Climate change, extreme weather events, air pollution and respiratory health in Europe.

Due to climate change and other factors, air pollution patterns are changing in several urbanised areas of the world, with a significant effect on respiratory health both independently and synergistically with weather conditions; climate scenarios show Europe as one of the most vulnerable regions. European studies on heatwave episodes have consistently shown a synergistic effect of air pollution and high temperatures, while the potential weather-air pollution interaction during wildfires and dust storms is unknown. Allergen patterns are also changing in response to climate change, and air pollution can modify the allergenic potential of pollens, especially in the presence of specific weather conditions. The underlying mechanisms of all these interactions are not well known; the health consequences vary from decreases in lung function to allergic diseases, new onset of diseases, exacerbation of chronic respiratory diseases, and premature death. These multidimensional climate-pollution-allergen effects need to be taken into account in estimating both climate and air pollution-related respiratory effects, in order to set up adequate policy and public health actions to face both the current and future climate and pollution challenges.

Acute effects of air pollution on pediatric asthma exacerbation: evidence of association and effect modification.

We investigated the short-term effects of particulate matter with aerodynamic diameter <10 µg/m(3) (PM(10)), sulfur dioxide (SO(2)), nitrogen dioxide (NO(2)) and ozone (O(3)) on pediatric asthma emergency admissions in Athens, Greece over the period 2001-2004. We explored effect modification patterns by season, sex, age and by the presence of desert dust transported mainly from the Sahara area. We used daily time-series data provided by the children's hospitals and the fixed monitoring stations. The associations were investigated using Poisson regression models controlling for seasonality, weather, influenza episodes, day of the week and holiday effects. A 10 µg/m(3) increase in PM(10) was associated with a 2.54% increase (95% confidence interval (CI): 0.06%, 5.08%) in the number of pediatric asthma hospital admissions, while the same increase in SO(2) was associated with a 5.98% (95% CI: 0.88%, 11.33%) increase. O(3) was associated with a statistically significant increase in asthma admissions among older children in the summer. Our findings provide limited evidence of an association between NO(2) exposure and asthma exacerbation. Statistically significant PM(10) effects were higher during winter and during desert dust days, while SO(2) effects occurred mainly during spring. Our study confirms previously reported PM(10) effects on emergency hospital admissions for pediatric asthma and further provides evidence of stronger effects during desert dust days. We additionally report severe effects of SO(2), even at today's low concentration levels.

The burden of heat-related mortality attributable to recent human-induced climate change.

Climate change affects human health; however, there have been no large-scale, systematic efforts to quantify the heat-related human health impacts that have already occurred due to climate change. Here, we use empirical data from 732 locations in 43 countries to estimate the mortality burdens associated with the additional heat exposure that has resulted from recent human-induced warming, during the period 1991-2018. Across all study countries, we find that 37.0% (range 20.5-76.3%) of warm-season heat-related deaths can be attributed to anthropogenic climate change and that increased mortality is evident on every continent. Burdens varied geographically but were of the order of dozens to hundreds of deaths per year in many locations. Our findings support the urgent need for more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.

Lung function and indicators of exposure to indoor and outdoor particulate matter among asthma and COPD patients.

OBJECTIVES: Misclassification of exposure related to the use of central sites may be larger for ultrafine particles than for particulate matter < or =2.5 microm and < or =10 microm (PM(2.5) and PM(10)) and may result in underestimation of health effects. This paper describes the relative strength of the association between outdoor and indoor exposure to ultrafine particles, PM(2.5) and PM(10) and lung function. METHODS: In four European cities (Helsinki, Athens, Amsterdam and Birmingham), lung function (forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)) and peak expiratory flow (PEF)) was measured three times a day for 1 week in 135 patients with asthma or chronic obstructive pulmonary disease (COPD), covering study periods of >1 year. Daily concentrations of particle number, PM(2.5) and PM(10) were measured at a central site in each city and both inside and outside the subjects' homes. RESULTS: Daily average particle number concentrations ranged between 2100 and 66 100 particles/cm(3). We found no association between 24 h average particle number or particle mass concentrations and FVC, FEV(1) and PEF. Substituting home outdoor or home indoor concentrations of particulate air pollution instead of the central site measurements did not change the observed associations. Analyses restricted to asthmatics also showed no associations. CONCLUSIONS: No consistent associations between lung function and 24 h average particle number or particle mass concentrations were found in panels of patients with mild to moderate COPD or asthma. More detailed exposure assessment did not change the observed associations. The lack of association could be due to the high prevalence of medication use, limited ability to assess lagged effects over several days or absence of an effect.

