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 1,369 records · Page 76Linked to original sources

PubMed1995

Fine particulate air pollution and mortality in two Southern California counties.

Several epidemiologic studies have reported associations between respiratory disease and particulate matter less than 2.5 microns in diameter (PM2.5) or fine particles. However, since daily fine particulate data from ambient monitors are seldom available, many studies have used estimates of PM2.5 based on visual range observed at local airports. This paper examines the impact of visibility-based estimates of PM2.5 on mortality from 1980 through 1986 in San Bernardino and Riverside Counties, located in the Los Angeles metropolitan area. Multiple regression analysis was used to isolate the effects of estimated fine particles on mortality while controlling for covariates, including season, day of week, maximum temperature, and dew point. The results are dependent on season. During the summer quarters, there was a small but statistically significant association of estimated fine particles with both total mortality (RR = 1.03, 95% CI = 1.00-1.05, evaluated at the mean PM2.5 value of 32.5 microg/m3) and respiratory-specific mortality. However, for the year taken as a whole, estimated fine particles were not associated with mortality (RR = 1.00; 95% CI = 0.99-1.02). The use of estimated fine particles introduces additional measurement error into the analysis. During the summer quarters, an effect of ozone on mortality was also detected, but this association could be due to confounding with temperature. Sensitivity analysis indicated that the fine particulate association found during the summer quarters was robust to alternative estimates deriving fine particles from visual range, alternative regression specifications, functional forms, and exposure averaging times. These findings are consistent with another recent study of mortality in Los Angeles County and add to the other findings of associations between particulate matter and various respiratory diseases outcomes.

Aged↗

PubMed2006

Comparison of two winter air quality episodes during the California Regional Particulate Air Quality Study.

The duration, strength, spatial extent, and chemical makeup of particulate matter (PM) are compared for two winter air quality episodes captured during the California Regional Particulate Air Quality Study (CRPAQS). Each episode, from the beginning of the buildup through dissolution, lasted about 3 weeks. The first episode occurred from December 14, 1999, through January 1, 2000, with peak 24-hr average fine particulate matter (PM2.5) concentrations reaching 129 microg/m3. The second episode occurred a year later, from December 18, 2000, through January 8, 2001, with peak 24-hr average PM2.5 concentrations reaching 179 microg/m3. Although similar in duration, each episode exhibited unique characteristics. One significant difference was the episode buildup rate; rapid in 1999, but slow and steady in 2000. The rapid buildup of the first episode resulted in more days with PM2.5 concentrations above the 24-hr federal standard, whereas the slow and steady increase of the second episode produced higher peaks. Spatial extent and progress also differed between the two episodes. The Northern Valley was impacted more during the December 1999 episode, and the Southern Valley during the December 2000 episode. The differences carried over into chemical composition. Ammonium nitrate dominated the PM2.5 mass during the December 1999 episode. The second episode reflected a dichotomy typical to the San Joaquin Valley, with Fresno concentrations dominated by organic and elemental carbon and the rest of the Valley concentrations dominated by ammonium nitrate. Each episode showed a regional as well as a local component. Ammonium nitrate concentrations, which result from more regional-scale secondary formation and mixing of emissions, were fairly uniform among the urban and rural sites. Carbon concentrations were always higher at urban sites than at rural sites, corresponding to the higher emissions density of primary carbon sources in urban areas.

Aerosols↗

PubMed1989

[Particulate contamination of infusion solutions and drug additives within the scope of long-term intensive therapy. 1. Energy dispersion electron images in the scanning electron microscope-REM/EDX].

During use of i.v. solutions, particulate matter may be introduced into the patient. X-ray analyses have shown that the particulate matter consists mainly of glass from ampules, rubber from stoppers of infusion bottles, and plastic from infusion sets. A new method is introduced: scanning electron microscopy-SEM- in combination with energy-dispersive X-ray analysis-EDX. using this technique all foreign particles larger than 0.8 microns can be detected and analyzed in any tissue. Especially in critically ill patients, particularly matter is deposited in the microcirculation of the lung. The particles cause a variety of pathologic changes (formation of thrombi, thromboembolization of the microcirculation, destruction of the vascular endothelium, formation of granulomas and foreign body giant cells). The adult respiratory distress syndrome could be produced or respiratory insufficiency might be aggravated following circulatory shock. It is therefore recommended that terminal in-line filters with small pore sizes be used for all i.v. solutions.

