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

AIM

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.

METHOD

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.).

RESULTS

Highest overall mean PM2.5 levels were observed in the outdoor dining areas (38 mcg/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).

CONCLUSION

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.