Coronavirus transmission risk when driving with passengers
Check out this answer from Consensus:
Driving with passengers in a confined space such as a car poses a potential risk for coronavirus transmission, similar to other forms of enclosed transportation. Effective measures, including optimizing airflow, maintaining physical distance, and reducing travel time, are essential to mitigate this risk. Further research and adherence to public health guidelines will be crucial in ensuring safe travel during the ongoing pandemic.
The COVID-19 pandemic has raised significant concerns about the transmission of the virus in various settings, including public and private transportation. Understanding the risk of coronavirus transmission when driving with passengers is crucial for developing effective preventive measures. This article explores the potential transmission risks associated with driving in passenger cars, drawing on findings from related studies on public transportation and enclosed environments.
Airflow and Transmission Risk in Passenger Cars
Airflow patterns within a passenger car can significantly influence the transmission risk of airborne diseases such as COVID-19. A study assessing the impact of airflow on coronavirus transmission in passenger cars found that the in-cabin microclimate plays a critical role in spreading pathogenic species between occupants. The study used numerical simulations to evaluate how different window configurations affect the concentration and residence time of infectious particles. It was observed that an airflow pattern traveling across the cabin, farthest from the occupants, could potentially reduce the transmission risk2.
Evidence from Public Transportation
Train Passengers
Research on COVID-19 transmission among train passengers provides valuable insights into the risks associated with confined spaces. A study involving 2,334 index patients and 72,093 close contacts on high-speed trains in China revealed that the attack rate varied based on seat location and co-travel time. Passengers seated adjacent to the index patient had the highest attack rate of 3.5%, while the risk decreased with increasing distance from the index patient. The study concluded that measures such as increasing seat distance and reducing passenger density could mitigate transmission risks1.
Bus Riders
An investigation into a COVID-19 outbreak among bus riders in Eastern China highlighted the potential for airborne transmission in enclosed spaces. The study found that individuals on a bus with a COVID-19 patient had a significantly higher risk of infection compared to those on a different bus. The absence of a significantly increased risk in the part of the bus closer to the index case suggested that airborne spread of the virus contributed to the high attack rate observed3.
Air Travel
The risk of COVID-19 transmission during air travel has also been a subject of study. Research on a 10-hour commercial flight identified a cluster of cases among passengers, with a strong association between seating proximity and infection risk. The study emphasized the importance of considering individual passengers’ risk for infection, the number of passengers, and flight duration in guidelines for preventing SARS-CoV-2 transmission4. Another study estimated the global risk of transmission during air travel to be low, with a probability of 1 case for every 1.7 million travelers, even with infectious persons onboard6.
Implications for Driving with Passengers
The findings from studies on public transportation can be extrapolated to understand the risks associated with driving with passengers in private cars. Key factors influencing transmission risk include:
- Airflow Management: Ensuring proper ventilation by opening windows to create an airflow pattern that minimizes the concentration of infectious particles.
- Seating Arrangements: Maintaining physical distance between occupants as much as possible to reduce the risk of transmission.
- Duration of Travel: Limiting the duration of trips to minimize exposure time.
Is there a coronavirus transmission risk when driving with passengers?
Linsey Marr has answered Likely
An expert from Virginia Tech in Aerobiology, Environmental Engineering, Infectious diseases
Great question! We don’t have data on COVID-19 yet, so I used some numbers for flu with symptoms, from Don Milton (https://www.pnas.org/content/115/5/1081). The ventilation rate I use are from (https://www.ncbi.nlm.nih.gov/pubmed/17637707)
1) No cough/sneeze = 1000 viruses in fine particles exhaled over 30 min, maybe not all infectious.
2) Compact car cabin volume = 3000 L. Worst-case ventilation rate if stopped, windows closed = 1 ACH. If air well-mixed, driver breathing at 6 L/min would inhale 4 viruses per minute. If moving and window open 3″, driver would inhale 0.1 viruses per minute.
3) This equates to 1 virus every 10 minutes. But this is for passenger with the flu. For the flu, there is some evidence that deposition of just one virus can cause illness, but I think there’s probably a dose-response relationship (i.e., higher exposure -> higher chance of illness).
We don’t know for COVID-19 so best to open all the windows and have max air on.