Adult↗

PubMed1995

[Prospective epidemiologic study on respiratory diseases in children in Cracow. Pilot study].

After introducing the main purpose of the project on the outdoor and indoor air quality and children's health in Cracow, the paper presents the results of the pilot study carried out in the higher polluted city area (suspended particulate matter: 51.5-74.5 micrograms/m3/year; SO2: 58.4-73.8 micrograms/m33/year) and in the less polluted area (suspended particulate matter: 31.7 micrograms/m3/year; SO2: 36.1 microgram/m3/year). The pilot study covered 171 children. There was an excess of chronic respiratory symptoms in children from the higher polluted area, but only the frequency of shortness of breath in boys and attacks of shortness of breath with wheezing in girls were significantly higher in those living in the polluted area. Spirometric indices were significantly lower in both boys and girls in the residence area with the higher air pollution level. The data on prevalence of respiratory diseases in the pilot study will be used to estimate the size of the sample needed in the other stages of the prospective study.

Air Pollution↗

PubMed2004

Urinary 8-hydroxy-2'-deoxyguanosine as a biomarker of oxidative DNA damage in workers exposed to fine particulates.

Residual oil fly ash (ROFA) is a chemically complex mixture of compounds, including metals that are potentially carcinogenic because of their ability to cause oxidative injury. In this study, we investigated the association between exposure to particulate matter with an aerodynamic mass median diameter <or= 2.5 micro m (PM2.5) and oxidative DNA damage and repair, as indicated by urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations, in a group of boilermakers exposed to ROFA and metal fumes. Twenty workers (50% smokers) were monitored for 5 days during an overhaul of oil-fired boilers. The median occupational PM2.5 8-hr time-weighted average was 0.44 mg/m3 (25th-75th percentile, 0.29-0.76). The mean +/- SE creatinine-adjusted 8-OHdG levels were 13.26 +/- 1.04 micro g/g in urine samples collected pre-workshift and 15.22 +/- 0.99 micro g/g in the post-workshift samples. The urinary 8-OHdG levels were significantly greater in the post-workshift samples than in the pre-workshift samples (p = 0.02), after adjusting for urinary cotinine levels, chronic bronchitis status, and age. Linear mixed models indicated a significant exposure-response association between PM2.5 exposure and urinary 8-OHdG levels (p = 0.03). Each 1-mg/m3 incremental increase in PM2.5 exposure was associated with an increase of 1.67 micro g/g (95% confidence interval, 0.21-3.14) in 8-OHdG levels. PM2.5 vanadium, manganese, nickel, and lead exposures also were positively associated with 8-OHdG levels (p <or= 0.05). This study suggests that a relatively young and healthy cohort of boilermakers may experience an increased risk of developing oxidative DNA injury after exposure to high levels of metal-containing particulate matter.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Residual oil fly ash amplifies allergic cytokines, airway responsiveness, and inflammation in mice.

Particulate matter (PM) air pollution may increase symptom severity in allergic asthmatics. To examine possible interaction, or greater than additive responses, between PM effects and allergic responses, an ovalbumin-sensitized and challenged (OVA) mouse model of allergic airways disease was utilized. After challenge, mice were intratracheally instilled with saline vehicle or 3 mg/kg (approximately 60 microg) residual oil fly ash (ROFA), a transition metal-rich emission source PM sample. Physiological and inflammatory responses were examined 1, 3, 8, and 15 d later. In response to intravenously administered methacholine, ROFA increased total respiratory system resistance and decreased compliance 1 d after exposure, whereas effects of OVA lasted at least 15 d after exposure. Significant interactions between OVA and ROFA were mainly observed 8 d after challenge and exposure, especially with respect to compliance. A strong interaction (p < 0.01) between OVA and ROFA exposure resulted in 8-fold (1 d) and 3-fold (3 d) increases in bronchoalveolar lavage (BAL) fluid eosinophil numbers. A similarly strong interaction (8-fold) was observed in BAL fluid interleukin-4 (IL-4) 1 d after challenge and exposure. Significant though less strong interactions were also found with respect to IL-4 and IL-5 by 3 d postchallenge/exposure. This study shows that allergen challenge and exposure to emission source particulate matter containing relatively high levels of transitions metals can interact to increase Th2 cytokine production, eosinophil recruitment, and airway hyperresponsiveness in previously sensitized mice.

