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PubMed1983

Beneficial effects of implanted muscle tissue on pulmonary particulate retention and survival following splenectomy.

Following splenectomy (SPLY) there is increased retention in the lung of injected particulate matter and an increased mortality from sepsis in experimental animals. Since it has been shown that autotransplanted splenic tissue (AST) decreased elevated pulmonary particulate retention after SPLY and improved the survival of animals following SPLY and sepsis, we attempted to determine whether the protective effect offered by AST was specific to the spleen. To determine this, four groups of rats were studied: Group I--sham; Group II--SPLY; Group III--received 100 mg of heterotopic AST in an omental pocket after SPLY; and Group IV--received 100 mg of heterotopic muscle tissue from the abdominal wall (AMT) in an omental pocket after SPLY. Six days after the above procedure, reticuloendothelial (RES) function was evaluated. The results indicate that both AST and AMT significantly decrease the abnormal pulmonary retention of particulate matter following SPLY. However, hepatic lipid retention was greater in the AMT than the AST group. Survival following sepsis was studied in other animals from Group I, II, III, and IV. At 7 days after the original operation, the cecum was ligated and punctured (CLP) and then removed 16 hours later. The splenic-as well as muscle-implanted animals showed significantly higher survival rates than the splenectomized animals. We therefore conclude that survival after SPLY can be improved by implanting either a fragment of the spleen or the muscle in the omental pocket. Since both tissues appeared necrotic at 7 days following implantation, the decreased pulmonary particulate retention and improved survival following SPLY and sepsis appear to be due to the presence of a necrotic tissue irrespective of its origin. These results suggest that the early effect of an implanted tissue is a nonspecific stimulation of phagocytosis.

Abdominal Muscles↗

PubMed1990

Comparative studies on the genotoxic activity of mainstream smoke condensate from cigarettes which burn or only heat tobacco.

The in vitro genotoxic activity of mainstream cigarette smoke condensate (CSC) from cigarettes which heat but do not burn tobacco was compared to that of CSC from cigarettes which burn tobacco. CSCs from five cigarettes were compared. Three of the cigarettes [the Kentucky reference research cigarette (1R4F), a commercially available ultra-low tar brand (ULT) and a commercially available ultra-low tar menthol brand (ULT-menthol]) burn tobacco while two of the cigarettes [a regular (TEST) and a menthol (TEST-menthol]) heat tobacco. CSC from all cigarettes were collected by identical standard techniques, which involved collecting mainstream smoke particulate matter on Cambridge filter pads under FTC smoking conditions. The pads were extracted with DMSO, and the CSCs obtained [10 mg total particulate matter (TPM)/ml DMSO] were evaluated at identical concentrations in an in vitro genetic toxicology test battery. CSCs from 1R4F, ULT, and ULT-menthol cigarettes were mutagenic in Ames bacterial strains TA98, TA100, TA1537, and TA1538 in the presence of metabolic activation (S9 from Aroclor-induced rat liver) but negative in strain TA1535. In the absence of metabolic activation, 1R4F, ULT, and ULT-menthol CSCs were not mutagenic except for a weak response in strain TA1537 for the 1R4F and ULT CSCs. TEST and TEST-menthol CSCs were nonmutagenic in all five bacterial strains, both with and without metabolic activation. CSCs from 1R4F, ULT, and ULT-menthol cigarettes were positive in the CHO-chromosomal aberration assay and in the CHO--sister chromatid exchange assay both with and without metabolic activation while TEST and TEST-menthol CSCs were negative in both assays, either with or without metabolic activation. CSCs from 1R4F, ULT, and ULT-menthol cigarettes were weakly positive in inducing DNA repair in cultured rat hepatocytes while TEST and TEST-menthol CSCs were negative in this assay. All five CSCs were nonmutagenic in the CHO-HGPRT assay both with and without metabolic activation. CSCs from the 1R4F, ULT, and ULT-menthol cigarettes were cytotoxic in the CHO-HGPRT assay, both with and without metabolic activation, while TEST and TEST-menthol CSCs were not cytotoxic under either condition. These results demonstrate that mainstream CSCs from the TEST and TEST-menthol cigarettes are neither genotoxic nor cytotoxic under conditions where CSCs from 1R4F, ULT, and ULT-menthol cigarettes are genotoxic and/or cytotoxic in a concentration-dependent manner.

Animals↗

PubMed2006

UV inactivation of bacteria in raw and pretreated liquid swine manure.

