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European countries reported more deaths due to COVID-19 than Asian countries at the beginning of the outbreak. What could be the reason? It could be because more people in developing Asian countries, including India, live in indoor spaces with good ventilation, say Indian doctors.
The viral load is higher in air-conditioned enclosed places due to a lack of ventilation. Spending more time in closed air-conditioned spaces means repeated exposure to the airborne virus. This can lead to a build-up of high viral load in the upper respiratory tract, which increases the severity of the disease and mortality, they explained in an article published in the Asia Pacific Journal of Public Health.
Doctors from the oncology department at Sir Ganga Ram hospital, Max Smart Superspeciality hospital in Delhi, and Kasturba Medical College in Mangalore collaborated for the article.
Overcrowded homes leading to the spread of COVID-19 in India
Dr Shyam Aggarwal, the first author of the paper and chairman of the oncology department at Sir Ganga Ram hospital, noted that people in the developing countries tend to spend less time in air-conditioned enclosed places. This, he said, could be the reason for fewer deaths reported from several Asian countries.
In European countries, people stay indoors longer in the winter months of January and February. This may have led to the surge in cases in these countries, he added.
Although not many people spend time in air-conditioned offices in India, several people live in small overcrowded houses, which are leading to the spread of the disease and transmission within families – Dr Aggarwal said.
The World Health Organization (WHO) had also not ruled out the aerosol transmission of COVID-19 infection in indoor locations, such as crowded and inadequately ventilated spaces.
There have been many reports of cluster infections across the world in inadequately ventilated spaces. For example, a cluster of 10 positive cases was reported from a restaurant in Guangzhou, China in January. A group of 52 people got infected with the virus after choir practice in Washington, US in March. Over 100 Covid-19 cases were reported from a dance fitness class in South Korea in February. In the most recent case, 27 COVID-19 positive cases were linked to a coffee shop in South Korea in August.
Ensure adequate outdoor air infusion
The doctors suggest increasing air exchange in enclosed air-conditioned spaces to decrease viral load and spreading infection. The number of air exchange – circulation of outdoor air in the air-conditioning system – has to be increased to about 12 to 15 exchanges an hour, said Dr Aggarwal.
A study published in May in the City and Environment Interaction journal had also revealed that lack of adequate ventilation in homes and offices can increase the risk of airborne spread of the novel coronavirus. The scientists highlighted the need for improving building ventilation to prevent indoor transmission of COVID-19. But they said mechanical ventilation may be ineffective. Mechanical ventilation is common in many commercial and public buildings, but it may instead create situations that increase the residence time of contaminated air inside a built space, they noted.
The WHO also suggested a few steps to improve ventilation in indoor public spaces and buildings. It recommends
- Using natural ventilation, opening windows if possible, and safe to do so.
- Increasing the percentage of outdoor air for mechanical systems after checking compatibility with the HVAC system.
- Running the HVAC system at maximum outside airflow for 2 hours before and after spaces are occupied.
- Keeping exhaust fans in restroom facilities at full capacity when the building is occupied.
Published : August 30, 2020 12:14 am | Updated:August 30, 2020 12:40 am
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