PM10 elemental composition and acute respiratory health effects in European children (PEACE project). Pollution Effects on Asthmatic Children in Europe

Nickel in ambient particulate matter and respiratory or cardiovascular outcomes: A critical review

Exposure to ambient particulate matter (PM) has been associated with respiratory and cardiovascular outcomes, and nickel has been more frequently associated with these outcomes than other metal constituents of ambient PM. Because of this, we evaluated whether the evidence to date supports causal relationships between exposure to nickel in ambient PM and respiratory or cardiovascular outcomes. We critically reviewed 38 studies in human populations published between 2012 and 2022. Although a large variety of respiratory and cardiovascular outcomes were examined, data were sparse for many. As a result, we focused our evaluation on seven respiratory outcomes and three cardiovascular outcomes that were each examined in ≥3 studies. Of these health outcomes, exposure to nickel in ambient PM has been statistically significantly associated with respiratory mortality, respiratory emergency hospital visits, asthma, lung function (i.e., forced expiratory volume in 1 s, forced vital capacity), cardiovascular mortality, and ischemic heart disease mortality. Studies of the health outcomes of focus are subject to multiple methodological limitations, primarily ecological fallacy (short-term exposure studies), exposure measurement error, confounding, model misspecification, and multiple comparisons issue. While some statistically significant associations were reported, they were not strong, precise, or consistent. Statistically significant findings for long-term exposure to nickel in PM were largely reported in studies that could not establish temporality, despite their cohort study design. Statistically significant findings for short-term exposure to nickel in PM were largely reported in studies that could establish temporality, although this cannot inform causal inference at the individual level due to the aggregate level data used. The biological plausibility of the associations is only supported at high concentrations not relevant to ambient exposures. Overall, the literature to date does not provide adequate support for a causal relationship between nickel in ambient PM and respiratory or cardiovascular outcomes.

Short-term effects of the chemical components of fine particulate matter on pulmonary function: A repeated panel study among adolescents

The effects of the chemical components of fine particulate matter (PM2.5) have been drawing attention. However, information regarding the impact of low PM2.5 concentrations is limited. Hence, we aimed to investigate the short-term effects of the chemical components of PM2.5 on pulmonary function and their seasonal differences in healthy adolescents living on an isolated island without major artificial sources of air pollution. A panel study was repeatedly conducted twice a year for one month every spring and fall from October 2014 to November 2016 on an isolated island in the Seto Inland Sea, which has no major artificial sources of air pollution. Daily measurements of peak expiratory flow (PEF) and forced expiratory volume in 1 s (FEV1) were performed in 47 healthy college students, and the concentrations of 35 chemical components of PM2.5 were analyzed every 24 h. Using a mixed-effects model, the relationship between pulmonary function values and concentrations of PM2.5 components was analyzed. Significant associations were observed between several PM2.5 components and decreased pulmonary function. Among the ionic components, sulfate was strongly related to decreases in PEF and FEV1 (-4.20 L/min [95 % confidence interval (CI): -6.40 to -2.00] and - 0.04 L [95 % CI: -0.05 to -0.02] per interquartile range increase, respectively). Among the elemental components, potassium induced the greatest reduction in PEF and FEV1. Therefore, PEF and FEV1 were significantly reduced as the concentrations of several PM2.5 components increased during fall, with minimal changes observed during spring. Several chemical components of PM2.5 were significantly associated with decreased pulmonary function among healthy adolescents. The concentrations of PM2.5 chemical components differed by season, suggesting the occurrence of distinct effects on the respiratory system depending on the type of component.

Could soluble minerals be hazardous to human health? Evidence from fibrous epsomite

From a toxicological point of view, particulates and fibres with high solubility in water and/or in biological environments have not been considered in detail and the knowledge to date in this area is very scarce. In this study, the water-soluble natural epsomite fibres from Perticara Mine (Italy) were investigated using SEM-EDS, XRPD, ICP-AES and alpha spectrometry measurements which were combined and integrated to characterise the fibres' morphology, crystal chemistry and mineralogy. The morphological and morphometric results showed that most of the fibres are of inhalable size (D_ae 5.09 μm) and can be potentially adsorbed from all parts of the respiratory tract. Chemical analysis reveals significant amounts of toxic elements (As, Co, Fe, Mn, Ni, Sr, Ti, Zn) and surprisingly high contents of radioactive isotopes (²¹⁰Po and ²²⁸Th) in epsomite crystals, making the inhalation of these fibres potentially hazardous to human health. Through this study, we want to focus on soluble minerals, such as epsomite, which can be present in both natural and anthropic environments and have never been considered from the point of view of their potential hazard.

Ultrafine particles, particle components and lung function at age 16 years: The PIAMA birth cohort study

BACKGROUND

Particulate matter (PM) air pollution exposure has been linked to lung function in adolescents, but little is known about the relevance of specific PM components and ultrafine particles (UFP).

OBJECTIVES

To investigate the associations of long-term exposure to PM elemental composition and UFP with lung function at age 16 years.

METHODS

For 706 participants of a prospective Dutch birth cohort, we assessed associations of forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) at age 16 with average exposure to eight elemental components (copper, iron, potassium, nickel, sulfur, silicon, vanadium and zinc) in PM_2.5 and PM₁₀, as well as UFP during the preceding years (age 13-16 years) estimated by land-use regression models. After assessing associations for each pollutant individually using linear regression models with adjustment for potential confounders, independence of associations with different pollutants was assessed in two-pollutant models with PM mass and NO₂, for which associations with lung function have been reported previously.

RESULTS

We observed that for most PM elemental components higher exposure was associated with lower FEV₁, especially PM₁₀ sulfur [e.g. adjusted difference -2.23% (95% confidence interval (CI) -3.70 to -0.74%) per interquartile range (IQR) increase in PM₁₀ sulfur]. The association with PM₁₀ sulfur remained after adjusting for PM₁₀ mass. Negative associations of exposure to UFP with both FEV₁ and FVC were observed [-1.06% (95% CI: -2.08 to -0.03%) and -0.65% (95% CI: -1.53 to 0.23%), respectively per IQR increase in UFP], but did not persist in two-pollutant models with NO₂ or PM_2.5.

