Interaction of Ambient Air Pollution With Asthma Medication on Exhaled Nitric Oxide Among Asthmatics

ABSTRACT

The interaction between ambient air pollution and asthma medication remains unclear. The authors compared airway inflammation response to air pollution among asthmatics. Increases of 10 ppb of nitrogen dioxide (NO₂) and of 10 μg/m³ of particulate matter < 10 micron in diameter (PM₁₀) daily concentrations were associated with an increase in exhaled nitric oxide (eNO) of 0.13 ppb (95% confidence interval = 0.06, 0.19) and of 0.07 ppb (95% confidence interval = 0.02, 0.12), respectively, in models adjusted for important covariates. The results show that the medication could not counteract airway inflammation effects of air pollution. Specifically, the patients on triamcinolone decreased the sensitivity to PM₁₀ but increased the sensitivity to NO₂. The patients on salmeterol were more vulnerable to both NO₂ and PM₁₀. This study indicates that the current pollution levels may still enhance airway inflammation among patients with persistent asthma even when they are on asthma medications.

KEYWORDS:

• air pollution
• asthma
• exhaled nitric oxide
• salmeterol
• triamcinolone

Notes

^aControlling for age, sex, race/ethnicity, asthma clinical center, season, week, daily average temperature, and daily average relative humidity.

^bLag 0 = lag of 0 day, lag 1 = lag of 1 day, lag 2 = lag of 2 days, lag 3 = lag of 3 days, and lag 0–3 = lag of 4 days (lag 0, 1, 2, and 3).

*p <.05.

^† p <.07.

^aControlling for age, sex, race/ethnicity, asthma clinical center, season, week, daily average temperature, and daily average relative humidity.

*p <.05.

^† p <.07.