EXPOSURE TO BIOMASS SMOKE AND CHRONIC AIRWAY DISEASE IN MEXICAN WOMEN- A CASE-CONTROL STUDY

A case-control study was performed in women older than 40 yr of age to evaluate the risk of cooking with traditional wood stoves for chronic bronchitis and chronic airway obstruction (CAO). The subjects were re cruited from patients attending a referral chest hospital in Mexico Ci ty. We selected 127 patients with chronic bronchitis or CAO, of which 63 had chronic bronchitis alone, 23 had CAO alone (FEV(1) less than 75 % of predicted), and 41 had both chronic bronchitis and CAO (cases). F our control groups were selected: 83 patients with pulmonary tuberculo sis, 100 patients with interstitial lung diseases, 97 patients with ea r, nose and throat ailments, and 95 healthy visitors to the hospital ( controls). Exposure to wood smoke, assessed as any or none, and as hou r-years (years of exposure multiplied by average hours of exposure per day) was significantly higher in cases than in controls. Crude odds r atios for wood smoke exposure were 3.9 (95% CI, 2.0 to 7.6) for chroni c bronchitis only, 9.7 (95% CI, 3.7 to 27) for CAO plus chronic bronch itis, and 1.8 (95% CI, 0.7 to 4.7) for CAO only. Differences in exposu re to wood smoke persisted after adjusting by stratification and logis tic regression for age, income, education, smoking, place of residence , and place of birth. Risk of chronic bronchitis alone and chronic bro nchitis with CAO increased linearly with hour-years of cooking with a wood stove; odds ratios for exposure to more than 200 hour-years compa red with nonexposed were 15.0 (95% CI, 5.6 to 40) for chronic bronchit is only and 75 (95% CI, 18 to 306) for chronic bronchitis with CAO. Th e findings support a causal role of domestic wood smoke exposure in ch ronic bronchitis and chronic airflow obstruction.