CONCLUSIONS

Long-term exposure to sulfur in PM₁₀ may result in lower FEV₁ at age 16. There is no evidence for an independent effect of UFP exposure.

Innovative Characterization of Particulate Matter Deposited on Urban Vegetation Leaves through the Application of a Chemical Fractionation Procedure

In this study, we have evaluated the efficiency of a chemical fractionation procedure for the characterization of both the water-soluble and the insoluble fraction of the main elemental components of particulate matter (PM) deposited on urban leaves. The proposed analytical approach is based on the chemical analysis of leaf washing solutions and membrane filters used for their filtration. The ionic concentration of leaf washing solutions was compared with their electrical conductivity, making it a valuable proxy for the quantification of the water-soluble and ionic fraction of leaf deposited PM. The chemical composition of both the water-soluble and the insoluble fraction of PM, resulting from this fractionation procedure, was compared with results obtained by scanning electron microscopy coupled with energy-dispersed X-Rays spectroscopy (SEM/EDX) and processed through chemometrics. Results obtained proved that the proposed approach is able to provide an estimation of total leaf deposited PM and it is highly reliable for the evaluation of the emission impact of different PM sources, being able to increase the selectivity of PM elemental components as specific source tracers; consequently providing useful information also for the assessment of human health risks.

Effects of ambient air pollution on daily hospital admissions for respiratory and cardiovascular diseases in Bangkok, Thailand

BACKGROUND

Although health effects of air pollutants are well documented in many countries especially in North America and Western Europe, few studies have been conducted in Thailand where pollution mix, weather conditions, and demographic characteristics are different. The present study aimed to investigate the effects of ambient air pollution on hospital admissions for cardiovascular and respiratory diseases in Bangkok, Thailand.

METHODS

We obtained daily air pollution concentration (O₃, NO₂, SO₂, PM₁₀, and CO) and weather variable monitored in Bangkok from January 2006 to December 2014. Daily hospital admissions for cardiovascular and respiratory diseases were obtained from the National Health Security Office during the study period. A time-series analysis with generalized linear model was used to examine the effects of air pollution on hospital admissions by controlling for long-term trend and other potential confounders. The effect modification by age (0-14 years, 15-64 years, ≥65 years) and gender was also examined.

RESULTS

An increase of 10 μg/m³ in O₃, NO₂, SO₂, PM₁₀, and 1 mg/m³ in CO at lag 0-1 day was associated with a 0.14% (95% CI: -0.34 to 0.63), 1.28% (0.87 to 1.69), 8.42% (6.16 to 10.74), 1.04% (0.68 to 1.41) and 6.69% (4.33 to 9.11) increase in cardiovascular admission, respectively; and 0.69% (95% CI: 0.18 to 1.21), 1.42% (0.98 to 1.85), 4.49% (2.22 to 6.80), 1.18% (0.79 to 1.57) and 7.69% (5.20 to 10.23) increase in respiratory admission, respectively. The elderly (≥65 years) seemed to be the most susceptible group to the effect of air pollution, whereas the effect estimate for male and female was not significantly different.

CONCLUSIONS

Results from this study contributed the evidence to support the effects of air pollution (O₃, NO₂, SO₂, PM₁₀, and CO) on hospital admissions for cardiovascular and respiratory diseases, which might be useful for public health intervention in Thailand.

Combined toxic effect of airborne heavy metals on human lung cell line A549

Many studies have demonstrated that heavy metals existing as a mixture in the atmospheric environment cause adverse effects on human health and are important key factors of cytotoxicity; however, little investigation has been conducted on a toxicological study of a metal mixture from atmospheric fine particulate matter. The objective of this study was to predict the combined effects of heavy metals in aerosol by using in vitro human cells and obtain a suitable mixture toxicity model. Arsenic, nickel, and lead were selected for mixtures exposed to A549 human lung cancer cells. Cell proliferation (WST-1), glutathione (GSH), and interleukin (IL)-8 inhibition were observed and applied to the prediction models of mixture toxicity, concentration addition (CA) and independent action (IA). The total mixture concentrations were set by an IC₁₀-fixed ratio of individual toxicity to be more realistic for mortality and enzyme inhibition tests. The results showed that the IA model was statistically closer to the observed results than the CA model in mortality, indicating dissimilar modes of action. For the GSH inhibition, the results predicted by the IA and CA models were highly overestimated relative to mortality. Meanwhile, the IL-8 results were stable with no significant change in immune reaction related to inflammation. In conclusion, the IA model is a rapid prediction model in heavy metals mixtures; mortality, as a total outcome of cell response, is a good tool for demonstrating the combined toxicity rather than other biochemical responses.

Particulate matter properties and health effects: consistency of epidemiological and toxicological studies

Identifying the ambient particulate matter (PM) fractions or constituents, critically involved in eliciting adverse health effects, is crucial to the implementation of more cost-efficient abatement strategies to improve air quality. This review focuses on the importance of different particle properties for PM-induced effects, and whether there is consistency in the results from epidemiological and experimental studies. An evident problem for such comparisons is that epidemiological and experimental data on the effects of specific components of ambient PM are limited. Despite this, some conclusions can be drawn. With respect to the importance of the PM size-fractions, experimental and epidemiological studies are somewhat conflicting, but there seems to be a certain consistency in that the coarse fraction (PM10-2.5) has an effect that should not be neglected. Better exposure characterization may improve the consistency between the results from experimental and epidemiological studies, in particular for ultrafine particles. Experimental data indicate that surface area is an important metric, but composition may play an even greater role in eliciting effects. The consistency between epidemiological and experimental findings for specific PM-components appears most convincing for metals, which seem to be important for the development of both pulmonary and cardiovascular disease. Metals may also be involved in PM-induced allergic sensitization, but the epidemiological evidence for this is scarce. Soluble organic compounds appear to be implicated in PM-induced allergy and cancer, but the data from epidemiological studies are insufficient for any conclusions. The present review suggests that there may be a need for improvements in research designs. In particular, there is a need for better exposure assessments in epidemiological investigations, whereas experimental data would benefit from an improved comparability of studies. Combined experimental and epidemiological investigations may also help answer some of the unresolved issues.

