Introduction:
To assess exposure to second-hand smoke (SHS) in bus stops and markets, settings excluded from the Spanish Law 42/2010 regulating smoking in closed and open public places.

Material and Methods:
Cross-sectional study in Barcelona assessing SHS exposure in 20 bus stops, 8 open markets, and 9 closed for comparison. We measured PM2.5 and vapour-phase nicotine as markers of SHS during 30 min (both in μg/m3), using a SidePak AM510 monitor and a cassette containing a filter treated with sodium bisulphate, respectively. We computed medians and interquartile ranges (IQR) and compared them according to traffic density, evidence of smoking (tobacco smell/butts), presence of smokers, wind speed, and type of bus stop (with/without shelter) or type of market (open/closed).

Results:
Median (IQR) PM2.5 concentration was 13.52 µg/m3 (9.62–17.68 µg/m3) in bus stops, being higher in those with evidence of smoking (14.04 vs. 8.84 µg/m3; p<0.05). Median nicotine concentration was 0.17 µg/m3 (0.07–0.40 µg/m3), with significant differences according to wind speed (0.36 µg/m3 when wind speed was ≤10 km/h vs. 0.09 µg/m3 when it was higher). In markets, median PM2.5 concentration was 31.98 µg/m3 (8.32–50.96 µg/m3) in open markets and 31.20 µg/m3 (20.80–32.76 µg/m3) in closed markets. Nicotine concentrations were 0.67 µg/m3 (0.11–1.52 µg/m3) and 0.13 µg/m3 (0.09–0.19 µg/m3), respectively, observing significant differences according to evidence of smoking (0.19 vs. 0.08 µg/m3 without evidence).

Conclusions:
Exposure to SHS is low, but still measurable in these settings. There is still room for improvement in smoking regulation in public open and semi-open spaces.

Funding:
Instituto de Salud Carlos III, Government of Spain and the European Regional Development Fund, ERDF (RTICC RD12/0036/0053 and grant PI1102054)