Ambient air pollution and respiratory health effects in mail carriers.

Mail carriers represent an occupational group suffering from respiratory symptoms and lung function impairment. Although environmental conditions may play role, information on the effects of air pollution exposure in this population is lacking. The present study was conducted in Athens, Greece, in order to investigate the adverse effects of long-term air pollution exposure on respiratory outcomes in mail carriers. A total of 226 mail carriers and 73 office employees were enrolled. Information on respiratory symptoms, medical, occupational, residential and smoking history was obtained through a questionnaire. Flow-volume curves were performed in the workplace using a portable spirometer. Individualised personal exposure assessment has been applied based on long-term residential and occupational subject history linked with geographical air pollution distribution. Furthermore, personal measurements were obtained for forty-one mail carriers using NO(2) and O(3) passive samplers, assuming that current air pollution exposure is sufficiently representative of long-term, previous exposure to make a plausible link with current health status. The analysis based on exposures estimated on the basis of residential and work addresses showed that the most exposed to PM(10) postal workers have rhinitis at a higher rate (OR=1.67, 95% CI: 1.01-2.75). In mail carriers there is indication that those exposed to higher concentrations of Omicron(3) or PM(10) have a greater possibility to present rhinitis (OR=1.63, 95% CI: 0.93-2.88 and OR=1.70, 95% CI: 0.96-3.03, respectively). The effect of O(3) on rhinitis became even more apparent in the analysis based on exposures assessed by personal measurements (OR=6.74, 95% CI: 1.24-36.55). Exposure to NO(2) was significantly associated with decrements in lung function. For office employees the exposure to air pollutants was not associated to any adverse respiratory outcome. Our findings suggest that air pollution is a contributing factor for the occurrence of rhinitis and lung function impairment in mail carriers.

Spatial variability in air pollution exposure in relation to socioeconomic indicators in nine European metropolitan areas: A study on environmental inequality.

A limited number of studies have addressed environmental inequality, using various study designs and methodologies and often reaching contradictory results. Following a standardized multi-city data collection process within the European project EURO-HEALTHY, we conducted an ecological study to investigate the spatial association between nitrogen dioxide (NO2), as a surrogate for traffic related air pollution, and ten socioeconomic indicators at local administrative unit level in nine European Metropolitan Areas. We applied mixed models for the associations under investigation with random intercepts per Metropolitan Area, also accounting for the spatial correlation. The stronger associations were observed between NO2 levels and population density, population born outside the European Union (EU28), total crimes per 100,000 inhabitants and unemployment rate that displayed a highly statistically significant trend of increasing concentrations with increasing levels of the indicators. Specifically, the highest vs the lowest quartile of each indicator above was associated with 48.7% (95% confidence interval (CI): 42.9%, 54.8%), 30.9% (95%CI: 22.1%, 40.2%), 19.8% (95%CI: 13.4%, 26.6%) and 15.8% (95%CI: 9.9%, 22.1%) increase in NO2 respectively. The association with population density most probably reflects the higher volume in vehicular traffic, which is the main source of NO2 in urban areas. Higher pollution levels in areas with higher percentages of people born outside EU28, crime or unemployment rates indicate that worse air quality is typically encountered in deprived European urban areas. Policy makers should consider spatial environmental inequalities to better inform actions aiming to lower urban air pollution levels that will subsequently lead to improved quality of life, public health and health equity across the population.

