Particulate Air Pollution and Health Effects for Cardiovascular and Respiratory Causes in Temuco, Chile: A Wood-Smoke- Polluted Urban Area

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1 TECHNICAL PAPER ISSN: J. Air & Waste Manage. Assoc. 59: DOI: / Copyright 2009 Air & Waste Management Association Particulate Air Pollution and Health Effects for Cardiovascular and Respiratory Causes in Temuco, Chile: A Wood-Smoke- Polluted Urban Area Pedro A. Sanhueza and Monica A. Torreblanca Department of Geographical Engineering, University of Santiago de Chile, Santiago, Chile Luis A. Diaz-Robles School of Environmental Engineering, Catholic University of Temuco, Temuco, Chile L. Nicolas Schiappacasse Department of Air Pollution Control, National Environmental Commission (CONAMA), Araucania Region, Chile Maria P. Silva and Teresa D. Astete Health Department, Araucania Region, Chile ABSTRACT Temuco is one of the most highly wood-smoke-polluted cities in the world. Its population in 2004 was 340,000 inhabitants with 1587 annual deaths, of which 24% were due to cardiovascular and 11% to respiratory causes. For hospital admissions, cardiovascular diseases represented 6% and respiratory diseases 13%. Emergency room visits for acute respiratory infections represented 28%. The objective of the study presented here was to determine the relationship between air pollution from particulate matter less than or equal to 10 m in aerodynamic diameter (PM 10 ; mostly PM 2.5, or particulate matter 2.5 m in aerodynamic diameter) and health effects measured as the daily number of deaths, hospital admissions, and emergency room visits for cardiovascular, respiratory, and acute respiratory infection (ARI) diseases. The Air Pollution Health Effects European Approach (APHEA2) protocol was followed, and a multivariate Poisson regression model was fitted, controlling for trend, seasonality, and confounders for Temuco during The results show that PM 10 had a significant association with daily mortality and morbidity, with the elderly (population IMPLICATIONS Significant statistical associations were found between daily mortality and morbidity in Temuco for cardiovascular and respiratory diseases and daily PM 10 concentration, mainly from woodstoves. The results suggest that wood combustion sources may be responsible for increased mortality in Temuco. This has an important implication in relation with the size and chemical composition of the particles, but also for monitoring and control strategies. Policy-makers should take into account these aspects along with economic considerations if protection of the public health is one of their major concerns. 65 yr of age) being the group that presented the greatest risk. The relative risk for respiratory causes, with an increase of 100 g/m 3 of PM 10, was with a 95% confidence interval (CI) of for mortality, (CI ) for hospital admissions, and for ARI (CI ). There is evidence in Temuco of positive relationships between ambient particulate levels and mortality, hospital admissions, and ARI for cardiovascular and respiratory diseases. These results are consistent with those of comparable studies in other similar cities where wood smoke is the most important air pollution problem. INTRODUCTION Particulate matter (PM) pollution produced mainly by residential wood combustion and vehicle traffic, but also by industrial activity has become the main source of concern over urban air quality in cities of colder climates. Atmospheric pollution has serious effects on public health, visibility problems, and ecological impacts and potentially contributes to global warming. 1 5 In Chile, almost 90% of the population lives in polluted urban areas such as Santiago, Temuco, Rancagua, Osorno, etc. 6,7 The air pollution of these cities is due to high economic growth, rapid urban expansion, domestic heating systems, strong growth of diesel vehicles, and industrial sources. The particular geographic and meteorological conditions of each city may have an additional effect. In these urban areas and during each fall-winter season, the population is exposed to dangerous levels of atmospheric pollutants, mainly PM. It has been discovered that the smallest particles can penetrate deep into the lungs and enter the blood stream, carrying toxins to the rest of the body 8 10 and affecting the respiratory and cardiovascular systems Fine particles aggravate cardiovascular diseases, increasing heart attacks and strokes, because they enter the blood stream Volume 59 December 2009 Journal of the Air & Waste Management Association 1481

