FE NO concentrations in World Trade Center responders and controls, 6 years post-9/11

The aim of this study was to evaluate whether underlying respiratory disease may be revealed by offline fractional exhaled nitric oxide (FE(NO)) testing among a cohort of New York State (NYS) World Trade Center (WTC) responders in comparison with a control group of similar but unexposed NYS employees, 6 years post-9/11. Participants (92 exposed, 141 unexposed) provided two breath samples that were collected in Mylar bags and sent to a central laboratory for FE(NO) testing. Participants also completed a brief questionnaire. Ambient air pollution was characterized using particulate matter (PM(2.5)) and ozone concentration data from the NYS Department of Environmental Conservation air-monitoring sites closest to each testing site for each day of sample collection. WTC exposure did not appear to be associated with elevated FE(NO) concentrations. FE(NO) concentrations were higher on days with elevated levels of PM(2.5) (≥ 35 μg/m³) and ozone (≥ 0.08 ppm). FE(NO) concentrations were higher in men and lower in smokers. Our results do not suggest an association between WTC exposure and elevated FE(NO) concentrations, 6 years post-9/11, in this moderately exposed cohort of responders. Results do suggest that FE(NO) concentrations were elevated in relation to higher levels of ambient air pollutants. Our results also offer useful reference values for future research involving FE(NO) testing. This study demonstrates that offline FE(NO) testing is a useful method for epidemiological studies requiring collection of samples in the field, potentially over a broad geographic area.