March 25, 2026

expert reaction to research letter on benzene in consumer-grade natural gas in Europe

A research letter published in Environmental Research Letters looks at benzene in consumer-grade natural gas. 

Prof Julian Peto, Professor of Epidemiology, London School of Hygiene & Tropical Medicine, said:

“This paper is a risk-modelling exercise that gives no estimate of actual risk. The predictions are summarised as the factor by which EU limits for environmental benzene exposure were exceeded in the worst-ventilated kitchens: “Modeled enhancements of benzene were sufficiently high to result in kitchen benzene concentrations exceeding the EU limit by several fold in cases with minimal air exchange.” Even less informative is the claim that benzene levels in European natural gas are “up to 73 times greater than those measured in three recent studies in North America”. How many cancers do the authors think are now being caused by benzene in European kitchens?”

Prof Oliver Jones, Professor of Chemistry, RMIT University, said:

“The benzene molecule consists of six carbon atoms arranged in a hexagonal ring, usually with a circle in the middle. It is one of the most recognisable features in almost any artistic representation of chemistry.

“Benzene is naturally found in domestic gas. It is volatile, so exposure is usually through breathing it in, and we are exposed to benzene through a range of sources every day. Filling up your car at the petrol station is one of the most common.

“It is true that indoor air quality is one of the least-studied areas of environmental health. It is also true that benzene is carcinogenic – but so are many other things, including alcoholic drinks and sunlight.  The question is not whether something is carcinogenic, but whether it is carcinogenic at the concentration to which we are exposed. For most of the samples tested in this study, the answer is no. Only 9% of the UK sites tested in this paper exceeded the benzene limit, and only 72 sites were tested, which is quite low given that there are over 25 million dwellings in the UK.

“While this study seems well conducted, and the issues raised are certainly worth investigating, I don’t think people should panic about this research. The readings were highly sensitive to ventilation conditions, so if you are worried, ensuring a good level of air flow in any room with a gas cooker would be a good precaution.”

Prof Roy Harrison FRS, Professor of Environmental Health, University of Birmingham, said:

“The authors have measured benzene levels in natural gas as supplied to the consumer, and have used measured rates of leakage into the home to estimate household exposure concentrations from this source.  Benzene is a genotoxic carcinogen with no totally safe exposure level, so these results deserve careful scrutiny. They also calculate concentrations arising from a pipeline leakage and estimate downwind exposures from an earlier event.

“While the work has been carefully conducted, the significance of the results is over-stated.  The air quality standard for benzene which they cite is derived from occupational cancer data extrapolated to a lifetime exposure, 24 hours a day, 7 days a week and is designed to be highly precautionary.  Levels of benzene in London arising from road traffic only a few years ago were well in excess of the majority of their concentration estimates, and the chances of exposure in the same home with a high leakage rate for a lifetime are low.  For the vast majority of people the benzene exposure from this source will be comparable to their exposure to outdoor sources and be one of the smaller risks of life (especially in comparison to other air pollutants).  The risk estimates for the pipeline leak are made by comparing a one-off exposure to the occupational exposure limit which is designed to protect workers exposed for 40 hours a week for a working lifetime, so are grossly exaggerated. The only legitimate concern, not mentioned in the paper, is that there are strong indications (as yet not proven) of benzene being a risk factor for childhood leukaemia.”

Prof Alastair Lewis, Professor of Atmospheric Chemistry, University of York, said:

“The differences in composition of natural gas are larger than people might expect, and the paper shows that European gas has higher benzene than that found in the US. However, the paper extrapolates gas composition and possible leaks to estimate an indoor air quality effect. To gauge whether there might be a problem, we can look directly at recent UK studies where benzene has been measured inside home directly [1].

“In a recent study of 124 homes in Bradford only 3 out of the 124 homes had indoor benzene higher than the 1/1000000 recommended maximum lifetime cancer risk. However, other Volatile Organic Compounds (not from natural gas) did regularly exceed the recommended limits. So, whilst it’s important to track gas leaks, current data on air in UK homes doesn’t indicate a widespread problem with high benzene concentrations.  But nonetheless, getting rid of gas appliances and electrifying instead is a clear win for indoor air quality, whether that is avoiding gas leaks or avoiding the combustion products from burning gas in homes.”

References:

[1] Yearlong study of indoor VOC variability: insights into spatial, temporal, and contextual dynamics of indoor VOC exposure – Environmental Science: Processes & Impacts (RSC Publishing) DOI:10.1039/D4EM00756E

‘Benzene and Other Hazardous Air Pollutants in Consumer-Grade Natural Gas in Europe’ by Tamara L Sparks et al. was published in Environmental Research Letters at 07:00 UK Time on Wednesday 25 March 2026. 

DOI: https://doi.org/10.1088/1748-9326/ae499f

Declared interests

Prof Oliver Jones: I conduct research on environmental pollutants. I have, in the past, received research funding from various water utilities and the Environment Protection Authority Victoria (though not for research on benzene).

Prof Alastair Lewis: “I’m currently a beneficiary of various grants and contracts related to air quality from NERC and Defra and hold a Royal Society Industry Fellowship working with business to reduce the solvent content of household products. I am Chair of the Defra Air Quality Expert Group, the DfT Science Advisory Council and the NERC Science and Innovation Advisory Committee.”

Prof Roy Harrison: “Roy Harrison is Professor of Environmental Health at the University of Birmingham.  He is a member of the Defra Air Quality Expert Group and the DHSC Committee on the Medical Effects of Air Pollution and has advised WHO.  He has research grants from UKRI and the EU Horizon Programme and no support of any kind from the hydrocarbon industry.”

For all other experts, no reply to our request for DOIs was received.