Exposure to second-hand nicotine vape at home is linked to a 40% increased risk of adverse respiratory symptoms in young adults, a US study shows.

The findings, published in Thorax, suggest that indirect exposure “should not be perceived as harmless”, the researchers say.

“The potential detrimental effect of [second-hand nicotine vape] exposure can be much greater for children who themselves are not smokers or vapers,” said study co-author Dr Talat Islam, an environmental epidemiologist at the University of Southern California in Los Angeles.

The team analysed data from 2100 adolescents (mean age 17) in the prospective Southern California Children’s Health Study, which collected annual surveys on respiratory health as well as active and second-hand nicotine exposure from 2014-19.