Effects of cold weather on mortality: results from 15 European cities within the PHEWE project.

Weather-related health effects have attracted renewed interest because of the observed and predicted climate change. The authors studied the short-term effects of cold weather on mortality in 15 European cities. The effects of minimum apparent temperature on cause- and age-specific daily mortality were assessed for the cold season (October-March) by using data from 1990-2000. For city-specific analysis, the authors used Poisson regression and distributed lag models, controlling for potential confounders. Meta-regression models summarized the results and explored heterogeneity. A 1 degrees C decrease in temperature was associated with a 1.35% (95% confidence interval (CI): 1.16, 1.53) increase in the daily number of total natural deaths and a 1.72% (95% CI: 1.44, 2.01), 3.30% (95% CI: 2.61, 3.99), and 1.25% (95% CI: 0.77, 1.73) increase in cardiovascular, respiratory, and cerebrovascular deaths, respectively. The increase was greater for the older age groups. The cold effect was found to be greater in warmer (southern) cities and persisted up to 23 days, with no evidence of mortality displacement. Cold-related mortality is an important public health problem across Europe. It should not be underestimated by public health authorities because of the recent focus on heat-wave episodes.

Has the risk of mortality related to short-term exposure to particles changed over the past years in Athens, Greece?

Although the health effects of short-term exposure to ambient particles have been well documented, there is a need to update scientific knowledge due to the continuously changing profile of the air pollution mixture. Furthermore the effect of the severe economic crisis in Greece that started in 2008 on previously reported associations has not been studied. We assessed the change in mortality risk associated with short-term exposure to PM10 in Athens, Greece during 2001-12. Time-series data on the daily concentrations of regulated particles and all cause, cardiovascular and respiratory mortality were analyzed using overdispersed Poisson regression models, controlling for time-varying confounders such as seasonality, meteorology, influenza outbreaks, summer holidays and day of the week. We assessed changes in risk over time by inclusion of an interaction term between particles' levels and time or predefined periods, i.e. 2001-07 and 2008-12. While the related mortality risks increased over the analyzed period, the difference before and after 2008 was significant only for total mortality (p-value for interaction .03) and driven by the difference observed among those ≥75 years. An interquartile increase in PM10 before 2008 was associated with 1.51% increase in deaths among ≥75 years (95% Confidence interval (CI): 0.62%, 2.40%), while after 2008 with a 2.61% increase (95%CI: 1.72%, 3.51%) (p-value for interaction .01). Our results indicate that despite the decline in particles' concentration in Athens, Greece during 2001-12 the associated mortality risk has possibly increased, suggesting that the economic crisis initiated in 2008 may have led to changes in the particles' composition due to the ageing of the vehicular fleet and the increase in the use of biomass fuel for heating.

Dose and time dependency of inflammatory responses in the mouse lung to urban air coarse, fine, and ultrafine particles from six European cities.

We investigated the dose and time dependency of inflammatory and cytotoxic responses to size-segregated urban air particulate samples in the mouse lung. Coarse (PM10-2.5), fine (PM2.5-0.2), and ultrafine (PM0.2) particles were collected in six European cities (Duisburg, Prague, Amsterdam, Helsinki, Barcelona, Athens) in selected seasons using a modified Harvard high-volume cascade impactor. Healthy C57Bl/6J mice were intratracheally exposed to the particulate samples in a 24-h dose-response study (1, 3, and 10 mg/kg) and in 4-, 12-, and 24-h time course studies (10 mg/kg). After the exposures, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: total cell number, cell differential, total protein, and lactate dehydrogenase (LDH) and cytokine (tumor necrosis alpha [TNF-alpha], interleukin-6 [IL-6], and keratinocyte-derived chemokine [KC]) concentrations. In general, PM10-2.5 samples had higher inflammatory activity than PM2.5-0.2 samples. PM0.2 samples showed negligible inflammatory activity. PM10-2.5 and PM2.5-0.2 samples caused large increases in BALF cytokine concentrations at 4 h, but not at 12 or 24 h, after exposure. The BALF total cell number and total protein concentrations increased significantly at 12 h for both the PM10-2.5 and PM2.5-0.2 samples, but only PM10-2.5 samples produced consistent, significant increases at 24 h after exposure. There was more heterogeneity in BALF cytokine and neutrophil cell number responses to PM2.5-0.2 samples than to PM10-2.5 samples between the sampling campaigns. Thus, particle size, sources, and atmospheric transformation processes affect the inflammatory activity and response duration of urban air particulate matter in the mouse lung.

