Abstract
Epidemiological studies show an association between short periods of exposure to air pollution with increase of hospital admissions for respiratory diseases. This study investigated if short-term exposures (1-hour) to relatively low levels of concentrated ambient fine particles (CAP) induce bronchial hyperresponsiveness and lung inflammation in mice. 45 Balb/C mice divided at two groups: 22 exposed to filtered air (FA) and 23 exposed to CAP (200 μg/m3 divided by 24 hours = ±8 μg/m3). The PM2.5 concentration inside the chamber was monitored in real time. The pulmonary responsiveness to methacholine (Mch) was obtained 30 minutes after exposure, and bronchoalveolar lavage (BALF) to verify lung inflammation, 24 hour after exposure. Lung mechanical showed significant differences between the groups on the parameters following: Penh, PEF (p<0.05), and PIF (p<0.01) was statistically different for the CAP compared to FA; in relation the dose, there was a increase of Penh at basal, PBS (p <0.05) and 50 mg/mL Mch (p <0.01) in CAP when compared to the FA; there was a decrease of PEF at basal, 6.25 and 12.5 mg/mL Mch (p <0.05) of CAP compared with FA; and was also observed a decrease of PIF at basal (p <0.01), PBS, 6.25 and 12.5 mg/mL Mch (p <0.05). BALF showed an increase in the total cells number (p<0.001), macrophages (p<0.01) and neutrophils (p<0.05) in the CAP when compared to FA. Our findings show that even though a daily mean concentration of PM2.5 below the average daily level recommended by the World Health Organization (25 μg/m3), a single exposure to CAP was capable of triggering pulmonary responsiveness and the increase in the lung inflammatory infiltration.
- © 2011 ERS