The impact of airborne particulate matter on pediatric hospital admissions for pneumonia among children in Jinan,China: A case-crossover study

This study aims to examine the effect of short-term changes in the concentration of particulate matter of diameter ≤2.5 µm (PM_2.5) and ≤10 µm (PM₁₀) on pediatric hospital admissions for pneumonia in Jinan, China. It explores confoundings factors of weather, season, and chemical pollutants. Information on pediatric hospital admissions for pneumonia in 2014 was extracted from the database of Jinan Qilu Hospital. The relative risk of pediatric hospital admissions for pneumonia was assessed using a case-crossover approach, controlling weather variables, day of the week, and seasonality. The single-pollutant model demonstrated that increased risk of pediatric hospital admissions for pneumonia was significantly associated with elevated PM_2.5 concentrations the day before hospital admission and elevated PM₁₀ concentrations 2 days before hospital admission. An increment of 10 μg/m³ in PM_2.5 and PM₁₀ was correlated with a 6% (95% CI 1.02–-1.10) and 4% (95% CI 1.00–1.08) rise in number of admissions for pneumonia, respectively. In two pollutant models, PM_2.5 and PM₁₀ remained significant after inclusion of sulfur dioxide or nitrogen dioxide but not carbon monoxide. This study demonstrated that short-term exposure to atmospheric particulate matter (PM_2.5/PM₁₀) may be an important determinant of pediatric hospital admissions for pneumonia in Jinan, China.

Implications: This study demonstrated that short-term exposure to atmospheric particulate matter (PM_2.5/PM₁₀) may be an important determinant of pediatric hospital admissions for pneumonia in Jinan, China, and suggested the relevance of pollutant exposure levels and their effects. As a specific group, children are sensitive to airborne particulate matter. This study estimated the short-term effects attribute to other air pollutants to provide references for relevant studies.     

The effects of air pollution on human mortality: does gender difference matter in African countries?

The relationship between environmental factors and human health has long been a concern among academic researchers. We use two indicators of environmental pollution, namely particulate matter (PM₁₀) and carbon dioxide (CO₂) to examine the effects of poor air quality on human mortality. This study explores an issue that has largely been ignored, particularly in the African literature, where the effect of air pollution on human mortality could be influenced by gender specification. We analyse a panel data from 35 African countries and our result suggests that the elevated levels of PM₁₀ and CO₂ have a significant effect on the increasing mortality rates in infants, under-five children and adults. Although the effect of poor air quality on adults is found to differ between genders, such difference is not statistically significant. We conclude that the air pollution effects, on average, are similar between genders in the African countries.     

The Chattanooga School Children Study: Effects of Community Exposure to Nitrogen Dioxide

Elementary schools in four areas of Greater Chattanooga were selected for a study of the effects of community exposure to nitrogen dioxide. One area, in close proximity to a large TNT plant, had high NO₂ exposure, another had relatively high suspended particulate exposure, and two areas served as “clean” controls. The similarity of the economic levels of the High-NO₂ and Control areas and the moderately lower economic level of the High-Particulate area were documented. Pollutant concentrations for NO₂ gas, suspended nitrates and sulfates, total suspended particulates, and soiling index were measured at stations located within the study areas. Ventilatory performance of second-grade school children in the High-NO₂ exposure area was significantly lower than the performance of children in the Control areas. The data suggested that ventilatory performance was adversely affected only when an NO₂ threshold was exceeded but that above this threshold no further impairment of performance could be detected.     

Indoor air and respiratory health in preadolescent children

The effect of indoor exposure to nitrogen dioxide, ammonia, particulate matter and parental tobacco smoke on respiratory health was studied over a period of six months in all second graders born and living in two area of continental Croatia 8–10 yr of age. The study group was divided into two sections corresponding to area of residence (industrial/rural). Information on respiratory symptoms was collected from a self-administered questionnaire completed by the parents of the children. The mean values of concentrations of indoor air pollution that had been recorded in 24-h samples of air collected at schools were mostly below threshold limit for ambient pollution. In addition, information on parental smoking, the density of habitation and the type of fuel used for heating and/or cooking in the home was obtained by a questionnaire. In the investigated period the prevalence of respiratory illness was 22% in the children exposed to lower indoor air pollution and 25% in those exposed to higher indoor air pollution. Exposure to parental smoking was also associated with more respiratory symptoms (28 : 19%). The results indicate that the measured air pollutants only had a slight effect on the respiratory health of preadolescent children. However, the effect of exposure to parental smoking was more pronounced.     