Source apportionment and water solubility of metals in size segregated particles in urban environments

Metals in atmospheric particulate matter (PM) have been associated with various adverse health effects. Different factors contributing to the characterization and distribution of atmospheric metals in urban environments lead to uncertainty of the understanding of their impact on public health. However, few studies have provided a comprehensive picture of the spatial and seasonal variability of metal concentration, solubility and size distribution, all of which have important roles in their contribution to health effects. This study presents an experimental investigation on the characteristics of metals in PM2.5 and coarse PM in two seasons from four urban sites in Hong Kong. The PM samples were extracted separately with aqua regia and water, and a total of sixteen elements were analyzed using ICP-MS and ICP-OES to determine the size segregated concentration and solubility of metals. The concentrations of major metals were distributed in similar patterns with the same order of magnitude among different urban sites. Source apportionment using Positive Matrix Factorization (PMF) indicated that three sources namely road dust, vehicular exhaust and ship emission are major contributors to the urban atmospheric metal concentrations in Hong Kong with distinctly different profiles between coarse PM and PM2.5 fractions. The individual metals were assigned to different sources, consistent with literature documentation, except potassium emerging with substantial contribution from vehicle exhaust emission. Literature data from past studies on both local and other cities were compared to the results from the present study to investigate the impact of different emission sources and control policies on metal distribution in urban atmosphere. A large variation of solubility among the metals reflected that the majority of metals in PM2.5 were more soluble than those in coarse PM indicating size dependent chemical states of metals. The data from this study provides a rich dataset of metals in urban atmosphere and can be useful for targeted emission control to mitigate the adverse impact of metallic pollution on public health.

Association of geographical distribution of air quality index and type 2 diabetes mellitus in Isfahan, Iran

Objectives:

Air pollution is a hazardous environmental problem with several adverse health effects including its impact on the development of chronic diseases as diabetes mellitus. This study aimed to investigate the association of geographical distribution of air quality index (AQI) and type 2 diabetes mellitus in an air-polluted city by using geographic information system (GIS).

Methods:

This cross-sectional study was conducted in Isfahan, Iran. The records that have been registered from 2009 to 2012 in major referral public diabetes clinics were gathered; they included data of 1467 diabetic patients. Their living area was represented with spots in the city map. AQI data were also interpolated from monitoring stations spreading around the city. The GIS maps of air pollutants and diabetes were developed and the associations were determined.

Results:

The density of diabetic population was higher in highly polluted areas compared with areas with the lower levels of air pollution. No significant correlation was documented between the distribution of diabetic patients and air pollution level throughout the city.

Conclusion:

Although the density of diabetic patients was higher in areas with higher air pollution, but the lack of association between AQI and the prevalence of diabetes might be because the air of different parts of the city was highly polluted, and we could not compare the prevalence of diabetes in areas with clean and polluted air.

Elemental composition of particulate matter and the association with lung function

BACKGROUND

Negative effects of long-term exposure to particulate matter (PM) on lung function have been shown repeatedly. Spatial differences in the composition and toxicity of PM may explain differences in observed effect sizes between studies.

METHODS

We conducted a multicenter study in 5 European birth cohorts-BAMSE (Sweden), GINIplus and LISAplus (Germany), MAAS (United Kingdom), and PIAMA (The Netherlands)-for which lung function measurements were available for study subjects at the age of 6 or 8 years. Individual annual average residential exposure to copper, iron, potassium, nickel, sulfur, silicon, vanadium, and zinc within PM smaller than 2.5 μm (PM2.5) and smaller than 10 μm (PM10) was estimated using land-use regression models. Associations between air pollution and lung function were analyzed by linear regression within cohorts, adjusting for potential confounders, and then combined by random effects meta-analysis.

RESULTS

We observed small reductions in forced expiratory volume in the first second, forced vital capacity, and peak expiratory flow related to exposure to most elemental pollutants, with the most substantial negative associations found for nickel and sulfur. PM10 nickel and PM10 sulfur were associated with decreases in forced expiratory volume in the first second of 1.6% (95% confidence interval = 0.4% to 2.7%) and 2.3% (-0.1% to 4.6%) per increase in exposure of 2 and 200 ng/m, respectively. Associations remained after adjusting for PM mass. However, associations with these elements were not evident in all cohorts, and heterogeneity of associations with exposure to various components was larger than for exposure to PM mass.

CONCLUSIONS

Although we detected small adverse effects on lung function associated with annual average levels of some of the evaluated elements (particularly nickel and sulfur), lower lung function was more consistently associated with increased PM mass.

Analytical methods for assessing metal bioaccessibility in airborne particulate matter: A scoping review

In contrast to the existence of standardized methods to assess metal bioaccessibility via the gastrointestinal route, there are no widely-accepted, established in vitro testing protocols to measure elemental solubility in the human lung. This may be attributed, in part, to the difficulty associated with simulating the lung's complex in vivo conditions. The purpose of this review is two-fold: (1) to determine how the bioaccessibility of metals associated with ambient particulate matter (PM) in the human lung has been assessed in the literature, and (2) examine the suitability and biological relevance of applied methods for the measurement of metal bioaccessibility employed to date. The review revealed that limited attention has been paid to the development and application of biologically-relevant in vitro methods to measure elemental solubility in ambient PM as a proxy for bioaccessibility in the human lung. Few studies (n=14) used synthetic lung fluids to simulate in vivo conditions, with only half extracting samples at a biologically-relevant temperature of 37°C. There was limited evidence suggesting that the use of water is less effective as a leaching agent compared to simulated lung fluids. In sum, this scoping review highlights a critical need to develop standardized methods for the systematic assessment of elemental bioaccessibility via the respiratory route. Priority should be placed on the validation of biologically-relevant methods, including the use of leaching agents and extraction parameters used, which allow for testing to be conducted in a reliable, yet cost efficient, manner.

