Researchers have found that exposure to second-hand smoke could damage the way the brain works and increase the risk of dementia.
According to experts at the University of Cambridge, people exposed to high levels of other people's smoke were 44% more likely to suffer cognitive impairment.
Previous research has confirmed that smoking can increase a smoker's risk of dementia, but this new study, led by Dr David Llewellyn, found that being exposed to other people's smoke could affect someone's memory and ability to perform.
Researchers looked at data from 4,800 non-smoking adults in England aged 50 and over, including some who had previously smoked but had since stopped. The participants were divided into four groups based on the levels of cotinine, which is a marker of nicotine exposure, in their saliva.
Neuropsychological tests were used to measure each person's brain function and the results were added together to record a score for cognitive function.
The results, published in the British Medical Journal, show that there was an 8% increase in suffering cognitive impairment in the second lowest cotinine concentration, compared with the lowest group.
People in the highest concentration group were 44% more likely to suffer cognitive impairment compared with those in the lowest group.