Comparison of the Annular Denuder System and the Transition Flow Reactor for Measurements of Selected Dry Deposition Species

An intensive field study was conducted in Research Triangle Park, North Carolina in the fall of 1986. Ambient concentrations of the following constituents were obtained: nitric acid, nitrous acid, nitrogen dioxide, sulfur dioxide, ammonia, hydrogen ion, and particulate nitrate, sulfate, and ammonium. Results collected using the annular denuder system (ADS) and the transition flow reactor (TFR) are presented and compared.

Both types of samplers had operational detection limits on daily (22-hour) samples that were generally below 1 μg m_-3 suggesting that both samplers can provide sensitive measurements for most of the constituents of interest. Both the ADS and TFR show reasonable (>25 percent) within-sampler precision for most of the measured species concentrations, except TFR fine particulate nitrate measurements where results were frequently negative (The TFR fine particulate nitrate measurement is calculated using subtraction of positive numbers).

Comparison of ADS and TFR daily results showed good agreement for total particulate sulfate, the sum of total (coarse plus fine) particulate and gaseous nitrate, and ammonia. As a result of different inlet particle collection efficiencies, the ADS fine particulate sulfate exceeded the TFR (5 percent). In the absence of a filter to collect volatilized particulate ammonium in the ADS, the sum of total particulate and gaseous ammonium in the TFR exceeded that in the ADS. Of potentially more importance, ADS measurements of SO₂ and H⁺ exceeded those of the TFR, while TFR measurements of HNO₃ exceeded those of the ADS. Results of this study suggest that the TFR may provide biased measurements of SO₂, H⁺, HNO₃, and Fine NO₃ ^- that cannot be corrected without modifications to the fundamental design of the sampling system.     

Long-term associations of morbidity with air pollution: A catalog and synthesis

I searched the National Institutes of Health MEDLINE database through January 2017 for long-term studies of morbidity and air pollution and cataloged them with respect to cardiovascular, respiratory, cancer, diabetes, hospitalization, neurological, and pregnancy-birth endpoints. The catalog is presented as an online appendix. Associations with PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm), PM₁₀ (PM with an aerodynamic diameter <10 μm), and nitrogen dioxide (NO₂) were evaluated most frequently among the 417 ambient air quality studies identified. Associations with total suspended particles (TSP), carbon, ozone, sulfur, vehicular traffic, radon, and indoor air quality were also reported. I evaluated each study in terms of pollutant significance (yes, no), duration of exposure, and publication date. I found statistically significant pollutant relationships (P < 0.05) in 224 studies; 220 studies indicated adverse effects. Among 795 individual pollutant effect estimates, 396 are statistically significant. Pollutant associations with cardiovascular indicators, lung function, respiratory symptoms, and low birth weight are more likely to be significant than with disease incidence, heart attacks, diabetes, or neurological endpoints. Elemental carbon (EC), traffic, and PM_2.5 are most likely to be significant for cardiovascular outcomes; TSP, EC, and ozone (O₃) for respiratory outcomes; NO₂ for neurological outcomes; and PM₁₀ for birth/pregnancy outcomes. Durations of exposure range from 60 days to 35 yr, but I found no consistent relationships with the likelihood of statistical significance. Respiratory studies began ca. 1975; studies of diabetes, cardiovascular, and neurological effects increased after about 2005. I found 72 studies of occupational air pollution exposures; 40 reported statistically significant adverse health effects, especially for respiratory conditions. I conclude that the aggregate of these studies supports the existence of nonlethal physiological effects of various pollutants, more so for non–life-threatening endpoints and for noncriteria pollutants (TSP, EC, PM_2.5 metals). However, most studies were cross-sectional analyses over limited time spans with no consideration of lag or disease latency. Further longitudinal studies are thus needed to investigate the progress of disease incidence in association with air pollution exposure.

