Abstract  Background: Dozens of studies link acute exposure to particulate matter (PM) air pollution to premature mortality and morbidity, but questions remain about which species and sources in the vast PM mixture are responsible for the observed health effects. While a few studies exist on the effects of species and sources in U.S. cities, European cities, which have a higher proportion of diesel engines and denser urban populations, have not been well characterized. Information on the effects of specific sources could aid in targeting pollution control and in articulating the biological mechanisms of PM. Objectives: Our study examines the effects of various PM sources on daily mortality for 2003 to 2007 in Barcelona, a densely populated city in the northeast corner of Spain. Methods: Source apportionment for both PM2.5 and PM10 (PM less than 2.5 and 10 microns in diameter) using positive matrix factorization identified eight different factors. Case-crossover regression analysis was used to estimate the effects of each factor. Results: Several sources of PM2.5, including vehicle exhaust, fuel oil combustion, secondary nitrate/organics, mineral, secondary sulfate/organics and road dust had statistically significant associations (p < 0.05) with all-cause and cardiovascular mortality. Also, in some cases relative risks for a respective interquartile range increase in concentration were higher for specific sources than for total PM2.5 mass. Conclusions: These results along with those from our multi-source models suggest that traffic, sulfate and construction dust are important contributors to the adverse health effects linked to PM.

Abstract  A forest tree growth-response to atmospheric deposition is expected to arise indirectly through soil chemical changes and would probably be observable only in the long term. We examined this hypothesis by evaluating the relationship between periodic height growth of mature northern red oak (Quercus rubra L.) trees and soil, physiography and atmospheric sulfate deposition along a 170-km west-to-east gradient of decreasing sulfate deposition in north central Pennsylvania, USA. Height increments for three common 20-year periods beginning in 1929, 1949 and 1969 were estimated from exponential-monomolecular growth functions fitted to stem analysis data for each of 45 trees in 13 ecologically analogous stands along the deposition gradient. Canonical analysis was used to identify a statistically manageable subset of the original 48 independent soil, site and tree (age, crown width) variables strongly, associated with height growth. Predictive models relating total (60-year) and the three 20-year height increments to the reduced variable set plus estimated average sulfate and nitrate deposition were derived by best subsets multiple regression. An inherent spatial gradient of decreasing height growth from western to eastern sites was apparent in even the earliest (1929-1948) increment. This inferred non-deposition-related spatial growth trend was accounted for in the 1949-1968 growth increment by introduction of the earliest (1929-1948) growth increment as a significant covariate in the regression modeL The inherent growth gradient largely disappeared by the 1969-1988 period as a probable consequence of converging growth rates reported to occur in oaks after age 60 years regardless of site quality. The 1969-1988 growth increment was not as strongly correlated with site factors as was growth in preceding periods, nor was early growth or sulfate deposition significantly related to this height increment. Growth effects from sulfate deposition, if any, would most likely occur within the recent (1969-1988) increment coincident with the period of naturally decreasing growth rate, when site differences and possibly environmental factors would have less influence on growth. Our results give no indication that wet sulfate inputs are affecting northern red oak height growth across the atmospheric deposition gradient.

Abstract  OBJECTIVE: To assess the association between daily exposure to air pollution and lung function in school children. METHODS: Panel study with a random sample of 118 students (between 6 and 15 years of age), enrolled in a public school of the city of Rio de Janeiro, state of Rio de Janeiro, and living within 2 km of the study site. Data on students' characteristics were obtained with a questionnaire, including the International Study of Asthma and Allergies in Childhood - ISAAC. Daily peak expiratory flow measurements were taken to measure lung function. Daily data on PM10, SO2, O3, NO2 and CO levels, temperature and humidity were provided by a portable monitor. Repeated measurements of lung function were associated with pollutant levels with a multilevel model adjusted for time trend, temperature, air humidity, exposure to smoking at home, presence of asthma, height, sex, weight and age of children. RESULTS: Mean peak expiratory flow was 243.5 l/m (sd=58.9). The lowest mean peak expiratory flow was 124 l/m, and the highest, 450 l/m. For the 10 microg/m(3) increase in PM10, there was a 0.34 l/min decrease in mean peak flow on the third day. For the 10 microg/m(3) increase in NO2, there was a decrease between 0.23 l/min and 0.28 l/min in mean peak flow after exposure. CO and SO2 effects on students' peak flow were not statistically significant. O3 showed a protective result: an increase in 10 microg/m(3) of O3 would be associated, after a day of exposure, with a 0.2 l/min increase in mean lung function. CONCLUSIONS: Even within acceptable levels most of the time, air pollution, especially PM10 and NO2, was associated with a decrease in lung function in children living in the city of Rio de Janeiro.

