Figure 2.

Association between the use of cleaning sprays at least once a week and the incidence of asthma symptoms or medication usage by country. Relative risk (RR) and 95% confidence interval (CI), adjusted within countries for study center, sex, age, smoking status, and employment in a cleaning job, are shown. The size of each box is proportional to the reciprocal of the variance of the estimate for the country. The diamond indicates 95% CI of the combined RR from the model, with country as the random effect (P = 0.15, test for heterogeneity). Countries are ranked from low to high frequency of spray use (see Table 5).