DUBAI: Every day some 7 billion elevator journeys take place. Those were the days when lifts can be packed with people. Well, not anymore. Today, there are well-established elevator mandates, discouraging passengers from talking, overcrowding, among others.
This may remain so for the foreseeable future. And that’s because elevators meet at least two conditions known to contribute to the easy spread of the coronavirus: High-touch surfaces and people confined in a tight space breathing each other’s air. In some countries, like Germany, France, The Netherlands, Norway, a “third wave” of COVID-19 cases are still spiking again exponentially, though case numbers are starting to drop in countries that have ramped up vaccinations, including the UAE.
❏ Wearing a mask is the first line of defence against air-borne coronavirus: There are reports of how asymptomatic virus carriers had become "super-spreaders".
❏ In April 2020, a study published in Nature, found the highest concentration of live virus in the air in and and around confined areas with little air flow, such as in the air within the 9-square-foot toilet areas in patients' hospital rooms, which were not ventilated.
❏ A CDC study also found that the coronavirus could travel up to 13 feet as an aerosol in hospital settings.
Science behind infection risk in elevators
The science behind elevator etiquette is well documented. There had been super-spreader events traced to elevator use. Air-borne coronaviruses can survive in a closed elevator for up to 20 minutes during normal operation, according to a Dutch study. The research, published in September 2020, was done by a team from the University of Amsterdam’s Institute of Physics, in collaboration with the Amsterdam UMC.
“We found that during normal operation, it take 12 to 18 minutes before the number of aerosol particles decreases by a factor of 100. When the elevator doors are permanently open, this time time reduces to 2 to 4 minutes,” said Daniel Bonn, one of the researchers.
Other studies have shown that coronavirus can be transmitted in the air by sneezing, coughing or talking, able to persist in the air for hours and on surfaces for days. Infections can be transmitted by touching surfaces too.
Risk lingers after infected carrier exits
What happens when an infected person talks for a minute in the elevator? The threat of infection lingers in the air for a longer time if an even after an infected carrier exits. “Speaking loudly can produce up to several hundred thousand droplets per minute, while a single cough can produce several million droplets,” the researchers noted.
“Inhalation of the air after an infected patient speaks or coughs in an elevator then implies a potential uptake of tens to many thousands of RNA copies of COVID-19 per minute, depending on the contagiousness of the infected patient.”
Instead of taking lifts, many have taken to climbing stairs, which can be inconvenient, but is a healthier option. And it’s not all bad news. While lifts may look like a breeding house of germs, chances of getting sick, or catching COVID-19 are on the lower side. Harvard University professor on healthy buildings Joseph Allen, who is also Commissioner of The Lancet COVID-19 Commission, offers a simple advice about good elevator etiquette:
- Wear a mask.
- Load the elevator in a checkerboard pattern;face forward.
- Announce your desired floor.
- Have the person near the buttons select for everyone; using their knuckles.
- And no conversations please.
Moreover, Allen recommends that building owners adopt ways to minimise elevator riders’ risk of exposure, such as: creating queuing lines in lobbies and staggering employees’ arrival and departure times. Experts also advice an infection control plan for elevators, and adherence to that plan, which are both crucial high-rise buildings.
The science behind elevator airflow
To mitigate viral exposure in lifts, elevator maker Otis commissioned a study at Purdue University on airflow and how affects potential exposure to the COVID-19 virus.
Dr. Qingyan Chen, renowned for his research into how to prevent the spread of infectious diseases through indoor air systems, led the study. On January 27, 2021, Otis released its elevator airflow study findings.
Highlights:
- Elevators have significant air exchange by design with ventilation openings required by code.
- Air circulation within the elevator is key, placing elevator rides on the lower end of the exposure risk activities scale.
- Exposure risk reduced an additional 50% when all passengers properly wear masks.
- In an elevator ride, the risk of COVID-19 exposure is low if simple mitigation measures are adhered to.
“Air exchange is important. Our findings concluded that the higher ventilation in an elevator, relative to the compared activities, results in lower exposure opportunity,” said Dr. Chen.
