Air Pollution inside Vehicles: Making a Bad Situation Worse

Thailand has successfully forwarded Article 8, Protection from Exposure to Tobacco Smoke, of the World Health Organization's Framework Convention on Tobacco Control (WHO FCTC). It achieved its 100% smoke-free goals in public places in 2010, next pursuing other bans in outdoor places to lower particulate matter air pollution (PM_2.5). Our aim was to expose the secondhand smoke levels in vehicles since SHS is a danger to everyone, but especially to children and youth. This is the first experimental study of its kind in Thailand. We measured PM_2.5 for 20 min under four conditions in 10 typical Thai vehicles, including commonly used sedans and small pickup trucks. We used an established protocol with two real-time air monitoring instruments to record PM_2.5 increases with different vehicle air exchange and air conditioning conditions. Monitoring was recorded in the vehicle's front and back seats. The most common Thai ventilation condition is all windows closed with fan/air conditioning (AC) in operation because of Thai tropical conditions. Mean exposure levels were three and nearly five times (49 and 72 μg/m³) the 24 h WHO standard of 15 μg/m³ in the back and front seats, respectively. These high PM_2.5 exposure levels warrant action to limit vehicle smoking for public health protection.