The study was conducted to investigate the effectiveness of ultraviolet (UV) irradiation for inactivating coliform bacterial indicators in liquid swine manure samples using a laboratory-scale, low-pressure UV collimated beam apparatus. Raw liquid swine manure was brought from the field and stored at 4 'C for preliminary settling for 24 hours, which was followed by alum treatment in a jar test apparatus. Both pre-settled and alum-treated supernatants were filtered separately through different pore-sized polycarbonate membrane filters. The unfiltered and filtered pre-settled and alum-treated supernatant samples were exposed to a range of UV fluences (i.e., doses) to determine the fluence-response relationship. After preliminary settling, alum treatment, and membrane filtration, UV absorbance values of undiluted swine manure samples at 254 nm varied between 4.0 and 4.2 cm(-1) with total suspended solids concentrations of 800 to 1,800 mg l(-1). Total coliforms were reduced by 2 - to 2.5-log10 at UV fluences of 80 to 100 mJ cm(-2). Relatively small log reductions (< 0.5-log10) were observed at lower fluences (below 20 mJ cm(-2) ) in undiluted manure samples. To reduce the UV absorbance of liquid swine manure, raw manure was diluted 1:50 and 1:10 with deionized water in subsequent experiments. Almost complete inactivation (> 4 to 5 log10) was achieved at UV fluences of 20 mJ cm(-2) or higher in the swine manure samples diluted to 1:50. Based on these findings, it was proposed that UV inactivation of coliform in the undiluted liquid swine manure was limited by association of bacterial cells with particulate matter of less than 10 microm in size. Dilution may have disrupted and reduced the association between the bacteria and this fine particulate matter resulting in better dispersion and more complete inactivation by UV.

Alum Compounds↗

PubMed2000

Urea hydrogen peroxide reduces the numbers of lactobacilli, nourishes yeast, and leaves no residues in the ethanol fermentation.

Urea hydrogen peroxide (UHP) at a concentration of 30 to 32 mmol/liter reduced the numbers of five Lactobacillus spp. (Lactobacillus plantarum, L. paracasei, Lactobacillus sp. strain 3, L. rhamnosus, and L. fermentum) from approximately 10(7) to approximately 10(2) CFU/ml in a 2-h preincubation at 30 degrees C of normal-gravity wheat mash at approximately 21 g of dissolved solids per ml containing normal levels of suspended grain particles. Fermentation was completed 36 h after inoculation of Saccharomyces cerevisiae in the presence of UHP, even when wheat mash was deliberately contaminated (infected) with L. paracasei at approximately 10(7) CFU/ml. There were no significant differences in the maximum ethanol produced between treatments when urea hydrogen peroxide was used to kill the bacteria and controls (in which no bacteria were added). However, the presence of L. paracasei at approximately 10(7) CFU/ml without added agent resulted in a 5.84% reduction in the maximum ethanol produced compared to the control. The bactericidal activity of UHP is greatly affected by the presence of particulate matter. In fact, only 2 mmol of urea hydrogen peroxide per liter was required for disinfection when mashes had little or no particulate matter present. No significant differences were observed in the decomposition of hydrogen peroxide in normal-gravity wheat mash at 30 degrees C whether the bactericidal agent was added as H(2)O(2) or as urea hydrogen peroxide. NADH peroxidase activity (involved in degrading H(2)O(2)) increased significantly (P = 0.05) in the presence of 0.75 mM hydrogen peroxide (sublethal level) in all five strains of lactobacilli tested but did not persist in cells regrown in the absence of H(2)O(2). H(2)O(2)-resistant mutants were not expected or found when lethal levels of H(2)O(2) or UHP were used. Contaminating lactobacilli can be effectively managed by UHP, a compound which when used at ca. 30 mmol/liter happens to provide near-optimum levels of assimilable nitrogen and oxygen that aid in vigorous fermentation performance by yeast.

Carbamide Peroxide↗

PubMed2006

Air pollutants and cough.

