GOV.WALES uses cookies which are essential for the site to work. Non-essential cookies are also used to tailor and improve services. By continuing to use this site, you agree to our use of cookies.
Unrhyw gyfrwng cemegol, ffisegol neu fiolegol sy'n addasu nodweddion naturiol yr atmosffer a thrwy hynny yn halogi'r amgylchedd, boed hynny o dan do neu yn yr awyr agored.