THE BURDEN OF ENVIRONMENTAL TOBACCO-SMOKE EXPOSURE ON THE RESPIRATORYHEALTH OF CHILDREN 2 MONTHS THROUGH 5 YEARS OF AGE IN THE UNITED-STATES - 3RD NATIONAL-HEALTH AND NUTRITION EXAMINATION SURVEY, 1988 TO 1994

Objective. To measure the effect of environmental tobacco smoke (ETS) on respiratory health in a national sample of young children. Methods. The study evaluated children 2 months through 5 years of age particip ating in the Third National Health and Nutrition Examination Survey, 1 988 to 1994. The group was a representative sample of the US populatio n (N = 7680). A parental report of household smoking or maternal smoki ng during pregnancy ascertained ETS exposure, Respiratory outcomes wer e based on parental report of wheezing, cough, upper respiratory infec tion, or pneumonia in the last 12 months and chronic bronchitis or phy sician-diagnosed asthma at any time. Logistic regression was used to a djust for age, sex, race/ethnicity, birth weight, day care, family his tory of allergy, breastfeeding, education level of head of household, and household size. Results. Approximately 38% of children were presen tly exposed to ETS in the home, whereas 23.8% were exposed by maternal smoking during pregnancy. ETS exposure increased chronic bronchitis a nd three or more episodes of wheezing among children 2 months to 2 yea rs old and asthma among children 2 months to 5 years old. For househol d exposure, a consistent effect was seen only at greater than or equal to 20 cigarettes smoked per day. Adjusted odds ratios for increased r isk (95% confidence interval) for household exposures greater than or equal to 20 cigarettes smoked per day vs none smoked) and maternal pre natal exposure (prenatal smoking vs no smoking), respectively, for chi ldren 2 months to 2 years old were chronic bronchitis, 2.5 (1.6, 4.1); 2.2, (1.6, 3); three or more episodes of wheezing, 2.7 (1.7, 4.2), 2. 1 (1.5, 2.9); and for children 2 months to 5 years old were asthma, 2. 1 (1.4, 3.2); 1.8 (1.3, 2.6). Reported use within the past month of pr escription medications for asthma (beta-agonists or inhaled steroids) was not different between those with asthma reporting ETS exposure and those reporting no exposure; percent of patients with asthma reportin g use of medication by household exposure was 0, 25.7%; 1 to 19 cigare ttes smoked per day, 32.9%; and greater than or equal to 20 cigarettes smoked per day, 23.1%; percent of patients with asthma reporting use of medication by maternal smoking during pregnancy was no, 28.9%; yes, 22.7%. Among children 2 months to 2 years of age exposed to ETS, 40% to 60% of the cases of asthma, chronic bronchitis, and three or more e pisodes of wheezing were attributable to ETS exposure, For diagnosed a sthma among children 2 months through 5 years old, there were 133 800 to 161 600 excess cases. Among exposed children 2 months through 2 yea rs of age, there were 61 000 to 79 200 excess cases of chronic bronchi tis and 126 700 to 172 000 excess cases of three or more episodes of w heezing. Conclusions. ETS exposure is common among children in the Uni ted States. The reported prevalence of asthma, wheezing, and chronic b ronchitis was increased with ETS exposures. No statistically significa nt increase in the prevalence of upper respiratory infection, pneumoni a, or cough was associated with ETS exposure. ETS exposure has little effect on the respiratory health of children between 3 and 5 years of age, with the exception of asthma. ETS appears to increase the prevale nce of asthma rather than the severity as measured by medication use. These findings reinforce the need to reduce the exposure of young chil dren to ETS.