SEARCH · PubMed Health

Results for “Particulate Matter”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources

PubMed1993

Effects on thyroid hormone metabolism and depletion of lung vitamin A in rats by airborne particulate matter.

Thyroxine (T4) and vitamin A are important regulators of normal epithelial differentiation and proliferation and might act in the promotion phase of carcinogenesis. Thyroid hormone and vitamin A metabolism are linked by a common plasma carrier protein, transthyretin (TTR). Polychlorinated biphenyls (PCBs) and related organochlorine compounds deplete vitamin A and thyroxine by interaction with TTR and alteration of their metabolism in hepatic and other organs. In the present report an outdoor airborne particulate matter (APM) extract was tested for both interaction with thyroid hormone and vitamin A metabolism, in order to address the question of whether APM has the potency to deplete vitamin A and thyroid hormones. Furthermore, studies were performed to characterize compounds present in APM that interact with TTR. A third aim was to compare the interaction of APM extracts with TTR and thyroxine-binding globulin (TBG), the major carrier protein for thyroxine in humans. Results showed that a single treatment of rats with an outdoor APM extract depleted plasma thyroxine and triiodothyronine levels and increased plasma retinol levels gradually over the time period studied, while liver retinol, lung retinol, and retinyl palmitate levels were depleted by 30-50%. As outdoor APM was able to inhibit T4-TTR binding in vitro, this suggests that the reduction in thyroxine levels in vivo is caused by the same phenomenon. Experiments showed that the neutral fraction of the APM extract accounted for most of the inhibitory activity on T4-TTR binding. Polycyclic aromatic hydrocarbons and nitrated derivatives are not likely to be responsible for the activity of the neutral fraction, because several representatives of these compounds showed no or very little interaction with TTR. Pentachlorophenol, a compound with known inhibitory activity on T4-TTR binding, was detected in the organic acid fraction of both a cigarette smoke sample and an outdoor APM sample. Finally, it was shown that several indoor and outdoor APM extracts only interact with TTR, but not with TBG. As APM has the potency to deplete lung vitamin A in vivo and vitamin A might have a protective effect in the process of lung carcinogenesis, APM might increase the susceptibility for the development of lung cancer.

Aerosols↗

PubMed1992

Inhibition of binding of thyroxin to transthyretin by outdoor and indoor airborne particulate matter and effects on thyroid hormone and vitamin A metabolism in rats.

Previous studies have indicated that chemicals, e.g., hydroxylated polychlorinated biphenyls (PCBs) decrease plasma thyroxin levels through interaction with transthyretin. As a consequence, plasma vitamin A and thyroxin are depleted. Both thyroxin and vitamin A are important regulators of normal epithelial differentiation and proliferation and might act in the promotion phase of carcinogenesis. In the present report, extracts of indoor and outdoor airborne particulate matter (APM), originating from different pollution sources, were tested for a possible interaction in vitro and in vivo with thyroxin and vitamin A. Results indicated that all APM extracts significantly interfered with thyroxin binding to transthyretin. In all cases, the more polluted samples inhibited binding more than the corresponding control samples. Exposure of rats to a cigarette smoke extract induced clear changes in plasma thyroxin and triiodothyronin hormone levels. Triiodothyronin levels were reduced most. Effects on plasma vitamin A levels were also found, but these were less clear. In addition a decrease in lung vitamin A levels was found, but this decrease was not statistically significant. Exposure of rats to an outdoor APM extract induced significant changes in plasma triiodothyronin levels. Effects on thyroxin levels were not significant, although the same trend was seen as for the cigarette smoke APM extract. No changes in plasma or liver vitamin A concentrations were induced by the outdoor APM extract. Lung vitamin A levels were decreased, but again this decrease was not statistically significant. Taken together, the present report shows that APM extracts have the potency to interfere with thyroid hormone metabolism both in vitro and in vivo and probably with vitamin A metabolism as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗

PubMed2004

Time-series studies of particulate matter.

