Tuesday, January 10, 2006

Exhaled NO - A New Tool for Measuring Particle Effects?

Environmental Health Perspectives Volume 113, Number 12, December 2005
Exhaled Nitric Oxide in Children with Asthma and Short-Term PM2.5 Exposure in Seattle

Therese F. Mar,1 Karen Jansen,1 Kristen Shepherd,2 Thomas Lumley,2 Timothy V. Larson,3 and Jane Q. Koenig1

1Department of Environmental Health and Occupational Sciences, 2Department of Biostatistics, and 3Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA

Abstract
The objective of this study was to evaluate associations between short-term (hourly) exposures to particulate matter with aerodynamic diameters <>2.5) and the fractional concentration of nitric oxide in exhaled breath (FeNO) in children with asthma participating in an intensive panel study in Seattle, Washington. The exposure data were collected with tapered element oscillation microbalance (TEOM) PM2.5 monitors operated by the local air agency at three sites in the Seattle area. FeNO is a marker of airway inflammation and is elevated in individuals with asthma. Previously, we reported that offline measurements of FeNO are associated with 24-hr average PM2.5 in a panel of 19 children with asthma in Seattle. In the present study using the same children, we used a polynomial distributed lag model to assess the association between hourly lags in PM2.5 exposure and FeNO levels. Our model controlled for age, ambient NO levels, temperature, relative humidity, and modification by use of inhaled corticosteroids. We found that FeNO was associated with hourly averages of PM2.5 up to 10-12 hr after exposure. The sum of the coefficients for the lag times associated with PM2.5 in the distributed lag model was 7.0 ppm FeNO. The single-lag-model FeNO effect was 6.9 [95% confidence interval (CI), 3.4 to 10.6 ppb] for a 1-hr lag, 6.3 (95% CI, 2.6 to 9.9 ppb ) for a 4-hr lag, and 0.5 (95% CI, -1.1 to 2.1 ppb) for an 8-hr lag. These data provide new information concerning the lag structure between PM2.5 exposure and a respiratory health outcome in children with asthma. Key words: airway inflammation, asthma, children, exhaled nitric oxide, particulate matter less than or equal to 2.5 ┬Ám, short-term exposure. Environ Health Perspect 113: 1791-1794 (2005). doi:10.1289/ehp.7883 available via http://dx.doi.org/ [Online 8 August 2005]

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BrooklynDodger Comments: This paper displays a new method for observing airway inflammation is more or less real time. The application of exhaled NO to measuring effects of fine particles or other airway irritants in the occupational environment in workers should be exploited.

Previously, the most feasible method of measuring "acute" effects was pre and post shift pulmonary function tests, mostly looking for changes in FEV1.0. This sealed the effects of cotton dust, tire curing fume, and metalworking fluids. But research grade PFT's are difficult to collect, pre and post shift testing is difficult to arrange, and exposure on the day of pre and post gets to be a challenge to measure. Blowing up a balloon seems easier to get done.

The 24-hour exposures associated with significant increased in exhaled NO were all well in compliance with EPA's NAAQS to PM 2.5.

EHP will download the full text article.

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