Air Pollutants↗

PubMed2004

Determination of soluble aluminium concentration in alkaline humic water using atomic absorption spectrophotometry.

The steps of the standard method to determine soluble aluminium concentration are filtering, followed by acidifying, then analysing with the atomic absorption spectrophotometer (AAS). When applied to alkaline humic water, acidification gives rise to the formation of humic acid as a brown particulate matter. Of the total soluble aluminium in the original water, 49-61% forms complexes with the particulate humic acid upon acidification. Although the AAS is capable of detecting the binding aluminium, the particulate nature of humic acid easily induces inaccurate readings as a result of the non-uniform distribution of the particulate matter. A more precise analysis of soluble aluminium concentration of alkaline humic water is shown to be achievable in basicified solutions instead. Basicified solutions keep humic acid in the soluble form; hence maintain the homogeneity of the sample.

Aluminum↗

PubMed2004

Partitioning of metal species during an enriched fuel combustion experiment. speciation in the gaseous and particulate phases.

Combustion processes are the most important source of metal in the atmosphere and need to be better understood to improve flue gas treatment and health impact studies. This combustion experiment was designed to study metal partitioning and metal speciation in the gaseous and particulate phases. A light fuel oil was enriched with 15 organometallic compounds of the following elements: Pb, Hg, As, Cu, Zn, Cd, Se, Sn, Mn, V, Tl, Ni, Co, Cr, and Sb. The resulting mixture was burnt in a pilot-scale fuel combustion boiler under controlled conditions. After filtration of the particles, the gaseous species were sampled in the stack through a heated sampling tube simultaneously by standardized washing bottles-based sampling techniques and cryogenically. The cryogenic samples were collected at -80 degrees C for further speciation analysis by LT/GC-ICPMS. Three species of selenium and two of mercury were evidenced as volatile species in the flue gas. Thermodynamic predictions and experiments suggest the following volatile metal species to be present in the flue gas: H2Se, CSSe, CSe2, SeCl2, Hg(0), and HgCl2. Quantification of volatile metal species in comparison between cryogenic techniques and the washing bottles-based sampling method is also discussed. Concerning metal partitioning, the results indicated that under these conditions, at least 60% (by weight) of the elements Pb, Sn, Cu, Co, Tl, Mn, V, Cr, Ni, Zn, Cd, and Sb mixed to the fuel were found in the particulate matter. For As and Se, 37 and 17%, respectively, were detected in the particles, and no particulate mercury was found. Direct metal speciation in particles was performed by XPS allowing the determination of the oxidation state of the following elements: Sb(V), Tl(III), Mn(IV), Cd(II), Zn(II), Cr(III), Ni(II), Co(II), V(V), and Cu(II). Water soluble species of inorganic Cr, As, and Se in particulate matter were determined by HPLC/ICP-MS and identified in the oxidation state Cr(III), As(V), and Se(IV).

Air Pollutants↗

PubMed1991

An experimental model to assess the value of laser angioplasty in the management of atheromatous disease of the carotid bifurcation.

Laser angioplasty is used to vaporize atheroma in limb arteries. The present investigation was undertaken to determine the nature, size and quantity of particulate matter generated, and the appearance of the intima of a carotid artery model after laser treatment. Particulate matter was not significantly increased following treatment of 39 autopsy carotid bifurcations, but superficial plaques were vaporized and the surface of fibrous lesions glazed. It is anticipated that atheromatous carotid vessels would be rendered less thrombogenic and the risk of cerebral embolism reduced later angioplasty.