Studies of air pollution and human health have evolved from descriptive studies of the early phenomena of large increases in adverse health effects following extreme air pollution episodes to time-series analyses based on the use of sophisticated regression models. In fact, advanced statistical methods are necessary to address the challenges inherent in the detection of a relatively small pollution risk in the presence of potential confounders. This paper reviews the history, methods, and findings of the time-series studies estimating health risks associated with short-term exposure to particulate matter (PM), though much of the discussion is applicable to epidemiological studies of air pollution in general. We review the critical role of epidemiological studies in setting regulatory standards and the history of PM epidemiology and time-series analysis. We also summarize recent time-series results and conclude with a discussion of current and future directions of time-series analysis of particulates, including research on mortality displacement and the resolution of results from cohort and time-series studies.

Air Pollutants↗

PubMed2000

Immune biomarkers in relation to exposure to particulate matter: a cross-sectional survey in 17 cities of Central Europe.

Human population data on air pollution and its effects on the immune system are scarce. A survey was conducted within the framework of the Central European Study of Air Quality and Respiratory Health (CESAR) to measure a panel of immune biomarkers in children of Bulgaria, Czech Republic, Hungary, Poland, Romania, and Slovakia. Seventeen cities were chosen to represent a wide range of exposure to outdoor air pollution. In each, ambient particulate matter of less than 10 microns diameter and less than 2.5 microns diameter (PM10 and PM2.5) were measured with a Harvard impactor. Blood was collected from 366 school children aged 9 to 11 yr between 11 April and 10 May 1996. The percentage of B, total T, CD4+, CD8+, and natural killer (NK) lymphocytes was determined by flow cytometry (Becton Dickinson); total immunoglobulins of class G, M, A and E (IgG, IgM, IgA, and IgE) were measured in serum using nephelometry (Behring). Associations between PM and each log-transformed biomarker concentration were studied by linear regression, in a two-stage model. The yearly average concentrations varied from 41 to 96 micrograms/m3 for PM10 across the 17 study areas, from 29 to 67 micrograms/m3 for PM2.5, and from 12 to 38 micrograms/m3 for PM10-2.5 (coarse). Number of B, CD4+, CD8+, and NK lymphocytes increased with increasing concentration of PM, having adjusted for age, gender, parental smoking, laboratory of analysis, and recent respiratory illness. Differences in lymphocyte number were larger and statistically significant for exposure to PM2.5. Similar results were found when we examined the association between PM and lymphocyte number separately for each laboratory. Total IgG was increased with increasing concentration of PM, significantly in the case of PM2.5. When we repeated the analyses with two other statistical approaches the results did not differ from those reported here. The effect of coarse PM on lymphocyte numbers appears small in comparison to PM2.5. One possible interpretation of our findings is that long-term exposure to airborne particulates leads to inflammation of the airways and activation of the cellular and humoral immune system.

Air Pollutants↗

PubMedDate not supplied

Carbonaceous aerosol in the breathable particulate matter (PM10) in urban area.

Carbonaceous material is a large fraction of urban aerosol and it is classified into Elemental Carbon (EC) and Organic Carbon (OC). EC particles are emitted from combustion sources. Because most combustion sources are anthropogenic and generally EC does not undergo chemical transformations, EC is a good indicator of primary anthropogenic primary pollution. OC particles species are emitted from primary emission sources either anthropogenic or biogenic sources. In this paper we have measured the ground concentration of Particulate Matter (PM), Total Carbon (TC), EC and OC in two Monitoring Stations in Rome. The first station is situated downtown Rome (near S.M. Maggiore Cathedral) where the traffic emission flux is strong. The second station is located in the inner a green park (Villa Ada Park): this site is not directly influenced by anthropogenic emissions. The results show that in Rome the TC contribution is about 30% of PM and the OC/EC vary between 0.5 and 1.5 according to the site we are considering. About the chemical particle composition the long-chain carboxylic have been identified as major constituent of organic aerosol and a range values are reported for two important compound class, the Polyciclic Aromatic Hydrocarbons and the nitro-PAHs wich are at very low levels.