Flavonoid classes and risk of peripheral arterial occlusive disease: a case-control study in Greece.

OBJECTIVE: To assess the relation between specific flavonoid classes and peripheral arterial occlusive disease (PAOD), an important manifestation of atherosclerosis. DESIGN: Using data from a case-control study conducted in Greece in 1980 on the nutritional epidemiology of PAOD, we have exploited recently published databases on the content of foods in specific flavonoid classes to assess the relation between intake of these compounds and PAOD. SETTING: A major teaching hospital in Athens, Greece. SUBJECTS: Cases were 100 patients with PAOD and controls 100 patients with minor surgical conditions admitted to the same hospital. INTERVENTIONS: No interventions. All cases and controls were interviewed in the hospital wards, and a 110-food item semiquantitative food frequency questionnaire was administered by the same interviewer. RESULTS: Flavonols, flavones and perhaps flavan-3-ols were inversely associated with PAOD risk, the odds ratios (and 95% confidence intervals) for increments equal to the corresponding standard deviations being 0.41 (0.20-0.86), 0.56 (0.32-0.96) and 0.53 (0.26-1.05), respectively. Total flavonoids were also significantly inversely associated with PAOD. CONCLUSIONS: On the basis of these results, the biological properties of flavonoids and evidence concerning their relation to other manifestations of atherosclerosis, we conclude that dietary intake of specific classes of flavonoids, as well as total flavonoids, may have a protective effect against PAOD. SPONSORSHIP: This study was partially supported by a grant to Harvard University by the Samourkas Foundation.

Consumption of olive oil and specific food groups in relation to breast cancer risk in Greece.

BACKGROUND: Experimental animal studies suggest that olive oil consumption, as contrasted to consumption of other fat types, does not enhance the occurrence of chemically induced mammary tumors, but human data are sparse. Furthermore, evidence is inconclusive concerning the role of food groups, as distinct from that of major nutrients, in the etiology of breast cancer in women. PURPOSE: This analysis was conducted to evaluate and quantify the effect of consumption of olive oil, margarine, and a range of food groups on the risk of breast cancer. METHODS: Data from a comprehensive, semiquantitative food-frequency questionnaire administered to 820 women with breast cancer and 1548 control women from the study base were used to calculate odds ratios (ORs) and X statistics of linear trend for the consumption of olive oil, margarine, and a series of food groups classified in quintiles. Adjustment for the effects of reproductive risk factors, energy intake, and mutual confounding influences was implemented through unconditional logistic regression modeling. RESULTS: Vegetable consumption and fruit consumption were independently associated with statistically significant reductions of breast cancer risk by 12% and 8%, respectively, per quintile increase; no significant associations were evident for the other food groups examined. Increased olive oil consumption was associated with significantly reduced breast cancer risk (OR = 0.75 [95% confidence interval = 0.57-0.98] for more than once a day versus once a day), whereas increased margarine consumption was associated with significantly increased risk (OR = 1.05 [95% confidence interval = 1.00-1.10] for an increment of four times a month). The olive oil association was apparently concentrated among postmenopausal women, but the relevant interaction term was not statistically significant; there was no suggestion of interaction with menopausal status for consumption of either vegetables, fruits, or margarine. CONCLUSIONS: Although major categories of macronutrients do not show significant associations with breast cancer risk in most studies, including the present one, vegetables and fruits are inversely, significantly, and strongly associated with this risk. There also is evidence that olive oil consumption may reduce the risk of breast cancer, whereas margarine intake appears to be associated with an elevated risk for the disease.

