The findings showed that at 12 months, only 27 percent of smokers had found jobs compared with 56 percent of non-smokers. Among those who had found jobs by 12 months, smokers earned on average 5 US dollars less per hour than non-smokers.

"We found that smokers had a much harder time finding work than non-smokers," said lead study author Judith Prochaska from Stanford University Medical Center in the US.

The team surveyed 131 unemployed smokers and 120 unemployed non-smokers at the beginning of the study and then at six and 12 months.

They used survey questions and a breath test for carbon monoxide levels to classify job seekers into either daily smokers or non-smokers. Smokers were on average younger, less educated and in poorer health than non-smokers.

After controlling for these variables, smokers still remained at a big disadvantage. After 12 months, the re-employment rate of smokers was 24 percent lower than that of non-smokers.

"We designed the analysis so that the smokers and non-smokers were as similar as possible in terms of the information we had on their employment records and prospects for employment at baseline," added co-author Michael Baiocchi.

Those who successfully quit smoking will have an easier time getting hired, the authors suggested.

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