Respiratory and cardiovascular effects of metals in ambient particulate matter: a critical review

In this review, we critically evaluated the epidemiological and toxicological evidence for the role of specific transition metals (As. Cr. Cu. Fe. Mn. Ni. Sc. Ti. V and Zn) in causing or contributing to the respiratory and cardiovascular health effects associated with ambient PM. Although the epidemiologic studies arc suggestive. and both the in vivo and in vitro laboratory studies document the toxicity of specific metals (Fe. Ni. V and Zn). the overall weight of evidence does not convincingly implicate metals as major contributors to health effects. None of the epidemiology studies that we reviewed conclusively implicated specific transition metals as having caused the respiratory and cardiovascular effects associated with ambient levels of PM. However, the studies reviewed tended to be internal ly consistent in identifying some metals (Fe, Ni, V and Zn) more frequently than others (As, Cu, Mn and Sc) as having positive associations wi th health effects. The major problem wi th which the epidemiological studies were faced was classifying and quantifying exposure. Community and population exposures to metals or other components of ambient PM were inferred from centrally- located samplers that may not accurately represent individual level exposures. Only a few authors reported findings that did not support the stated premise of the study; indeed, statistic ally significant associations are not necessarily biologically significant. It is likely that ·'negative studies" are under-represented in the published literature, making it a challenge to achieve a balanced evaluation of the role of metals in causing health effects associated with ambient PM. Both the in vivo and in vitro study results demonstrated that individual metals (Cu. Fe. Ni. V and Zn) and extracts of metals from ambient PM sources can produce acute inflammatory responses. However. the doses administered to laboratory animals were many orders of magnitude greater than what humans experience from breathing ambient air. The studies that used intratracheal instillation have the advantage of delivering a known dose to a specific anatomical location. but arc not analogous to an inhaled dose that is distributed over the surface area of the respiratory tract. Studies. in which laboratory animals or human volunteers inhaled CAPs best represent exposures to the general human population. The in vivo and in vitro studies reviewed provide indications that the probable mechanisms involved in the respiratory and cardiac effects from high metal exposures include: an inflammatory response mediated by formation of ROS, upregulation of genes coding for inflammatory cytokines, altered expression of genes involved in cell signaling pathways and maintenance of metals homeostasis.The fact that doses of metals many orders of magnitude greater than those existing in ambient air were required to produce measurable adverse effects in animals makes it doubtful that metals play any major role in respiratory and cardiovascular effects produced from human exposure to ambient PM. We suggest that future research priorities should focus on testing at more environmentally relevant exposure levels and that any new toxicological studies be written to include dosages in units that can be easily compared to human exposure levels.

Panel studies of air pollution on children's lung function and respiratory symptoms: a literature review

OBJECTIVE

This article reviews panel studies of air pollution on children's respiratory health and proposes future research directions.

METHODS

The PubMed electronic database was used to search published original epidemiological studies in peer-reviewed journals from 2000 to November 2011. Children's age was limited to ≤18 years old. A total of 33 relevant articles were obtained, with 20 articles relating to lung function, 21 articles relating to respiratory symptoms, and 8 articles examining both.

RESULTS

Most studies suggested the adverse effects of air pollution on children's lung function and respiratory symptoms. Particles and NO(2) showed more significant results, whereas effects of SO(2) were not consistent. A few studies indicated that O(3) interacted with temperature and sometimes seemed to be a protective factor for children's respiratory health. Negative associations between air pollutants and pulmonary health were more serious in asthmatic children than in healthy subjects. However, many outcomes depended on the number of lag days. Peak expiratory flow (PEF) was the most usual measurement for children's lung function, followed by forced expiratory volume in 1 second (FEV(1)).

CONCLUSIONS

There are significant adverse effects of air pollution on children's pulmonary health, especially for asthmatics. Future studies need to examine the lag effects of air pollution on children's lung function and respiratory symptoms. Ambient temperature is predicted to change worldwide due to climate change, which will threaten population health. Further research is needed to examine the effects of ambient temperature and the interactive effects between air pollution and ambient temperature on children's lung function and respiratory symptoms.

Forecasting hourly PM(10) concentration in Cyprus through artificial neural networks and multiple regression models: implications to local environmental management

In the present work, two types of artificial neural network (NN) models using the multilayer perceptron (MLP) and the radial basis function (RBF) techniques, as well as a model based on principal component regression analysis (PCRA), are employed to forecast hourly PM(10) concentrations in four urban areas (Larnaca, Limassol, Nicosia and Paphos) in Cyprus. The model development is based on a variety of meteorological and pollutant parameters corresponding to the 2-year period between July 2006 and June 2008, and the model evaluation is achieved through the use of a series of well-established evaluation instruments and methodologies. The evaluation reveals that the MLP NN models display the best forecasting performance with R (2) values ranging between 0.65 and 0.76, whereas the RBF NNs and the PCRA models reveal a rather weak performance with R (2) values between 0.37-0.43 and 0.33-0.38, respectively. The derived MLP models are also used to forecast Saharan dust episodes with remarkable success (probability of detection ranging between 0.68 and 0.71). On the whole, the analysis shows that the models introduced here could provide local authorities with reliable and precise predictions and alarms about air quality if used on an operational basis.

[Modeling critical episodes of air pollution by PM10 in Santiago, Chile. Comparison of the predictive efficiency of parametric and non-parametric statistical models]

OBJECTIVE

To evaluate the predictive efficiency of two statistical models (one parametric and the other non-parametric) to predict critical episodes of air pollution exceeding daily air quality standards in Santiago, Chile by using the next day PM10 maximum 24h value. Accurate prediction of such episodes would allow restrictive measures to be applied by health authorities to reduce their seriousness and protect the community's health.

METHODS

We used the PM10 concentrations registered by a station of the Air Quality Monitoring Network (152 daily observations of 14 variables) and meteorological information gathered from 2001 to 2004. To construct predictive models, we fitted a parametric Gamma model using STATA v11 software and a non-parametric MARS model by using a demo version of Salford-Systems.

RESULTS

Both models showed a high correlation between observed and predicted values. However, the Gamma model predicted PM10 values below 240 μg/m³ more accurately than did MARS. The latter was more efficient in predicting PM10 values above 240 μg/m³ throughout the study period.

CONCLUSION

MARS models are more efficient in predicting extreme PM10 values and allow health authorities to adopt preventive methods to reduce the effects of these levels on the population's health. The reason for this greater accuracy may be that MARS models correct variations in the series over time, thus better fitting the curve associated with PM10 concentrations.