Dietary factors and risk of breast cancer: combined analysis of 12 case-control studies.

We conducted a combined analysis of the original data to evaluate the consistency of 12 case-control studies of diet and breast cancer. Our analysis shows a consistent, statistically significant, positive association between breast cancer risk and saturated fat intake in postmenopausal women (relative risk for highest vs. lowest quintile, 1.46; P less than .0001). A consistent protective effect for a number of markers of fruit and vegetable intake was demonstrated; vitamin C intake had the most consistent and statistically significant inverse association with breast cancer risk (relative risk for highest vs. lowest quintile, 0.69; P less than .0001). If these dietary associations represent causality, the attributable risk (i.e., the percentage of breast cancers that might be prevented by dietary modification) in the North American population is estimated to be 24% for postmenopausal women and 16% for premenopausal women.

A case-control study of the relationship between smoking, diet, and gallbladder disease.

Eighty-four women with roentgenographically confirmed gallbladder disease and 171 control women hospitalized at a trauma hospital in Athens, Greece, were interviewed regarding demographic, reproductive, smoking, and dietary characteristics. A food-frequency approach was used to elicit consumption of 120 food or beverage items during the period before the onset of the current illness or hospitalization. The patients were substantially less likely to be regular cigarette smokers before the current admission. Additionally the patients reported significantly less frequent consumption of total items contained in the following food groups: sugars; pulses, nuts, beans; fish; and dairy products. On average they also consumed significantly fewer alcoholic beverages. On the other hand, the patients reported more frequent consumption of items in the following food groups: cereals, potatoes, fruits, meats, fats and oils, and coffee/tea. After controlling for confounding between food groups through multiple logistic regression models, the patients were still found to be less frequent consumers of vegetables and alcoholic beverages but more frequent consumers of potatoes and items in the cereal group. These analyses also confirmed the reduced likelihood of the patients being smokers.

Ubiquitous presence of O6-methylguanine in human peripheral and cord blood DNA.

O6-Methylguanine (O6-meG) is a powerful premutagenic lesion that can arise from exposure to methylating agents. Although it has been reported to occur in human DNA, no systematic epidemiological analysis of its occurrence in populations suffering general environmental exposure is available. We report here results from a study of the presence of O6-meG in maternal and cord blood leukocyte DNA of women not knowingly exposed to methylating agents. Using a modification of an already existing method capable of detecting the lesion at levels as low as 16 nmol/molG, the adduct was detected in 31 of 36 maternal and 30 of 36 cord samples, at levels ranging up to 192 nmol/molG. Adduct levels in maternal blood DNA were significantly higher than those in cord blood DNA (P < 0.05), and there was a strong correlation between adduct levels in the two tissues (P < 0.001). In bivariate analysis, no significant association of adduct levels in either tissue and residence air pollution, active and passive smoking status, or eating habits was found. However, intake of fruits/vegetables and of vitamin supplements showed nonstatistically significant trends toward being associated with lower adduct levels in both maternal and cord blood DNA. The same trend was observed after multivariate analysis where all the above variables were controlled for. These findings indicate that premutagenic methylation DNA damage is commonplace in individuals not known to have suffered excessive exposure to environmental methylating agents or their precursors and are compatible with an endogenous origin of this damage, possibly associated with endogenous nitrosation processes.

Pregnancy estrogens in relation to coffee and alcohol intake.

