From Felix Ansell, Haworth, West Yorkshire, UK
Graham Lawton is right to mention open fires and wood burners as serious culprits when it comes to indoor pollution, but there is a dilemma when considering the balance between outdoor and indoor pollution(22 April, p 38).
Old houses with open fireplaces were designed to “breathe” through their chimneys. While an open fire certainly sends much of the heat it produces up the chimney, it also vents most of the pollutants it produces: smoke, obviously, but also coal dust and ash, carried up the chimney by a continuous flow of air. Presumably this airflow also helps remove other indoor pollutants.
