Health effects of indoor combustion products.

. home, but the burning of fuel produces smoke and gases which present a problem of disposal. The difficulty is obviously greatest in a cold damp climate, where it is necessary simultaneously to retain the heat, exclude ’ the rain, and get rid of the fumes. Chimneys first appeared in England in the late twelfth century but most large medieval houses still had a central hearth in the great hall, ventilated by a louvre in the roof, until the sixteenth century, when fireplaces against walls and chimney stacks came into general use.