Aged↗

PubMed2000

Cytotoxicity of PM(2.5) and PM(2.5--10) ambient air pollutants assessed by the MTT and the Comet assays.

Ambient air particulate matters are classified into two distinct modes in size distribution, namely the coarse and fine particles. Correlation between high particulate concentration and adverse effects on human populations has long been recognized, however, the toxicology of these adverse effects has not been clarified. In the current report, the cytotoxic effects of the solvent-extractable organic compounds (SEOC) from fine particles smaller than 2.5 microm (PM(2.5)) and from coarse particles between 2.5-10 microm (PM(2.5-10)) were studied. Nine 24h consecutive monthly samples were tested to determine the correlation between cytotoxicity and total SEOC in two size fractions of particulate air pollution. Cytotoxicity of SEOC was measured by two micro-scale mammalian cells-based bioassays: the MTT cell proliferation assay, and the Comet assay for the detection of DNA damage. A well-defined mammalian cell line - Rat 6 rodent fibroblast was employed in the study. The SEOC extracts of air particulate matters were sub divided into two equal parts. One part was dissolved in DMSO, the other in KOH/hexane and then conjugated with bovine serum albumin to produce a lipid-soluble fraction for testing. The DMSO fraction would contain mainly the polycyclic aromatic hydrocarbons (PAH), alkanes and alkanols, while the lipid-soluble fraction would be enriched with fatty acids. The results from MTT assay showed that cytotoxicity of the PM(2.5) was much more severe than the PM(2.5-10), suggesting that toxic SEOC were confined to the fine particles. By and large, the DMSO solubles were much more toxic than the lipid solubles. The degree of cytotoxicity of the DMSO soluble samples is positively correlated to the amount of particulates present in the ambient air. For the PM(2.5), the winter samples were significantly more toxic than the summer samples in terms of cell killing, which seemed to be a direct reflection of the total loading of organic matter in the samples. Results from Comet assays showed that SEOC samples of PM(2.5) derived from winter months induced DNA damage at dosages resulting in no obvious cell killing in the MTT assay. Thus, long-term exposure to non-killing dosage of air pollutants may lead to the accumulation of DNA lesions, which may be one of the mechanisms responsible for the chronic adverse health effects of particulate air pollution.

Aerosols↗

PubMed2000

Indoor and outdoor air quality investigation at schools in Hong Kong.

Five classrooms in Hong Kong (HK), air-conditioned or ceiling fans ventilated, were chosen for investigation of indoor and outdoor air quality. Parameters such as temperature, relative humidity (RH), carbon dioxide (CO2), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), respirable particulate matter (PM10), formaldehyde (HCHO), and total bacteria counts were monitored indoors and outdoors simultaneously. The average respirable particulate matter concentrations were higher than the HK Objective, and the maximum indoor PM10 level exceeded 1000 microg/m3. Indoor CO2 concentrations often exceeded 1000 microl/l in air-conditioning and ceiling fan classrooms, indicating inadequate ventilation. Maximum indoor CO2 level reached 5900 microl/l during class at the classroom with cooling tower ventilation. Increasing the rate of ventilation or implementation of breaks between classes is recommended to alleviate the high CO2 level. Other pollution parameters measured in this study complied with the standards. The two most important classroom air quality problems in Hong Kong were PM10 and CO2 levels.

Air Pollution↗

PubMed2002

A regional atmospheric fate and transport model for atrazine. 1. Development and implementation.

