Short-term effects of various ozone metrics on cardiopulmonary function in chronic obstructive pulmonary disease patients: Results from a panel study in Beijing, China.

Background Short-term exposure to ambient air pollution has been associated with lower pulmonary function and higher blood pressure (BP). However, controversy remains regarding the relationship between ambient multiple daily ozone (O 3 ) metrics and cardiopulmonary health outcomes, especially in the developing countries. Objectives To investigate and compare the short-term effects of various O 3 metrics on pulmonary function, fractional exhaled nitric oxide (FeNO) and BP in a panel study of COPD patients. Methods We measured pulmonary function, FeNO and BP repeatedly in a total of 43 patients with COPD for 215 home visits. Daily hourly ambient O 3 concentrations were obtained from central-monitoring stations close to subject residences. We calculated various O 3 metrics [daily 1-h maximum (O 3 -1 h max), maximum 8-h average (O 3 -8 h max) and 24-h average (O 3 -24 h avg)] based on the hourly data. Daily indoor O 3 concentrations were estimated based on estimated indoor/outdoor O 3 ratios. Linear mixed-effects models were used to estimate associations of various O 3 metrics with cardiopulmonary function variables. Results An interquartile range (IQR) increase in ambient O 3 -8 h max (80.5 μg/m 3 , 5-d) was associated with a 5.9% (95%CI: −11.0%, −0.7%) reduction in forced expiratory volume in 1 s (FEV 1 ) and a 6.2% (95%CI: −10.9%, −1.5%) reduction in peak expiratory flow (PEF). However, there were no significant negative associations between ambient O 3 -1 h max, O 3 -24 h avg and FEV 1 , PEF. An IQR increase in ambient O 3 -1 h max (85.3 μg/m 3 , 6-d) was associated with a 6.7 mmHg (95%CI: 0.7, 12.7) increase in systolic BP. The estimated indoor O 3 were still significantly associated with reduction of FEV 1 and PEF. No significant associations were found between various O 3 metrics and FeNO. Conclusions Our results provide clues for the adverse cardiopulmonary effects associated with various O 3 metrics in COPD patients and highlight that O 3 -8 h max was more closely associated with respiratory health variables. [ABSTRACT FROM AUTHOR]