Dangerous carbon monoxide alarms sold on eBay, Amazon, AliExpress and Wish, Which? warns

Carbon Monoxide alarm (Image: Expert Reviews)

Dangerous carbon monoxide (CO) alarms are being sold on eBay, Amazon, AliExpress and Wish. Yet the government is failing to take the urgent action needed to give online marketplaces more legal responsibility for preventing unsafe products on their platforms, Which? has warned.

The consumer association bought cheap CO alarms from sellers on popular online marketplaces and its tests revealed that there is a risk they would fail to alert households to the presence of the lethal, odourless gas that can cause death. 

Last week, the government provided an update on its long-delayed product safety review. It failed to provide reassurances that an independent regulator would be given effective powers to crack down on unsafe products on online marketplaces any time soon. The review was launched in March 2021 but has still not resulted in any real action to tackle the problem, and this could now be delayed until after the next general election.

Which? found 149 listings for unsafe CO alarms across four online marketplaces. These have all been removed by the marketplaces after Which? flagged them. Ebay is the only online marketplace that discloses sales figures which showed that at least 1,311 of the dangerous alarms Which? found had been purchased.

The five unsafe CO alarm models labelled ‘Don’t Buys’ by Which?, all unbranded and made in China, featured prominently on the online marketplaces when listings were filtered by cheapest first, in some cases being sold for as little as £5. 

One of the models, a battery-operated carbon monoxide alarm, was first flagged to eBay by Which? seven years ago. This year’s tests show this model still can not be relied on to sound when people need it to. It failed to respond to carbon monoxide 10 times out of 28 CO detection tests and it was far too quiet when it did sound. Five of the cheapest 10 carbon monoxide alarms on eBay were for this model of dangerous alarm.

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.

A separate unbranded alarm failed to sound in 15 carbon monoxide detection tests. Which? found it to be equally unresponsive with low, but still dangerous, levels of CO as it was with high and lethal concentrations of the gas.  It was not loud enough to pass Which?’s tests either and was available for sale from six sellers on Amazon and eBay.

In total, across the five alarms, Which? found 46 listings on AliExpress, 42 on eBay, 41 on Wish and 20 on Amazon. 

Figures indicate that carbon monoxide poisoning has caused more than 200 accidental deaths in England and Wales in the last decade.

In contrast to the dangerous unbranded alarms, 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.

Which? believes online marketplaces need to do much more to prevent unsafe product listings appearing in the first place, rather than removing these products reactively when a problem is flagged. 

Says Sue Davies, Which? Head of Consumer Protection Policy:

“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.”

Right of Replies


‘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. We continuously review and update our safety measures which aim to prevent the sale of unbranded carbon monoxide detectors and have conducted further sweeps of our site to remove any similar listings.’


‘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. We have removed these products pending further investigation.’


‘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. As a third-party marketplace, AliExpress does not take custody of the goods being sold. We have very clear rules and policies in place that must be adhered to by all the sellers on our platform.’


‘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 by Which? do not comply with those standards, so we have acted quickly to remove them, along with any similar and identical items. Meanwhile we are contacting the merchants responsible for listing those items to remind them of the importance of complying with product safety rules.’

Chris Price
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