Abstract  Heavy metals in various size modes of the atmospheric aerosol are a concern for human health. Their and other elements' concentrations are indicative for anthropogenic and natural aerosol sources. Si, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Hg, and Pb were determined as a complementary contribution to a study on aerosol cycling during the wet season, June 2004, in a humid, subtropical climate, i.e. in the city of Salina Cruz, situated on the Pacific coast of the Isthmus of Tehuantepec (16.2 degrees N, 95.2 degrees W), Mexico. For mass ( gravimetry) and elemental analyses, particles were collected by a Berner low-pressure round nozzle cascade impactor using four stages corresponding to 0.1-0.25, 0.25-1.0, 1.0-4.0, and 4-16 mm of aerodynamic particle size. The impaction plates were modified such that approx. 1/6 consisted of a plastic support (Persplex(R)) for total reflection X-ray fluorescence spectrometry (TXRF). The elements' total content was determined by TXRF without any further sample pretreatment. Limits of quantification (LOQ) for elemental content in individual impactor stages corresponded to 25-60 ng m(-3) for Si; 0.8-4 ng m(-3) for Cl, K, Ca, Ti, and V; 3-20 pg m(-3) for Cr, Mn, Fe, Cu, Ni, and Zn; and 7-50 pg m(-3) for As, Se, Br, Rb, Sr, Hg, and Pb. In some samples, however, high blank values for the supports gave an LOQ 6-19 ng m(-3) for Cl; 3-7 ng m(-3) for Ca; 3-7 ng m(-3) for Fe, Ni, Cu, and Zn; and 60-70 ng m(-3) for Pb. The influence of local natural, industrial, and vehicle traffic sources for heavy-metal mobilization was obvious. Heavy-metal abundances did not coincide with regionally distributed pollutants. V and Ni were found at particularly elevated levels advected with the sea breeze, which points to ships as sources. Br and Pb were found at particularly low levels. The concentrations of Br, Rb, Sr, and Pb were found below LOQ at least in some, As, Co, Se, and Hg in all of the samples. The elements' characteristic differences in mass size distributions were obvious despite the coarse size resolution. During the cycling of air masses from land to sea and back again, enrichment of super-micrometre particles in the near ground aerosol was observed under dry weather conditions. Rain preferentially removed the large particles with which heavy metals have been associated.

Abstract  Abstract: For several years several vehicle emission control technologies have been developed and introduced to reduce the contribution of road traffic to air pollution. However, this contribution in the Île de France region, around Paris, France, has been estimated to still be significant. We present a modeling study of the effect of the future evolution of traffic emissions on air quality at the urban scale. The aim is to assess the respective contribution of the different processes involved in the nonlinear chemistry of photochemical air pollution (change in emissions and/or chemical behaviour) that explain the observed evolution of concentrations of traffic-related pollutants at monitoring urban background stations. The modeling results suggest that the reduction of NO _x emissions must be coupled with more stringent measures on NMVOC emissions than those currently planned in the transportation sector to avoid an increase of O₃ concentrations in some densely populated areas. The modeled NO₂ concentrations in Paris reach a maximum in 2010 due to an increase of the NO₂ emissions related to the evolution of the NO₂/NO _x ratio of the Diesel vehicle emissions. The reduction of PM emissions leads to a non-proportional decrease in PM concentrations, which results mostly from the decrease in Diesel particulate emissions.