The Community Multiscale Air Quality (CMAQ) modeling system is adapted to simulate the regional transport and fate of atrazine, one of the most widely used herbicides in the United States. Model chemistry and deposition are modified, and a gas-to-particle partitioning algorithm is added to accommodate semivolatile behavior. The partitioning algorithm depends on humidity, temperature, and particulate matter concentration and composition. Results indicate that gaseous atrazine will usually dominate warm season atmospheric concentrations, but particulate form can surpass gas forms when atmospheric humidity is high (> 70%) and less-acidic (pH > 2.5) aqueous aerosol component is present. Implementation of the modified CMAQ for atrazine is illustrated, and, within the limits of our current understanding, preliminary transport and fate patterns appear to be reasonable. This research represents one of the first attempts to include a gas-to-particulate matter partitioning mechanism in an Eulerian grid-model.

Air Movements↗

PubMed1987

Augmentation of elastase-induced emphysema by cigarette smoke: effects of reducing tar and nicotine content.

The effects of reducing the tar and nicotine concentration of cigarette smoke were examined in a rat model of smoke-augmented, porcine pancreatic elastase- (PPE-) induced, pulmonary emphysema. Sixty-eight female Long-Evans rats were divided approximately evenly into seven groups: control, PPE, PPE plus sham smoke, high-tar/nicotine cigarette smoke (2R1; 38.8 mg total particulate matter and 2.2 mg nicotine per cigarette), low-tar/nicotine cigarette smoke (1R4F; 10.8 mg total particulate matter and 0.8 mg nicotine per cigarette), PPE + 2R1, and PPE + 1R4F. Three days after intratracheal administration of PPE (400 IU/kg), animals in the smoke-treated groups were exposed to 8-10 puffs of cigarette smoke daily, 7 d/wk for 12 wk. Sham-treated animals received room air in place of cigarette smoke. At the conclusion of the exposures, pulmonary function tests were performed under general anesthesia. Cigarette-smoke exposure alone did not produce significant changes in pulmonary function. Elastase-treated groups demonstrated significant increases in total lung capacity, functional residual capacity, and dynamic and static compliance, as well as significant decreases in carbon monoxide (CO) diffusing capacity and CO diffusion coefficient. Morphometric measurements of mean linear intercept demonstrated a loss of alveolar fine structure with enlargement of distal airspaces in PPE-treated rats. Exposure to either 2R1 or 1R4F cigarette smoke significantly enhanced many of the emphysematous changes produced by PPE, but there were no significant differences between the effects of the two smokes. These data indicate that reducing the tar and nicotine concentration of cigarette smoke does not lessen its ability to augment PPE-induced pulmonary emphysema in the rat.

Animals↗

PubMed1982

Chlorine resistance patterns of bacteria from two drinking water distribution systems.

The relative chlorine sensitivities of bacteria isolated from chlorinated and unchlorinated drinking water distribution systems were compared by two independent methods. One method measured the toxic effect of free chlorine on bacteria, whereas the other measured the effect of combined chlorine. Bacteria from the chlorinated system were more resistant to both the combined and free forms of chlorine than those from the unchlorinated system, suggesting that there may be selection for more chlorine-tolerant microorganisms in chlorinated waters. Bacteria retained on the surfaces of 2.0-microns Nuclepore membrane filters were significantly more resistant to free chlorine compared to the total microbial population recovered on 0.2-micron membrane filters, presumably because aggregated cells or bacteria attached to suspended particulate matter exhibit more resistance than unassociated microorganisms. In accordance with this hypothesis, scanning electron microscopy of suspended particulate matter from the water samples revealed the presence of attached bacteria. The most resistant microorganisms were able to survive a 2-min exposure to 10 mg of free chlorine per liter. These included gram-positive spore-forming bacilli, actinomycetes, and some micrococci. The most sensitive bacteria were readily killed by chlorine concentrations of 1.0 mg liter-1 or less, and included most gram-positive micrococci, Corynebacterium/Arthrobacter, Klebsiella, Pseudomonas/Alcaligenes, Flavobacterium/Moraxella, and Acinetobacter.

Bacteria↗

PubMed2002

Elevated serum immunoglobulin E to Cryptomeria japonica pollen in rats exposed to diesel exhaust during fetal and neonatal periods.