2 and provoke an inflammatory response, interrupting the heart beat and increasing coagulation, in some cases producing premature death. 9,10,16,17 A consistent strong relation between PM exposure and lung and cardiovascular diseases has been published in more than 40 epidemiological studies in humans. 12,13,18 24 Injurious effects also have been observed in susceptible groups of the population (e.g., the asthmatic, the young, and the elderly) when they have suffered prolonged exposure to high concentrations of PM. 25,26 In the last decade, many epidemiological studies have been published on the association between PM exposure and health effects, 22 as well as indicating which statistical techniques have been used in those studies Wood-Smoke-Polluted Cities and Health Several epidemiological studies with time series have been developed in communities polluted with smoke from residential wood combustion. The first was conducted in Seattle, WA, in the United States over a period of 1 yr, 30 during which time there were 2955 emergency admissions for asthma in 8 hospitals. The average 24-hr PM 10 (PM with aerodynamic diameter 10 m) concentrations were in the range of g/m 3, with a mean of 29.6 g/m 3. Using a Poisson regression and controlling variables for meteorology, seasonality, age, hospital, and day of the week, the daily cases of emergency admissions for people less than 65 yr of age were significantly associated with the previous day s PM 10 exposure. The relative risk (RR) with an increase of 30 g/m 3 of PM 10 was 1.12 (confidence interval [CI] ). Wood smoke contributed approximately 85% of the PM in residential zones of Seattle during the winter study period. Two time series studies were developed in Santa Clara County, California, an area where wood smoke is the source that contributes most PM 10 in winter. 31 The work of Fairley 32 was one of the first times series studies in this county ( ), indicating an association between the relatively low levels of PM 10, principally from wood smoke, and the increment of daily mortality after adjustment for temperature, relative humidity (RH), year, and season. Another study in Santa Clara County, which analyzed the relationship between emergency admissions for asthma and PM 10 concentrations in winter, found a RR of 1.4 (CI ) when the PM 10 increased by 60 g/m A study in Christchurch, New Zealand, examined the association between hospital admissions and PM 10 for The PM 10 concentrations for this period averaged 25 g/m 3, with a maximum of 283 g/m 3. The results were separated into total cardiovascular admissions and total respiratory admissions. The risk excess was 3.37% (CI %) for respiratory admissions and 1.26% (CI %) for cardiovascular admissions when the PM 10 increased by 15 g/m Hales et al. 35 drew a relationship between daily mortality excess risk and PM 10 for the same city in New Zealand from 1988 to Using a Poission regression and controlling for season, the authors found that an increase in PM 10 of 10 g/m 3 was associated (after a lag of 1 day) with a 1% (CI 0.5% 2.2%) increase in all-cause mortality and a 4% (CI 1.5% 5.9%) increase in respiratory mortality. In Christchurch ( 370,000 inhabitants) approximately 80% of the PM air pollution is caused by wood-burning domestic heating Finally, in a recent study from 1997 to 2002, Sanhueza et al. 39 found a strong relationship between PM and daily mortality among subjects over 65 yr old in Temuco, Chile. In this study, a strong relationship was found between PM 10 and the causes of daily mortality and morbidity. Using a Poisson regression and after a confounding adjustment, the RR for respiratory mortality of a 100- g/m 3 increment in PM 10 was (CI ) and (CI ) for cardiovascular mortality. The city of Temuco, located 800 km south of Santiago, Chile (38.5 south), suffers from severe wood smoke particulate pollution events, especially during the period from April to September (fall and winter in the Southern Hemisphere) each year. 40 In fact, almost 70% of the population uses wood for cooking or heating in winter, and it is estimated that 87% of PM 10 winter emissions originate from residential wood combustion. 39 This situation is very particular in a few cities all over the world, where the highest concentrations occur at evening-night, mainly for primary PM emissions. 