Implications: Relationships of air pollution with excess mortality are better known than with long-term antecedent morbidity. I cataloged 489 studies of cardiovascular, respiratory, cancer, and neurological effects, diabetes, and birth outcomes with respect to 12 air pollutants. About half of the studies reported statistically significant relationships, more frequently with noncriteria than with criteria pollutants. Indoor and cumulative exposures, coarse or ultrafine particles, and organic carbon were seldom considered. Significant relationships were more likely with less-severe endpoints such as blood pressure, lung function, or respiratory symptoms than with incidence of cancer, chronic obstructive pulmonary disease (COPD), heart failure, or diabetes. Most long-term studies are based on spatial relationships; longitudinal studies are needed to link the progression of pollution-related morbidity to mortality, especially for the cardiovascular system.     

Characterization of Several Integrative Sampling Methods for Nitric Acid,Sulphur Dioxide and Atmospheric Particles

Laboratory and field experiments were performed to evaluate integrative measurement methods for atmospheric nitrates, sulphate and sulphur dioxide. Denuder tubes and several filter media were tested under laboratory and field conditions. Effects of sampling variables such as temperature and relative humidity, flow rates, concentration, loading capacity and artifacts due to NO, NO₂ and SO₂ were also evaluated. The integrative filter sampling method and the ion chromatographic analytical procedure gave a measurement precision (relative standard deviation) of ±11.5 percent for particulate NO₃ ^? on Teflon and ±15.6 percent for gaseous HNO₃ on nylon; for both these constituents, the detection limit was about 0.1 μ m^?3.     

Relationship of Indoor N02 Concentrations to Use of Unvented Gas Appliances

In preparation for a prospective study of the relationship of residential nitrogen dioxide exposure and respiratory infections in infants, we conducted a pilot study to assess NO₂ concentrations in a sample of homes in Albuquerque, New Mexico. The methods used to characterize concentrations are described. Three locations in 144 homes were monitored with passive diffusion samplers for two two-week cycles during November and December 1984. Two-week average NO₂ concentrations in the activity room ranged from 2.0 to 168.7 ppb. NO₂ concentrations in the activity room and the infant’s bedroom were fivefold higher in homes with gas stoves than in homes with electric stoves. Sixty-four percent of homes with gas stoves had activity room concentrations that exceeded the highest outdoor concentration. Multiple regression models Indicated that the outdoor concentration, use of a gas stove, particularly one with pilot lights, presence of a gas dryer in the living area, and use of a floor or wall furnace contributed to NO₂ concentrations. Use of a toaster or microwave oven in a house with a gas stove reduced NO₂ concentrations. The results of this study demonstrate a broad range of NO₂ concentrations in Albuquerque. We conclude with suggestions for an exposure assessment strategy that would be valid and feasible in the context of a large epidemiologic study of the health effects of NO₂.     

Determinants of exposure to fine particulate matter (PM2.5) for waiting passengers at bus stops

This research evaluates commuter exposure to particulate matter during pre-journey commute segments for passengers waiting at bus stops by investigating 840 min of simultaneous exposure levels, both inside and outside seven bus shelters in Buffalo, New York. A multivariate regression model is used to estimate the relation between exposure to particulate matter (PM_2.5 measured in μg m^?3) and three vectors of determinants: time and location, physical setting and placement, and environmental factors. Four determinants have a statistically significant effect on particulate matter: time of day, passengers’ waiting location, land use near the bus shelter, and the presence of cigarette smoking at the bus shelter. Model results suggest that exposure to PM_2.5 inside a bus shelter is 2.63 μg m^?3 (or 18 percent) higher than exposure outside a bus shelter, perhaps due in part to the presence of cigarette smoking. Morning exposure levels are 6.51 μg m^?3 (or 52 percent) higher than afternoon levels. Placement of bus stops can affect exposure to particulate matter for those waiting inside and outside of shelters: air samples at bus shelters located in building canyons have higher particulate matter than bus shelters located near open space.     

Estimates of community exposure and health risk to sulfur dioxide from power plant emissions using short-term mobile and stationary ambient air monitoring