Is there a future for biomonitoring of elemental air pollution? A review focused on a larger-scaled health-related (epidemiological) context

The present paper focuses on biomonitoring of elemental atmospheric pollution, which is reviewed in terms of larger-scaled biomonitoring surveys in an epidemiological context. Based on the literature information, today's availability of solar-powered small air filter samplers and fibrous ion exchange materials is regarded as adequate or an even better alternative for biomonitor transplant materials used in small-scaled set-ups, but biomonitors remain valuable in larger-scaled set-ups and in unforeseen releases and accidental situations. In the latter case, in-situ biomonitoring is seen as the only option for a retrospective study: biomoniors are there before one even knows that they are needed. For biomonitoring, nuclear analytical techniques are discussed as key techniques, especially because of the necessary multi-element assessments in both source recognition and single-element interpretation. To live up to the demands in an epidemiological context, larger-scaled in-situ biomonitoring asks for large numbers of samples, and consequently, for large total sample masses, this all to ensure representation of both local situations and survey area characteristics. Possibly, this point should direct studies into new "easy-to-sample" biomonitor organisms, of which high masses and numbers may be obtained in field work, rather than continue with biomonitors such as lichens. This also means that both sample handling and processing are of key importance in these studies. To avoid problems in comparability of analytical general procedures in milling, homogenization and digestion of samples of large masses, the paper proposes to involve only few but high-quality laboratories in the total element assessment routines. In this respect, facilities that can handle large sample masses in the assessment of element concentrations are to be preferred. This all highlights the involvement of large-sample-volume nuclear facilities, which, however, should be upgraded and automated in their operation to ensure the necessary sample throughput in larger-scaled biomonitoring.

Roles of oxidative stress in signaling and inflammation induced by particulate matter

This review reports the role of oxidative stress in impairing the function of lung exposed to particulate matter (PM). PM constitutes a heterogeneous mixture of various types of particles, many of which are likely to be involved in oxidative stress induction and respiratory diseases. Probably, the ability of PM to cause oxidative stress underlies the association between increased exposure to PM and exacerbations of lung disease. Mostly because of their large surface area, ultrafine particles have been shown to cause oxidative stress and proinflammatory effects in different in vivo and in vitro studies. Particle components and surface area may act synergistically inducing lung inflammation. In this vein, reactive oxygen species elicited upon PM exposure have been shown to activate a number of redox-responsive signaling pathways and Ca(2+) influx in lung target cells that are involved in the expression of genes that modulate relevant responses to lung inflammation and disease.

Airborne particulate matter and human health: toxicological assessment and importance of size and composition of particles for oxidative damage and carcinogenic mechanisms

Air pollution has been considered a hazard to human health. In the past decades, many studies highlighted the role of ambient airborne particulate matter (PM) as an important environmental pollutant for many different cardiopulmonary diseases and lung cancer. Numerous epidemiological studies in the past 30 years found a strong exposure-response relationship between PM for short-term effects (premature mortality, hospital admissions) and long-term or cumulative health effects (morbidity, lung cancer, cardiovascular and cardiopulmonary diseases, etc). Current research on airborne particle-induced health effects investigates the critical characteristics of particulate matter that determine their biological effects. Several independent groups of investigators have shown that the size of the airborne particles and their surface area determine the potential to elicit inflammatory injury, oxidative damage, and other biological effects. These effects are stronger for fine and ultrafine particles because they can penetrate deeper into the airways of the respiratory tract and can reach the alveoli in which 50% are retained in the lung parenchyma. Composition of the PM varies greatly and depends on many factors. The major components of PM are transition metals, ions (sulfate, nitrate), organic compound, quinoid stable radicals of carbonaceous material, minerals, reactive gases, and materials of biologic origin. Results from toxicological research have shown that PM have several mechanisms of adverse cellular effects, such as cytotoxicity through oxidative stress mechanisms, oxygen-free radical-generating activity, DNA oxidative damage, mutagenicity, and stimulation of proinflammatory factors. In this review, the results of the most recent epidemiological and toxicological studies are summarized. In general, the evaluation of most of these studies shows that the smaller the size of PM the higher the toxicity through mechanisms of oxidative stress and inflammation. Some studies showed that the extractable organic compounds (a variety of chemicals with mutagenic and cytotoxic properties) contribute to various mechanisms of cytotoxicity; in addition, the water-soluble faction (mainly transition metals with redox potential) play an important role in the initiation of oxidative DNA damage and membrane lipid peroxidation. Associations between chemical compositions and particle toxicity tend to be stronger for the fine and ultrafine PM size fractions. Vehicular exhaust particles are found to be most responsible for small-sized airborne PM air pollution in urban areas. With these aspects in mind, future research should aim at establishing a cleared picture of the cytotoxic and carcinogenic mechanisms of PM in the lungs, as well as mechanisms of formation during internal engine combustion processes and other sources of airborne fine particles of air pollution.

Effects of airborne particulate matter on respiratory morbidity in asthmatic children

Background

The effects of airborne particulate matter (PM) are a major human health concern. In this panel study, we evaluated the acute effects of exposure to PM on peak expiratory flow (PEF) and wheezing in children.

Methods

Daily PEF and wheezing were examined in 19 asthmatic children who were hospitalized in a suburban city in Japan for approximately 5 months. The concentrations of PM less than 2.5 µm in diameter (PM_2.5) were monitored at a monitoring station proximal to the hospital. Moreover, PM_2.5 concentrations inside and outside the hospital were measured using the dust monitor with a laser diode (PM_2.5(LD)). The changes in PEF and wheezing associated with PM concentration were analyzed.

Results

The changes in PEF in the morning and evening were significantly associated with increases in the average concentration of indoor PM_2.5(LD) 24 h prior to measurement (-2.86 L/min [95%CI: -4.12, -1.61] and -3.59 L/min [95%CI: -4.99, -2.20] respectively, for 10-µg/m³ increases). The change in PEF was also significantly associated with outdoor PM_2.5(LD) concentrations, but the changes were smaller than those observed for indoor PM_2.5(LD). Changes in PEF and concentration of stationary-site PM_2.5 were not associated. The prevalence of wheezing in the morning and evening were also significantly associated with indoor PM_2.5(LD) concentrations (odds ratios = 1.014 [95%CI: 1.006, 1.023] and 1.025 [95%CI: 1.013, 1.038] respectively, for 10-µg/m³ increases). Wheezing in the evening was significantly associated with outdoor PM_2.5(LD) concentration. The effects of indoor and outdoor PM_2.5(LD) remained significant even after adjusting for ambient nitrogen dioxide concentrations.