Abstract  Nowadays, air over major cities throughout the world has become overburdened with gases produced by automobiles. The death rate due to automobile pollution is increasing rapidly in the metropolitan areas. With passage of time, people realized that polluted air has serious effects on their health, climate and economics. Weather and climate have integrated impact on human activities resulting in worldwide concentration of the particulates of environmental pollution, viz., chlorofluorocarbons, carbon dioxide, methane, nitrogen oxide, lead and several other dust and gaseous particles. Like many other mega cities in the world the ambient air quality of Quetta, Pakistan is also deteriorating nowadays. Automobile exhausts and certain industrial pollutants produce O₃ by photochemical reactions. The particulate matter, particularly less than 10 μm in size, can pass through the natural protective mechanism of human respiratory system and plays an important role in genesis and augmentation of allergic disorders. Sources of air pollution in the area and the unique problem arising out of the emission from the vehicles, industries, etc. have been described. Ambient air quality was monitored along with micrometeorological data and the results are discussed. The status of air pollution in the area has been evaluated and a questionnaire survey was conducted to estimate the allergic symptoms and exposure to assess the respiratory disorders. The data are analyzed to evaluate the critical situation arising out of the emission of air pollutants and the impact on human health due to respirable diseases (RDs) in middle class sub-population (activity-wise) in the area assessed. A strategic air quality management plan has been proposed. For the mitigation of air pollution problems in the city, different measures to be adopted to maintain the balance between sustainable development and environmental management have been discussed. Air pollution has significant effects on exacerbation of asthma, allergy and other respiratory diseases.

Abstract  Firework events are capable of inducing particulate matter (PM) episodes that lead to exceedances of regulatory limit values. As short-term peaks in ambient PM concentration have been associated with negative impacts on respiratory and cardiovascular health, we performed a detailed study of the consequences of firework events in London on ambient air quality and PM composition. These changes were further related to the oxidative activity of daily PM samples by assessing their capacity to drive the oxidation of physiologically important lung antioxidants including ascorbate, glutathione and urate (oxidative potential, OP). Twenty-four hour ambient PM samples were collected at the Marylebone Road sampling site in Central London over a three week period, including two major festivals celebrated with pyrotechnic events: Guy Fawkes Night and Diwali. Pyrotechnic combustion events were characterized by increased gas phase pollutants levels (NO_x and SO₂), elevated PM mass concentrations, and trace metal concentrations (specifically Sr, Mg, K, Ba, and Pb). Relationships between NO_x, benzene, and PM₁₀ were used to apportion firework and traffic source fractions. A positive significant relationship was found between PM oxidative burden and individual trace metals associated with each of these apportioned source fractions. The level of exposure to each source fraction was significantly associated with the total OP. The firework contribution to PM total OP, on a unit mass basis, was greater than that associated with traffic sources: a 1 μg elevation in firework and traffic PM fraction concentration was associated with a 6.5 ± 1.5 OP^T μg^-1 and 5.2 ± 1.4 OP^T μg^-1 increase, respectively. In the case of glutathione depletion, firework particulate OP (3.5 ± 0.8 OPGSH μg^-1) considerably exceeded that due to traffic particles (2.2 ± 0.8 OPGSH μg^-1). Therefore, in light of the elevated PM concentrations caused by firework activity and the increased oxidative activity of this PM source, there is value in examining if firework derived PM is related to acute respiratory outcomes.

Abstract  Background and objective: Increased air pollutants correlate with increased incidence of cardiovascular disease potentially due to vascular dysfunction. We have reported that acute diesel engine exhaust (DE) exposure enhances vasoconstriction and diminishes acetylcholine (ACh)-induced dilation in coronary arteries in a nitric oxide synthase (NOS)-dependent manner. We hypothesize that acute DE inhalation leads to endothelial dysfunction by uncoupling NOS. Methods: Rats inhaled fresh DE (300 μg particulate matter/m³) or filtered air for 5 hr. After off-gassing, intraseptal coronary arteries were isolated and dilation to ACh recorded using videomicroscopy. Results: Arteries from DE-exposed animals dilated less to ACh than arteries from air-exposed animals. NOS inhibition did not affect ACh dilation in control arteries but increased dilation in the DE group, suggesting NOS does not normally contribute to ACh-induced dilation in coronary arteries but does contribute to endothelial dysfunction after DE inhalation. Cyclooxygenase (COX) inhibition did not affect ACh dilation in the DE group, but combined inhibition of NOS and COX diminished dilation in both groups and eliminated intergroup differences, suggesting that the two pathways interact. Superoxide scavenging increased ACh dilation in DE arteries, eliminating differences between groups. Tetrahydrobiopterin (BH₄) supplementation with sepiapterin restored ACh-mediated dilation in the DE group in a NOS-dependent manner. Superoxide generation (dihydroethidium staining) was greater in DE arteries, and superoxide scavenging, BH₄ supplementation, or NOS inhibition reduced the signal in DE but not air arteries. Conclusion: Acute DE exposure appears to uncouple NOS, increasing reactive oxygen species generation and causing endothelial dysfunction, potentially because of depletion of BH₄ limiting its bioavailability.