To estimate plausible health effects associated with peak sulfur dioxide (SO₂) levels from three coal-fired power plants in the Baltimore, Maryland, area, air monitoring was conducted between June and September 2013. Historically, the summer months are periods when emissions are highest. Monitoring included a 5-day mobile and a subsequent 61-day stationary monitoring study. In the stationary monitoring study, equipment was set up at four sites where models predicted and mobile monitoring data measured the highest average concentrations of SO₂. Continuous monitors recorded ambient concentrations each minute. The 1-min data were used to calculate 5-min and 1-hr moving averages for comparison with concentrations from clinical studies that elicited lung function decrement and respiratory symptoms among asthmatics. Maximum daily 5-min moving average concentrations from the mobile monitoring study ranged from 70 to 84 ppb (183–220 µg/m³), and maximum daily 1-hr moving average concentrations from the mobile monitoring study ranged from 15 to 24 ppb (39–63 µg/m³). Maximum 5-min moving average concentrations from stationary monitoring ranged from 39 to 229 ppb (102–600 µg/m³), and maximum daily 1-hr average concentrations ranged from 15 to 134 ppb (40–351 µg/m³). Estimated exposure concentrations measured in the vicinity of monitors were below the lowest levels that have demonstrated respiratory symptoms in human clinical studies for healthy exercising asthmatics. Based on 5-min and 1-hr monitoring, the exposure levels of SO₂ in the vicinity of the C.P. Crane, Brandon Shores, and H.A. Wagner power plants were not likely to elicit respiratory symptoms in healthy asthmatics.

Implications: Mobile and stationary air monitoring for SO₂ were conducted to quantify short-term exposure risk, to the surrounding community, from peak emissions of three coal-fired power plants in the Baltimore area. Concentrations were typically low, with only a few 5-min averages higher than levels indicated during clinical trials to induce changes in lung capacity for healthy asthmatics engaged in exercise outdoors.     

Street-level concentrations of nitrogen dioxide and suspended particulate matter in Hong Kong

The concentrations of respirable suspended particulates (PM₁₀), fine suspended particulates (PM_2.5) and nitrogen dioxide (NO₂) were measured in various locations over the territory of Hong Kong. In order to study the contributions of these pollutants from motor vehicles and their characteristics, the attention was focused on the roadside, street-level concentrations. A statistical analysis of the sampling results was conducted to obtain general characteristics of the roadside particulate and nitrogen dioxide pollution and to investigate the effects of traffic volume and meteorological factors on the pollution levels. High correlation coefficients are found between PM₁₀, PM_2.5 and NO₂ concentration.     

Meta-Analysis of Time-Series Studies of Air Pollution and Mortality: Effects of Gases and Particles and the Influence of Cause of Death,Age, and Season

Abstract

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 μg/m³ particulate matter (PM) of median diameter <10 μm (PM₁₀); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO₂; 1.6% (1.1-2.0%) per 31.2 ppb O₃; and 0.9% (0.7-1.2%) per 9.4 ppb SO₂ (daily maximum concentration for O₃, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM₁₀ and SO₂. Larger effect sizes were observed for respiratory mortality for all pollutants except O₃. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Phenogenetic response of silver birch populations and half-sib families to elevated ozone and ultraviolet-B radiation at juvenile age

Phenogenetic response of silver birch populations and half-sib families to separate and combined elevated ozone (O₃) concentrations and ultraviolet-B (UV-B) radiation dozes was studied at juvenile age in the climatic chambers. Significant population and family effects were found for seedling height, lamina width, and leaf damage. The exposure to UV-B radiation decreased genetic variation at the stage of seed germination. Complex exposure to UV-B and O₃ caused an increase of genetic variation at the stage of intensive seedling growth: seedling height genetic variation in separate treatments increased from 23.7–38.6 to 33.7–65.7%, the increase for lamina width was from 10.2–13.9 to 13.6–31.8%. Different populations and families demonstrated differing response to elevated complex UV-B and O₃ exposure. Changes of genetic intra-population variation were population-specific. Such changes in genetic variation under the impact of stressors can alter adaptation, stability, and competitive ability of regenerating populations in a hardly predictive way.     

Thyroid status in juvenile alligators (Alligator mississippiensis) from contaminated and reference sites on Lake Okeechobee, Florida, USA

Exposure to environmental contaminants has been shown to alter normal thyroid function in various wildlife species, including the American alligator (Alligator mississippiensis). Abnormalities in circulating levels of the thyroid hormone thyroxine (T₄) have been reported in juvenile alligators from several contaminated lakes in Florida. To further elucidate these functional thyroid abnormalities, this study examines the structure of thyroids and circulating T₄ concentrations from juvenile alligators collected from three sites of varying contamination on Lake Okeechobee, Florida. The following variables were used to characterize thyroid morphology: epithelial cell height, width and area, percent colloid, and follicle area. These variables were compared among study sites and between genders. No difference was detected in epithelial cell height, epithelial cell area, or follicle area among the sites, whereas significant differences in epithelial cell width (p=0.02) and percent colloid (p=0.008) were found. Animals from the most contaminated site (Belle Glade) had significantly greater epithelial cell widths and significantly less colloid present in their follicles compared to animals from the reference site (West). Gender did not have a significant interaction with site for any variable measured. Thyroxine (T₄) concentrations were elevated in the intermediately contaminated site (Conservation Area 3A) compared to the other sites (p<0.0001). It is proposed that the disruptions seen in Lake Okeechobee alligators are due to disruptions at both the thyroid and extra-thyroidal tissues.     

