Smokers spend less time in closed environments. They are not always welcome in super-spreader indoor environments, and they spend less time with non-smokers than non-smokers do (most non-smokers do mind the smell of tobacco).<p>Also, it's not that hard to find another paper with an opposite conclusion:
<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301735/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301735/</a>