Raefer Wallis is a man very much in demand.
An unassuming Canadian, he is widely regarded as a leading global expert on healthier buildings, and specifically, the quality of their interior air.
Due to the coronavirus pandemic, he says he has seen requests for his services from around the world soar tenfold this year.
"Since Covid the rush for indoor air quality improvements has gone through the roof," says Mr Wallis, who is also a practising architect.
Prior to coronavirus turning us into home workers, many of us worked in modern office buildings that don't have windows that open.
Instead, the flow of fresh air is determined by a centrally controlled heating, ventilation and air conditioning (HVAC) system.
As the Covid-19 vaccines continue to be rolled out in the months ahead, more and more of us are going to be returning to working in such offices in 2021, at least some of the time, whether we like it or not.
For firms and their employees, this means an increased focus on the HVAC system in their buildings, not just in terms of the virus that causes Covid-19, but the common cold and other airborne bugs that might be being blown around on the ventilation system's jet streams.
Does your office building have any technologies in place to monitor and filter out these and other contaminants? And is enough fresh air being pulled into the building from outside?
"The more unknown something is, the scarier it gets, so air quality is like the monster in the closet," says Mr Wallis, who is the founder of air quality monitoring business Reset.
"But the more you learn, the less scary it gets. Once you know what the problems are, you can apply the right solutions."
His business tests and certifies sensor-based systems that enable firms to monitor the air quality in their offices, both in terms of viruses and other pollutants, but also carbon dioxide levels. We all breathe out CO2, but if amounts are even slightly raised, numerous studies show that it can impair a person's thinking and decision making.
"Imagine three people sitting in a mid-sized conference room," says Mr Wallis. "[Without proper ventilation] it can take 45 minutes for CO2 to reach a level whereby the brain starts to be impaired.
"And if at least one of those people are sick, it could take between five and 30 minutes for them to produce enough virus particles to contaminate the other two."
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Mr Wallis adds that most HVAC systems are designed to replace all the air in a building every 20 to 30 minutes, pumping used air outside, and pulling in fresh. However, he says that with Covid the recommendation is to increase that to every 10 to 15 minutes.
Christian Weeks, boss of US air purification business enVerid, says they have seen "unprecedented amounts of enquiries" this year.
His says that his firm's technology, which attaches to a building's HVAC system, removes viruses and other contaminants using "sophisticated sorbents [absorbent materials] to scrub the air... at the molecular level".
Danny Bluestone, the founder of UK website design business Cyber-Duck, says he is increasingly aware of the need to ensure his staff have the best possible air quality when they start to return to working in the office next year.
"We employ about 60 to 70 people, across two buildings, plus some working overseas," he says. "As most staff have been working at home this year, I have been in one of the offices pretty much on my own since March.
"And since then I haven't been ill once. I have not been around anyone with germs, so it really does make you focus more on the air quality in the office."
He says that the firm recently installed better HVAC systems for summers, and has ensured that windows can be opened at other times of the year, to allow more natural ventilation.
But what should a company, or building owner, do if there is air pollution outside? Israeli-founded firm ClimaCell sells software systems that track such pollution, and can be used to inform HVAC systems to increase the purification of air being brought into the building.
"We're now having more conversations about air quality, and we know that Covid is a factor," says ClimaCell director Ayala Rudoy. "People are generally more aware of their surroundings, and what they're breathing in."
Psychotherapist Danielle Sandler says that with many people nervous about having to return to the office, employers have to take any concerns about air quality seriously.
"Never before have we seen so much anxiety... and many employees haven't been back to the office for more than eight months," she says.
"So it's really important that firms are sensitive... when we do eventually transition back to the workplace."