40 In Temuco, the records from the monitoring stations show high levels of PM 10 concentration with a 24-hr 98th percentile from 188 g/m 3 in 2001 to 172 g/m 3 in 2002 (Figure 1). For this reason, it was declared a nonattainment area for PM 10 in In 2004, Temuco had a population of 340,000 inhabitants with 1587 annual deaths, of which 24% were due to cardiovascular and 11% to respiratory causes. For hospital admissions, cardiovascular diseases represented 6% and respiratory diseases 13%. Emergency room visits for acute respiratory infections (ARIs) represented 28% of the total. This study focuses on the development of models to relate the daily 24 hr PM 10 concentrations with daily mortality and morbidity end points, represented by cardiovascular and respiratory diseases in the city of Temuco. METHODS Health and Pollution Data Daily mortality data for cardiovascular and respiratory diseases in Temuco from 1998 to 2004 (International Classification of Disease, 10th revision, ICD-10) were used from the National Statistics Institute, the official source of statistical data in Chile. For daily hospital admissions, data for the period from 2001 to 2004 were extracted from the regional hospital. The daily ARI from 2001 to 2006 were extracted from all the emergency room visits to the regional hospital of the city. The meteorology data were provided by the National Environmental Commission (CONAMA) in the Araucania Region from the Las Encinas monitoring station, which is located in the center of a vacant lot in a new residential area, 2.7 km west of the city center (Figure 2). A beta attenuation monitor (BAM; Environment S.A.) measures hourly PM 10. The database was completed with the daily PM 10 data, together with meteorological variables (air temperature, RH, and wind speed). Several indexes were generated, such as the Thermohygrometric and Steadman indexes, and minimum and maximum variables. Calendar effects were modeled using dummy variables for day of the week and month. The seasonality was controlled by using the Fourier series for different wavelengths. Finally, the missing PM 10 data were imputed by using regression 1482 Journal of the Air & Waste Management Association Volume 59 December 2009

3 Figure hr PM 10 concentration by BAM time series at the Las Encinas site in Temuco, Chile (from July 21, 2000 to September 30, 2006). models with meteorology from other years as independent variables. Statistical Methods The Air Pollution Health Effects European Approach (APHEA2) and the Spain Multicenter Study for Air Pollution and Morbidity-Mortality (EMECAM) protocols were used as guides for this study. 41,42 These procedures involve a standardized approach to specify a multivariate Poisson regression model to assess air pollution and weather effects while controlling for trends and season using generalized additive model (GAM) parameterization. The data were analyzed using multivariate Poisson regression fitted using S-Plus software (Insightful Corporation) with the gam.exact algorithm. Trend and seasonality were introduced first and then the meteorological variables and their transformations. The average of lags 0 and 1 were used. Models were developed for total population and different age groups ( 65 yr and 65 yr), and for total, warm, and cold periods. Figure 2. Las Encinas monitoring station in Temuco city, Chile. Volume 59 December 2009 Journal of the Air & Waste Management Association 1483

4 Table 1. Summary statistics for mortality, morbidity, meteorology, and PM 10. Variable Units N Min Mean Max Mortality All causes, all ages Deaths/day Cardiovascular Deaths/day causes Respiratory causes Deaths/day Hospital admissions All causes, all ages Admissions/day Cardiovascular Admissions/day causes Respiratory causes Admissions/day Emergency room visits ARI causes, all Emergencies/day ages ARI causes, 65 Emergencies/day yr ARI causes, 64 Emergencies/day yr Temperature C PM 10 Daily average g/m RESULTS Summary statistics for the mortality, morbidity, meteorology, and PM 10 variables are shown in Table 1. The mortality database was made up of daily information on numbers of deaths from cardiovascular and respiratory causes, meteorology, and air quality from January 1, 1998 to December 31, 2004, completing 2557 observations. The morbidity data for hospital admissions were analyzed from 2001 to 2004, obtaining a total of 1461 observations. Finally, the emergency room data for ARI were analyzed from May 10, 2001 to December 31, 2006, completing 2062 observations. For daily PM 10 data, the maximum concentration was 321 g/m 3, which is higher than the maximum daily values measured in Christchurch, New Zealand, ( g/m 3 ). 