Aerosols↗

PubMed1999

Health-related monitoring and assessment of airborne particulate matter. An overview of recent IAEA programs.

Since 1992, the International Atomic Energy Agency (IAEA) has been promoting studies of air pollution using a standard design of air sampler that provides separation on filters into two size fractions with cutoffs of 2.5 and 10 microns (approximately). These are the size ranges presently considered to have the most important health consequences. Such filter samples are highly amenable to analysis using nuclear and related techniques. After reviewing some of the health effects of airborne particulate matter and current air quality standards and guidelines, this article provides an overview of current and recent IAEA programs in this area, which involve collaborative activities with participants in more than 40 countries.

Air Pollutants↗

PubMed1999

Statistical considerations in determining the health significance of constituents of airborne particulate matter.

Because of the U.S. Environmental Protection Agency's (EPA) new ambient air quality standard for fine particles, the need is likely to continue for more detailed scientific investigation of various types of particles and their effects on human health. Epidemiology studies have become the method of choice for investigating health responses to such particles and to other air pollutants in community settings. Health effects have been associated with virtually all of the gaseous criteria pollutants and with the major constituents of airborne particulate matter (PM), including all size fractions less than about 20 microns, inorganic ions, carbonaceous particles, metals, crustal material, and biological aerosols. In many of the more recent studies, multiple pollutants or agents (including weather variables) have been significantly associated with health responses, and various methods have been used to suggest which ones might be the most important. In an ideal situation, classical least-squares regression methods are capable of performing this task. However, in the real world, where most of the pollutants are correlated with one another and have varying degrees of measurement precision and accuracy, such regression results can be misleading. This paper presents some guidelines for dealing with such collinearity and model comparison problems in both single- and multiple-pollutant regressions. These techniques rely on mean effect (attributable risk) rather than statistical significance per se as the preferred indicator of importance for the pollution variables.

Air Pollution↗

PubMed2006

CD28 in thymocyte development and peripheral T cell activation in mice exposed to suspended particulate matter.

The CD28:B7 signaling pathway is very important for the activity of mature peripheral T lymphocytes and thymocyte development. The proper development of thymocytes into mature single positive CD4+and CD8+ T cells is crucial for almost all immune functions. In naturally occurring conditions, T cells maturation in the thymus is influenced by environmental agents. The expression of CD28 and the distribution of CD28(low/high) thymocytes have been examined at various stages of thymocyte development in BALB/c mice exposed to air-suspended particulate matter (ASM). Acute exposure to ASM resulted in the decrease of CD28 expression in the total thymocyte population. The increase of the percentage of CD28(low) and the decrease of CD28(high) thymocytes were observed, which may account for the acceleration of thymocyte development under the conditions of elevated risk resulting from the exposure of animals to environmental xenobiotics. ASM exposure resulted in the increase of the level of proliferation of lymph node T cells induced by anti-CD3 and anti-CD28 monoclonal antibodies activation despite normal expression of CD28 molecule. In contrast, the level of proliferation of spleen T cells was lowered or normal dependently of the concentration of stimuli used for activation. Results of these studies demonstrate that acute exposure of mice to ASM can result in the progression of two contrasting processes in the immune system: upregulation of thymocyte development, which contributes to the maintenance of peripheral T cell pool, and over-activation of lymph node lymphocytes, which may lead to uncontrolled immunostimulation.

Air Pollutants↗

PubMed1996

The increase in hay fever: pollen, particulate matter and SO2 in ambient air.

To investigate whether the rise in allergic disease is explicable on the basis of an increase in the concentrations of allergen and urban air pollutants to which the population has been exposed, we compared the concentrations of grass pollen, sulphur dioxide and black smoke to which two samples of children with previously measured prevalences of hay fever had been exposed, in Cardiff, South Glamorgan. In these studies there had been a 59% increase in the prevalence of hay fever among 12 year old school children between 1973 and 1988. Exposures to grass pollen of the two populations had been no different, but the earlier sample, with the lower prevalence of hay fever, had been exposed to substantially higher concentrations of ambient particulate matter and sulphur dioxide. The rise in prevalence of hay fever, occurring without a rise in grass pollen concentrations, supports the hypothesis that the population has become more susceptible to airborne allergen. This increased susceptibility is unlikely to be a consequence of concomitant exposure to sulphur dioxide and particulate air pollution.

