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.

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.

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.

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.

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.

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.

The temporal pattern of mortality responses to ambient ozone in the APHEA project.

BACKGROUND: The temporal pattern of effects of summertime ozone (O(3)) in total, cardiovascular and respiratory mortality were investigated in 21 European cities participating in the APHEA-2 (Air Pollution and Health: a European Approach) project, which is fundamental in determining the importance of the effect in terms of life loss. METHODS: Data from each city were analysed separately using distributed lag models with up to 21 lags. City-specific air pollution estimates were regressed on city-specific covariates to obtain overall estimates and to explore sources of possible heterogeneity. RESULTS: Stronger effects on respiratory mortality that extend to a period of 2 weeks were found. A 10 microg/m(3) increase in O(3) was associated with a 0.36% (95% CI -0.21% to 0.94%) increase in respiratory deaths for lag 0 and with 3.35% (95% CI 1.90% to 4.83%) for lags 0-20. Significant adverse health effects were found of summer O(3) (June-August) on total and cardiovascular mortality that persist up to a week, but are counterbalanced by negative effects thereafter. CONCLUSIONS: The results indicate that studies on acute health effects of O(3) using single-day exposures may have overestimated the effects on total and cardiovascular mortality, but underestimated the effects on respiratory mortality.

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.

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.

The truth-telling issue and changes in lifestyle in patients with cancer.

OBJECTIVE: To compare the attitudes of patients with cancer toward making changes in lifestyle, according to their awareness of the diagnosis. METHOD: Personal interviews with 50 patients with breast cancer, 24 patients with prostate cancer and 50 patients with colorectal cancer were conducted in a cancer hospital in Athens, Greece. ANALYSIS: Multiple logistic regression models were used to estimate the odds ratio as a measure of the association of the characteristics of participants with changes in lifestyle. RESULTS: Overall, 22.6% of the patients were not aware of the diagnosis. Among the changes in lifestyle, 41.1% reported changing their diet to a healthier one, 22.6% of the smokers reduced or stopped smoking and 13.7% added new physical activity. Compared with uninformed patients, those who were aware of the diagnosis, after adjusting for the confounding effect of educational status (an index of socioeconomic status), were 2.5 times as likely to make dietary changes (p<0.1). Among the other characteristics under study, older patients were less likely to add new physical activity than younger ones (p<0.01), and newly diagnosed patients were more likely to stop or reduce smoking (p<0.1) than patients with a diagnosis made more than 12 months previously. CONCLUSION: Patients with cancer are motivated to attempt changes in lifestyle and can benefit from more factual information about the diagnosis.

Seasonal confounding in air pollution and health time-series studies: effect on air pollution effect estimates.

A major statistical challenge in air pollution and health time-series studies is to adequately control for confounding effects of time-varying covariates. Daily health outcome counts are most commonly analysed by Poisson regression models, adjusted for overdispersion, with air pollution levels included as a linear predictor and smooth functions for calendar time and weather variables to adjust for time-varying confounders. Various smoothers have been used so far, but the optimal strategy for choosing smoothers and their degree of smoothing remains controversial. In this work, we evaluate the performance of various smoothers with different criteria for choosing the degree of smoothing in terms of bias and efficiency of the air pollution effect estimate in a simulation study. The evaluated approaches were also applied to real mortality data from 22 European cities. The simulation study imitated a multi-city study. Data were generated from a fully parametric model. Model selection methods which optimize prediction may lead to increased biases in the air pollution effect estimate. Minimization of the absolute value of the sum of the partial autocorrelation function of the model's residuals (PACF), as a criterion to choose the degree of smoothness, gave the smallest biases. The penalized splines (PS) method with a large number of effective dfs (e.g. 8-12 per year) could be used as the basic, relatively conservative, analysis whereas the PS and natural splines in combination with PACF could be applied to provide a reasonable range of the effect estimate.

