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 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 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.