European household gas has unsafe levels of cancer-causing chemical, scientists warn

The study, led by researchers from Stanford University and the research institute PSE Healthy Energy, tested gas samples collected from 72 homes in the UK, the Netherlands and Italy. On average, gas in British homes contained around 37 times more benzene than samples previously measured in North America, while levels in the Netherlands were about 66.5 times higher, the researchers said.

Using the North American findings as a benchmark, the team reported differences by city. London’s gas contained about 64 times more benzene, Amsterdam about 73 times more, and Milan about 8.5 times more, compared with the earlier North American data.

The study also raised concerns about leaks inside kitchens. When researchers checked appliances while stoves were switched off, they found leaks in roughly 40% of kitchens. They estimated that about 9% of homes had leaks large enough to exceed recommended exposure limits under UK and EU guidelines.

A key problem, researchers said, is that many people may not get a clear warning. Gas utilities add sulphur-based odorants so leaks can be detected by smell, but the study found odour levels were often too low to alert households before benzene concentrations could rise to hazardous levels.

Ventilation helped reduce indoor pollution, opening windows or using extractor hoods lowered concentrations during cooking, but researchers said constant leaks would require hours of ventilation a day, making the issue hard to manage at the household level.

“This is really a systemic problem,” lead author Dr Tamara Sparks said, arguing that stronger measures, such as improving leak detection and increasing odorisation levels, could help people identify smaller leaks sooner and reduce long-term exposure risks.