Two more Covid-19 cases were linked to a barber shop in Bedok on Monday, bringing the total number linked to the Atatcutz Singapore cluster to eight. The cluster was announced last Saturday.

The earliest case detected in the cluster was a 26-year-old Malay-sian man who works as a delivery rider for Pizza Hut in Hougang Green. His infection was confirmed on June 1.

Four barbers at the Bedok shop have been infected, including one who works part-time.

The remaining four cases are either close contacts of or live in the same household as the barbers.

Within the cluster so far, at least one person is believed to have been a customer at the shop.

The Straits Times answers questions on the risk of infection at the hairdresser and other places where personal services are provided, such as nail salons.

Q: What is the risk of being infected by my hairdresser?

A: Experts have told The Straits Times previously that the risk of transmission is much higher indoors than outdoors, especially if ventilation is lacking and people are in close proximity.

Associate Professor Hsu Li Yang, vice-dean of global health at the National University of Singapore's Saw Swee Hock School of Public Health, said the risk to customers and service providers at massage shops, hair and nail salons is probably in between that at restaurants and at other retail outlets.

For instance, many hairdressing salons and shops are small, fairly cramped spaces where the air exchange is relatively poor.

"Customers will have to be in this space for at least 10 minutes and usually far longer. Most hairdressers are in much closer contact with customers relative to other shop owners or assistants," he said.

Q: What precautions are in place?

A: According to the latest guidelines issued by the authorities, for hairdressing services, all capes and towels must be changed after every service.

All hairdressing equipment, such as scissors, combs and brushes, must be disinfected and sanitised after use by each customer.

For beauty services in general, the guidelines say all operators must not serve food and drinks to customers, and should remove shared items such as magazines and newspapers.

Employees must sanitise their hands before and after each customer's treatment. Masks must be worn by customers and employees at all times.

Services that require masks to be removed have been disallowed since May 16 in the current period of heightened alert until June 13, with the exception of medical or dental services.

Q: What should customers do to keep safe?

A: Avoid going to the hair salon when it is crowded. Where possible, make an appointment and do not linger at the shop premises before and after the hair service.

They can also consider reducing the frequency of visits during this period where possible, said Prof Hsu, and minimise talking to the hairdresser and other customers.

Dr Ling Li Min, an infectious diseases physician at Rophi Clinic, suggested that long sessions could be split into two separate sessions.

Both staff and customers should keep their masks on at all times, she added.

"Customers should take spare masks, as they can easily get wet or dirty during the session."

The Ministry of Health has advised that masks with at least 95 per cent bacterial filtration efficiency should be worn.

Hair salons should try to ensure good ventilation where possible, such as keeping doors open, said Dr Ling.