37,43 Following the APHEA2/EMECAM protocols, several multivariate Poisson models with confounding control were developed for cardiovascular and respiratory mortality and morbidity, for age groups and for total, warm, and cold periods. PM 10 with average lags of 0 and 1 day were used for all causes (mortality, hospital admissions, and emergency room visits). Table 2 shows the regression coefficients ( ) along with the standard errors (SE), relative risk (RR), and attributable proportion (AP) for the significant and nonsignificant mortality models. The greatest RR for mortality (total period), with a PM 10 increment of 100 g/m 3, was for respiratory and cardiovascular causes in adults more than 64 yr old, with a RR of in both cases. For the same susceptible group, and considering the warm season, the risk was not significant, whereas for the cold season, the mortality RR for respiratory causes was (CI ) with a PM 10 increment of 100 g/m 3. Table 3 presents the results for the hospital admissions models (significant and no significant models). The greatest hospital admission RR for a PM 10 increment of 100 g/m 3 was for cardiorespiratory causes in adults older than 64 yr of age during the warm period, with a RR of (CI ). Table 4 shows the results for the RR of emergency room visits. The greatest RR was the group of adults more than 64 yr of age during the cold period, with a RR of (CI ). These results for mortality and morbidity are comparable with epidemiological studies done in Christchurch, New Zealand, and Seattle, WA, where wood smoke is also a major air pollution problem. DISCUSSION In Chile there are few epidemiological studies to establish the link between air quality and health, most of them done in Santiago. Using a multiple regression analysis and controlling for confounders, Ostro et al. 44 established a relationship between PM 10 and daily mortality in Santiago during 1989 and The authors found a risk increment of 4% of the total deaths associated with average PM 10 levels of 115 g/m 3. In a second study, Ostro et al. 45 related the number of the hospital admissions in children younger than 15 yr of age with PM 10 concentrations in Santiago. Their principal conclusion was that this pollutant increased the lower respiratory diseases significantly when its concentration increased by 50 g/m 3,an increment between 4 and 12% in children younger than 2 yr, and between 3 and 9% in children aged between 3 and 15 yr. Sanhueza et al. 46 related the cases of daily mortality due to respiratory and cardiovascular causes in persons older than 64 yr and PM pollution in Santiago during the period Using a Poission regression and the APHEA protocol, 47 the authors concluded that an increment of 100 g/m 3 in the daily average PM 10 concentration was related with a RR of (CI ) of total deaths, (CI ) of deaths due to cardiovascular causes, and (CI ) of 1484 Journal of the Air & Waste Management Association Volume 59 December 2009

5 Table 2. Results for mortality models. Period Model SE ( ) Upper 95% Lower 95% RR AP Total Resp total Resp Resp Card total Card Card MCRT MCR MCR Warm Resp total Resp Resp Card total Card Card MCRT MCR MCR Cold Resp total Resp Resp Card total Card Card MCRT MCR MCR Notes: MCRT total cardiorespiratory mortality (all ages), Card cardiovascular mortality, MCR cardiorespiratory mortality, Resp respiratory mortality. deaths due to respiratory causes. These results were obtained after controlling for confounders such as meteorological variables, seasonality, and other co-pollutants. Those pollutants (sulfur dioxide and ozone) presented a smaller RR than that for PM. In another study, Ilabaca et al. 48 analyzed the effect of finer PM (PM 2.5,orPM 2.5 m in aerodynamic diameter) on emergency admissions for pneumonia and other respiratory diseases in children younger than 15 yr of age attending the Calvo Mackenna Hospital in Santiago. Using a Poisson regression and controlling for confounders, their main conclusions indicated that increments of 45 g/m 3 in the daily average of PM 2.5 concentrations were associated with an increment of 6.7% (CI %) in pneumonia cases, 3 days after the occurrence of the increment. Cifuentes et al. 49 related the daily mortality cases of inhabitants from the metropolitan region of Santiago with PM 2.5 and PM between 2.5 and 10 m in aerodynamic diameter (PM ) between 1988 and Using Poisson regression and controlling for confounders, the authors concluded that the mortality increment associated with average PM 2.5 levels of 64 g/m 3 was 4.2%, and 4.3% for PM (daily average level of 47.3 g/m 3 ). In a cohort study of more than 504 infants younger than 4 months of age in the south of Santiago, Pino et al. 50 analyzed the relationship between obstructive bronchitis and PM The authors found that an