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How do we assess the risks in our daily lives?

Text updated on 2020-09-19

The COVID-19 epidemic makes us reconsider our daily life from a new angle: how to limit the risks of SARS-CoV-2 coronavirus infection? To help you assess the risks in our daily lives, we offer you an easy-to-use risk scale and a questionnaire to evaluate the risk of infection in everyday situations.

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

The risk of contamination increases in areas where the COVID-19 epidemic is active (i.e., many cases of patients with COVID-19). 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 as for a 70-year-old person. For vulnerable people or those who frequent vulnerable people, caution is advised.

Infection 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 represent the different levels:

Risk level 0

Level 1 risk

Risk level 2

Level 3 risk

Level 4 risk

scale diagram

To assess the risk of infection for a particular life situation, answer the questions in this QUESTIONNAIRE!

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 have to be particularly careful: be careful of high-risk activities. Finally, even if one does not fear much for oneself, caution 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 with 11 scientists involved in an active literature review on the COVID-19. Various everyday situations were assessed 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.

The choice of the physical distance of 1-2 meters is based on experimental data of droplet and aerosol circulation, which depends on many parameters: ventilation (the more it is ventilated, the faster the particles will disappear), the strength of particle emission (the louder you speak, the more out of breath you get and the higher the particle emission), the exposure time (the longer you stay in a place, the higher the particle concentration). The distance of 1 or 2 meters is an arbitrary estimate that must be re-evaluated according to the different parameters mentioned above. If everyone is out of breath in a poorly ventilated area, a distance of 1 or 2 meters is not sufficient to protect individuals. If no one is talking in a well-ventilated area, one meter may be sufficient.

Jones, N. R., Qureshi, Z. U., Temple, R. J., Larwood, J. P., Greenhalgh, T., & Bourouiba, L. (2020). Two meters or one: what is the evidence for physical distancing in covid-19?. bmj, 370.

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?

Does the severity of the COVID disease depend on the dose of virus received?

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?