New guidance from Health Canada presents a compilation of best practices for assessing and maintaining indoor air quality (IAQ) in office buildings. That includes considerations for contaminant mitigation, ventilation, operational stewardship, resolving IAQ issues and engaging professional services. It also comes with sample checklists and a companion document with more details about specific contaminants and procedures for detecting them.
“The quality of the air in an office building is the result of the complex interactions between the ventilation system (if present), the building (i.e., age, condition, component materials, structure and envelope), the climate, the quality of the outdoor air, the furnishings and products present, the work processes, and the occupants and their activities,” states the introduction to the guidance, which Health Canada’s Safe Environments Directorate released in mid-September. “Good operational practices can prevent many indoor air quality issues. However, when issues do arise, they can be addressed by implementing corrective actions after identifying the potential cause(s).”
The guidance begins with 10 broad recommendations then drills more deeply into how each might be achieved. Collectively, suggested best practices encompass a mix of: technical/mechanical measures related to ventilation, filtration/air cleaning and humidity control; rigorous scrutiny to detect and quickly address potential sources of mould; and policies to help prevent undue contaminants associated with housekeeping practices, procurement of building products and furnishings, or renovation and fit-out projects.
Various negative impacts on IAQ are tallied, including: insufficient air exchange; moisture penetration; emissions from problematic building materials; permeating soil-based hazards such as radon or environmental contaminants; compromised outdoor air supply; and the activity and density of building occupants. Generally, building and facilities managers are striving to control such factors, while also maintaining the temperature in the range of 20 to 23.5⁰ Celsius in the winter or 23 to 26⁰ C in the summer and keeping relative humidity below 50 per cent.
Technical/mechanical measures
The guidance references some ASHRAE standards as a baseline for expected performance, including: Standard 55, Thermal Environmental Conditions for Human Occupancy; Standard 62.1, Ventilation and Acceptable Indoor Air Quality; and Standard 241, Control of Infectious Aerosols. It also highlights ASHRAE’s framework for responding to wildfire smoke and potential heightened levels of particulate matter, released last year as Guideline 44-2024.
A MERV 13 air filter is recommended as the minimum for buildings with return air systems. However, the guidance acknowledges this may not be practically feasible for all ventilation systems, and that gains in the ability to capture particulate and pathogens must be balanced against the increased pressure required to move air through the filter.
Alternatively, or additionally, portable air cleaners are identified as an option to either augment existing building ventilation or in scenarios where there is no mechanical ventilation. Prospective purchasers are advised to choose certified devices that employ a HEPA filter and to pay attention to the product specifications indicating the room size for which it is bested suited and the clean air delivery rate (CADR), which indicates its proficiency for removing particulate such as dust, pollen, viruses and tobacco smoke. That comes with a reminder that portable air cleaners are ineffectual against gases, like carbon dioxide (CO2) or carbon monoxide (CO).
The guidance also addresses other ventilation-related topics such as CO2 monitoring, HVAC zone controls, devices that emit UV radiation for infection control and preventative system maintenance. As well, it recommends a risk assessment to examine how the HVAC system might make the building vulnerable to cybersecurity attacks or to accidental or deliberate dissemination of chemical/biological/environmental toxins.
Operational stewardship
Another section of the guidance focuses on tasks and functions related to building maintenance, space design, procurement and housekeeping. These are characterized as “stewardship” when there is a conscious effort to consider how they can influence indoor air quality.
“Stewardship includes the day-to-day proactive upkeep and maintenance of the building and building envelope. By promptly identifying and addressing issues, operators or employers will be able to eliminate or reduce the causes of poor air quality, ideally before the issue becomes serious,” the guidance states. “Building operators should develop and maintain good communication with occupants, and educate employers, custodians, maintenance staff and occupants about the importance of air quality and good practices to follow.”
Building staff should be trained and encouraged to become moisture police. The guidance recommends regular inspection of the building envelope and plumbing piping to check for deterioration or deficiencies that could allow water or air penetration. Staff should be able to spot, and have a process to report, evidence such as condensate around windows, water pipes and exterior walls, efflorescence on brick or concrete, or damage and discoloured walls, floors or ceiling tiles. As well, buildings should be routinely inspected after heavy rainstorms, when accumulated snow melts rapidly or during extreme heat events.
Moisture and potential excess humidity are also flagged as housekeeping concerns. In particular, it’s important for carpet cleaning technicians to maximize water extraction from the carpet material. The task should also be scheduled for times when building occupancy is low and, ideally, avoided during highly humid periods in summer months.
Sloppy plant watering can likewise turn carpets into mould repositories. Plants should always be placed on a stand or in a container that holds runoff rather than directly on the carpet surface.
The guidance includes several other recommendations related to housekeeping practices and special ventilation requirements for construction projects within buildings. Procurement policies figure in both cases, with an emphasis on controlling the introduction of building materials, furnishings and products that emit gases that could have negative environmental and/or health consequences.
Outreach to occupants
Occupant activity may present a more daunting challenge for property and facilities managers. The 10 overarching best practices set out in the introduction to the guidance include recommendations to:
- maintain protocols to reduce viral and bacterial transmission among building occupants;
- ensure occupants follow workplace procedures related to the use of scents and cleaning products; and
- assess any potential mismatches of intended space and occupant activities, in the context of renovation, fit-out and expansion projects.
These imply something of an enforcer role for building management or employers, with an associated potential for landlord-tenant or manager-worker tensions.
Although it does not specifically address such scenarios, the guidance does extensively outline recommended processes for assessing and resolving IAQ issues. It also acknowledges some of the human emotions that may come into play, and highlights the importance of training, science-based evidence and educational outreach.
“Training should be relevant to the audience and can include how to identify a potential indoor air quality issue and how to report concerns,” the guidance advises. “Occupants should also be made aware of issues unrelated to indoor air, such as ergonomic and psychosocial risk factors (e.g., relationships with co-workers, control over workload), as they can affect perceptions of indoor air quality.”
