# Benzene and other hazardous air pollutants in consumer-grade natural gas in Europe

## TL;DR

Natural gas leaks in European homes contain high levels of benzene, a harmful pollutant, which may lead to dangerous exposure levels that are hard to detect by smell.

## Contribution

This study provides new data on benzene levels in European natural gas and models potential health risks from leaks.

## Key findings

- Benzene levels in European natural gas were 9 to 73 times higher than in North America.
- Three homes had modeled benzene exposure above EU annual limit values.
- Low odorant levels in gas suggest hazardous leaks may be underreported.

## Abstract

Consumer-grade natural gas leaks contribute to methane-induced climate change and can degrade air quality. However, limited leakage and gas composition data exist outside of North America. Here, we measured stove-off gas leakage in 35 homes and chemically characterized 78 unburned gas samples from residential stoves across seven cities in the United Kingdom, Netherlands, and Italy. On average, benzene in unburned gas was substantially elevated compared to North America (9 to 73 times higher), while sulfur-based odorants were lower. Modeling of indoor and outdoor benzene enhancements from gas leaks showed potential for hazardous benzene exposure, often undetectable by odor. Three of 35 homes exhibited a stove-off leak that, combined with city-median benzene in gas, resulted in modeled benzene enhancements above the European Union’s annual limit value (1.6 ppbv). The combination of high benzene and relatively low odorization in natural gas suggests that hazardous leaks are likely underreported in Europe.