(20.6) 255 (79.4) 321 0 (0) 0 (0) 0 Subtotal 215 (18.8) 930 (81.1) 1,145 98 (17.1) 474 (82.9) 572 Children's Health * Low birth weight and cooking smoke in Guatemala Environmental Health Perspectives * VOLUME 110 | NUMBER 1 | January 2002 111 combined and between clean fuels and open fire users are highly significant (p < 0.0001).
When fuel type was entered as the three categories presented in Table 2 (clean fuel, chimney stove, open fire), adjusted mean birth weights were 2,834 (gas/electricity), 2,765 (wood/coal stove with chimney), and 2,733 (open fire). The overall difference was nonsignificant, but the difference between the clean fuel group and the chimney stove group was marginally significant (p = 0.054).
Allowing for the classification error introduced by the rela- tively crude categorization of exposure, this effect could be expected to be greater among women consistently exposed to indoor bio- fuel pollution from poorly ventilated open fires. Although errors introduced by variations in setting, measurement, type of exposure and other factors, as well as random error (as reflected in the wide confidence interval and marginal significance), make it unwise to overinterpret the actual magnitude of the effect on birth weight, there is nevertheless a degree of consistency between this study and those on active smoking, passive smoking, and urban air pollution.