increment of 10 g/m 3 of PM 2.5 was related to an increase of 5% (CI 0 9%) of cases. Recently, Cakmak et al. 25 associated daily mortality with PM 10 in seven municipalities of the metropolitan area of Santiago, Chile, during Their study is the first research in Chile to analyze the susceptibility among the elderly including different age ranges. Using a Poisson regression and a confounding adjustment, the normalized results of these authors indicate that a daily PM 10 increment of 100 g/m 3 was related with an increment of 5.36% of mortality risk for persons younger than 65 yr old, 11.25% for those between 65 and 74 yr old, 15.02% for those between 65 and 84 yr old, and 16.73% for those more than 85 yr old. 25 Their results suggest that the very elderly are particularly susceptible to death caused by ambient PM exposure. In Temuco, only one time series epidemiological study exists to establish the link between air quality and health. 39 As mentioned above, a strong relationship between PM 10 and daily mortality and morbidity causes of cardiovascular and respiratory diseases were found for adults older than 65 yr. Those results are similar to those found in the study presented here for mortality, in which the period analyzed included more years and morbidity results. In fact, the RR for respiratory causes for an increase of 100 g/m 3 in PM 10 was (CI ) for mortality, (CI ) for hospital admissions, and (CI ) for ARI in adults older than 65 yr. These results are also comparable with those found for Seattle and Christchurch Volume 59 December 2009 Journal of the Air & Waste Management Association 1485

6 Table 3. Results for hospital admission models. Period Model SE ( ) Upper 95% Lower 95% RR AP Total Resp total Resp Resp Card total Card Card CR total CR CR Warm Resp total Resp Resp Card total Card Card CR total CR CR Cold Resp total Resp Resp Card total Card Card CR total CR CR Notes: Resp respiratory morbidity (total all ages), Card cardiovascular morbidity (total all ages), CR cardiorespiratory morbidity (total all ages). Applying the same methodology in an older study in Santiago, Chile, Sanhueza et al. 39 found that the RR estimates in Temuco were higher than those in Santiago, (CI ) for respiratory mortality and (CI ) for cardiovascular mortality, suggesting that the inhabitants of Temuco would be exposed to a higher mortality risk that those of Santiago with equal increments in PM 10 concentration. One of the reasons for this difference in the RR for mortality could be the chemical composition and size distribution of the particles in each city. With respect to the chemical composition of the ambient particles, Tsapakis et al. 7 indicated that the main air pollution sources in Temuco are residential wood heating stoves and cooking stoves, whereas the pollution in Santiago is caused by diesel from mobile sources. Their results presented higher levels of polycyclic aromatic hydrocarbons (PAHs) and other airborne toxins in Temuco than Santiago. For example, the benzo(a)pyrene concentration in Temuco was 98.5 ng/m 3 versus 10.9 ng/m 3 in Santiago; the benzoanthracene concentration was ng/m 3 in Temuco versus 8.5 ng/m 3 in Santiago; and total PAH concentrations were 751 and 129 ng/m 3 in Temuco and Santiago, respectively. 7 These high PAH concentrations have also been found in Christchurch, New Zealand, where some studies have analyzed urinary 1-hydroxypyrene in nonsmoking male schoolchildren, a biomarker for studying PAH exposure in humans. 37 Particle size distribution also differs between Temuco and Santiago. In the winter season, PM 2.5 represents a higher proportion of the total PM 10 in Temuco (80 90%) than in Santiago (30 60%). 39 These situations could explain the generation of higher toxicity in the exposed population in Temuco than in Santiago, because finer Table 4. Results for emergency room visit models. Period Model SE ( ) Upper 95% Lower 95% RR AP Total ARI total ARI ARI Warm ARI total ARI ARI Cold ARI total ARI ARI Journal of the Air & Waste Management Association Volume 59 December 2009

