Background: Throughout Asia, smoking is commonplace at crowded public beaches. Evidence has clearly shown the dangers of secondhand smoke (SHS) indoors, but no naturalistic studies have determined levels of SHS in outdoor air.
Methods: We measured SHS exposure at two public beaches in Thailand where families lounge in beach chairs under beach umbrellas. Researchers unobtrusively collected PM2.5 in close proximity to smokers by placing instruments downwind from smokers. We collected 88 samples of second-by-second measurements over 10-min periods. The density of people, smokers and children in each sampling area was also recorded.
Results: At the two beaches, mean levels were 260 and 504 µg/m3; peak levels reaching up to 716 and 1335 µg/m3. Five of the 88 samples were below the outdoor standard for Thailand of 50 µg/m3. Density counts in sampled zones were up to 4 smokers and 15 children under 12 years of age. Findings show high beach exposures suggesting regulatory protections, especially for children whose exposures can produce multiple health consequences.
Conclusions: Action should be taken to prohibit smoking on Thai beaches as in other outdoor settings because peak levels of PM2.5 almost always exceeded the outdoor standard in Thailand and pose a danger to health.