Fine particulate matter alters the microecology of the murine respiratory tract

Fine particulate matter is a global challenge to human health. We investigated the effects and potential mechanisms of fine particulate matter on respiratory tract microecology in a lung injury mouse model. BALB/c mice were randomized into exposed and control groups. We found that the levels of soluble tumor necrosis factor receptor I was increased following the PM2.5 exposure. 16S rRNA sequencing of respiratory tract lavage fluid confirmed that the composition of the respiratory tract microecology was altered by the exposure. Lactobacillus was the most abundant of bacterial species present. Collectively, these results establish a link between exposure to fine particulate matter and alterations to the respiratory tract microecology. Elucidation of the underlying mechanisms may lead to treatment strategies in lung injury.

     

Air pollutants and health outcomes: Assessment of confounding by influenza

We assessed confounding of associations between short-term effects of air pollution and health outcomes by influenza using Hong Kong mortality and hospitalization data for 1996–2002.Three measures of influenza were defined: (i) intensity: weekly proportion of positive influenza viruses, (ii) epidemic: weekly number of positive influenza viruses ≥4% of the annual number for ≥2 consecutive weeks, and (iii) predominance: an epidemic period with co-circulation of respiratory syncytial virus <2% of the annual positive isolates for ≥2 consecutive weeks. We examined effects of influenza on associations between nitrogen dioxide (NO₂), sulfur dioxide (SO₂), particulate matter with aerodynamic diameter ≤10 μm (PM₁₀) and ozone (O₃) and health outcomes including all natural causes mortality, cardiorespiratory mortality and hospitalization. Generalized additive Poisson regression model with natural cubic splines was fitted to control for time-varying covariates to estimate air pollution health effects. Confounding with influenza was assessed using an absolute difference of >0.1% between unadjusted and adjusted excess risks (ER%).Without adjustment, pollutants were associated with positive ER% for all health outcomes except asthma and stroke hospitalization with SO₂ and stroke hospitalization with O₃. Following adjustment, changes in ER% for all pollutants were <0.1% for all natural causes mortality, but >0.1% for mortality from stroke with NO₂ and SO₂, cardiac or heart disease with NO₂, PM₁₀ and O₃, lower respiratory infections with NO₂ and O₃ and mortality from chronic obstructive pulmonary disease with all pollutants. Changes >0.1% were seen for acute respiratory disease hospitalization with NO₂, SO₂ and O₃ and acute lower respiratory infections hospitalization with PM₁₀. Generally, influenza does not confound the observed associations of air pollutants with all natural causes mortality and cardiovascular hospitalization, but for some pollutants and subgroups of cardiorespiratory mortality and respiratory hospitalization there was evidence to suggest confounding by influenza.     

Assessment of ambient air quality in the port of Naples

Two experimental monitoring campaigns were carried out in 2012 to investigate the air quality in the port of Naples, the most important in southern Italy for traffic of passengers and one of the most important for goods. Therefore, it represents an important air pollution source located close to the city of Naples. The concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and BTEX (benzene, toluene, ethylbenzene, and xylenes) in the air were measured at 15 points inside the Naples port area through the use of passive samplers. In addition, a mobile laboratory was positioned in a fixed point inside the port area to measure continuous concentration of pollutants together with particulate matter, ambient parameters, and wind direction and intensity. The pollution levels monitored were compared with those observed in the urban area of Naples and in other Mediterranean ports. Even though the observation time was limited, measured concentrations were also compared with limit values established by European legislation. All the measured pollutants were below the limits with the exception of nitrogen dioxide: its average concentration during the exposition time exceeded the yearly limit value. A spatial analysis of data, according to the measured wind direction and intensity, provided information about the effects that ship emissions have on ambient air quality in the port area. The main evidence indicates that ship emissions influence sulfur dioxide concentration more than any other pollutants analyzed.

