At the Hong Kong desert airport, cleaners are constantly spraying baggage carts, elevator buttons and check-in counters with antimicrobial solutions. In New York City, workers are constantly disinfecting the surfaces of buses and subways. In London, several pubs spent a lot of money on intensive surface cleaning, only to reopen after the lockdown before closing again in November.
Around the world, workers soap, scrub, and spray surfaces with a sense of urgency: fighting the coronavirus. However, scientists are increasingly saying that there is little or no evidence that contaminated surfaces can spread the virus. In crowded enclosed spaces such as airports, the virus exhaled by infected people and remaining in the air is a much greater threat.
Washing your hands with soap and water for 20 seconds – or disinfectant in the absence of soap – is still the recommended measure to stop the virus from spreading. However, rubbing surfaces is of little use in reducing the threat from the virus indoors, experts say, and health officials are urged to focus on improving indoor ventilation and air filtration.
“In my opinion, a lot of time, energy, and money is wasted disinfecting surfaces and, most importantly, diverting attention and resources from preventing airborne transmission,” said Dr. Kevin P. Fennelly, a respiratory infection specialist for the United States National Health Service Institutes.
Some experts suggest that Hong Kong, a crowded city of 7.5 million people and a long history of infectious disease outbreaks, is a case study of the excessive surface cleaning that gives ordinary people a false sense of security about the coronavirus. .
Viruses are released through activities that spread breath droplets – speaking, breathing, screaming, coughing, singing, and sneezing. Disinfectant sprays are often made of toxic chemicals that can have a significant impact on indoor air quality and human health, says Shelly Miller, an aerosol specialist at the University of Colorado at Boulder.
“I can’t understand why anyone would believe that disinfecting an entire person would reduce the risk of transmitting the virus.”
“Theater of Hygiene”
A number of respiratory illnesses, including the common cold and flu, are caused by germs that can spread to contaminated surfaces. When the coronavirus outbreak hit mainland China last winter, it seemed logical to assume that these objects were the main means of spreading the pathogen.
Studies soon found that the virus appeared to survive up to three days on some surfaces, including plastic and steel. (Further studies have shown that much of these are likely dead fragments of the virus that are not infectious.)
The World Health Organization also highlighted surface transmission as a risk, saying airborne spread was only a problem if health professionals participated in certain medical procedures that produce aerosols.
However, there was growing scientific evidence that the virus could stay in the air in small droplets in still air for hours and infect people if they inhale, especially in crowded indoor spaces with poor ventilation.
In July, an article in the medical journal The Lancet argued that some scientists exaggerated the risk of coronavirus infection on surfaces without considering evidence from studies of their close relatives, including Sars-CoV, that spanned the 2002-03 SARS epidemic caused. .
“This is extremely strong evidence that object transmission, at least for the original SARS virus, was very low,” the study author, Rutgers University microbiologist Emanuel Goldman, said via email. “There is no reason to believe that the new Sars-CoV-2 coronavirus will behave significantly differently in this type of experiment,” he added.
Within days of the Goldman study being published in the Lancet, more than 200 scientists asked the WHO to recognize that the coronavirus can spread in the air in any indoor climate. Given the tremendous public pressure on the matter, the agency realized that the transmission of aerosols indoors could lead to outbreaks in poorly ventilated places like restaurants, nightclubs, offices and places of worship.
In October, the US Center for Disease Control and Prevention, which has been claiming since May that surfaces “are not the primary way virus spreads,” said breath droplet transmission was the “primary mode of transmission.”
But by then, the paranoia of touching everything from handrails to shopping bags had increased. And the instinct to scrub surfaces as a precautionary measure against Covid – “hygiene theater”, as Atlantic magazine called it – was already deeply rooted.
Personal care product sales grew more than 30% for the quarter through September, according to Procter & Gamble. In all regions of the world, sales rose by double digits, including in Greater China by more than 20%.
What about air
The impact of Covid-19 in Hong Kong – more than 6,000 confirmed cases and 108 deaths as of Nov. 27 – is relatively minor for any city. Even so, some experts say it took too long to address the risk of indoor aerosol transmission.
In the beginning, the authorities requested that Hong Kong restaurants install partitions between the tables. However, as Hong Kong authorities gradually relaxed restrictions on internal meetings, including allowing wedding parties for up to 50 people, there is a fear of possible new indoor outbreaks.
Some experts are particularly concerned that the droplets of the coronavirus could spread through the overcrowded vents in the offices, as the city has not yet developed a robust culture of remote working.
“People take their masks off at lunch or when they return to the booth, assuming this is their private space,” said Yeung King-lun, professor of chemical and biological engineering at Hong Kong University of Science and Technology .
“But remember, the air you breathe is basically community.”
Translation by Luiz Roberto Mendes Gonçalves