We’ve been hearing a lot about deep cleaning. When the last passengers and crew on the Diamond Princess cruise ship in Japan completed their 14-day quarantine on March 2, following a coronavirus outbreak aboard, the ship underwent a thorough disinfection. Since then, not a day has gone past without mention of a club, gym, restaurant, bank or bar closing for a deep cleaning. But how does it differ from regular or spring cleaning? Firstly, deep cleaning isn’t a scientific concept and likely means different things to different people and businesses. Hong Kong’s Centres for Disease Control and Prevention is a good starting point. It has issued guidelines on how to clean and disinfect community facilities after people suspected or confirmed to have Covid-19 – the disease caused by the novel coronavirus – have been there, and recommends focusing on frequently touched surfaces. It must be a good time to be in the decontamination business, one industry that has not seen activity drop off a cliff. All phone lines to ISS Hong Kong, the local arm of the global provider of facility services, including cleaning services, were busy and the Post ’s call went to voicemail. When the receptionist returned the call and forwarded the Post to the cleaning department, that voicemail box was full and not taking messages. Eventually we spoke to the company’s chief commercial officer, Grace Liang, who says the firm has seen a surge of enquiries. What coronavirus pandemic means for couples getting married ISS made its name in Hong Kong 17 years ago when it was called in to support the Prince of Wales Hospital, cleaning up after the severe acute respiratory syndrome (Sars) outbreak in Ward 8A. “We were one of the few cleaning companies that was able to pull a team together with the right training, supervision and chemicals,” Liang says. “Until now we are very active in offering cleaning services for hospitals.” General cleaning refers to that done on a daily basis, focusing on washrooms and carpets, and other easy to access areas, and is often done around people using that space. Deep cleaning, however, is much more intense. “[Deep cleaning] causes more disruption so it’s done at the weekend or overnight when the users aren’t present. Chemicals could be used, and we need time for carpets to dry,” Liang says. The company’s disinfection service is even more intense and requires a specialised team with the correct gear, PPE (personal protective equipment) masks and hazmat suits. If a ULV (ultra-low volume) fogger is used then time must be allowed for the chemical agents to settle. Liang says most cleaning inquiries are requests to have surfaces cleaned, such as furniture and door handles, as well as carpeting and hard flooring. “Cleaning is very much in demand and we also offer a package for fogging,” she explains, referring to a procedure that uses a high-grade disinfectant and virucide known to be highly effective against many communicable diseases, including coronaviruses. Disinfectant products don’t work properly if the surfaces are not visually clean. So, the message is: clean and wash with soapy water first. Then disinfect with disinfectants like common household bleach Dr Joyce Lai, general practitioner at a clinic in Central, Hong Kong While it’s important to keep these high-touch areas clean, Liang says other areas are being ignored, chiefly ventilation systems – not just the air-conditioning system, but the air duct itself. “These are things that are often not attended to for 10 or even 20 years. You can’t see how dirty it is. We still don’t know how long the virus can stay in the air,” she says. If the air-conditioning system itself is clean, but the air duct that draws fresh air from outside is not, then the air in an office is dirty. This can be further complicated by the fact that the system might be shared by several work spaces. “The root, where the air comes in, may be dirty. And if the air ducts are connected to different offices then any germs will be spread further,” Liang says. Some venues have been undergoing a “deep clean” after a person infected with the virus visited, while others are getting ahead of the game and closing for a short period to conduct their own thorough cleans. The Foreign Correspondents’ Club (FCC) of Hong Kong closed for two days earlier in March, exercising what it called “an abundance of caution” after a member who visited 19 days earlier was confirmed to be infected with the virus. “We didn’t need to do it because we were well over the 14 days, but it was a preventive measure and it will help in the future because we’ve done the big work already,” says Didier Saugy, the club’s general manager. The FCC used its own staff – the entire team of 80 plus, from chefs to bar staff – with the support of a chemical supplier for the appropriate cleaning agents to scrub the club from top to bottom. “We pulled out everything, cleaned every corner, sanitised everything, allowed it to dry and then put it back properly. I don’t think that level of cleaning has ever been done before. We now have a very clean club,” Saugy says. Those looking to do a deep cleaning of their own home are advised to read the directions on cleaning products for information about how long it needs to be in contact with germs to work effectively. Dr Joyce Lai, a general practitioner at a clinic in Hong Kong’s Central district, says it never hurts to clean more since we know the coronavirus can survive on surfaces for an extended period of time – from hours to days – or even longer given the ideal environment. “The outer envelope [of the coronavirus] is quite fragile, and easily killed with common disinfectants,” says Lai, adding that the World Health Organisation said that regular household disinfectant can kill it. “Disinfectant products don’t work properly if the surfaces are not visually clean. So, the message is: clean and wash with soapy water first. Then disinfect with disinfectants like common household bleach,” Lai says. There is a lot of misinformation going around. Earlier this month, widely circulated recipes on the internet recommended using vodka to combat the virus. This is a total myth – save it for a cocktail and instead refer to the US Environmental Protection Agency, which last week issued a five-page list of chemicals and products that will ward off Sars-CoV-2, the official name of the novel coronavirus. Meanwhile spare a thought for the army of cleaners around the world who are working long hours to keep potentially dangerous spaces virus-free. “They are doing a good cause for the community, they’re on the frontline,” Lai says. “They are taking a risk that a lot of people aren’t willing to take.” ISS has a cleaning workforce of 7,000 people in Hong Kong, and Liang calls for greater recognition of these essential employees. “It’s not easy work. In these difficult times, in facilities where confirmed cases like hospitals, public transport, they are working day in and day out while we are working from home. We need to recognise the importance of these people.”