Abstract  China's economy has developed rapidly in the recent two decades. Economic development is usually linked with increase in energy consumption and consumption emissions, which in turn leads to worsening of air quality. Due to the adoption of various control measures, the ambient air quality in a number of large cities in China has actually improved. The ambient air TSP and SO(2) levels in China have been decreasing in the last decade. However, ambient air NO(x) level has been increasing due to the increased number of motor vehicles. Coal has been and is still the major source of energy in China. Ambient air pollution in large cities has changed from the conventional coal combustion type to the mixed coal combustion/motor vehicle emission type. A series of epidemiological studies on air pollution and health effects ranging from mortality, morbidity to functional changes have been conducted in China. The results showed that ambient air pollution had acute and chronic effects on mortality, morbidity, hospital admissions, clinical symptoms, lung function changes, etc. The exposure-response relationship between air pollutants and daily mortality, morbidity, hospital admissions, and lung function has been established accordingly.

Abstract  Upper Silesian Industrial Zone (Katowice Voivodship, Poland), the country most industrialized and densely populated region is well recognized for the magnitude of environmental problems. Due to local lead mining and processing environmental exposure to lead is considered one of the most important hazards to the health of children. In the past, clinically confirmed cases of lead intoxication in children have been found and recent blood lead monitoring in major point source impact areas have documented increased blood lead concentration in children. However, much less is known about blood lead concentrations in general population of children who are exposed to increased levels of lead in ambient and soil. The study was undertaken in order to estimate the mean blood lead concentration (PbB) and its range in children aged seven years residing in urban non-point source impact area of Katowice Voivodship, and to examine potential determinants of increased blood lead concentration in these children. In a systematic sample of 431 children aged 7 years (208 girls and 223 boys), living in two large cities in the centre of Upper Silesian Industrial Zone the geometric mean and standard deviation of PbB was 7.94 +/- 1.48 micrograms/dl (range 4.0-38.0 micrograms/dl) and did not depend on sex or the city of residence. PbB equal to or larger than 15 micrograms/dl was found in 8.1% of children and PbB equal to or larger than 10 micrograms/dl in 27.4% of children. Blood lead concentration was associated with a number of factors that could be classified as family factors, housing and environmental factors. The identified risk factors add credibility to suggested directions of preventive measures that should extend beyond already implemented lead emission control in the industry and involve increased use of unleaded gasoline, upgrading of housing conditions and promotion of proper hygienic standards on a household level. The findings of the study indicate that children living in urban area of Upper Silesian Industrial Zone are at risk of overexposure to lead in environment, and justify the implementation of population-based screening program targeting children in younger age groups in the region.

Abstract  The nitrogen oxides discussed in this document are nitric oxide (NO) and nitrogen dioxide (NO2). In combustion processes, NO is primarily formed and subsequently oxidized to NO2 in the atmosphere. Traffic is the major source to human outdoor exposure to NO and NO2 in urban areas. In homes with gas-fueled stoves or water heaters, the concentration of NO2 is generally higher indoors than outdoors. Upon inhalation, NO2 penetrates deep into the lung. In animal experiments, NO2 causes biochemical and morphological changes in lung tissue, affects host defense mechanisms, and causes decreased pulmonary function. The lowest observed effect level after prolonged exposure is 560 mug.m-3. In short-term controlled studies on humans, NO2 causes bronchoconstriction and an increase in bronchial responsiveness. A meta-analysis indicates a lowest observed effect level of 200 mug.m-3 for increased bronchial responsiveness in asthmatics. Epidemiologic studies on children living in homes with gas stoves suggest an increased risk of lower respiratory illness at average indoor NO2 concentrations of about 40-80 mug.m-3, with short-term peaks exceeding 1000 mug.m-3. The studies focusing on outdoor exposure provide some evidence of increased respiratory disease rates for children and nonsmoking adults living in areas with long-term average NO2 concentrations of 30-100 mug.m-3; however, the specific role of NO2 is not clear. Based on controlled studies on humans, a 1-h guideline value of 100 mug.m-3 for NO2 in ambient air (eg, as the 99th percentile) is recommended. This value would correspond to a long-term average (half-year mean) of about 40 mug.m-1. The epidemiologic evidence is not considered sufficient for a long-term guideline for NO2. NO is formed endogenously for purposes such as signaling in the nervous system, the mediation of vasodilation, and the mediation of cytotoxicity in macrophages. After the inhalation of high concentrations of NO, lung vasodilator effects occur. No health-based guideline value for NO in ambient air is suggested.