Short-term effects of nitrogen dioxide on mortality: an analysis within the APHEA project.

The short-term effects of nitrogen dioxide (NO(2)) on total, cardiovascular and respiratory mortality in 30 European cities participating in the Air Pollution on Health: a European Approach (APHEA)-2 project were investigated. The association was examined using hierarchical models implemented in two stages. In the first stage, data from each city were analysed separately, whereas in the second stage, the city-specific air pollution estimates were regressed on city-specific covariates to obtain overall estimates and to explore sources of possible heterogeneity. A significant association of NO(2) with total, cardiovascular and respiratory mortality was found, with stronger effects on cause-specific mortality. There was evidence of confounding in respiratory mortality with black smoke and sulphur dioxide. The effect of NO(2) on total and cardiovascular mortality was observed mainly in western and southern European cities, and was larger when smoking prevalence was lower and household gas consumption was higher. The effect of NO(2) on respiratory mortality was higher in cities with a larger proportion of elderly persons in the population and higher levels of particulate matter with a 50% cut-off aerodynamic diameter of 10 mum. The results of this large study are consistent with an independent effect of nitrogen dioxide on mortality, but the role of nitrogen dioxide as a surrogate of other unmeasured pollutants cannot be completely ruled out.

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.

Investigating the dose-response relation between air pollution and total mortality in the APHEA-2 multicity project.

BACKGROUND: Several recent studies have reported significant health effects of air pollution even at low levels of air pollutants, but in most of these studies linear non-threshold relations were assumed. AIMS: To investigate the NO2 mortality dose-response association in nine cities participating in the APHEA-2 project using two different methods: the meta-smooth and the cubic spline method. METHODS: The meta-smooth method developed by Schwartz and Zanobetti is based on combining individual city non-parametric smooth curves; the cubic spline method developed within the APHEA-2 project combines individual city estimates of cubic spline shaped dose-response relations. The meta-smooth method is easier and faster to implement, but the cubic spline method is more flexible for further investigation of possible heterogeneity in the dose-response curves among cities. RESULTS: In the range of the pollutant common to all cities the two methods gave similar and comparable curves. Using the cubic spline method it was found that smoking prevalence acts as an effect modifier with larger NO2 effects on mortality at lower smoking prevalence. CONCLUSIONS: The NO2-mortality association in the cities included in the present analysis, could be adequately estimated using the linear model. However, investigation of the city specific dose-response curves should precede the application of linear models.

Flavonoid intake and breast cancer risk: a case--control study in Greece.

Flavonoids have been investigated for possible inverse associations with various chronic degenerative diseases, but there are no epidemiologic data concerning a possible association between several of the main flavonoid categories and breast cancer risk. We have applied recently published data on the flavonoid content of several foods and beverages on dietary information collected in the context of a large case-control study of 820 women with breast cancer and 1548 control women, conducted in Greece. We found a strong, statistically significant inverse association of flavone intake with breast cancer. The odds ratio for an increment equal to one standard deviation of daily flavone intake (i.e. 0.5 mg day(-1)) was 0.87, with 95% confidence interval 0.77-0.97. The association persisted after controlling for fruit and vegetable consumption, or for other flavonoid intake. This inverse association is compatible with and may explain the reported inverse association of breast cancer with consumption of vegetables, particularly leafy vegetables. After controlling for dietary confounding, there was no association of breast cancer risk with flavanones, flavan-3-ols, flavonols, anthocyanidins or isoflavones.

Respiratory effects of sulphur dioxide: a hierarchical multicity analysis in the APHEA 2 study.