BACKGROUND: The possible participation of diesel exhaust inhalation during the fetal period in the elevation of IgE against pollen in postnatal life was investigated. METHOD: The experiment was conducted using rat pups. Group I; exposed to clean air (Control). Group 2, 3; exposed to total or filtered diesel exhaust during the fetal period (Total-C-C, Filtered-C-C). Group 4, 5; exposed to total or filtered diesel exhaust during the suckling period (C-Total-C, C-Filtered-C). Group 6,7; exposed to total or filtered diesel exhaust during the weaning period (C-C-Total, C-C-Filtered). Total diesel engine exhaust contained 1.73 mg/m3 particulate matter and 0.79 ppm nitrogen dioxide; filtered exhaust contained the same gases as the total exhaust without particulate matter. Intraperitoneal injection of 5 mg crude cedar pollen was performed at 2-week intervals from the 49th day after birth. RESULTS: The mean IgE titers measured by the P-K reaction in the Control, Total-C-C, Filtered-C-C, C-Total-C, C-Filtered-C, C-C-Total and C-C-Filtered were 64.0 &PlusMinus; 2.7, 469.5 &PlusMinus; 1.6, 332.0 &PlusMinus; 1.7, 380.4 &PlusMinus; 1.7, 394.8 &PlusMinus; 1.7, 115.9 &PlusMinus; 1.3 and 57.0 &PlusMinus; 2.8 respectively after the fourth immunization. There were significant differences between Total-C-C, Filtered-C-C, C-Total-C, C-Filtered-C and Control (p < 0.01, p < 0.01, p < 0.05, p < 0.01, respectively). The mean IgE titers by ELISA were 0.47 &PlusMinus; 0.06, 0.79 &PlusMinus; 0.35, 0.86 &PlusMinus; 0.46, 0.80 &PlusMinus; 0.22, 0.56 &PlusMinus; 0.08, 0.46 &PlusMinus; 0.04 and 0.45 &PlusMinus; 0.03, respectively. IgE titers in Filtered-C-C and C-Total-C were significantly higher than in Control (p < 0.05 for each). CONCLUSIONS: Inhalation of diesel exhaust during differentiation of the immune system accelerated the elevation of IgE against pollen.

Journal Article↗

PubMed2001

The masculinization of the fetus during pregnancy due to inhalation of diesel exhaust.

This study was conducted to determine the impact of diesel exhaust inhalation on the fetus. Seventy-two pregnant rats and 18 nonpregnant rats were divided into three groups: a group exposed to total diesel engine exhaust containing 5.63 mg/m(3) particulate matter, 4.10 ppm nitrogen dioxide, and 8.10 ppm nitrogen oxide; a group exposed to filtered exhaust without particulate matter; and a group exposed to clean air. The exposure period was from day 7 until day 20 of pregnancy. In addition, 15 pregnant rats were treated with aromatase inhibitors or testosterone to clarify the process by which diesel exhaust exerts its toxicity. The anogenital distance was significantly longer in male and female fetuses from both exhaust-exposed groups than in those of the control. Differentiation of the testis, ovary, and thymus was delayed and disturbed. Maternal testosterone and progesterone levels, which increased due to pregnancy whether or not the rats were exposed, were significantly higher and lower, respectively, in the pregnant rats exposed to total exhaust and filtered exhaust. The serum adrenocorticotropic hormone (ACTH) level and urinary excretion of 17-hydroxycorticosteroids (OHCS) did not differ among the pregnant groups. These results indicate that elevated testosterone did not result from elevated maternal adrenal function. The feto-placental-ovarian unit and inhibition of aromatase activity and synthesis caused by diesel exhaust inhalation might have played an essential role in the accumulation of testosterone. Since both exhaust-exposed groups showed almost the same reactions toward the inhalation, the gaseous phase must have included the relevant toxicants.

Adrenal Glands↗

PubMed1997

Effect of airborne particulate extracts on monocyte oxidative metabolism.