Abstract  #Daily levels of particulate matter (PM) in the ambient air (PM 2.5 and PM 10) were measured in a northern city of Thailand (Chiang Mai) from March 1998 to October 1999. Twenty-four-hour air particulate matter samples were collected each day with Airmetric Minivol portable air samplers. Monthly averages of PM 2.5 from four stations in Chiang Mai varied from 15.39 to 138.31 Ág/m3 and 27.29 to 173.40 Ág/m3 for PM 10. The PM 2.5 annual average was 58.48 mg/m3 and PM 10, 86.38 Ág/m3. Daily PM 2.5 (24 h values) during the winter months in Chiang Mai frequently exceeded 200-300 Ág/m3. The maximum concentrations of PM 2.5 (24 h average) in Chiang Mai air from December 1998 to April 1999 were 2.8-, 3.5-, 4.2-, 6.5- and 3.2-fold higher than the US Environmental Protection Agency (US EPA), PM 2.5, 24 h standard of 65 Ág/m3. From May to October, the mean 24 h levels of PM 2.5 and PM 10 were at acceptable levels. The data shows that during the winter season (December to March), levels of PM 2.5 and PM 10 in the Chiang Mai atmosphere are very high, and there may be significant health implications associated with these high concentrations. During the summer season, the fine particles were generally within the acceptable levels. To our knowledge, these are the first measurements of PM 2.5 to be reported for the city of Chiang Mai and they indicate considerable ambient fine particle exposures to the Chiang Mai population. In addition, dichloromethane extracts of airborne particulate matter PM 2.5 or PM 10 collected in the months of winter in the city of Chiang Mai were mutagenic to Salmonella typhimurium strain TA100 without metabolic activation. The mutagenicity appeared to track particle concentrations and increased in the presence of S9 mix.

Abstract  Recent studies have linked atmospheric particulate matter with human health problems. In many urban areas, mobile sources are a major source of particulate matter (PM*) and the dominant source of fine particles or PM2.5 (PM smaller than 2.5 Ám in aerodynamic diameter). Dynamometer studies have implicated diesel engines as being a significant source of ultrafine particles (< 0.1 Ám), which may also exhibit deleterious health impacts. In addition to direct tailpipe emissions, mobile sources contribute to ambient particulate levels by brake and tire wear and by resuspension of particles from pavement. Information about particle emission rates, size distributions, and chemical composition from in-use light-duty (LD) and heavyduty (HD) vehicles is scarce, especially under real-world operating conditions. To characterize particulate emissions from a limited set of in-use vehicles, we studied on-road emissions from vehicles operating under hot-stabilized conditions, at relatively constant speed, in the Tuscarora Mountain Tunnel along the Pennsylvania Turnpike from May 18 through 23, 1999. There were five specific aims of the study. (1) obtain chemically speciated diesel profiles for the source apportionment of diesel versus other ambient constituents in the air and to determine the chemical species present in real-world diesel emissions; (2) measure particle number and size distribution of chemically speciated particles in the atmosphere; (3) identify, by reference to data in years past, how much change has occurred in diesel exhaust particulate mass; (4) measure particulate emissions from LD gasoline vehicles to determine their contribution to the observed particle levels compared to diesels; and (5) determine changes over time in gas phase emissions by comparing our results with those of previous studies. Comparing the results of this study with our 1992 results, we found that emissions of C8 to C20 hydrocarbons, carbon monoxide (CO), and carbon dioxide (CO2) from HD diesel emissions substantially decreased over the seven-year period. Particulate mass emissions showed a similar trend. Considering a 25-year period, we observed a continued downward trend in HD particulate emissions from approximately 1,100 mg/km in 1974 to 132 mg/km (reported as PM2.5) in this study. The LD particle emission factor was considerably less than the HD value, but given the large fraction of LD vehicles, emissions from this source cannot be ignored. Results of the current study also indicate that both HD and LD vehicles emit ultrafine particles and that these particles are preserved under real-world dilution conditions. Particle number distributions were dominated by ultrafine particles with count mean diameters of 17 to 13 nm depending on fleet composition. These particles appear to be primarily composed of sulfur, indicative of sulfuric acid emission and nucleation. Comparing the 1992 and 1999 HD emission rates, we observed a 48% increase in the NOx/CO2 emissions ratio. This finding supports the assumption that many new-technology diesel engines conserve fuel but increase NOx emissions.

