I think it is important to re-emphasise that the available evidence indicates notable exposure to second hand tobacco smoke in some outdoor smoking areas and adjacent smoke-free indoor areas.[1,2] Second-hand smoke concentrations in a variety of outdoor locations can reach levels comparable to indoor concentrations where smoking is allowed. Second-hand smoke odour is detectable from 23 feet away and various irritation levels began 13 feet away from a smoker. Furthermore, anyone positioned downwind from an outdoor source of second-hand smoke will be exposed, even at significant distances from the source.
 Sureda, X., Fernández, E., López, M.J., Nebot, M., 2013. Second-hand smoke exposure in open and semi-open settings: a systematic review. Environ. Health Perspect. 121, 766–773
 Klepeis, N.E., Ott, W.R., Switzer, P., 2007. Real-time measurement of outdoor tobacco smoke particles. J. Air Waste Manag. Assoc. 57, 522–534
 Tobacco Free Youth Education, Outdoor Exposure to Second Hand Smoke: What’s the Danger? (undated) Available at: http://www.tobaccofreeparks.org/fckfiles/Outdoor%20Air%20ETS%20Factsheet...
Competing interests: No competing interests