Risk of Cardiovascular Hospitalizations from Exposure to Coarse Particulate Matter (PM10) Below the European Union Safety Threshold

The association between exposure to air pollution and acute cardiovascular (CV)
events is well documented; however, limited data are available evaluating the
public health safety of various "doses" of particular matter (PM) below currently
accepted safety thresholds. We explored the cross-sectional association between
PM with aerodynamic diameter <10 μm (PM10) and daily CV hospitalizations in
Brescia, Italy, using Poisson regression models adjusted for age, gender, and
meteorologic indices. Average daily exposure to PM10 obtained from arithmetic
means of air pollution data were captured by 4 selected monitoring stations. PM10
data were expressed as daily means (lag 0-day) or 3-day moving averages (lag
3-day) and categorized according to the European Union daily limit value of
50 μg/m(3). From September 2004 to September 2007, data from 6,000 acute CV
admissions to a tertiary referral center were collected. An increase of 1 μg/m(3)
PM10 at lag 0-day was independently associated with higher rates of acute
hospitalizations for composite CV-related events (relative risk [RR] 1.004, 95%
confidence interval [CI] 1.002 to 1.006), acute heart failure (RR 1.004, 95% CI
1.001 to 1.008), acute coronary syndromes (RR 1.002, 95% CI 0.999 to 1.005),
malignant ventricular arrhythmias (RR 1.004, 95% CI 0.999 to 1.010), and atrial
fibrillation (RR 1.008, 95% CI 1.003 to 1.012). Similar results were obtained
using PM10 lag 3-day data. The excess PM10 CV hospitalization risk (by lag 0-day
and lag 3-day) did not vary significantly above and below the 50 μg/m(3) safety
threshold or by age and gender. In conclusion, increased levels of PM10, even
below the current limits set by the European Union, were associated with excess
risk for admissions for acute CV events.