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Article | Exploring the potential for the drift of secondhand smoke from outdoor to indoor dining areas of restaurants in New Zealand

A study of eight restaurants in downtown Wellington City suggests outdoor secondhand smoke drifts indoors and is trapped inside.

University of Otago, Wellington researchers Dr Amber Pearson and Frederieke van der Deen say that to maximise the health protection of both patrons and restaurant staff members, completely or at least partially restricting outdoor smoking at restaurants may be needed.



To examine levels of fine particulates of secondhand smoke (SHS) in outdoor dining/smoking areas and the adjacent indoor dining areas of restaurants to assess possible drift via open windows/doors.


We measured fine particulates (PM2.5 mcg/m3) with real-time aerosol monitors as a marker of SHS inside where smoking is banned and outside dining areas (which permit smoking) of eight restaurants in Wellington. We also collected related background data (e.g. number of smokers, time windows/doors were open, etc.).


Highest overall mean PM2.5 levels were observed in the outdoor dining areas (38 µg/m3), followed by the adjacent indoor areas (34 mcg/m3), the outdoor ambient air (22 mcg/m3) and the indoor areas at the back of the restaurant (21 mcg/m3). We found significantly higher PM2.5 levels indoor near the entrance compared to indoor near the back of the restaurant (p=0.006) and in the outdoor smoking area compared to outdoor ambient levels (p<0.001). Importantly, we did not detect a significant difference in mean PM2.5 levels in outdoor smoking areas and adjacent indoor areas (p=0.149).


Similar PM2.5 concentrations in the outdoor and adjacent indoor dining areas of restaurants might indicate SHS drifting through open doors/windows. This may especially be a problem when smoking patronage is high, the outdoor dining area is enclosed, and during peak summer season when restaurants generally have all doors and windows opened. Tighter restrictions around outdoor smoking at restaurants, to protect the health of both patrons and staff members, may be needed.


Van der Deen, F.S., Pearson, A., Petrović, D., Collinson, L. (2014). Exploring the potential for the drift of secondhand smoke from outdoor to indoor dining areas of restaurants in New Zealand. New Zealand Medical Journal, 127 (1396).


To read the full article please view here (note password access required until Jan 2015.)

To view the media articles on Stuff please view here, and the NZ Herald here.

For further information or to request this paper, please contact:
Frederieke van der Deen
University of Otago, Wellington

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