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How do we assess the risks in our daily lives?

Text updated on 2020-06-19

The outbreak of the COVID-19 epidemic is leading us to reconsider our daily lives from a new angle: how can we limit the risks of SARS-CoV-2 infection that we take for ourselves and for others? To evaluate the risks in our daily life: a risk scale, easy to use and a questionnaire to go further.

Contamination by the SARS-CoV-2 coronavirus depends on several parameters:

Not all everyday life situations are the same, some are without risk of contamination, such as a walk alone in the forest, while others present a maximum risk of contamination, such as an aperitif with friends over a bowl of peanuts.

In addition to the risk of contamination, there is also the risk of developing a severe form of COVID-19. The risk is not the same for a 10-year-old child and a 70-year-old person. For vulnerable people or those who frequent vulnerable people, caution is advised.

Risk Scale

To get an idea of the risk of being infected with the SARS-CoV-2 coronavirus or of infecting someone, we propose a scale from 0 to 4 which illustrates different situations in everyday life, from the least risky (risk = 0) to the most risky (risk = 4).

To illustrate the risk scale, here are some typical situations that will help you to represent the different levels:

  1. Risk level 0: You are at home by videoconference, or you call your friends, colleagues, relatives. No one outside your home is with you. This is Risk 0. Smile! You don't need a mask!

Some typical risk situations 0

  1. Risk level 1: You are taking a walk in the forest with a friend. You don't have a mask. You talk to each other but you are more than a meter away from each other. The risk is low: 1 in 4.

Some typical risk situations 1

3. Risk level 2: You are on a bus with your mask on. Even if you are careful to stay away from other passengers, you are in an enclosed area. There is a risk of touching a surface that has not been disinfected. The risk is medium. It is 2 out of 4.

Some typical risk 2 situations

4. Risk level 3: You are in a work meeting with your colleague for more than an hour. He hands you his computer to share a video, a photo, etc. You both touch the keyboard, a surface that has not been disinfected. You don't have a mask. The risk is high. It's 3 out of 4.

Some typical risk 3 situations

5. Risk level 4: This is the aperitif, you have invited your friends to your home. You all dip your hands in the bowl of peanuts that is on the coffee table. This is the maximum risk! It's 4 out of 4.

Some typical risk situations 4

scale diagram

Risk Assessment Questionnaire

If you are in doubt and you don't know how to assess the risk of an activity you have planned or a situation you are about to experience, you can use this risk assessment questionnaire!

It is difficult to list all life situations and special cases. To overcome this limitation, we have broken down the situations of everyday life into several parameters: alone or with someone, outside or inside, with or without a mask, with common objects or not, and so on. This breakdown makes it possible to cover the vast majority of situations in personal and professional life. To estimate the risk, simply answer the 20 questions on the scale and you will obtain a risk score ranging from 0 to 4.

In conclusion: for risk management, it is up to each individual to decide what risks he or she takes, within the framework allowed by law. Those who are vulnerable, or who are in contact with vulnerable people, will need to be particularly careful: we see them deliberately choosing a risk activity poorly.4 Finally, even if one does not fear much for oneself, prudence is necessary to protect others and limit the spread of the epidemic as much as possible.

Disclaimer :

The creation of the scale and the choice of situations illustrating each level of risk were based on the results of a survey carried out in June 2020 among 11 scientists engaged in an active literature watch on COVID-19. Various everyday situations were evaluated via 50 questions using a risk scale ranging from 0 to 4. The score associated with each situation is that estimated by at least 75% of the scientists in the group. This risk scale as well as the risk assessment questionnaire are presented for information purposes only and do not constitute medical advice, nor do they engage the responsibility of their authors.

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In closed environments the risk of transmission of the SARS-CoV-2 coronavirus is 18.7 times greater than in the open air.

Nishiura, H., Oshitani, H., Kobayashi, T., Saito, T., Sunagawa, T., Matsui, T., ... & Suzuki, M. (2020). Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19). medRxiv. PREPRINT

Ventilation in closed environments is one of the important factors in reducing the concentration of SARS-CoV-2 coronavirus.

Liu, Y., Ning, Z., Chen, Y., Guo, M., Liu, Y., Gali, N. K., ... & Liu, X. (2020). Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals. Nature, 1-4.

In a Chinese air-conditioned restaurant, contamination of the customers occurred in the ventilation flow of the air conditioning system.

Lu, J., Gu, J., Li, K., Xu, C., Su, W., Lai, Z., ... & Yang, Z. (2020). COVID-19 outbreak associated with air conditioning in restaurant, Guangzhou, China, 2020. Emerging infectious diseases, 26(7).

The physical distance between people (more than one meter) and masks prevents the transmission of the SARS-COV-2 coronavirus.

Chu, D. K., Akl, E. A., Duda, S., Solo, K., Yaacoub, S., Schünemann, H. J., ... & Hajizadeh, A. (2020). Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 andCOVID-19: a systematic review and meta-analysis. The Lancet.

Talking increases aerosol emission and transmission of the SARS-CoV-2 coronavirus in closed environments.

Stadnytskyi, V., Bax, C. E., Bax, A., & Anfinrud, P. (2020). The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission. Proceedings of the National Academy of Sciences, 117(22), 11875-11877.

The louder we speak, the larger and more numerous the aerosol particles emitted.

Asadi, S., Wexler, A. S., Cappa, C. D., Barreda, S., Bouvier, N. M., & Ristenpart, W. D. (2019). Aerosol emission and superemission during human speech increase with voice loudness. Scientific reports, 9(1), 1-10.

Measurement of the stability of the SARS-CoV-2 coronavirus under different environmental conditions.

Chin, A., Chu, J., Perera, M., Hui, K., Yen, H. L., Chan, M., ... & Poon, L. (2020). Stability of SARS-CoV-2 in different environmental conditions. The Lancet, 2020.

Further reading

What is the purpose of social distancing?

What is the recommended distance between two people?

How do you decontaminate groceries?

What is the risk of dying from this COVID-19 for an infected person?

Do I have to wear a mask if I don't have any symptoms?

Do I have to wear a mask inside / outside?

Can a mask be "worse than nothing"?

Why put on a mask?

How do you put on and take off your mask?

Why are superspreader events crucial to understanding the COVID-19 epidemic?

Can the SARS-CoV-2 coronavirus be caught by going to the bathroom?

Why do we have to be careful if we live with a vulnerable person?

Who are the vulnerable people?