Air Pollutants↗

PubMed2003

Chemical characteristics of airborne particulate matter near major roads and at background locations in Macao, China.

PM10 and PM2.5 samples were collected near major roads and at the background locations in Macao using a TEOM1400a+ACCU system. The chemical analysis of these particles indicated the presence of 36 elements, water-soluble ions and carbonaceous species. The greatest contributors to total PM10 and PM2.5 mass were OC, sulfate, nitrate, ammonium, EC, Na, Cl and crustal elements including Si, Ca, Al, Fe, K and Mg. Organic material is the largest single fraction of airborne particulate matter in Macao. It contributes 32.8-41.5% and 38.2-48.4% of PM10 and PM2.5 at the roadsides, and as high as 29.7% and 33.4-39.4% of PM10 and PM2.5 at background locations, respectively. EC contributes 3.7-7.8% and 8.0-12.9% of PM10 and PM2.5, and crustal material is 10.2-15.4% and 7.6-12.2% of PM10 and PM2.5 near major roads, respectively. The share of EC at background locations is much lower than that at the roadsides, however, the contribution of crustal material is the same in both locations. At the roadsides, secondary aerosols, including sulfate, nitrate and ammonium, account for 16.6-29.0% and 15.8-38.0% of the total PM10 and PM2.5, respectively, as compared to 29.1-36.2% and 23.2-33.8% of total PM10 and PM2.5, respectively, at background locations. In PM2.5, Na and Cl contribute 1-3%, while the average amount of these two elements increase to 1-15% of the total PM10 in Macao.

Journal Article↗

PubMed2006

Impact of banning of two-stroke engines on airborne particulate matter concentrations in Dhaka, Bangladesh.

Vehicular air pollution is common in growing metropolitan areas throughout the world. Vehicular emissions of fine particles are particularly harmful because they occur near ground level, close to where people live and work. Two-stroke engines represented an important contribution to the motor vehicle emissions where they constitute approximately half of the total vehicle fleet in Dhaka city. Two-stroke engines have lower fuel efficiency than four-stroke engines, and they emit as much of an order of magnitude and more particulate matter (PM) than four-stroke engines of similar size. To eliminate their impact on air quality, the government of Bangladesh promulgated an order banning all two-stroke engines from the roads in Dhaka starting on December 31, 2002. The effect of the banning of two-stroke engines on airborne PM was studied at the Farm Gate air quality-monitoring station in Dhaka (capital of Bangladesh), a hot spot with very high-pollutant concentrations because of its proximity to major roadways. The samples were collected using a "Gent" stacked filter unit in two fractions of 0-2.2 microm and 2.2-10 microm sizes. Samples of fine and coarse fractions of airborne PM collected from 2000 to 2004 were studied. It has been found that the fine PM and black carbon concentrations decreased from the previous years because of the banning of two-stroke engine baby taxies.

Air Pollutants↗

PubMed2005

Interaction between ozone and airborne particulate matter in office air.

