Comparisons of combined oxidant capacity and redox-weighted oxidant capacity in their association with increasing levels of FeNO.

BACKGROUND

Some ozone (O) and nitrogen dioxides (NO) health effects studies use O (sum value) as a surrogate. However, little is known about how this related to O (weighted value).

OBJECTIVE

We investigated the effects of redox-weighted oxidant capacity (O) on fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation, in a set of chronic obstructive pulmonary disease (COPD) patients. We also compare combined oxidant capacity (O) and O in their associations with increasing levels of FeNO.

METHODS

We measured FeNO values in 600 participants who have COPD at Shanghai Pulmonary Hospital. O was calculated directly by the sum of O and NO. The redox-weighted oxidant capacity was calculated by denoting O as the weighted average of redox potentials. We applied generalized additive models (GAM) to investigate the impacts of O and O on FeNO levels, respectively. We fitted the same models for the influence of O and NO individually and jointly on FeNO levels to compare the result of O and O.

RESULTS

O were significantly linked with FeNO levels. The impact was robustest in current day after exposure, and were closely linked with the adjustment of PM. A 10 μg m increase in average O concentrations was linked to 0.88 (95% CI: -1.46, 3.28) increase, whereas a 10 μg m increase in average O concentration was linked to 0.62 (95% CI: -0.79, 2.07) increase in FeNO. In two-pollutant models, an increase of 10 μg m in average O concentrations with adjustment of NO was associated with 0.57 (95% CI: -1.26, 2.01) increase in FeNO. The impact estimates of O and O were statistically significant among males, non-smoking and elders who age above 65 years old.

CONCLUSIONS

This analysis demonstrated that O is used as a better indicator of atmospheric oxidative capacity as a proxy of O and NO in further epidemiological studies.