When the skytrain was being built, engineers promised that it would help reduce the city's noise pollution. Instead, the concessionaire soon installed televisions inside the cars that pump noisy advertisements that riders cannot escape. Loudspeakers on platforms also blast annoying commercials at passengers as they wait, and at residents of nearby buildings. This affects hundreds of thousands of Bangkokians every day. The concessionaire, the Bangkok Mass Transit Public Company, claimed respond to customer complaints in its successful application for OHSAS 18001 certification, even though groups like the Quiet Bangkok campaign have called for the loudspeakers to be turned off. The BTS should live up to its claims of corporate social responsibility and switch to silent advertising using on-screen subtitles.