Formaldehyde. The standard is set at 0.5 ppm for time-weighted average (TWA) and 1.5 ppm for a short-term exposure limit (STEL).

As an employee, you must:

  • Follow any instruction, education or training provided by your employer about air quality, and use any equipment that is required (including personal protective equipment).
  • Be aware of changing conditions.
  • Report any hazards.

General Regulation - Occupational Health and Safety Act
N.B. Reg. 91-191

Part III AIR QUALITY

Section 18

18. (1) Sections 19, 20, 21, 24, 24.1and 25 do not apply to an underground mine.

(2) Sections 19, 20, 24, 24.1, 25 and 25.2 do not apply to a confined space under Part XVII.

(3) Sections 19, 20, 24, 24.1, and 25.2 and paragraph 22(a) do not apply where a firefighter is engaged in structural fire-fighting.

[N.B. Reg. 96-106, s. 2; 97-121, s. 5; 2001-33, s. 5; 2010-129, s. 1]

Section 19

19. (1) An employer shall ensure that an area where an employee works contains at least 8.5 m3 of air space for each employee in that area.

(2) When calculating the air space requirement under subsection (1), height above 3 m shall be excluded from the calculation.

Section 20 Ventilation

20. (1) An employer shall ensure that a place of employment is adequately ventilated by

(a) natural ventilation which introduces outside air provided by openings having a combined area equal to at least 5% of the floor area, or

(b) mechanical ventilation conforming to ASHRAE standard 62- 1989, "Ventilation for Acceptable Indoor Air Quality".

(2) Where mechanical ventilation is used and the ASHRAE standard referred to in subsection (1) does not specify supply rates of acceptable outside air required, an employer shall ensure that the minimum amount of outside air introduced shall be 8 litres/second/ person.

(3) An employer shall ensure that a ventilation system prevents the return of exhausted air through the outside air intake.

(4) An employer shall ensure that exhausted air is replaced by air that

(a) does not constitute a hazard to the health of employees,

(b) does not contain air contaminants in concentrations that exceed 10% of the threshold limit values,

(c) is heated, when necessary, to maintain the minimum temperature specified in section 21, and

(d) is properly distributed so as not to cause undue drafts or disturbance of conditions.

Section 21 Temperature

21. (1) Subject to subsection (2), an employer shall ensure that the temperature of an area where an employee works in an enclosed place of employment is maintained as follows:

(a) where light work is performed while sitting, such as any mental work, precision work, reading or writing, the minimum temperature required is 20°C;

(b) where light physical work is performed while sitting, such as electric machine sewing or work with small machine tools, the minimum temperature required is 18°C;

(c) where light or moderate physical work is performed while standing, such as machine tool work, assembly work or trimming, the minimum temperature required is 16°C; and

(d) where heavy physical work is performed while standing, such as drilling or manual work with heavy tools, the minimum temperature required is 12°C.

(2) Where it is impractical to heat an area where an employee works to the temperature required by subsection (1), an employer shall provide a suitable place where the employee may go to get warmed.

Section 23.1 Threshold Limit Values for Formaldehyde and Lead Sulfide

23.1 The threshold limit value for formaldehyde, as adopted by the ACGIH and set out in the ACGIH publication entitled "1997 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices" shall be deemed to be and shall be read as follows:

(a) formaldehyde - 0.5ppm TWA and 1.5 ppm STEL.

[N.B. Reg. 2001-33, s. 7]

Section 24 Air Contaminants

24. (1) An employer shall ensure that an air contaminant is kept at a level of concentration that does not constitute a hazard to the health or safety of an employee exposed to it and, where a threshold limit value exists in respect of an air contaminant, that the exposure of the employee to the air contaminant at no time exceeds the threshold limit value.

(2) Where the installation of engineering controls is practical, an employer shall install and use appropriate engineering controls to comply with subsection (1).

(3) Where practical, an employer shall ensure that air contaminants are removed at their source.

(4) Where an employer or an employee has reason to believe that the level of concentration of an air contaminant may be approaching 50% of the threshold limit value, the employer shall ensure that the air is tested to determine the level of concentration of the air contaminant.

Section 24.1

24.1 (1) Where the exposure of an employee to an air contaminant occurs other than during the course of an eight hour work day and forty hour work week, an employer shall use the Brief and Scala model as referenced on page 10 of the ACGIH publication "1997 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices" to adjust the threshold limit values.

(2) An employer shall ensure that the exposure of an employee to an air contaminant at no time exceeds the adjusted threshold limit values if the exposure of an employee to an air contaminant occurs other than during the course of an eight hour work day and forty hour work week.

(3) An employer shall ensure that there is appropriate medical surveillance of employees exposed to the air contaminants for at least twelve months after the threshold limit values for the air contaminants have been adjusted according to the Brief and Scala method.

[N.B. Reg. 2001-33, s. 8]

Section 25

25. Where

(a) the level of concentration of an air contaminant may exceed 50% of the threshold limit value in conditions that are part of the normal work procedure,

(b) there is the possibility of accidental exposure to a level of concentration of an air contaminant in excess of the threshold limit value, or

(c) the oxygen content of the atmosphere is less than or may be less than 19.5% by volume,

an employer shall provide adequate respiratory protective equipment to each employee who may be exposed to the conditions described in paragraphs (a) to (c).

Section 25.2 Dust

25.2 Where work is carried out in an area where dust may create a hazard to the health of employees, an employer shall take such measures with respect to the dust as are sufficient to protect employees from the risk of damage to health.

[N.B. Reg. 2001-33, s. 9]