The Sixteenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts
We evaluated the short-term effect of Particle Number Concentration (a proxy for ultrafine particles) and PM10 on mortality and hospital admissions between 1998–2002 in a large Italian city.
Mortality data were classified by cause of death into three groups: total (ICD9 0–799), respiratory (ICD9 460–519) and cardiovascular (ICD9 390–459) diseases. Hospital admissions data concerns subjects with a primary diagnosis of respiratory or cardiovascular diseases. The collection of PNC data is ongoing since April 2001 with a Condensation Particle Counter (CPC 3022A, TSI Inc). For the period 1998–2000, however, daily PNC values were retrospectively estimated using values of other pollutants and meteorological variables as predictors in a regression model. During the study period, PM10 data were collected in the context of the air quality monitoring system of Rome.
A Poisson Generalized Additive Model (GAM) was fitted for each outcome using penalized regression splines of time, pressure, apparent temperature and average apparent temperature of the last four days. Day of the week, holidays, influenza epidemics and an indicator of population reduction were considered as confounders. Lagged effects were accounted for by studying the effect of up to 3 lags, the average of the last two days, and the average of the last 5 days. Stratified analysis was also performed by age groups.
To evaluate the sensitivity of our results, Generalized Linear Models using natural cubic splines with fixed degree of freedom were fitted.
The estimated relative risk at lag 0–1 (average of the last 2 days) for an interquartile range (IQR=26750 n/cm3) of PNC was 1.037 (95% CI 1.018–1.056) for total mortality, 1.040 (95% CI 1.013–1.068) for cardiovascular mortality and 1.018 (95% CI 0.960–1.079) for respiratory mortality. The corresponding relative risks for PM10 (IQR=26.8 mg/m3) were 1.034 (95% CI 1.019–1.048), 1.041 (95% CI 1.019–1.062), and 1.027 (95% CI 0.979–1.077). The effects were stronger among people aged 65 years or more. Similar associations were found for cardiovascular and respiratory hospital admissions. GAM and GLM gave very similar results.
In conclusion, the results indicate an association between both PM10 and ultrafine particles and mortality/morbidity from cardiovascular and respiratory causes, especially on elderly people.