UNLABELLED: This study investigated the hypotheses that humans are affected by air pollution caused by ozone and house dust, that the effect of simultaneous exposure to ozone and dust in the air is larger than the effect of these two pollutants individually, and that the effects can be measured as release of cytokines and changes of the respiratory function. Experimental exposures of eight atopic but otherwise healthy subjects were performed in a climate chamber under controlled conditions. The three controlled exposures were about 75 microg/m3 total suspended particulate matter, 0.3 p.p.m. ozone, and the combination of these. The exposure duration was 3 h. The outcome measures were interleukins and cells in nasal lavages (NAL), respiratory function, bronchial metacholine responsiveness, rhinometry symptoms and general well-being in a questionnaire and time course of general irritation on a visual analogue scale. Indications of interactions between exposure types were demonstrated for peak expiratory flow (PEF) (P<0.05) and for discomfort symptoms (P<0.03). Non-significant interactions were found for the concentration of interleukin-8 in NAL. The combined exposure was found to cause significantly more effects than either ozone exposures or dust exposures. This is interpreted as indications of a potentiation caused by the combined exposures to dust and ozone. The findings in this study are based on a limited number of subjects and thus should not be over-interpreted. However, they support the hypothesis that ozone at relatively high concentrations interacts with dust exposures to cause decrements in PEF and increase in discomfort measures. PRACTICAL IMPLICATIONS: If confirmed at lower ozone and dust concentrations this finding could help to explain many problems with indoor air quality reported in offices throughout the world.

Adult↗

PubMed2005

Short term effects of particulate matter on cause specific mortality: effects of lags and modification by city characteristics.

BACKGROUND: Consistent evidence has shown increased all-cause mortality, and mortality from broad categories of causes associated with airborne particles. Less is known about associations with specific causes of death, and modifiers of those associations. AIMS: To examine these questions in 20 US cities, between 1989 and 2000. METHODS: Mortality files were obtained from the National Center for Health Statistics. Air pollution data were obtained from the Environmental Protection Agency website. The associations between daily concentrations of particulate matter of aero-diameter < or =10 microm (PM10) and daily mortality from all-cause and selected causes of death, were examined using a case-crossover design. Temporal effects of PM10 were examined using lag models, in first stage regressions. City specific modifiers of these associations were examined in second stage regressions. RESULTS: All-cause mortality increased with PM10 exposures occurring both one and two days prior the event. Deaths from heart disease were primarily associated with PM10 on the two days before, while respiratory deaths were associated with PM10 exposure on all three days. Analyses using only one lag underestimated the effects for all-cause, heart, and respiratory deaths. Several city characteristics modified the effects of PM10 on daily mortality. Important findings were seen for population density, percentage of primary PM10 from traffic, variance of summer temperature, and mean of winter temperature. CONCLUSIONS: There was overall evidence of increased daily mortality from increased concentrations of PM10 that persisted across several days, and matching for temperature did not affect these associations. Heterogeneity in the city specific PM10 effects could be explained by differences in certain city characteristics.

Air Pollutants↗

PubMed2005

Characterization of model error in a simulation of fine particulate matter exposure distributions of the working age population in Helsinki, Finland.

Exposure models are needed for comparison of scenarios resulting from alternative policy options. The reliability of models used for such purposes should be quantified by comparing model outputs in a real situation with the corresponding observed exposures. Measurement errors affect the observations, but if the distribution of these errors for single observations is known, the bias caused for the population statistics can be corrected. The current paper does this and calculates model errors for a probabilistic simulation of 48-hr fine particulate matter (PM2.5) exposures. Direct and nested microenvironment-based models are compared. The direct model requires knowledge on the distribution of the indoor concentrations, whereas the nested model calculates indoor concentrations from ambient levels, using infiltration factors and indoor sources. The model error in the mean exposure level was <0.5 microg m(-3) for both models. Relative errors in the estimated population mean were +1% and -5% for the direct and nested models, respectively. Relative errors in the estimated SD were -9% and -23%, respectively. The magnitude of these errors and the errors calculated for population percentiles indicate that the model errors would not drive general conclusions derived from these models, supporting the use of the models as a tool for evaluation of potential exposure reductions in alternative policy scenarios.

Adult↗

PubMed1977

The identification of particulate matter in biological tissues and fluids.

Sections, 1-2 micron thick, of Araldite embedded tissue were prepared to provide a link between optical and electron microscopy for the identification of crystals. This technique permits examination of individual particles by means of polarising light microscopy, electron microscopy, X-ray energy spectroscopy and electron diffraction. It provides a reliable method for routine and research studies. It has led to the positive identification of individual crystals of calcium pyrophosphate dihydrate and hydroxyapatite in synovial fluids. The method can be applied to the identification of other particulate matter in a variety of biological specimens.