Epidemiological studies have shown that exposure to air pollution is associated with respiratory symptoms and decreases in lung function. This paper reviews recent literature showing that exposure to particulate matter, irritant gases, environmental tobacco smoke (ETS), mixed pollutants, and molds is associated with an increase in cough and wheeze. Some pollutants, like particulate matter and mixed pollutants, appear to increase cough at least as much as wheeze. Others, like irritant gases, appear to increase wheeze more than cough. For ETS, exposure during childhood is associated with cough and wheeze in adulthood, suggesting that the pollutant permanently alters some important aspect of the lungs, immune system or nervous system. We have shown in animal studies that pollutants change the neural control of airways and cough. Second hand smoke (SHS) exposure lengthened stimulated apnoea, increased the number of stimulated coughs, and augmented the degree of stimulated bronchoconstriction. The mechanisms included enhanced reactivity of the peripheral sensory neurones and second-order neurones in the nucleus tractus solitarius (NTS). NTS effects were due to a substance P mechanism at least in part. Ozone and allergen increased the intrinsic excitability of second-order neurones in the NTS. The animal studies suggest that the cough and wheeze experienced by humans exposed to pollutants may involve plasticity in the nervous system.

Adult↗

PubMed1999

Indoor air quality investigations at five classrooms.

Five classrooms, air-conditioned or naturally ventilated, at five different schools were chosen for comparison of indoor and outdoor air quality. Temperature, relative humidity (RH), carbon dioxide (CO2), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter with diameter less than 10 microns (PM10), formaldehyde (HCHO), and total bacteria counts were monitored at indoor and outdoor locations simultaneously. Respirable particulate matter was found to be the worst among parameters measured in this study. The indoor and outdoor average PM10 concentrations exceeded the Hong Kong standards, and the maximum indoor PM10 level was even at 472 micrograms/m3. Air cleaners could be used in classrooms to reduce the high PM10 concentration. Indoor CO2 concentrations often exceeded 1,000 microliters/l indicating inadequate ventilation. Lowering the occupancy and increasing breaks between classes could alleviate the high CO2 concentrations. Though the maximum indoor CO2 level reached 5,900 microliters/l during class at one of the sites, CO2 concentrations were still at levels that pose no health threats.

Air Conditioning↗

PubMed1990

Pesticide loss to the atmosphere.

Pesticides may be transformed by chemical and biological processes or transported from the site of application by several processes including runoff, movement through the soil to ground water, volatilization, transport on soil particles, and wind erosion. Contamination of water by pesticide residues is a matter of concern as is contamination of the earth's atmosphere. The form in which a pesticide enters the air and the dimensions of pesticide-containing particulate matter affect movement and deposition. Local transport over distances of several miles may be responsible for adverse effects on nontarget species. Effects of long-range transport are more difficult to assess, but pesticides increase the burden of organic chemicals in the atmosphere. Field measurements of pesticide volatilization and deposition of residues in rainfall, particulate matter, fog, etc., provide information on the relative importance of these processes. Adequate information concerning chemical reactions of pesticides in air is lacking. Because it is desirable to minimize low-level human and environmental exposure resulting from airborne pesticide residues, potential for losses to the air should be taken into account in selecting pesticide formulations and application methods.

Agriculture↗

PubMed2002

Development of a chemiluminescent enzyme immunoassay for urinary 1-hydroxypyrene.

A chemiluminescent enzyme-immunoassay for urinary 1-hydroxypyrene has been developed and optimized. The enzymatic activity of horseradish peroxidase-labeled tracer was measured with an enhanced chemiluminescent system and the results were compared with those from conventional colorimetric detection. The method fulfilled all the requirements of accuracy and precision and the detection limit was 0.001 pmol/well, which enabled analysis in less than 1 microL urine. Subjects working in the center of Bologna who were exposed daily to vehicular exhaust gas were studied. Their urinary 1-hydroxypyrene concentrations were compared with the levels of benzo( a)pyrene in air particulate matter. Urinary 1-hydroxypyrene, which ranged from 0.5 to 10 nmol L(-1), correlated poorly with the concentration of benzo( a)pyrene in air particulate matter, which ranged from 5 to 140 ng m(-3). No significant effect of vehicle exhaust gas exposure was observed among the different groups of subjects working in different areas of the town. Thus, at a relatively low level of exposure 1-hydroxypyrene does not seem to be a sensitive biomarker of exposure to polycyclic aromatic hydrocarbons.

Adult↗

PubMed2004

Monitoring trace metals in urban aerosols from Buenos Aires city. Determination by plasma-based techniques.