“If all passengers properly wear masks, the relative exposure risk drops 50%. Air purification, called NPBI, can reduce this by an additional 20-30%,” he added. Dr. Chen earlier served as Principal Director of the Federal Aviation Administration’s Center of Excellence for Airliner Cabin Environment Research.
Recommendation
“We compared the relative exposure risk of elevators to other common activities in a typical workday, including an hour-long bus ride and eight hours in an office environment. Riding an elevator was a lower exposure risk activity, given the short duration of an elevator ride.”
The team found significant amount of air exchange present in most elevators can be combined with simple mitigation strategies — including all riders properly wearing a surgical-style mask — and the installation of a common type of air purification system — puts an elevator ride on the lower end of the exposure spectrum.
The study came up with the following conclusions:
- A short elevator ride represents a relatively low risk of exposure compared to several everyday activities
- The risk of a short elevator ride is less than outdoor dining
- It is comparable to a trip to the supermarket — when simple mitigation protocols are in place and adhered to.
Case study: 'super-spreader' infects 71 people via elevator
In 2020, a super-spreader event was reported when an infected person unintentionally infected 71 other people like after using the elevator in her apartment block. On March 19, 2020 a Chinese woman reportedly returned to her home in Heilongjiang province, China, after a trip to the US.
The asymptomatic woman, whose identity was not revealed by authorities, tested negative when she returned from her trip but was told to self-isolate in her house. The Centers for Disease Control and Prevention (CDC) stated the woman returned eight days after the area last reported any new COVID-19 cases. Researchers believe the contaminated the elevator in her building had infected at least 71 people.
Although she had not taken the lift with anyone else, it is believed her downstairs neighbour contracted the virus after he used the lift at some point after her.
Then it was a domino of infections: The neighbour infected her mother and another person when they visited her home to attend a party with another group. There, a stroke patient and his two sons who were at the party tested positive for COVID-19. Epedimiologists discovered the father was admitted to hospital where he and his two sons infected 28 people, including five nurses and one doctor. They went on to infect another 20 people in the second hospital.
The investigators re-tested the woman who had travelled from the US. She was found to have had antibodies — suggesting she had previously had COVID-19.
After the mass infection event in the residential building, Chinese CDC researchers wrote: “We believe [the traveller] was an asymptomatic carrier and that [the downstairs neighbour] was infected by contact with surfaces in the elevator in the building where they both lived.” They added, "Our results illustrate how a single asymptomatic Sars-CoV-2 infection could result in widespread community transmission."
CDC guidance on elevators
The US Centres for Disease Control and Prevention (CDC) has developed “special considerations for elevators and escalators”:
- Ask elevator occupants to avoid speaking, when possible.
- Consider limiting the number of people in an elevator and leaving steps empty between passengers on escalators, where possible, to maintain social distancing.
- Encourage occupants to take stairs when possible, especially when elevator lobbies are crowded or when only going a few flights.
- Where feasible, designate certain stairwells or sides of stairwells as “up” and “down” to better promote social distancing.
- Use floor markings in elevator lobbies and near the entrance to escalators to reinforce social distancing. Place decals inside the elevator to identify where passengers should stand, if needed.
- Use stanchions (for lobbies only; not inside elevators) or other ways to mark pathways to help people travel in one direction and stay 6 feet apart.
- Encourage the use of cloth face coverings by all elevator and escalator occupants.
- Post signs reminding occupants to minimise surface touching. They should use an object (such as a pen cap) or their knuckle to push elevator buttons.
- Encourage elevator and escalator passengers to wash their hands and avoid touching their face after holding on to handrails or touching buttons.
- Consider adding supplemental air ventilation or local air treatment devices in frequently used elevator cars.
Among respondents, 23% said they don’t like speaking to people they don’t know; 17% said they would avoid getting in an elevator if someone they didn’t like was in it.
Whatever the case, experts says it better if 100% of elevators passengers were not to talk in such a small confined space for now.