Total estrogen (TE), estradiol (E2), estriol (E3), and human placental lactogen (hPL) levels were determined by radioimmunoassay in the blood of 141 pregnant women during their 26th and 31st weeks of pregnancy and the results were studied in relation to coffee and alcohol intake. After controlling for maternal age, maternal weight at the corresponding week of pregnancy, parity, and tobacco smoking, as well as for mutual confounding effects, coffee intake, ascertained at the 26th week, was found to be negatively related to pregnancy E2 levels (P = 0.04 during the 26th week, and P = .16 during the 31st week), whereas alcohol intake, also ascertained at the 26th week, was found to be positively related to pregnancy TE levels (P = .04 during the 26th week, and P = .18 during the 31st week). The negative relation between coffee consumption on the one hand and E2 (and possibly TE) levels on the other may be responsible for the inverse association between maternal coffee intake and birth weight; the latter association has been repeatedly confirmed in the literature, although it was neither strong nor statistically significant in the present study. The relations of maternal coffee and alcohol consumption with pregnancy estrogen levels, if confirmed, could be utilized in studies exploring the role of prenatal exposure to these hormones in the etiology of gonadal germ-cell tumors and possibly other diseases.

Health effects of air pollution in southern Europe: are there interacting factors?

Recent results suggest that adverse health effects of air pollution exist at levels of pollutants around or even below air quality standards set by national and international institutions. Furthermore, there are indications that air pollution effects on health may be partly determined by specific mixtures of air pollutants and may be altered by other environmental, behavioral, and social patterns. Southern European countries share some common characteristics in terms of climate, geography, and life activity patterns. Results from studies undertaken in France, Greece, Italy, Portugal, and Spain investigating short- and long-term air pollution health effects are presented and their consistency demonstrated. These results provide adequate evidence that health effects--particularly short-term--of the currently measured urban air pollution levels exist. However, information available so far does not allow an assessment of regional differences in the health effects of air pollution as far as the Mediterranean region of Europe is concerned. It is suggested that the interaction between the traditional pollution (mainly characterized by high levels of black smoke and SO2) and photochemical pollution must be investigated in this area, as well as the possible interaction between air pollution and high temperature and other meteorologic factors. In addition, measurements of individual exposure to different pollutants, affected by the pollutant's levels in specific micro-environments and the individual's time-activity pattern, must be undertaken for a better understanding of the air pollution-health link. Finally, the importance of the reported air pollution health effects in terms of public health must be addressed more closely.

Atmospheric circulation types and daily mortality in Athens, Greece.

We investigated the short-term effects of synoptic and mesoscale atmospheric circulation types on mortality in Athens, Greece. The synoptic patterns in the lower troposphere were classified in 8 a priori defined categories. The mesoscale weather types were classified into 11 categories, using meteorologic parameters from the Athens area surface monitoring network; the daily number of deaths was available for 1987-1991. We applied generalized additive models (GAM), extending Poisson regression, using a LOESS smoother to control for the confounding effects of seasonal patterns. We adjusted for long-term trends, day of the week, ambient particle concentrations, and additional temperature effects. Both classifications, synoptic and mesoscale, explain the daily variation of mortality to a statistically significant degree. The highest daily mortality was observed on days characterized by southeasterly flow [increase 10%; 95% confidence interval (CI), 6.1-13.9% compared to the high-low pressure system), followed by zonal flow (5.8%; 95% CI, 1.8-10%). The high-low pressure system and the northwesterly flow are associated with the lowest mortality. The seasonal patterns are consistent with the annual pattern. For mesoscale categories, in the cold period the highest mortality is observed during days characterized by the easterly flow category (increase 9.4%; 95% CI, 1.0-18.5% compared to flow without the main component). In the warm period, the highest mortality occurs during the strong southerly flow category (8.5% increase; 95% CI, 2.0-15.4% compared again to flow without the main component). Adjusting for ambient particle levels leaves the estimated associations unchanged for the synoptic categories and slightly increases the effects of mesoscale categories. In conclusion, synoptic and mesoscale weather classification is a useful tool for studying the weather-health associations in a warm Mediterranean climate situation.

Investigating regional differences in short-term effects of air pollution on daily mortality in the APHEA project: a sensitivity analysis for controlling long-term trends and seasonality.

