The APSARA National Authority welcomes the focus placed on the problem of air pollution at Angkor in the article “ In Cambodia, toxic air threatens timeless ruins ” by Denise Hruby, published in the Cambodia Daily on July 21st 2014. APSARA wishes to add some points of background and explanation of how seriously the authority is taking this issue. Background In 1992, Angkor was inscribed on the UNESCO World Heritage List on the basis of four different criteria; it was regarded not only as a “masterpiece of human genius” but also because of its landscape, traditional settlement and human interaction with the environment. The conservation of these values, which make Angkor so outstanding, lies at the heart of the mission of the APSARA National Authority, which for 20 years has worked closely with the international community in the development and implementation of policies and methods aimed at achieving the most effective and sustainable conservation of the site. While ...