V.Kasiulevičius: How can the environment and our behavior reduce the number of Covid-19 cases?



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1. Does temperature affect the survival of the virus in air? Low temperatures can greatly increase the viability of the virus, while high temperatures reduce it. It is believed that the spread of infection in meat processing plants around the world may be due to increased survival of the virus and the spread of low temperature conditions.

2. Does relative humidity affect the spread of infection? Lipid-enveloped viruses, including SARS-CoV-2, are believed to survive better in low humidity conditions and this is a major reason for the flu season in winter, when indoor air is drier. In drier climatic conditions, people become more susceptible to infections, develop respiratory epithelial damage, impaired mucociliary clearance, and increase mucin production. If the humidity is higher than 85%, larger air droplets and aerosol particles are formed than with lower humidity, so they settle to the ground more quickly and the risk of infection is reduced. According to previous studies, up to 40-60% humidity can help reduce the viability of viruses.

3. Smoking can increase the entry of viruses into the air from diseased airways., because smokers have to remove their mask to smoke a cigarette (!!!), smokers inhale and exhale more deeply, increasing the amount of virus excreted or inhaled, but the smoke itself does not cause a stronger elimination of the particles respiratory tract virus. Smoking destroys the airway epithelial lashes that vibrate in smokers’ lungs. It is the vibrating epithelial eyelashes of the respiratory tract that are responsible for eliminating viruses from the respiratory system and protecting against infections. However, the tabs contain ACE2 receptors, which the virus uses as a gateway to infection. Therefore, smokers are less likely to be infected with COVID-19. But if smokers become infected, they are more likely to develop a more serious form of COVID-19.

Sigismund Gedvila / 15min photo / Smoking on the balcony

Sigismund Gedvila / 15min photo / Smoking on the balcony

Four. When is the risk of infection greatest? When we are close to an infected person, that is, at a distance of less than 1 or 2 meters, although the aerosols spread almost up to 9 meters inside when coughing and sneezing. It should be noted that, in our opinion, “stopped” indoor air is actually constantly moving at 0.05 to 0.1 m / sec. speed. Air movement creates not only an additional hazard but also a dilution effect. If we are more than 2 meters from the other person, the risk is reduced. On the contrary, the risk increases when a large group of people meet in a closed room and are also contributed by negative factors: poor ventilation of the premises, unused masks, talking, singing or shouting. Many outbreaks occur in choirs, bars, meat processing plants. On the contrary, in the subway or in cinemas, where better ventilation is much rarer or infections are not known.

5. What reduces the risk of infection in the room? There is a low risk of infection when other people enter the same room (cabinet, hall, auditorium) where the person became infected after two hours. It would appear that in the form of aerosols, the virus can stay in the air for up to 12 hours, but in reality it takes much less time. 95 percent in homes. the indoor air changes between 30 minutes and 10 hours. In public buildings, meanwhile, 95 percent of the air change is much faster, taking 12 minutes to 2 hours. In a hospital, 95 percent of the air change can occur in as little as 5 minutes. And it all depends on the speed of ventilation in the room or exhaust ventilation. If you have not been in the same office, room or auditorium with the patient, the risk of infection is low. There have been several documented cases of infection in non-diseased apartment buildings where there was no direct contact, but infections did occur, but these cases appear to be related to sewer lines in high-rise buildings (cases in Hong Kong and China) instead droplet or aerosol infections.

6. Is there a risk of getting infected outdoors? The data collected by the researchers shows that it is much safer outdoors than indoors with the same activity and distance between people. Some cases of such infections have been described and have been associated with field interviews. Crowded outdoor areas, especially more enclosed spaces (such as between two-story buildings) on a windless, sunless day, are riskier. This is because the lower wind speed does not disperse the droplets and aerosols that carry the virus, while there is less ultraviolet radiation to inactivate the virus.

7. Does sunlight destroy the virus? Yes, sunlight is very effective in killing the virus, especially at high radiation intensities. For example, the virus survives from 1 pm (at 21 ° C and 40% RH) for up to 10 min with an ultraviolet index of 2 and only about 2 min. when this index reaches 10. Interestingly, as early as 1978 the use of high intensity ultraviolet radiation was proposed to control measles outbreaks.

8. Is it safe to go to a pool, beach, or park during a pandemic? If the density of people is not high and people can keep their distance and wear masks when other people are closer, outdoor recreation is associated with a low risk of infection. There is also no evidence that the virus is transmitted by water.

9. Are schools a safe place during a pandemic? Unfortunately, schools are not the safest place, as school facilities often meet many criteria for effective transmission of the virus: closed space, high density of people, insufficient ventilation, distance, prolonged contact, constant and loud conversation, singing, screaming, deep breathing. There is much discussion about how children transmit the disease. There is some evidence that younger children infect other people less often, but older children infect other people just as often as adults. Schools must work in contact during a pandemic if there are not many cases in the community. In school classrooms and corridors, it is important to increase ventilation, wear masks, maintain distance, speak louder for everyone, and reduce the number of children in classrooms. Many researchers recommend periodic testing for teachers and students.

“If there are any inaccuracies in the text, I will definitely correct them taking into account your comments,” says V. Kasiulevičius on his Facebook account.



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