BACKGROUND: Sulphur dioxide (SO(2)) was associated with hospital admissions for asthma in children in the original APHEA study, but not with other respiratory admissions. AIMS: To assess the association between daily levels of SO(2) and daily levels of respiratory admissions in a larger and more recent study. METHODS: Time series of daily counts of hospital emergency admissions were constructed for asthma at ages 0-14 years and 15-64 years, COPD and asthma, and all respiratory admissions at ages 65+ years in the cities of Birmingham, London, Milan, Paris, Rome, Stockholm, and in the Netherlands for periods of varying duration between the years 1988 and 1997. A two stage hierarchical modelling approach was used. In the first stage generalised additive Poisson regression models were fitted in each city controlling for weather and season. These results were then combined across cities in a second stage ecological regression that looked at potential effect modifiers. RESULTS: For an increase of 10 micro g/m(3) of SO(2) the daily number of admissions for asthma in children increased 1.3% (95% CI 0.4% to 2.2%). Effect modification among cities by levels of other air pollutants or temperature was not found. The SO(2) effect disappeared after controlling for PM(10) or CO, but correlation among these pollutants was very high. Other respiratory admissions were not associated with SO(2). CONCLUSION: SO(2) is associated with asthma admissions in children, indicating that reduction in current air pollution levels could lead to a decrease in the number of asthma admissions in children in Europe.

Short-term effects of ambient particles on mortality in the elderly: results from 28 cities in the APHEA2 project.

Within the framework of the APHEA2 (Air Pollution on Health: a European Approach) project, the effects of ambient particles on mortality among persons > or = 65 yrs were investigated. Daily measurements for particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) and black smoke (BS), as well as the daily number of deaths among persons > or = 65 yrs of age, from 29 European cities, have been collected. Data on other pollutants and meteorological variables, to adjust for confounding effects and data on city characteristics, to investigate potential effect modification, were also recorded. For individual city analysis, generalised additive models extending Poisson regression, using a locally weighted regression (LOESS) smoother to control for seasonal effects, were applied. To combine individual city results and explore effect modification, second stage regression models were applied. The per cent increase (95% confidence intervals), associated with a 10 microg x m(-3) increase in PM10, in the elderly daily number of deaths was 0.8%, (0.7-0.9%) and the corresponding number for BS was 0.6%, (0.5-0.8%). The effect size was modified by the long-term average levels of nitrogen dioxide (higher levels were associated with larger effects), temperature (larger effects were observed in warmer countries), and by the proportion of the elderly in each city (a larger proportion was associated with higher effects). These results indicate that ambient particles have effects on mortality among the elderly, with relative risks comparable or slightly higher than those observed for total mortality and similar effect modification patterns. The effects among the older persons are of particular importance, since the attributable number of events will be much larger, compared to the number of deaths among the younger population.

Air pollution in relation to manifestations of chronic pulmonary disease: a nested case-control study in Athens, Greece.

Chronic pulmonary diseases are a major cause of morbidity and mortality worldwide. The present study is a case-control study nested in a defined cohort, undertaken in Athens, Greece, in order to investigate the association between long-term exposure to ambient air pollution and the development of chronic bronchitis, emphysema or chronic obstructive pulmonary disease (COPD). Individualized personal exposure assessment has been applied based on long-term residential and occupational subject history linked with geographical air pollution distribution. The first consecutive 3904 participants from the European Prospective Study into Cancer and Nutrition (EPIC), all residents of Athens, were asked to complete a questionnaire. One hundred and sixty-eight participants reporting a history of COPD symptomatology and 168 healthy controls recruited from the same study base individually matched for age and gender, were visited by a physician at their homes for conducting spirometry and a medical interview. Eighty-four of the 168 self-identified as cases were diagnosed as having chronic bronchitis, emphysema or COPD. Logistic regression models were used for statistical evaluation. Cases were more exposed to air pollution compared to controls. The estimated odds ratio (OR) indicates an increase of 37% in the risk of medically confirmed cases per exposure quartile (p = 0.02). When most of the subjects exposed are considered vs. all others, there is a twofold increase in disease risk (p = 0.03). Our findings provide evidence that long-term exposure to air pollution is an important factor in the development of chronic respiratory diseases.