Whether it’s for only a few days a week or full-time, many employees in Ontario are returning to their offices in some capacity. While many see this as a sign that we are getting closer to the end of the pandemic, it also brings concerns.

“For two and a half years, we’ve been overwhelmed with information about how dangerous COVID could be, so we are going to have concerns about returning to enclosed indoor spaces because of that potential for exposure,” says Michael Puccini, a Health and Safety Consultant with WSPS. “To address this, employers must make communication a priority. They need to share with their employees what has been done over the past two years to improve the indoor air quality in the office. Ideally, this should be done before they walk through the doors.”

Main Concern: Droplets and Aerosol

Michael emphasizes the importance of clearly communicating with employees, so they understand the steps that have been taken to ensure that they are returning to a safe and healthy workplace. Addressing their main concern-how a virus gets from one person to another-is a good place to start.

Viruses can spread through aerosol. We all generate aerosol (e.g., microdroplets) by doing things like talking, coughing, and sneezing. One way to protect ourselves from exposure to a virus is to reduce the concentration of aerosols in the air we breathe. “We can do this by filtration or dilution,” says Michael. “When you do these things, you are controlling the level of air quality in that office environment.”

5 tips to improve your indoor air quality: dilution and filtration

Before your office is buzzing with workers, have your building’s HVAC system reviewed by a qualified professional. Focus on diluting and filtering the indoor air, keeping the following five tips in mind.

1. Bring in more outdoor air. When you bring in more of the outside air, you dilute the air that is already indoors. Doing this reduces the concentration of aerosols that employees are exposed to indoors.
2. Filter the indoor air. If you are not able to bring in enough fresh air from outside, filter the air that is circulating inside. With effective filtration, you can remove the aerosols before the air recirculates.
3. Determine how much outside air is required for adequate dilution. When determining how much dilution is necessary, follow recommendations from competent authorities, such as Health Canada and Ontario Public Health. “The American Society of Heating, Refrigeration, and Air Conditioning Engineers-ASHRAE – is another organization that we can look to for recommendations on indoor air quality,” says Michael. “ASHRAE makes recommendations with respect to the volume of ventilation required based on the occupancy of the indoor area.”
4. Understand the level of filtration needed to effectively reduce the risk of exposure. “When looking at the efficiency of the filter, we look at the MERV rating,” says Michael. The higher the number, the more efficient the filter. For example, a MERV 8 filter is more efficient at removing particulate than a MERV 4 filter. “If you are going to increase the MERV rating of your filters, consult an HVAC technician first,” cautions Michael. That’s because when you move to a higher MERV filter, you are also increasing the system’s resistance to airflow. An HVAC professional can ensure that you are not going to overwhelm your system and unintentionally introduce new air quality problems.
5. Consider leaving the HVAC system running overnight. To conserve energy, many office buildings have the HVAC system set to be off throughout the night and then start up again in the morning before people are expected to arrive. Michael recommends leaving the system running overnight so that it continues to filter and recirculate the air. Employees will walk into fresh, clean indoor air each morning. If it’s not feasible to leave the system running overnight, have it power up several hours before the arrival of your employees.

These steps, along with ongoing deep cleaning and the support of mask-friendly workplaces, will make the return to the office much less stressful for your employees.

How WSPS Can Help

Consulting 

Connect with a WSPS Occupational Hygiene Consultant for services, such as indoor air quality evaluations.

Training

• Indoor Air Quality: An Introduction (eCourse, 1 hour)

60-second Safety Tip Videos

• How can an employer tell if a workplace has poor indoor air quality? 
• How can employers test their workplace’s indoor air quality?
• How do seasonal changes impact indoor air quality?