Workers Health & Safety Centre

Optimal airflow in vehicles may help reduce COVID-19 transmission, study

If you travel by passenger vehicle, where you sit and which windows you open may reduce the risk of COVID-19 transmission among the occupants says a new study.

The study, thought to be the first to examine the microclimate inside a car, offers important insights for the transmission of respiratory diseases, such as COVID-19, inside vehicles. The findings will be of particular interest to drivers who transport passengers, rideshare app users and workers whose commute may unavoidably involve carpooling.

Achieving effective airflow and ventilation

Research has shown close, closed, confined spaces can elevate the risk of airborne transmission of COVID-19. Researchers from the University of Massachusetts and Brown University wanted to examine one such environment, a vehicle interior, in greater detail.

They set out to assess air flow patterns in a passenger vehicle and to quantify the air exchange between driver and passenger with windows opened and closed. For the latter they computed air-changes-per-hour and used a passive agent as a proxy for infectious particles.

The study, published in Science Advances, found not unexpectedly that vehicles with all windows closed and with air conditioning running provide the poorest air circulation. Conversely, vehicles with all windows opened had almost double the air flow when compared to two or three windows being open. 
Cold weather and passenger preference can make it difficult to keep all windows open. The researchers learned air flow typically enters through back windows and exits through front windows. This can expose drivers to more airborne transmission than a backseat occupant. Establishing effective, cross-ventilation airflow is critical to reducing airborne transmission between driver and passenger.
If all windows cannot be opened, airflow is improved when:
  • Occupants sit on opposite sides of the car (e.g., passenger in back right seat)
  • Front right and rear left windows are open. Although counterintuitive, opening a third window had little added effect. Opening the back right window negatively impeded airflow.

The researchers also note, the study was intended to examine ways to lower not eliminate airborne transmission of disease and their findings should not replace public health guidance such as wearing masks where required and when physically distancing is difficult, for instance in an enclosed vehicle.

Prevention measures for drivers and passengers

During COVID-19 more are turning to ridesharing apps as an alternative to public transit leading some public health units to create their own COVID-19 guidance for taxi and ride share vehicles.

The U.S. Centers for Disease Control and Prevention (CDC) also has guidance for passenger drivers and for the public offers advice to slow the spread of COVID-19 when using transportation.

Workers Health & Safety Centre has also published a valuable information resource for passenger vehicle and truck drivers confronting COVID-19 which summarizes the advice of these resources.

In addition to opening vehicle windows, general guidance to drivers and passengers includes:
  • limit passenger occupancy and discourage shared rides with unknown passengers
  • Ensure passengers wear a mask that fully covers their nose and mouth
  • Avoid having passengers sit in the front seat
  • Encourage contactless methods of payment
  • Install plexiglass shields as a barrier between the driver and passenger
  • Provide alcohol-based hand rub, tissues and a no-touch disposal receptacle for passenger use
  • Display information on cough and sneeze etiquette and other public health guidance
  • Disinfect commonly touched surfaces especially after passengers’ sneeze and cough.

WHSC virtual classroom. Learning and safety assured.

The COVID-19 crisis presented an unprecedented challenge in terms of providing access to WHSC’s essential and mandatory training programs. WHSC quickly retooled our delivery model in a way we could still ensure the integrity of our training and safety of participants and instructors. This we achieved with our WHSC virtual classroom training.  

For virtual training, all that is required by the participant is a high-speed internet connection and a computer with a functioning camera and audio. When registering be sure to supply the participant’s home address, as resource materials critical to successful participation will be shipped to this address.

Be sure to check out our complete schedule of virtual classroom training, including COVID-19GHS-WHMIS and Certification Part I, Part II and Refresher training. Properly trained, certified joint health and safety committee members can play a critical role in creating safe and healthy workplaces and in controlling COVID-19 exposures. For this reason, we have offered JHSC Certification training in safe, virtual classrooms throughout the pandemic and will continue to do so this winter. 

Beyond scheduled classes, and where participant numbers warrant, we can also work with you to coordinate almost any of our training courses in a virtual classroom for all workers, workplace representatives and supervisors.

Need more information still?
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Additional related resources:
Ventilation to prevent COVID-19 airborne transmission: WHSC webinar
Safer commuting during COVID-19: WHSC webinar
WHSC Public Transit Workers Confronting COVID-19
WHSC Respiratory and Eye Protection-COVID-19 Safeguards
WHSC COVID-19 Enhanced Ventilation
OHCOW COVID-19 Resources