Conclusion

Indoor and outdoor PM_2.5(LD) concentrations were associated with PEF and wheezing among asthmatic children. Indoor PM_2.5(LD) had a more marked effect than outdoor PM_2.5(LD) or stationary-site PM_2.5.

Aluminium and iron air pollution near an iron casting and aluminium foundry in Turin district (Italy)

This work reports the results of an environmental survey carried out in an industrial area in the Province of Turin: its main aim is to assess the levels of iron and aluminium in the outside air during the period from July to September to assess the influence of industrial activity (a cast-iron and aluminium foundry) which is interrupted during the month of August, on the level of metals present in the air. Conducting the analysis during this period of time made it possible to avoid the confounding effect of pollution due to domestic central heating. The measurements were taken from nine areas at different distances from the foundry in the area and according to the direction of the prevailing winds, as deduced from the historical data. The results of this survey show a statistically significant difference in iron and aluminium levels in the outside air in the geographic areas between the two main periods examined: during August (no foundry activity) v/s July-September (foundry activity). The values recorded are: Aluminium 0.4+/-0.45 microg/m(3) v/s 1.12+/-1.29 microg/m(3) (p<0.0001); Iron 0.95+/-0.56 microg/m(3) v/s 1.6+/-1.0 microg/m(3) (p<0.0001). There were no statistically significant differences between the nine sampling points from the point of view of the sampling sites, climate conditions and wind directions. We found no correlation with car traffic, in terms of the number of vehicles, and metals. The values of iron tended to be higher in the areas farther away from the foundry site in the areas located along the path of the prevailing winds.

Comparative overview of indoor air quality in Antwerp, Belgium

This comprehensive study, a first in Belgium, aimed at characterizing the residential and school indoor air quality of subgroups that took part in the European Community Respiratory Health Survey and the International Study of Asthma and Allergy in Childhood [Masoli M, Fabian D, Holt S, Beasley R. Global Burden of Asthma, Medical Research Institute of New Zealand, University of Southampton; 2004.] questionnaire-based asthma and related illnesses studies. The principal aim was to perform a base-line study to assess the indoor air quality in Antwerp in terms of various gaseous and particulate pollutants. Secondly, it aimed to establish correlations between these pollutants investigated, the pollutant levels in the indoor and outdoor micro-environments, findings of the previous questionnaire-based studies and an epidemiological study which ran in conjunction with this study. Lastly, these results were compared and evaluated with current indoor and ambient guidelines in various countries This paper presents selected results on PM1, PM2.5 and PM10 mass concentrations and elemental C estimates as black smoke, as well as gaseous NO(2), SO(2), O(3) and BTEX concentrations of 18 residences and 27 schools. These are related to current guidelines of Flanders, Germany, Norway, China and Canada and evaluated with reference to selected similar studies. It was found that indoor sources such as tobacco smoking and carpets, the latter causing re-suspension of dust, are responsible for elevated indoor respirable particulate matter and place school children and residents at risk. Both PM2.5 and PM10 equalled or exceeded the current guidelines adopted by Flanders, noting that 12-h and 24-h PM2.5 were compared with an annual limit value. Indoor and ambient NO(2) concentrations in the school campaign were higher than the annual EU ambient norm. The other studied pollutant levels were below the current guidelines.

Source-specific fine particles in urban air and respiratory function among adult asthmatics

Fine and ultrafine particles in ambient air are more consistently associated with severe adverse health effects than coarse particles. We assessed whether the effects of PM(2.5) on peak expiratory flow (PEF) and respiratory symptoms in asthma patients differ by the source or the chemical properties of particles. A panel of 57 adult asthmatics was followed for 181 days from November 1996 to April 1997 with 3 daily PEF measurements and diaries. Air quality, including elemental analyses of PM(2.5) filters every 2 days (n= 83), was monitored at a central site. Daily concentrations of PM(2.5) from different sources were estimated using principal component analysis and multiple linear regression. Associations of PM(2.5) from different sources with respiratory endpoints were examined using a generalized least squares autoregressive model after adjustment for covariates. PM(2.5) attributable to local combustion was consistently negatively associated with all measurements of PEF. One interquartile increase (1.3 microg/m(3)) in 5-day average concentrations of PM(2.5) attributable to local combustion was associated with an average 1.14 L/min decline in evening PEF (95% CI: -1.95 to -0.33 L/min). We also observed that PM(2.5) attributable to long-range transport was positively, and soil-derived PM(2.5) negatively, associated with PEF. No consistent associations were observed between source-specific PM(2.5) and respiratory symptoms or between individual chemical elements and any respiratory endpoints. Our results suggest that the negative effects of PM(2.5) on PEF in adult asthmatics are mainly mediated by particles related to local combustion sources.

The health relevance of ambient particulate matter characteristics: coherence of toxicological and epidemiological inferences

The aim of this article is to review progress toward integration of toxicological and epidemiological research results concerning the role of specific physicochemical properties, and associated sources, in the adverse impact of ambient particulate matter (PM) on public health. Contemporary knowledge about atmospheric aerosols indicates their complex and variable nature. This knowledge has influenced toxicological assessments, pointing to several possible properties of concern, including particle size and specific inorganic and organic chemical constituents. However, results from controlled exposure laboratory studies are difficult to relate to actual community health results because of ambiguities in simulated PM mixtures, inconsistent concentration measurements, and the wide range of different biological endpoints. The use of concentrated ambient particulates (CAPs) coupled with factor analysis has provided an improved understanding of biological effects from more realistic laboratory-based exposure studies. Epidemiological studies have provided information concerning sources of potentially toxic particles or components, adding insight into the significance of exposure to secondary particles, such as sulfate, compared with primary emissions, such as elemental and organic carbon from transportation sources. Recent epidemiological approaches incorporate experimental designs that take advantage of broadened speciation monitoring, multiple monitoring stations, source proximity designs, and emission intervention. However, there continue to be major gaps in knowledge about the relative toxicity of particles from various sources, and the relationship between toxicity and particle physicochemical properties. Advancing knowledge could be facilitated with cooperative toxicological and epidemiological study designs, with the support of findings from atmospheric chemistry.

