“…are numerous. Contamination by carbon monoxide ( CO ) ( Anderson, 1971;Miller et al, 1989;Le Âvesque et al, 1990;Kwok, 1993;Lee et al, 1993;Johnson et al, 1995 ) is discussed in particular, but also nitrogen dioxide (NO 2 ) (Hedberg et al, 1989;Lee et al, 1993 ). Almost invariably, the source of the problem was the improper adjustment of the resurfacing machine combined with inadequate building ventilation.…”