Κατσουγιάννη Ελένη-Κλεάνθη, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Σαμόλη Ευαγγελία, Επίκουρη Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Δημακοπούλου Κωνσταντίνα, Μεταδιδάκτορας, Ιατρική Σχολή, ΕΚΠΑ
Many studies have provided strong evidence that high temperatures and heat waves are strongly associated with adverse effects on people’s health and especially on mortality in most large cities. They investigated the temperature effects on all cause and cause specific mortality. Heterogeneity in these effects between different cities or areas with different climate conditions is well studied but there is limited evidence about spatial variability of the effects of temperature on mortality within a metropolitan area, like Athens, known as within-city variability. We estimated the temperature threshold, which is the temperature of minimum mortality, and the heat-related risk of total, cardiovascular and respiratory mortality (all ages and by age-group) in Athens metropolitan area. The study area was divided into 6 sectors and 42 municipalities, in order to explore heterogeneity in heat-related effects within the city. The temperature-mortality association was estimated for Athens area, for six sectors separately and for 42 municipalities. We studied the warm period (April-September) of years 2000-2012. Poisson regression used to estimate Athens’ and sectors’ temperature thresholds and the change in mortality risk. The average of lags 0-3 of maximum temperature was considered as the daily exposure. Meteorological data were derived from the E-OBS dataset for Athens’ sectors and from the meteorological station in Thiseio for total area. We evaluated the variability of temperature effects that were estimated in sectors and municipalities. We tried to explain the observed heterogeneity using spatial factors that could behave as effect modifiers.
The temperature threshold was 31.5°C for Athens metropolitan area and varied between the 6 sectors from 24.8°C (west) to 27.5°C(center). The percent increase in total mortality per 1°C increase in maximum temperature above the threshold of 31.5°C was estimated to be 4.16% (95% CI: 3.73, 4.6) when the estimated increase in cardiovascular mortality was 5.34% (95% CI: 4.74, 5.93) and in respiratory mortality was 5.9% (95% CI: 4.57, 7.24). Using the E-OBS dataset for the sectors, the highest increase in total and respiratory mortality was in Piraeus (3.08%, 95% CI:2.38, 3.78 and 6.53%, 95% CI: 4.34, 8.77 respectively) and in center for cardiovascular mortality (3.96%, 95% CI: 3.12, 4.81). The same pattern was found considering different models for the investigation of temperature-mortality relationship in the sectors, using temperature measurements from Thiseio station. Higher effect was estimated among the elderly (> 75 years old) for total and cardiovascular mortality (7.68%, 95% CI: 4.39,11.08 and 6.17, 95% CI:5.49, 6.86 respectively) and for respiratory mortality in age group 65-74 (7.68%, 95% CI: 4.39,11.08). There was evidence for spatial variability of the effects of temperature on total and cardiovascular mortality within the city. Population density, percent of buildings’ area, road length and average maximum temperatures of an area were associated with the observed heterogeneity in temperature effects. The results could be used for further investigation of the within city variation of heat-related effects and help public health authorities to implement mitigation strategies to protect the population from temperature extremes and heat waves that tend to be more often and intense.