Alveolar macrophages lie on the air side of the alveolar-capillary barrier of the lung. They originate from circulating monocytes and are an important first-line host defense against inhaled microorganisms. In monocytes and macrophages, phagocytosis is associated with an increase in O2 consumption and superoxide anion (O2-) generation, that is, "the respiratory burst". O2- is the precursor of highly reactive, oxygen-derived free radicals that are used to kill potential pathogens. Although it is well known that airborne particulate matter inhibits the phagocytic activity of alveolar macrophages, very little is known about the effect of airborne particulate extracts on the respiratory burst. In this study, monocytes isolated from the peripheral blood were incubated for 2 hr at 37 degrees C with increasing concentrations of particulate extract and then stimulated for 30 min with phorbol 12-myristate 13 acetate (PMA) or with Zymosan. The released O2- was measured by the superoxide dismutase inhibitable reduction of cytochrome C. The results cleary showed that, at a particulate concentration of 0.17 mg/mL, the production of O2- was reduced to 22% and 40% of the control values when the cells were stimulated with PMA and Zymosan, respectively. Concomitantly, there was a release of LDH in the supernatant (50% of the total), indicating that a large proportion of cells were damaged by the treatment with the environmental pollutants, and some cytosolic components were released from the cells. Giemsa staining of the treated monocytes revealed the presence of many cells with a dispersed cytosol; the nucleus, although not destroyed, had a different shape. It was suggested that the airborne particulate matter has a toxic effect that induces the disintegration of the plasma membrane. Cytosolic factors (proteins and coenzymes) necessary for O2- production leak from the cells and superoxide generation is therefore reduced. It remains to be determined whether this phenomenon also occurs in vivo.

Air Pollutants↗

PubMed2004

Land use-related chemical composition of street sediments in Beijing.

BACKGROUND: More than 10 million people are currently living in Beijing. This city faces severe anthropogenic air pollution caused by an intense vehicle increase (11% per year in China), coal combusting power plants, heavy industry, huge numbers of household and restaurant cookers, and domestic heating stoves. Additionally, each year dust storms are carrying particulate matter from the deserts of Gobi and Takla Makan towards Beijing, especially in spring. Other geogenic sources of particulate matter which contribute to the air pollution are bare soils, coal heaps and construction sites occurring in and around Beijing. Streets function as receptor surfaces for atmospheric dusts. Thus, street sediments consist of particles of different chemical compositions from many different sources, such as traffic, road side soils and industry. METHODS: Distributions and concentrations of various chemical elements in street sediments were investigated along a rural-urban transect in Beijing, China. Chemical elements were determined with X-ray fluorescence analysis. Factor analysis was used to extract most important element sources contributing to particulate pollution along a main arterial route of the Chinese capital. RESULTS AND DISCUSSION: The statistical evaluation of the data by factor analysis identifies three main anthropogenic sources responsible for the contamination of Beijing street sediments. The first source is a steel factory in the western part of Beijing. From this source, Mn, Fe, and Ti were emitted into the atmosphere through chimneys and by wind from coal heaps used as the primary energy source for the factory. The second source is a combination of traffic, domestic heating and some small factories in the center of Beijing discharging Cu, Pb, Zn and Sn. Calcium and Cr characterize a third anthropogenic element source of construction materials such as concrete and mortar. Beside the anthropogenic contamination, some elements like Y, Zr, Nb, Ce, and Rb are mainly derived from natural soils and from the deserts. This is supported by mineral phase analysis, which showed a clear imprint of material in road dusts coming from the West-China deserts. CONCLUSIONS: Our results clearly show that the chemical composition of urban road dusts can be used to identify distinct sources responsible for their contamination. The study demonstrates that the chemistry of road dusts is an important monitor to assess the contamination in the urban environment. Chemical composition of street sediments in Beijing comprises the information of different sources of atmospheric particles. RECOMMENDATIONS AND OUTLOOK: This study is only a small contribution to the understanding of substance fluxes related to Beijing's dust. More effort is required to assess Beijing's dust fluxes, since the dust harms the living quality of the inhabitants. Especially the measurable superimposing of long scale transported dust from dry regions with the anthropogenic polluted urban dust makes investigations of Beijing's dust scientifically valuable.

Air Pollutants↗