Aged↗

PubMed2003

A constant-volume rapid exhaust dilution system for motor vehicle particulate matter number and mass measurements.

An improved version of the constant volume sampling (CVS) methodology that overcomes a number of obstacles that exist with the current CVS dilution tunnel system used in most diesel and gasoline vehicle emissions test facilities is presented. The key feature of the new sampling system is the introduction of dilution air immediately at the vehicle tailpipe. In the present implementation, this is done concentrically through a cylindrical air filter. Elimination of the transfer hose conventionally used to connect the tailpipe to the dilution tunnel significantly reduces the hydrocarbon and particulate matter (PM) storage release artifacts that can lead to wildly incorrect particle number counts and to erroneous filter-collected PM mass. It provides accurate representations of particle size distributions for diesel vehicles by avoiding the particle coagulation that occurs in the transfer hose. Furthermore, it removes the variable delay time that otherwise exists between the time that emissions exit the tailpipe and when they are detected in the dilution tunnel. The performance of the improved CVS system is examined with respect to diesel, gasoline, and compressed natural gas vehicles.

Air Pollutants↗

PubMed2003

Distribution of chloropigments in suspended particulate matter and benthic microbial mat of a meromictic lake, Lake Kaiike, Japan.

We investigated the distribution of chloropigments in a small meromictic lake, Lake Kaiike, south-west Japan. In the water-column, concentrations of Chl a related to cyanobacteria, BChl a related to purple sulphur bacteria, and three types of BChl e homologues (BChls e1, e2 and e3) related to brown-coloured green sulphur bacteria, were maximal at the redox boundary. Below the redox boundary, absolute concentrations of Chl a and BChl a gradually decreased with depth, whereas BChls e remained rather constant. Suspended particulate matter (SPM) at the deeper region of the anoxic water-column was enriched in highly alkylated BChl e homologues compared with SPM at the redox boundary. The shift in the relative content of highly alkylated BChl e homologues beneath the boundary was associated with community related adaptation of brown-coloured green sulphur bacteria to changes in light quality/quantity, resulting from the optical absorption and reflectance of SPMs in the overlying water-column. Benthic microbial mats were characterized by high abundances of BChls e, in which highly alkylated homologues were substantially abundant. This suggests that the BChls e in the microbial mat may be derived from the low-light adapted brown-coloured green sulphur bacteria forming the bacterial mat.

Bacteriochlorophyll A↗

PubMed2005

Fine (PM2.5) and coarse (PM2.5-10) particulate matter on a heavily trafficked London highway: sources and processes.

A large dataset for PM2.5 and PMcoarse (PM2.5-10) concentrations monitored near a busy London highway (Marylebone Road) has been analyzed to define the factors that lead to high concentrations. The following have been highlighted as major influencing parameters: wind speed, prevailing wind direction (because of its role on the microscale dispersion within the street), the daily cycle of the atmospheric boundary layer (stable during the night/ convective and mixed during the day), and traffic density. The mainly diesel heavy-duty vehicles are the main source of fine particulate matter at Marylebone Road. In particular, lorries (trucks) dominate PM10 exhaust emissions which are mainly in the fine (<2.5 microm) size range. A strong correlation with PMcoarse suggests that the heavy-duty traffic is largely responsible for this component also. Substantial local increments in PM2.5 and PMcoarse due to traffic have been estimated and a large part of the increment in PMcoarse concentrations is inferred to arise from resuspended road dust emissions since the contribution of abrasion processes estimated from emission factors is modest. Despite the strong influence of traffic on PM concentrations measured at Marylebone Road the analysis of factors leading to the highest 5% of hourly concentrations of PM10 at Marylebone Road reveals that almost half of these events were due to building works. The other events occurred when all or most of the key factors occurred simultaneously (heavy traffic, poor dispersion, etc.). Some episodes of high PM2.5 concentrations were associated with long-range transport in which the regional PM2.5 constituted most of the local concentrations.

Air Pollutants↗