The sight of smokers huddled around the doorways of pubs and restaurants is all too common since smoking was banned in all Irish workplaces in 2004. However new research suggests that this practice may reduce some of the health protection offered by the ban.

Smoking has been banned in Spanish hospitality venues, such as bars and restaurants, since 2011, so scientists decided to analyse the reduction of nicotine in such venues.

They found a 90% decrease in the presence of nicotine and particulate matter (pollution) in the air of these venues, which is ‘attributable to the regulations that have been in place for the last two years'. This, they noted, corresponded to findings carried out in countries with similar bans such as Ireland and Scotland.

However, they also found increased levels of nicotine and particulate matter inside venues where people smoked directly outside, such as at the entrance or on terraces.

The findings were based on samples taken at venues before and after the ban was introduced in Spain in January 2011.

The average concentration of nicotine in the atmosphere in venues where people smoked outside was 1.13 µg/cubic meter (m3). However in venues where smoking outside was not permitted, the concentration inside the venue was just 0.41 µg/m3.

The researchers called for more studies into the levels of nicotine exposure in outside areas.

"The potential need to establish consumption restrictions in certain places should also be considered," they added.

Details of these finsings are published in the journal, Nicotine & Tobacco Research.