Currently
there are no regulations in Ontario that establish
“safe” exposure limits for airborne contaminants that
are typically
found in non-industrial, commercial,
residential or institutional settings. Ontario
Regulation 833 “Control of Exposure to Biological or
Chemical Agents” (made under the Occupational Health &
Safety Act) provides airborne exposure limits for a
variety of chemicals. These exposure limits are
applicable to manufacturing facilities, where it is
assumed that people to whom the limits are intended to
protect are “healthy workers”. Individuals that may
have pre-existing medical conditions, severe allergies,
chemical sensitivities and other such conditions would
not be expected to work in such an environment.
However, such individuals may very well be part of the
working population in non-industrial environments such
as offices. In addition, these limits are set to
protect against the onset of specific illnesses or
health effects and in many instances the levels are not
intended to protect against irritation or to limit odours. Therefore, exposure limits provided in O.Reg
833 are not directly applicable for non-industrial
environments.
In the
absence of specific legislation for indoor environments,
the “general duty clause” applies. This clause, common
to all Canadian occupational health and safety
legislation, states that an employer must provide a safe
and healthy workplace. Thus, making sure the air is of
good quality is the employer’s duty, regardless of
whether any specific regulated limits have been
established.
Several organizations have
published guidelines and standards developed
specifically for determining the quality of air in
commercial, institutional and residential facilities. A
common thread throughout the majority of guidelines is
reference to Standards published
by the American Society
of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE). ASHRAE Standard 55-1992, “Thermal
Environmental Conditions for Human Comfort”
provides recommended ranges for thermal comfort
parameters (temperature, relative humidity, air speed,
etc.). The ranges provided are based on occupant
activity and clothing factors and are set to satisfy the
majority of occupants in the space with respect to
comfort conditions. The purpose of ASHRAE Standard
62-2001, “Ventilation for Acceptable Indoor Air
Quality” is to specify minimum ventilation rates
and indoor air quality that will be acceptable to human
occupants and are intended to minimize the potential for
adverse health effects. This standard considers
chemical, physical, and biological contaminants that can
affect air quality.
The above ASHRAE Standards
serve as a baseline in determining acceptable air
quality. General principles of IAQ which provide
helpful information for better understanding, assessing,
communicating, managing, and solving IAQ issues are
incorporated into numerous IAQ documents published by a
number of interest groups. Health Canada has published
two main guidelines with respect to air quality titled
“Indoor Air Quality in
Office Buildings: A Technical Guide”
(1995) and
“Exposure Guidelines for Residential Indoor Air Quality”
(July 1989). In the U.S., the Environmental
Protection Agency (EPA) has taken a leading role in
providing advice for personnel such as Building
Managers, School and Practitioners. They have published
documents titled “Building Air Quality – A Guide
for Building Owners and Facility Managers”
(December 1991) and “Indoor Air Quality - Tools
for Schools” (August 2000). Worldwide, the
World Health Organization (WHO) has also established air
quality guidelines for the European Community, “Air
Quality Guidelines for Europe” (2000) as well as
the more global “Guidelines for Air Quality”
(April 1999).
Heating, Ventilating and
Air-Conditioning (HVAC) systems can have a major
negative impact on air quality if not properly designed,
sized, installed, operated or maintained. In addition
to manufacturer recommendations, other groups have
published guidelines for properly managing HVAC systems
as they relate to air quality. The Canadian Standards
Association (CSA) Standard Z204-94, “Guideline for Managing Indoor Air Quality in Office
Buildings” and ASHRAE Standard 62-2001 are two
documents that have devoted sections to address this
issue.