In vitro studies of copper release from powder particles in synthetic biological media

The aim of this paper is to provide quantitative data on copper release from powder particles of different copper materials, including artificial copper patina, Cu(2)O and metallic Cu, when exposed to different synthetic biological media to simulate an inhalation scenario and/or skin contact. Generated data may contribute in risk assessment of potential health effects following exposure to and handling of various copper materials. All tests were performed in vitro to determine total copper concentrations, release rates of total copper, and to elucidate its time-dependence. The copper release process was interpreted in terms of specific surface area, surface morphology-, and composition. All powder materials show a time-dependent release process with total copper release rates less than 3 microg/cm(2) per hour at steady state conditions, for all media investigated. The importance of using relevant test media when simulating different interstitial lung conditions and difficulties encountered when comparing powder particles of essentially different properties are thoroughly discussed.

Metal release from stainless steel particles in vitro-influence of particle size

Human inhalation of airborne metallic particles is important for health risk assessment. To study interactions between metallic particles and the human body, metal release measurements of stainless steel powder particles were performed in two synthetic biological media simulating lung-like environments. Particle size and media strongly influence the metal release process. The release rate of Fe is enhanced compared with Cr and Ni. In artificial lysosomal fluid (ALF, pH 4.5), the accumulated amounts of released metal per particle loading increase drastically with decreasing particle size. The release rate of Fe per unit surface area increases with decreasing particle size. Compared with massive sheet metal, fine powder particles (<4 microm) show similar release rates of Cr and Ni, but a higher release rate of Fe. Release rates in Gamble's solution (pH 7.4), for all powders investigated, are significantly lower compared to ALF. No clear trend is seen related to particle size in Gamble's solution.

Seasonal variations in air pollution particle-induced inflammatory mediator release and oxidative stress

Health effects associated with particulate matter (PM) show seasonal variations. We hypothesized that these heterogeneous effects may be attributed partly to the differences in the elemental composition of PM. Normal human bronchial epithelial (NHBE) cells and alveolar macrophages (AMs) were exposed to equal mass of coarse [PM with aerodynamic diameter of 2.5-10 microm (PM(2.5-10)], fine (PM(2.5)), and ultrafine (PM(<0.1)) ambient PM from Chapel Hill, North Carolina, during October 2001 (fall) and January (winter), April (spring), and July (summer) 2002. Production of interleukin (IL)-8, IL-6, and reactive oxygen species (ROS) was measured. Coarse PM was more potent in inducing cytokines, but not ROSs, than was fine or ultrafine PM. In AMs, the October coarse PM was the most potent stimulator for IL-6 release, whereas the July PM consistently stimulated the highest ROS production measured by dichlorofluorescein acetate and dihydrorhodamine 123 (DHR). In NHBE cells, the January and the October PM were consistently the strongest stimulators for IL-8 and ROS, respectively. The July PM increased only ROS measured by DHR. PM had minimal effects on chemiluminescence. Principal-component analysis on elemental constituents of PM of all size fractions identified two factors, Cr/Al/Si/Ti/Fe/Cu and Zn/As/V/Ni/Pb/Se, with only the first factor correlating with IL-6/IL-8 release. Among the elements in the first factor, Fe and Si correlated with IL-6 release, whereas Cr correlated with IL-8 release. These positive correlations were confirmed in additional experiments with PM from all 12 months. These results indicate that elemental constituents of PM may in part account for the seasonal variations in PM-induced adverse health effects related to lung inflammation.

Modeling age-related particle deposition in humans

Inhalation of airborne material poses a potential health risk to various subpopulations one of which is children. Little is known about the fate of particles in the respiratory tracts of children. Modeling efforts have been limited due largely to the lack of adequate information on lung geometry during growth. Lung morphometry measurements in children and adults between 3 months and 21 years of age were used to create 5-lobe lung geometries. Each lobe had a dichotomous, symmetric branching structure and was structurally different from the other lobes. The lung geometries were used in a multiple-path particle deposition model to calculate particle deposition fractions in different regions, lobes and airway generations of the lungs. Simulated breathing patterns were representative of resting breathing. Age-dependent, semi-empirical expressions of particles losses in the nasal airways, which were based on fits to the available experimental measurements, showed larger nasal deposition in adults than in children. Predicted tracheobronchial deposition patterns were similar among different ages for a given particle size. In the alveolar region, the predicted deposition fraction varied with age such that a clear trend could not be identified. Deposition fraction in a lobe was proportional to the volume of air going to that lobe. Deposition fractions in the lower left and right lobes were similar but higher than those in the other lobes for a given particle diameter. Lobar deposition fraction adjusted for lobar lung volume or lung deposition fraction adjusted for lung volume was found to be a unique property for an individual and presented a means for age-dependent deposition comparisons. The adjusted tracheobronchial and pulmonary deposition fractions were greatest for infants and decreased with age. A similar trend was also observed for deposition fraction per unit area as a function of airway generation. The distribution of particle deposition fraction per unit surface area varied with particle size for an individual, with ultrafine particles being more uniformly distributed throughout the lungs and coarse particles depositing primarily in the first few tracheobronchial airways. The trend of particle deposition with age indicates that children, particularly infants, may be at a greater health risk from exposure to airborne particulate matter and noxious materials all other conditions being equal. The age-dependent predicted deposition fraction pattern per unit area of different size particles has implications in the calculation of inhaled reference concentrations as well as site-specific delivery of drugs and other therapeutic compounds to the lungs of patients.