Short-term effects of air pollution on daily mortality in eight western and five central-eastern European countries have been reported previously, as part of the APHEA project. One intriguing finding was that the effects were lower in central-eastern European cities. The analysis used sinusoidal terms for seasonal control and polynomial terms for meteorologic variables, but this is a more rigid approach than the currently accepted method, which uses generalized additive models (GAM). We therefore reanalyzed the original data to examine the sensitivity of the results to the statistical model. The data were identical to those used in the earlier analyses. The outcome was the daily total number of deaths, and the pollutants analyzed were black smoke (BS) and sulfur dioxide (SO(2)). The analyses were restricted to days with pollutant concentration < 200 microg/m(3) and < 150 microg/m(3) alternately. We used Poisson regression in a GAM model, and combined individual city regression coefficients using fixed and random-effect models. An increase in BS by 50 microg/m(3) was associated with a 2.2% and 3.1% increase in mortality when analysis was restricted to days < 200 microg/m(3) and < 150 microg/m(3), respectively. The corresponding figures were 5.0% and 5.6% for a similar increase in SO(2). These estimates are larger than the ones published previously: by 69% for BS and 55% for SO(2). The increase occurred only in central-eastern European cities. The ratio of western to central-eastern cities for estimates was reduced to 1.3 for BS (previously 4.8) and 2.6 for SO(2) (previously 4.4). We conclude that part of the heterogeneity in the estimates of air pollution effects between western and central-eastern cities reported in previous publications was caused by the statistical approach used and the inclusion of days with pollutant levels above 150 microg/m(3). However, these results must be investigated further.

Earthquake-related stress and cardiac mortality.

The acute effects of earthquake-related psychological stress on total and cardiac mortality were investigated using mortality data from the city of Thessaloniki (Greece) which was hit on 19 and 20 June 1978, by two strong earthquakes, measuring 5.2 and 6.4 degrees on the Richter scale, respectively. During the a priori specified three-day period of 19, 20 and 21 June, mortality from cardiac and 'all other' pathological causes increased significantly. The estimated relative risks (and 95% confidence intervals) were 3.0 (1.5-5.9) for atherosclerotic heart disease, and 1.6 (1.1-2.3) for 'all other' diseases (excluding external causes) as underlying conditions. Stress-related cardiac deaths (proximate cause) were more common when atherosclerotic heart disease was the underlying condition (p approximately 0.10), but there was no evidence of any age or sex predilection.

Short-term effects of air pollution on daily mortality in Athens: a time-series analysis.

BACKGROUND: Athens has a serious air pollution problem which became evident in the early 1970s. Studies for the years 1975-1982 have indicated a positive association of sulphur dioxide (SO2) with total daily mortality. Since 1983 the pollution profile in Athens has gradually changed but the levels of smoke, SO2 and carbon monoxide (CO) remain relatively high. METHODS: The association of air pollution with daily all-cause mortality in Athens for the years 1984-1988 was investigated using daily values of SO2, smoke and CO. Autoregressive models with log-transformed daily mortality as the dependent variable, were used to adjust for temperature and relative humidity (both lagged by 1 day), year, season and day of week, as well as for serial correlations in mortality. RESULTS: Graphic analysis revealed non-linear monotonically increasing relationships between total mortality and SO2, smoke and CO, with steeper exposure-response slopes at lower air pollution levels. Air pollution data lagged by 1 day had the strongest association with daily mortality. In three separate autoregression models for log(SO2), log(smoke) and log(CO) the regression coefficients for each were highly statistically significant (P < 0.001). Further multiple regression modelling showed that SO2 and smoke are both independent predictors of daily mortality, though to a lesser extent than temperature and relative humidity. The inclusion of CO in the model did not further improve the prediction of daily mortality. The magnitude of association is small, for instance, a 10% reduction in smoke is estimated to decrease daily mortality by 0.75% (95% confidence interval [CI]: 0.51-0.99). However, it cannot be accounted for by climatic and seasonal effects, so that a causal influence of air pollution on daily mortality seems plausible. CONCLUSIONS: These findings suggest that current air pollution levels in Athens (and many other industrialized cities) may be responsible for substantial numbers of premature deaths, and hence remain an important public health issue.