Abstract  In a previous panel study in Paris, France, detrimental effects of moderately high levels of winter air pollution on the symptoms and lung function of asthmatic children were demonstrated. A new study was conducted, with the aim of assessing the short-term effects of photo-oxidant and particulate air pollution on childhood asthma during spring and early summer in Paris. Eighty-two medically diagnosed asthmatic children were followed up for 3 months. Outcomes included the incidence and prevalence of asthma attacks, nocturnal cough, supplementary use of beta2-agonists, symptoms of airway irritation, and peak expiratory flow (PEF) value and its variability. The statistical methods controlled for the lack of independence between daily health outcomes, temporal trends and pollen and weather conditions. Black smoke and nitrogen dioxide (NO2) were associated with increases in the occurrence of nocturnal cough and respiratory infections. Ozone (O3) was associated with an increase in the occurrence of asthma attacks and respiratory infections and with changes in lung function, as shown by an increase in PEF variability and a decrease in PEF. Statistically significant interactions were demonstrated between O3 and temperature and between O3 and pollen count for asthma attacks. O3 levels had a greater effect on additional bronchodilator use and on irritations of the eyes, nose and throat on days on which no steroids were used. Particulate matter was associated with eye irritation only. This study showed that, although within international air quality standards, the prevailing levels of photo-oxidant and particulate pollution in spring and early summer had measurable short-term effects on children with mild-to-moderate asthma.

Abstract  The Korean peninsula has a long history of dust clouds blown by winds from the arid deserts of Mongolia and China in springtime; these are called Asian dust events. Public concern about the possible adverse effects of this dust has increased, because the dust arrives in Korea after having passed over heavily industrialized eastern China. The present study explored the effect of Asian dust events on daily mortality in Seoul, South Korea, during the period 1995-1998. We evaluated the association between daily death counts and the dust events using Poisson regression analysis, adjusted for time trends, weather variables, and the day of the week. Between 1995 and 1998, we identified 28 Asian dust days in Seoul. The estimated percentage increase in the rate of deaths from 3-day moving averages of exposure was 1.7% (95/ confidence interval: - 1.6 to 5.3) for all causes, 2.2% (95% confidence interval: - 3.5 to 8.3) for deaths of persons aged 65 years and older, and 4.1% (95% confidence interval: - 3.8 to 12.6) for cardiovascular and respiratory causes. Our results provide weak evidence that the Asian dust events are associated with risk of death from all causes. However, the association between the dust events and deaths from cardiovascular and respiratory causes was stronger and it suggests that persons with advanced cardiovascular and respiratory disease may be susceptible to the Asian dust events.

Abstract  This review compiles personal and indoor microenvironment particulate matter (PM) monitoring needs from recently set research objectives, most importantly the NRC published "Research Priorities for Airborne Particulate Matter (1998)". Techniques and equipment used to monitor PM personal exposures and microenvironment concentrations and the constituents of the sampled PM during the last 20 years are then reviewed. Development objectives are set and discussed for personal and microenvironment PM samplers and monitors, for filter materials, and analytical laboratory techniques for equipment calibration, filter weighing and laboratory climate control. The progress is leading towards smaller sample flows, lighter, silent, independent (battery powered) monitors with data logging capacity to store microenvironment or activity relevant sensor data, advanced flow controls and continuous recording of the concentration. The best filters are non-hygroscopic, chemically pure and inert, and physically robust against mechanical wear. Semiautomatic and primary standard equivalent positive displacement flow meters are replacing the less accurate methods in flow calibration, and also personal sampling flow rates should become mass flow controlled (with or without volumetric compensation for pressure and temperature changes). In the weighing laboratory the alternatives are climatic control (set temperature and relative humidity), and mechanically simpler thermostatic heating, air conditioning and dehumidification systems combined with numerical control of temperature, humidity and pressure effects on flow calibration and filter weighing.