In vitro effects on macrophages induced by noncytotoxic doses of silica particles possibly relevant to ambient exposure

The RAW 246.7 macrophage cell line was exposed in vitro to aged crystalline silica particles of respirable size for 24 h at a range of doses starting from 15 microg/2 x 10(6) cells, which is a realistic exposure level of macrophages in the airways of ambiently exposed individuals. The particle sample used for the experiments was prepared to mimic some aspects of ambient crystalline silica particles: size distribution, morphology, and surface reactivity. Our purpose was to determine whether a nontoxic quartz load comparable to that of ambient exposure would be able to induce macrophage activation and impairment of the phagocytic ability, factors altering the lung's capacity to deal with increased particle loads (as occurs during high-pollution episodes) or infections and affecting the local and systemic responses through the release of biologically active compounds (cytokines, reactive oxygen species, NO, isoprostanes). Exposure of RAW 264.7 cells to aged silica particles induced macrophage activation (evidenced by the morphological features observed with scanning electron microscopy and by the release of TNF-alpha and IL-6) and impairment of phagocytosis of test particles, even at noncytotoxic doses. The reduction of the phagocytic function of the cells after silica treatment was dose-dependent, as evidenced by an increase of the population of unphagocytic cells, paralleled by a decrease of the actively phagocytizing cell population. We evaluated the oxidative stress induced by aged silica particles, quantifying the peroxidation products (8-isoprostanes) in the culture media of treated cells, and found a strong release at low doses. Isoprostanes are a complex family of compounds which have been used as in vivo markers of lipid peroxidation in human disorders, but that, as far as we know, have never been evaluated in relation to airborne particulate matter exposure. Lipid peroxides are involved in various cellular events in the inflammatory response, and isoprostanes are also supposed to exert important biological actions on airway and pulmonary vascular smooth muscles and on platelets.

Particulate air pollution and panel studies in children: a systematic review

BACKGROUND

Panel studies have been used to investigate the short term effects of outdoor particulate air pollution across a wide range of environmental settings.

AIMS

To systematically review the results of such studies in children, estimate summary measures of effect, and investigate potential sources of heterogeneity.

METHODS

Studies were identified by searching electronic databases to June 2002, including those where outcomes and particulate level measurements were made at least daily for > or =8 weeks, and analysed using an appropriate regression model. Study results were compared using forest plots, and fixed and random effects summary effect estimates obtained. Publication bias was considered using a funnel plot.

RESULTS

Twenty two studies were identified, all except two reporting PM10 (24 hour mean) >50 microg x m(-3). Reported effects of PM10 on PEF were widely spread and smaller than those for PM2.5 (fixed effects summary: -0.012 v -0.063 l x min(-1) per microg x m(-3) rise). A similar pattern was evident for symptoms. Random effects models produced larger estimates. Overall, in between-study comparisons, panels of children with diagnosed asthma or pre-existing respiratory symptoms appeared less affected by PM10 levels than those without, and effect estimates were larger where studies were conducted in higher ozone conditions. Larger PM10 effect estimates were obtained from studies using generalised estimating equations to model autocorrelation and where results were derived by pooling subject specific regression coefficients. A funnel plot of PM10 results for PEF was markedly asymmetrical.

CONCLUSIONS

The majority of identified studies indicate an adverse effect of particulate air pollution that is greater for PM2.5 than PM10. However, results show considerable heterogeneity and there is evidence consistent with publication bias, so limited confidence may be placed on summary estimates of effect. The possibility of interaction between particle and ozone effects merits further investigation, as does variability due to analytical differences that alter the interpretation of final estimates.

The health effects of fossil fuel derived particles

Over the past 10 years there has been increasing evidence that particles generated by the combustion of fossil fuels adversely affect health. To what extent should paediatricians be concerned about particle pollution? This review assesses what we know, and what we still need to know about the health effects of fossil fuel particles.

Biomonitoring of trace element air pollution: principles, possibilities and perspectives

This paper discusses the biomonitoring of trace element air pollution. Much attention is given to both lichens and mosses as the dominant plant species used in biomonitoring surveys. Biomonitoring is regarded as a means to assess trace element concentrations in aerosols and deposition. This implies that the monitor should concentrate the elements of interest and quantitatively reflect its elemental ambient conditions. Environmental impact on the biomonitor's behaviour is viewed as resulting in changes in the dose-response relationships. The current literature is briefly reviewed, for plant's behaviour modelling, for laboratory studies on physiological processes responsible for accumulation, retention and release, and for field work on quantification of dose-response relationships. Monitoring of elemental atmospheric availability is presented as deriving its relevance from presumed impact on both ecosystem performance and human health; source apportionment is regarded as an important parallel result for purposes of emission regulatory management. For source apportionment, the paper argues in favor of multi-elemental determinations, supplemented by information on organic compounds and elemental chemical forms. Furthermore, the discussion points towards more explicit coupling of biomonitoring data to knowledge and databases on both emission registration, ecosystem performance and human health. This means that multidisciplinary programs should be set up, which accommodate expert inputs from biomonitoring, emission control programs, analytical chemistry, ecology, and epidemiology.

The role of outdoor air pollution and climatic changes on the rising trends in respiratory allergy

Evidence suggests that allergic respiratory diseases such as hay fever and bronchial asthma have become more common world-wide in the last two decades, and the reasons for this increase are still largely unknown. A major responsible factor could be outdoor air pollution, derived from cars and other vehicles. Studies have demonstrated that urbanization and high levels of vehicle emissions and westernized lifestyle is correlated with the increasing frequency of pollen-induced respiratory allergy. People who live in urban areas tend to be more affected by pollen-induced respiratory allergy than those from of rural areas. Pollen allergy has been one of the most frequent models used to study the interrelationship between air pollution and respiratory allergic diseases. Pollen grains or plant-derived paucimicronic components carry allergens that can produce allergic symptoms. They may also interact with air pollution (particulate matter, ozone) in producing these effects. There is evidence that air pollutants may promote airway sensitization by modulating the allergenicity of airborne allergens. Furthermore, airway mucosal damage and impaired mucociliary clearance induced by air pollution may facilitate the access of inhaled allergens to the cells of the immune system. In addition, vegetation reacts with air pollution and environmental conditions and influence the plant allergenicity. Several factors influence this interaction, including type of air pollutants, plant species, nutrient balance, climatic factors, degree of airway sensitization and hyperresponsiveness of exposed subjects.