1. Brimblecombe, P.The Big Smoke, Methuen, London (1987), p. 30.
2. Brimblecombe, P.Air Composition and Chemistry, Cambridge University Press, Cambridge (1996), p. 109.
3. Brimblecombe, op. cit. (1987), p. 146.
4. Recording of pre-industrial atmospheric environment by ancient crusts on stone monuments