Understanding Ventilation, COVID-19 Spread, & Your Gym

The author of this article, Paul Hackett, is a chartered safety & health practitioner and OSHCR registered consultant with extensive international experience and a former sports, fitness, and aquatics facilities operator. He is also a member of the IHRSA-led experts group who developed the key considerations and risk assessment tools to help clubs reopen and stay open.

Good ventilation reduces the concentration of the virus in the air and will therefore reduce the risk of airborne transmission in a facility. Poor ventilation will increase the concentration and consequently increase the risk of transmission.

Ventilation is also intimately linked to heating and this is especially relevant in cold weather. We have to balance providing adequate ventilation with the need to heat the building and keep our customers and staff warm.

Some buildings were designed to be completely air conditioned and will be very difficult to alter airflow and volume. The adjustments we make may need to be in the volume of people using the building rather than the mechanical capability of the ventilation. As of yet, we have no truly indicative measure to the effectiveness of our ventilation to remove potentially contaminated air, so we have to use a substitute, which is the only one recommended to date—CO2 levels.

For operators in established facilities, the quality of ventilation is normally established at the design and construction stage of the facility’s life and providing we have been sensible and funded adequate mechanical and electrical services, there will be little we can do to improve ventilation or air conditioning after it has been commissioned. If you’re unsure, ask the advice of your heating ventilation and air conditioning (HVAC) engineer or adviser.

Points to Consider

• Good ventilation can help reduce the risk of spreading coronavirus, so focus on improving general ventilation, preferably through fresh air or mechanical systems.
• Where possible, consider ways to maintain and increase the supply of fresh air, for example, by opening windows and doors (unless fire doors).
• Also consider if you can improve the circulation of outside air and prevent pockets of stagnant air in occupied spaces. You can do this by using ceiling fans or desk fans for example, provided good ventilation is maintained.
• The risk of transmission through the use of ceiling and desk fans is extremely low providing there is good ventilation in the area being used, preferably provided by fresh air.
• The risk of air conditioning spreading COVID-19 in the workplace is extremely low as long as there is an adequate supply of fresh air and ventilation.
• You can continue using most types of air conditioning systems as normal. But, if you use a centralized ventilation system that removes and circulates air to different rooms it is recommended that you turn off recirculation and use a fresh air supply.
• You do not need to adjust air conditioning systems that mix some of the extracted air with fresh air and return it to the room as this increases the fresh air ventilation rate.
• Also, you do not need to adjust systems in individual rooms or portable units as these operate on 100% recirculation. You should still, however, maintain a good supply of fresh air ventilation in the room.

In poorly ventilated indoor spaces, airborne aerosols are a possible transmission route. It is preferable not to recirculate air from one space to another. But in certain weather conditions closing the recirculation dampers in some systems may make the supply air unacceptably cold and cause a reduction in the rate of supply of outside air to the occupied spaces below the recommended minimum, 10 l/s/p, liters per second per person, for typical offices, in order to maintain an acceptable temperature.

In these instances, there is a balance between two risks: the greater risk arising from recirculating some air of cross-contamination between rooms or zones, which is relatively low risk, against the risk of increasing contaminant build-up as a result of not maintaining adequate provision of outside air, which poses higher risks. Recirculation should be considered if this is the only way of maintaining adequate provision of outside air to occupied spaces without causing undue occupant thermal discomfort.

Less Sophisticated Rooms & Studios

If a room is not fitted with air conditioning or mechanical ventilation systems, it is possible to operate with doors and windows open a little during operating times and supplement the heating with portable equipment. This will also need a delicate balance to prevent people from being too cold while getting plenty of fresh air. The workout or gym sessions should be altered to balance exercise with the temperature that the building can maintain.

Other factors:

• Doors that should remain closed because they are fire doors: Every effort should be made to ensure that they are held open by a device that will close in case of an alarm sounding.
• Electrical loading: Use of temporary heaters or fans may increase the electrical loading of the building. This can be made worse by use of socket multipliers and extension leads, again potentially leading to electrical overloading, overheating, and fires.
• Security doors that are left open can be walked through by non-members, so increased vigilance may be needed. Locking up will become more of a necessity to ensure all doors are secure when leaving the building.

Air Conditioning Systems

With a split air system above, fresh air is added to heated/cooled air and circulated in the room, studio, or gym. These units will add fresh air.

Some systems that are commonly known as “air conditioning” or “air conditioning units” only condition the air in a room—i.e., warm the air or cool the air but are not part of a wider ventilation system. They are often referred to as “comfort cooling” or “comfort heating”. These systems take air already in a room and warm or cool it before releasing it back (recirculate it) into the room. It is important to understand that these systems are not delivering outside air and are not diluting any airborne pathogens

Can we use UV to disinfect air in the building?

Ultraviolet germicidal irradiation, UVGI, is a long-established technology using UV-C light at wavelengths around 254 nm. It appears to have considerable potential to inactivate COVID-19 and other pathogenic coronaviruses, as at the appropriate wavelength it disrupts the structure of the nucleic acids, which form the virus genome.

Early studies indicate that COVID-19 is relatively easily inactivated by UV-C light and when aerosolized the virus is likely to show a similar susceptibility to UV as other coronaviruses in air.

It may be possible to install UVC disinfection equipment within some mechanical ventilation systems. But this has not been attempted very often in normal buildings and is usually in place to work as a virucide on expelled air to prevent contamination getting into the natural environment.

HEPA Filters

HEPA filters (High Efficiency Particulate Air filters) are used in clean rooms and healthcare facilities but would generally filter the air on the way into the room rather than what is exhaled from the users.

Can we use carbon dioxide as a measure of air quality?

• We all breathe and exhale CO2
• The measure of CO2 in the sports building ventilation indicates we are all breathing
• Where CO2 exceeds required levels, one will need to increase fresh air incoming or open windows/doors
• Over 1,500 ppm ventilation needs to be improved
• Good below 800 ppm (10-15 per person)
• If CO2 sensors are to be deployed, they should be nondispersive infrared (NDIR) CO2 sensors, which actually detect CO2 in the space, rather than the less expensive e\co sensors that do not detect CO2 and infer a CO2 concentration by measuring room volatile organic compound (VOC) concentrations instead.

Poor ventilation in restricted indoor spaces could easily facilitate the transmission of COVID-19. Transmission is thought to be primarily through respiratory droplets and it is thought that aerosols may be playing an important role. Aerosols remain suspended longer than large droplets.

Although some questions remain as to what size droplets are the principal carriers, it is agreed that coughing, sneezing, shouting, singing, and speaking produces enough droplets of various sizes to facilitate transmission.

With that in mind, ventilation rates should not be increased so much as to keep aerosols airborne in the direction of other customers. The direction of respiration in gyms needs to be accounted for in the positioning of equipment and the relationship to ventilation outlets. Customers should be kept out of the downwind drafts.

Ventilation has only been associated with outbreaks where the building has been crowded and where the direction of the ventilation flow took contaminated air over to susceptible people. So the ventilation helped transmit the virus in an airflow. Ventilation also needs to be adequate for the size of the room or the occupancy reduced until there is sufficient fresh air for the number of people using it.

Risk Assessment

Each operator will need to look at their own circumstances and operating protocols and decide whether it is reasonable to reopen, some will be able to without much change to normal day-to-day procedures, others may find it is not yet safe enough or commercially viable to reopen.

In some regions it may not be possible to open yet, however, it might be worthwhile to ensure that heating and ventilation systems are scrupulously serviced, maintained, and cleaned to be at their best for reopening.