Implications: Two monitoring campaigns were carried out to measure BTEX, SO₂, NO₂, and PM₁₀ (particulate matter with an aerodynamic diameter <10 μm) air concentrations in the port of Naples. NO₂ hourly average and PM₁₀ daily average comply with European legislative standards. Spatial variation of pollutants long the axis corresponding to the prevailing wind direction seems to indicate a certain influence of ship emissions for SO₂. For NO₂ and PM₁₀, a correlation between concentrations in the harbor and those measured by the air quality monitoring stations sited in the urban area of Naples was observed, indicating a possible contribution of the near road traffic to the air pollution in the port of Naples.     

Controlled Exposures of Volunteers to Respirable Carbon and Sulf uric Acid Aerosols

Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, we exposed 15 healthy and 15 asthmatic volunteers in a controlled- environment chamber (21°C, 50 percent relative humidity) to four test atmospheres: (i) clean air; (ii) 0.5-μm H2SO4 aerosol at =100 μg/m³, generated from water solution; (iii) 0,5-μm carbon aerosol at =250 μg/m³, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (iv) carbon as in (iii) plus =100 μg/m³ of ultrafine H2SO4 aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (iv) became attached to carbon particle surfaces, and that most particles remained in the sub-μm size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation =50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at endexposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H₂SO₄ or carbon, separate or interactive, on health measures. Group data showed no more than small equivocal effects of any exposure on any health measure. One individual's responses were consistent with a clinically significant excess airway constriction from H₂SO₄ plus carbon, and 2-3 others showed slight excess responses to the combined pollutants, but all these observations might have reflected chance variations. We conclude that coexisting carbon aerosol did not increase respiratory irritancy of H₂SO₄, in most healthy and asthmatic subjects exposed for 1 hr under simulated "worst-case" ambient conditions.     

Association between Levels of Fine Particulate and Emergency Visits for Pneumonia and other Respiratory Illnesses among Children in Santiago,Chile

ABSTRACT

Recent evidence has implicated the fine fraction of particulate as the major contributor to the increase in mortality and morbidity related to particulate ambient levels. We therefore evaluated the impact of daily variation of ambient PM_2.5 and other pollutants on the number of daily respiratory-related emergency visits (REVs) to a large pediatric hospital of Santiago, Chile. The study was conducted from February 1995 to August 1996. Four monitoring stations from the network of Santiago provided air pollution data. The PM2.5 24-hr average ranged from 10 to 111 μg/m³ during September to April (warm months) and from 10 to 156 μg/m³ during May to August (cold months). Other contaminants (ozone (O₃), nitrogen dioxide (NO₂), and sulfur dioxide (SO₂)) were, in general, low during the study period. The increase in REVs was significantly related to PM₁₀ and PM_2.5 ambient levels, with the relationship between PM_2.5 levels and the number of REVs the stronger. During the cold months, an increase of 45 ìg/m³ in the PM_2.5 24-hr average was related to a 2.7% increase in the number of REVs (95% CI, 1.1–4.4%) with a two-day lag, and to an increase of 6.7% (95% CI, 1.7–12.0%) in the number of visits for pneumonia with a three-day lag. SO₂ and NO₂ were also related to REVs. We conclude that urban air pollutant mixture, particularly fine particulates, adversely affect the respiratory health of children residing in Santiago.     

Will photosynthetic capacity of aspen trees acclimate after long-term exposure to elevated CO2 and O3?

Photosynthetic acclimation under elevated carbon dioxide (CO₂) and/or ozone (O₃) has been the topic of discussion in many papers recently. We examined whether or not aspen plants grown under elevated CO₂ and/or O₃ will acclimate after 11 years of exposure at the Aspen Face site in Rhinelander, WI, USA. We studied diurnal patterns of instantaneous photosynthetic measurements as well as A/C_i measurements monthly during the 2004-2008 growing seasons. Our results suggest that the responses of two aspen clones differing in O₃ sensitivity showed no evidence of photosynthetic and stomatal acclimation under either elevated CO₂, O₃ or CO₂ + O₃. Both clones 42E and 271 did not show photosynthetic nor stomatal acclimation under elevated CO₂ and O₃ after a decade of exposure. We found that the degree of increase or decrease in the photosynthesis and stomatal conductance varied significantly from day to day and from one season to another.