Fig. 2

The plots of the univariate effect of \(\text {PM}_{10}, \text {SO}_2, \text {NO}_2, \text {O}_3\), and CO on COPD. The x-axis is the standardized value for each exposure factor, and the y-axis is the corresponding exposure-response function (h) estimate. As the values of \(\text {PM}_{10}\) and \(\text {O}_3\) increase, the probability of contracting COPD increases.