The whole-trip exposure consists of exposure inside vehicles and outside vehicles. The time commuters spent outside vehicles includes the time between stations and the destination, and the waiting time at the bus or MRT stations. Logbooks were used by bus and MRT commuters to record time, unusual activities, and events related to exposures. It is inconvenient for motorcycle and car commuters to use logbooks while driving, therefore, video cameras were equipped for them to record their travels and unusual events, which were later identified after the trip.