Abstract  The air pollution problem can be depicted as a system consisting of several basic components: source, concentration, exposure, dose, and adverse effects. Exposure, the contact between an agent (e.g., an air pollutant) and a target (e.g., a human respiratory tract), is the key to linking the pollution source and health effects. Human exposure to air pollutants depends on exposure concentration and exposure duration. Exposure concentration is the concentration of a pollutant at a contact boundary, which usually refers to the human breathing zone. However, ambient concentrations of regulated pollutants at monitoring sites have been measured in practice to represent actual exposure. This can be a valid practice if the pollutants are ones that are predominantly generated outdoors and if the monitoring sites are appropriately selected to reflect where people are. Results from many exposure studies indicate that people are very likely to receive the greatest exposure to many toxic air pollutants not outside but inside places such as homes, offices, and automobiles. For many of these pollutants, major sources of exposure can be quite different from major sources of emission. This is because a large emission source can have a very small value of exposure effectiveness, i.e., the fraction of pollutant released from a source that actually reaches the human breathing zone. Exposure data are crucial to risk management decisions for setting priorities, selecting cost-effective approaches to preventing or reducing risks, and evaluating risk mitigation efforts. Measurement or estimate of exposure is essential but often inadequately addressed in environmental epidemiologic studies. Exposure can be quantified using direct or indirect measurement methods, depending upon the purpose of exposure assessment and the availability of relevant data. The rapidly developing battery and electronic technologies as well as advancements in molecular biology are expected to accelerate the improvement of current methods and the development of new methods for future exposure assessment.

Abstract  Exposure to fine airborne particulate matter (PM2.5) is associated with cardiovascular events and mortality in older and cardiac patients. Potential physiologic effects of in-vehicle, roadside, and ambient PM2.5 were investigated in young, healthy, nonsmoking, male North Carolina Highway Patrol troopers. Nine troopers (age 23 to 30) were monitored on 4 successive days while working a 3 P.M. to midnight shift. Each patrol car was equipped with air-quality monitors. Blood was drawn 14 hours after each shift, and ambulatory monitors recorded the electrocardiogram throughout the shift and until the next morning. Data were analyzed using mixed models. In-vehicle PM2.5 (average of 24 Ág/m3) was associated with decreased lymphocytes (û11% per 10 Ág/m3) and increased red blood cell indices (1% mean corpuscular volume), neutrophils (6%), C-reactive protein (32%), von Willebrand factor (12%), next-morning heart beat cycle length (6%), next-morning heart rate variability parameters, and ectopic beats throughout the recording (20%). Controlling for potential confounders had little impact on the effect estimates. The associations of these health endpoints with ambient and roadside PM2.5 were smaller and less significant. The observations in these healthy young men suggest that in-vehicle exposure to PM2.5 may cause pathophysiologic changes that involve inflammation, coagulation, and cardiac rhythm.

Abstract  Exposure to airborne fine particles (PM2.5) is implicated in excess of 50 000 yearly deaths in the USA as well as a number of chronic respiratory illnesses. Despite intense interest in the toxicity of PM2.5, the mechanisms by which it causes illnesses are poorly understood. Since the principal source of airborne fine particles is combustion and combustion sources generate free radicals, we suspected that PM2.5 may contain radicals. Using electron paramagnetic resonance (EPR), we examined samples of PM2.5 and found large quantities of radicals with characteristics similar to semiquinone radicals. Semiquinone radicals are known to undergo redox cycling and ultimately produce biologically damaging hydroxyl radicals. Aqueous extracts of PM2.5 samples induced damage to DNA in human cells and supercoiled phage DNA. PM2.5-mediated DNA damage was abolished by superoxide dismutase, catalase, and deferoxamine, implicating superoxide radical, hydrogen peroxide, and the hydroxyl radical in the reactions inducing DNA damage.

