Estimated differences between CAFP and CA exposures for spirometric endpoints (FVC and FEV
) measured immediately after and, at 3 h and 22 h after a two-hour exposure. The estimates are expressed as % point differences per 100 μg/m3 increase in PM concentration relative to the pre-exposure level. Horizontal bars correspond to 95% confidence interval around the mean value. The asterisk indicates significant difference between CA and CAFP exposure (p = 0.008).