Does Temperature Modify the Association between Air Pollution and Mortality? A Multicity Case-Crossover Analysis in Italy

Department of Epidemiology, Rome E Health Authority, Rome, Italy.
American journal of epidemiology (Impact Factor: 5.23). 07/2008; 167(12):1476-85. DOI: 10.1093/aje/kwn074
Source: PubMed


Adverse health effects of particulate matter <10 μm in aerodynamic diameter (PM10) and high temperatures are well known, but the extent of their interaction on mortality is less clear. This paper describes
effect modification of temperature in the PM10–mortality association and tests the hypothesis that higher PM10 effects in summer are due to enhanced exposure to particles. All deaths of residents of nine Italian cities between 1997
and 2004 were selected. The case-crossover approach was adopted to estimate the effect of PM10 on mortality by season and temperature level. Three strata of temperature corresponding to low, medium, and high “ventilation”
were identified, and the interaction between PM10 and temperature within each stratum was examined. Season and temperature levels strongly modified the PM10–mortality association: for a 10-μg/m3 variation in PM10, a 2.54% increase in risk of death in summer (95% confidence interval: 1.31, 3.78) compared with 0.20% (95% confidence interval:
−0.08, 0.49) in winter. Analysis of the interaction between PM10 and temperature within temperature strata resulted in positive but, in most cases, nonstatistically significant coefficients.
The authors found much higher PM10 effects on mortality during warmer days. The hypothesis that such an effect is attributable to enhanced exposure to particles
in summer could not be rejected.

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Available from: Carlo A Perucci, Feb 02, 2015
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    • "Temperature may act as an effect modifier, but this idea remains controversial (Hales et al., 2000; Katsouyanni et al., 1993; Roberts, 2004; Samet et al., 1998). However, in several recent studies, a significant interaction was detected (Park et al., 2011; Qian et al., 2008; Ren and Tong, 2006; Stafoggia et al., 2008). Season-specific approaches have also shown that the adverse effects of air pollution are more apparent in the warm season, although substantial variations have been observed across locations (Nawrot et al., 2007; Peng et al., 2005). "
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    ABSTRACT: Substantial epidemiologic literature has demonstrated the effects of air pollution and temperature on mortality. However, there is inconsistent evidence regarding the temperature modification effect on acute mortality due to air pollution. Herein, we investigated the effects of temperature on the relationship between air pollution and mortality due to non-accidental, cardiovascular, and respiratory death in seven cities in South Korea. We applied stratified time-series models to the data sets in order to examine whether the effects of particulate matter <10μm (PM10) on mortality were modified by temperature. The effect of PM10 on daily mortality was first quantified within different ranges of temperatures at each location using a time-series model, and then the estimates were pooled through a random-effects meta-analysis using the maximum likelihood method. From all the data sets, 828,787 non-accidental deaths were registered from 2000-2009. The highest overall risk between PM10 and non-accidental or cardiovascular mortality was observed on extremely hot days (daily mean temperature: >99th percentile) in individuals aged <65years. In those aged ≥65years, the highest overall risk between PM10 and non-accidental or cardiovascular mortality was observed on very hot days and not on extremely hot days (daily mean temperature: 95-99th percentile). There were strong harmful effects from PM10 on non-accidental mortality with the highest temperature range (>99th percentile) in men, with a very high temperature range (95-99th percentile) in women. Our findings showed that temperature can affect the relationship between the PM10 levels and cause-specific mortality. Moreover, the differences were apparent after considering the age and sex groups. Copyright © 2015 Elsevier B.V. All rights reserved.
    Full-text · Article · Apr 2015 · Science of The Total Environment
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    • "Fouillet et al. (2006) found that the excess risk of deaths linked to O 3 and temperature together during the August 2003 HW in France ranged from 10.6% in Le Havre to 174.7% in Paris. Stafoggia et al. (2008) estimated that a 10 μg/m 3 increase in PM 10 concentration results in a 2.54% and 0.20% rise in risk of death in summer and winter, respectively. "
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    ABSTRACT: Meteorological (T and RH values) and air pollution data (PM10, NO2 and O3 concentrations) observed in Athens, Thessaloniki and Volos were analyzed to assess the air quality and the thermal comfort conditions and to study their synergy, when extreme hot weather prevailed in Greece during the period 2001–2010. The identification of a heat wave day was based on the suggestion made by the IPCC to define an extreme weather event. According to it, a heat wave day is detected when the daily maximum hourly temperature value exceeds its 90th percentile. This temperature criterion was applied to the data recorded at the cities center. Air quality was assessed at three sites in Athens (city center, near the city center, suburb), at two sites in Thessaloniki (city center, suburb) and at one site in Volos (city center), while thermal comfort conditions were assessed at the cities center. Mean pollution levels during the heat wave days and the non-heat wave days were calculated in order to examine the impact of the extreme hot weather on air quality. For this purpose, the distributions of the common air quality index and the exceedances of the air quality standards in force during the heat wave days and the non-heat wave days were also studied. Additionally, the variation of the daily maximum hourly value of Thom's discomfort index was studied in order to investigate the effect of extreme hot weather on people's thermal comfort. Moreover, the values of the common air quality index and Thom's discomfort index were comparatively assessed so as to investigate their synergy under extreme hot weather.
    Full-text · Article · Jan 2015 · Atmospheric Research
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    • "Previous studies commonly examined the linear interaction effects between air pollution and temperature. Even though the linear interaction assumption may be satisfied within specific PM 10 or temperature strata, the cutoff is difficult to determine (Stafoggia et al., 2008). Ren et al. (2006) used the mean of PM 10 as the cutoff. "
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    ABSTRACT: It remains uncertain whether air pollution modifies the magnitude and time course of the temperature-mortality association. We applied a distributed lag non-linear model (DLNM) combined with non-linear interaction terms to assess the modifying effects of particulate matter with an aerodynamic diameter of 10 μm or less (PM10) on the association between mean temperature and mortality in Guangzhou, China. We found that both cold and hot effects increased with the quartiles of PM10. The elderly were more vulnerable to cold and hot effects. Men suffered more from cold-related mortality than women, with the gender difference enlarging with the quartiles of PM10. We identified statistically significant interaction effects between PM10 and mean temperature on mortality (except for respiratory mortality). Cold and hot effects basically appeared acutely on highly polluted days, while effects were delayed on lowly polluted days. The findings indicate the importance of reducing PM10 emission on extremely temperature days. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Full-text · Article · Nov 2014 · Environmental Pollution
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