Oh, charcoal. Are you dirty? Clean? Both? Neither? Whatever the case, a new class of grooming products includes charcoal as a key ingredient.

Last year, Clinique added Charcoal Face Wash to its men's line, while Dermalogica debuted a detoxifying Charcoal Rescue Masque over the summer.

In terms of services, New York salon Mario Badescu will throw in a charcoal mask as an add-on to facials, while Ling Skin Care offers a "charcoal facial detox". Pressed Juicery has taken an inside-out approach, with an "activated charcoal lemonade" on its menu.

"Activated charcoal has been around in the medical profession for hundreds and hundreds of years," says Ms Diana Howard, vice-president for research and development at Dermalogica. "They use it when someone ingests poison. Most ambulances carry it."

Ms Elena Arboleda, salon director at Mario Badescu, says: "It's basically a toxin magnet."

Ms Howard thinks the grooming industry's recent embrace of charcoal "can be attributed to the fact that we, as a society, are so much more aware of chemicals in our environment, and toxins and pollutants".

It certainly does not hurt that, in these selfie-crazed times, the novelty of a face caked in a grey mask is social-media-genic. Just check the hashtag #charcoalmask on Instagram for proof.

Not everyone is convinced of charcoal's cleansing properties. "I think anything like this should be approached with a healthy dose of scepticism," said Dr Evan Rieder, a dermatologist at NYU Langone Medical Center.

Dr Rieder noted that there is no proof that charcoal's cleansing properties work on skin and that, for now, all the reports of the benefits are anecdotal. "The concept is attractive," he said. "It could work."

The scepticism from the scientific community has not stopped the flow of new products into the market.

"I think you're going to see more and more of it," Ms Howard said.

"It's definitely here to stay for a while."

NYTIMES