Across the four marketplaces, Which? found 149 listings for unsafe carbon monoxide (CO) alarms sold for as little as £5 that did not reliably detect the odourless, deadly gas.

During tests, the consumer champion found an unbranded alarm failed to respond to carbon monoxide a third of the time it was exposed to CO (10 out of 28 tests). When it did sound, it was far too quiet.

eBay is the only online marketplace that discloses sales figures which showed that at least 1,311 dangerous alarms had been bought by unsuspecting shoppers.

Worryingly, one of the models, a battery operated carbon monoxide alarm, was first flagged to eBay by Which? seven years ago.

Which? found 88 sellers listing the same dangerous alarm on AliExpress, Amazon, eBay and Wish, with eBay sellers alone accounting for close to 600 sales.

Another unbranded CO and smoke alarm that was inadequate at detecting danger was listed by 22 eBay sellers, with 718 sales recorded. Which? also found two sellers listing it on AliExpress. Across Which?’s CO tests it failed to trigger 22 times when CO was in the air.

Which? also tested 10 CO alarms from leading brands including FireAngel, Firehawk, Kidde and Google (Nest). The alarms from well known brands detected the killer gas every time regardless of how much was in the air.

Carbon monoxide a silent killer

The findings come as figures from the Office for National Statistics revealed that in 2021, 43 people died from accidental carbon monoxide poisoning, while more than 200 accidental deaths in England and Wales have been recorded in the last decade.

After an approach by Which?, the four websites removed the listings. But Which? said online marketplaces need to do much more to prevent unsafe product listings appearing in the first place, rather than removing these products reactively when they are flagged.

The results come after the Government published a consultation on 2 August to update the UK’s product safety laws to match the digital age. However, Which? argued that the reforms have exposed the need for an independent UK product safety regulator with a duty to put consumer interests first.

It also wants to see tough enforcement action, including fines, against online marketplaces that break the rules.

‘Fatal consequences’

Sue Davies, Which? head of consumer protection policy, said: “Which? has been raising concerns about dangerous CO alarms for years, yet online marketplaces continue to allow them on their sites and into people’s homes, despite the potentially fatal consequences.

“This is the latest in a long line of examples of unsafe products being readily available on online marketplaces, with far too little action taken by the platforms to prevent them being allowed for sale.

“The Government cannot delay any longer. It must move at pace to establish new regulations that put consumer safety first and enable tough enforcement action against online marketplaces that break the rules.”

What do the online marketplaces say?

eBay

“We take the safety of our users very seriously and immediately removed the listings reported to us by Which?. We only allow sellers to list approved brands of carbon monoxide detectors and can confirm that action has been taken against the sellers.”

Amazon

“Safety is a top priority at Amazon. We require all products to comply with applicable laws and regulations and have developed industry-leading tools to prevent unsafe or non-compliant products from being listed in our stores.”

AliExpress

“We take product safety very seriously and work hard to create a safe shopping environment. The items identified as part of the investigation by Which? have been removed.”

Wish

“All of our merchants are required to adhere to local laws and safety standards wherever their goods are sold. It’s clear that the products identified do not comply with those standards, so we have acted quickly to remove them, along with any similar and identical items.”