7 particles penetrate more deeply into the respiratory system, even entering the blood stream and thus the cardiovascular system and other organs, which could be affected by PAHs and other airborne toxins. Considering the studies of Sanhueza and Cakmak, the mortality risk in the susceptible population in Temuco could be higher than in Santiago; therefore, it might be suggested that better air quality management tools must be provided in this urban area to protect human health. There is evidence in Temuco of a relationship between ambient particulate levels and mortality, hospital admissions, and ARIs for cardiovascular and respiratory diseases. These results are consistent with those of comparable studies in other similar cities where wood smoke is the most important air pollution problem. Although this study was focused on PM 10, which is the particle size regulated in Chile, further analysis should be done for PM 2.5 because this fraction has been shown to have the most serious effects on human health. The latest investigations in the United States focus on ultrafine particles ( 0.1 m) as the size to be regulated in the future. ACKNOWLEDGMENTS This work was funded through a grant from CONAMA, Araucania Region, Chile (contract no LE06). REFERENCES 1. Molina, M.J.; Molina, L.T. Megacities and Atmospheric Pollution; J. Air & Waste Manage. Assoc. 2004, 54, Chow, J.C.; Bachmann, J.D.; Wierman, S.S.G.; Mathai, C.V.; Malm, W.C.; White, W.H.; Mueller, P.K.; Kumar, N.; Watson, J.G. Visibility: Science and Regulation Discussion; J. Air & Waste Manage. Assoc. 2002, 52, Watson, J.G. Visibility: Science and Regulation; J. Air & Waste Manage. Assoc. 2002, 52, Diaz-Robles, L.A.; Fu, J.S.; Reed, G.D. Modeling and Source Apportionment of Diesel Particulate Matter; Environ. 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8 41. Ballester, F.; Saez, M.; Perez-Hoyos, S.; Iniguez, C.; Gandarillas, A.; Tobias, A.; Bellido, J.; Taracido, M.; Arribas, F.; Daponte, A.; Alonso, E.; Canada, A.; Guillen-Grima, F.; Cirera, L.; Perez-Boillos, M.J.; Saurina, C.; Gomez, F.; Tenias, J.M. The EMECAM Project: a Multicentre Study on Air Pollution and Mortality in Spain: Combined Results for Particulates and for Sulfur Dioxide; Occup. Environ. Med. 2002, 59, Katsouyanni, K.; Schwartz, J.; Spix, C.; Touloumi, G.; Zmirou, D.; Zanobetti, A.; Wojtyniak, B.; Vonk, J.M.; Tobias, A.; Ponka, A.; Medina, S.; Bacharova, L.; Anderson, H.R. Short-Term Effects of Air Pollution on Health: a European Approach Using Epidemiologic Time Series Data: the APHEA Protocol; J. Epidemiol. Comm. Health 1996, 50, S12-S Kingham, S.; Durand, M.; Aberkane, T.; Harrison, J.; Wilson, J.G.; Epton, M. Winter Comparison of TEOM, MiniVol and DustTrak PM 10 Monitors in a Woodsmoke Environment; Atmos. Environ. 2006, 40, Ostro, B.; Sanchez, J.M.; Aranda, C.; Eskeland, G.S. Air Pollution and Mortality: Results from a Study of Santiago, Chile; J. Expo. Anal. Environ. Epidemiol. 1996, 6, Ostro, B.D.; Eskeland, G.S.; Sanchez, J.M.; Feyzioglu, T. Air Pollution and Health Effects: a Study of Medical Visits among Children in Santiago, Chile; Environ. Health Perspect. 1999, 107, Sanhueza, P.; Vargas, C.; Jimenez, J. Daily Mortality in Santiago and its Relationship with Air Pollution; Rev. Med. de Chile 1999, 127, Katsouyanni, K.; Zmirou, D.; Spix, C.; Sunyer, J.; Schouten, J.P.; Ponka, A.; Anderson, H.R.; Lemoullec, Y.; Wojtyniak, B.; Vigotti, M.A.; Bacharova, L. Short-Term Effects of Air-Pollution on Health: a European Approach Using Epidemiologic Time-Series Data. The APHEA Project: Background, Objectives, Design; Eur. Respir. J. 1995, 8, Ilabaca, M.; Olaeta, I.; Campos, E.; Villaire, J.; Tellez-Rojo, M.M.; Romieu, I. Association between Levels of Fine Particulate and Emergency Visits for Pneumonia and Other Respiratory Illnesses among Children in Santiago, Chile; J. Air & Waste Manage. Assoc. 1999, 49, Cifuentes, L.A.; Vega, J.; Kopfer, K.; Lava, L.B. Effect of the Fine Fraction of Particulate Matter Versus the Coarse Mass and Other Pollutants on Daily Mortality in Santiago, Chile; J. Air & Waste Manage. Assoc. 2000, 50, Pino, P.; Walter, T.; Oyarzun, M.; Villegas, R.; Romieu, I. Fine Particulate Matter and Wheezing Illnesses in the First Year of Life; Epidemiol. 2004, 15, About the Authors Pedro A. Sanhueza, Ph.D., is an environmental engineer, and Monica A. Torreblanca is an environmental engineer with the Department of Geographical Engineering at the University of Santiago, Chile. Luis A. Diaz-Robles, Ph.D., is an environmental engineer with the School of Environmental Engineering at the Catholic University of Temuco, Chile. L. Nicolas Schiappacasse has a Ph.D. in environmental chemistry and is with CONAMA, Araucania Region, Chile. Maria P. Silva is a medical doctor and Teresa D. Astete is a nurse with the Health Department of the Araucania Region, Chile. Please address correspondence to: Pedro A. Sanhueza, Department of Geographical Engineering, University of Santiago of Chile, 3363 B. O Higgins Avenue, Santiago, Chile; phone: ; fax: ; e- mail: pesahech@gmail.com Journal of the Air & Waste Management Association Volume 59 December 2009