Abstract  During the period 29 June 1986-9 August 1986, a field health study assessing the acute health effects of air pollutants on children was conducted at a summer girls camp on the northern shore of Lake Erie in SW Ontario. Continous air pollution measurements of SO2, O3, NO(x), particulate sulfates, light scattering, and meteorological measurements including temperature, dew point, and wind speed and direction were made. Twelve-hour integrated samples of size fractioned particles were also obtained using dichotomous samplers and Harvard impactors equipped with an ammonia denuder for subsequent hydrogen ion determination. Particulate samples were analyzed for trace elements by X-ray fluorescence and Neutron Activation, and for organic and elemental carbon by a thermal/optical technique. The measured aerosol was periodically very acidic with observed 12-h averaged H+ concentrations in the range < 10-560 nmoles m-3. The aerosol H+ appeared to represent the net strong acidity after H2SO4 reaction with NH3(g). Average daytime concentrations were higher than night-time for aerosol H+, sulfate, fine mass and ozone. Prolonged episodes of atmospheric acidity, sulfate, and ozone were associated with air masses arriving at the measurement site from the west and from the southwest over Lake Erie. Sulfate concentrations measured at the lakeshore camp were more than twice those measured at inland sites during extreme pollution episodes. The concentration gradient observed with onshore flow was potentially due to enhanced deposition near the lakeshore caused by discontinuities in the meteorological fields in this region.

Abstract  The present secondary National Ambient Air Quality Standard (NAAQS) for O3, established in 1979, is based on limited information from a few field studies on vegetation and may not be protective of crop damage due to O3, alone or in combination with other pollutants. Considerable information from field studies conducted in the past decade indicate that there is poor functional correspondence between agricultural production and the air quality index of the current secondary NAAQS for O3. Because the current O3 NAAQS is based on data for extreme values of air quality, the index (or form) of the NAAQS ignores key features of hourly exposure data that are desirable and important to minimizing the risk of crop damage. Previous analyses of existing vegetation effects data indicate that exposure indices that cumulated the hourly O3 concentrations over the season, as well as preferentially weighted the higher concentrations appear to have major advantages over the mean and peak indices on the basis of statistical fits to the data. The peak-weighted, cumulative indicators whose form and level are determined from crop studies were found useful in achieving a target production level that is higher than that of the current O3 NAAQS indicator with fewer violations. These alternative air quality indicators compare favorably with the current O3 NAAQS in terms of protection against adverse welfare effects and air quality properties to better identify areas having adequate air quality.

Abstract  #At a central elementary school in the capital of Upper Austria children aged 7-10 years underwent repeated respiratory health checkups (questionnaires, diaries, spirometry). Between March and May 2001 the daily means of the signals of a diffusion charging sensor, measuring the "active surface" of suspended particles, and a photoelectric aerosol sensor, measuring the particle-bound polycyclic aromatic hydrocarbons, were related to spirometric results of the total 164 children examined and to the daily symptom scores of a susceptible subgroup. Significant reductions of forced vital capacity (p=0.006) and forced expiratory volume in the first second (p=0.001) and significant increases of wheezing (p=0.001), shortness of breath (p=0.041), cough in the evening (p=0.031) and at night (p=0.018) were found with increase of "active surface" of suspended particles measured at the adjacent outdoor monitoring station, but not with the increase of particle-bound polycyclic aromatic hydrocarbons. Monitoring "active surface" of particles with diameters of about 10 nm-1 m by means of a diffusion charging sensor might provide additional information in surveillance of particulate matter for prevention of acute effects on respiratory health.

Abstract  Toluene exposure was studied in 62 male rotogravure printers, employed in three plants. The exposure level as measured by personal sampling during a week ranged from 8 to 1080 mg/m3 (median 96). The concentration of toluene in venous blood sampled directly after work correlated significantly with the time-weighted average (TWA) for toluene in air during the preceding workshift (n = 57, Spearman's r = 0.84, P less than 0.00001). The post-shift toluene level in venous blood is usable for biological monitoring of exposure. An air level of 100 mg/m3 corresponds to an average blood toluene level of 2.9 mumol/l; an air level of 300 mg/m3 to 8.2 mumol/l. The elimination of toluene is slow. Thus, toluene was detected in most Monday pre-shift blood samples and the levels increased statistically significantly during the work week (median 0.21 versus 0.42 mumol/l, P less than 0.0001). The toluene level in venous blood sampled directly before work on Thursday/Friday was found to be a function of the estimated mean exposure during the work week. In a multiple linear regression analysis, the mean exposure during the week was a good predictor for the concentration of toluene in venous blood before work at the end of the week (n = 52, r = 0.71). Thus, pre-shift blood values at the end of the week can be used as a biological index for the weekly exposure, when the variation of the ambient toluene concentration is known. The slow decrease of toluene in venous blood was followed in six workers for two weeks after cessation of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)