A study was undertaken, within the framework of a 3 years national project, to assess the content of 13 elements in airborne particulate matter collected in representative zones of the metropolitan area of Buenos Aires. The sampling strategy followed consisted in collecting simultaneously 67 samples of PM10 particulate matter in 9 sampling sites covering an area of about 30 km2 during one week. The collection was performed on ash-free fibre-glass filters using high volume samplers. A combination of aqua regia and perchloric acid was used for leaching metals from filters. Key elements, namely Al, Ca, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Sn, Zn and Zr, were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) at micro g g(-1) and ng g(-1) levels. Analyte concentration varied from 130 ng g(-1)(Mo) to over 30%(Ca). Multivariate statistical analysis was performed on the data set including the measured elemental compositions for the monitored period. The atmospheric concentration found for Pb confirms the decreasing levels of this element since the introduction of unleaded gasoline in 1995: 88 ng m(-3)(2001) < 220 ng m(-3)(1997) < 3900 ng m(-3)(1994). The average S concentration above 3 microg m(-3) is somehow unexpectedly high for Buenos Aires since the relatively low S content of liquid fuels and the massive usage of natural gas imply low emissions of this element from combustion activities. To the best of our knowledge, S concentrations are reported for the first time for this city.

Aerosols↗

PubMed2000

Association between particulate- and gas-phase components of urban air pollution and daily mortality in eight Canadian cities.

Although some consensus has emerged among the scientific and regulatory communities that the urban ambient atmospheric mix of combustion related pollutants is a determinant of population health, the relative toxicity of the chemical and physical components of this complex mixture remains unclear. Daily mortality rates and concurrent data on size-fractionated particulate mass and gaseous pollutants were obtained in eight of Canada's largest cities from 1986 to 1996 inclusive in order to examine the relative toxicity of the components of the mixture of ambient air pollutants to which Canadians are exposed. Positive and statistically significant associations were observed between daily variations in both gas- and particulate-phase pollution and daily fluctuations in mortality rates. The association between air pollution and mortality could not be explained by temporal variation in either mortality rates or weather factors. Fine particulate mass (less than 2.5 microns in average aerometric diameter) was a stronger predictor of mortality than coarse mass (between 2.5 and 10 microns). Size-fractionated particulate mass explained 28% of the total health effect of the mixture, with the remaining effects accounted for by the gases. Forty-seven elemental concentrations were obtained for the fine and coarse fraction using nondestructive x-ray fluorescence techniques. Sulfate concentrations were obtained by ion chromatography. Sulfate ion, iron, nickel, and zinc from the fine fraction were most strongly associated with mortality. The total effect of these four components was greater than that for fine mass alone, suggesting that the characteristics of the complex chemical mixture in the fine fraction may be a better predictor of mortality than mass alone. However, the variation in the effects of the constituents of the fine fraction between cities was greater than the variation in the mass effect, implying that there are additional toxic components of fine particulate matter not examined in this study whose concentrations and effects vary between locations. One of these components, carbon, represents half the mass of fine particulate matter. We recommend that measurements of elemental and organic carbon be undertaken in Canadian urban environments to examine their potential effects on human health.

Air Pollutants↗

PubMed1988

Augmentation of elastase-induced emphysema by cigarette smoke. Effects of reduced nicotine content.

To examine the role of nicotine in the augmentation of elastase-induced emphysema by cigarette smoke, animals that had been pretreated with porcine pancreatic elastase (PPE) were exposed to cigarette smokes that had a five-fold difference in their nicotine concentrations. Young adult female Long-Evans rats were divided into seven groups: (1) untreated controls; (2) low nicotine cigarette smoke exposure (Kentucky 2A1 reference cigarettes; 35.0 mg total particulate matter, 0.42 mg nicotine, and 0.38 mg nitrogen oxides per cigarette); (3) high nicotine cigarette smoke exposure (Kentucky 2R1 reference cigarettes; 38.8 mg total particulate matter, 2.2 mg nicotine, and 0.34 mg nitrogen oxides per cigarette; (4) PPE alone; (5) PPE + sham smoke exposure; (6) PPE + 2A1 smoke exposure; and (7) PPE + 2R1 smoke exposure. Three days after intratracheal administration of PPE (400 IU/kg), animals in the smoke-treated groups were exposed to 10 puffs of cigarette smoke daily, 7 days/wk for 14 wk. Sham-treated animals received room air in place of cigarette smoke. After the exposures, pulmonary function tests were performed under general anesthesia. Whole lungs were examined for gross pathologic changes, and samples of lung tissue were harvested for quantitative morphometry. Cigarette smoke exposure alone did not produce significant changes in pulmonary function or structure. On the other hand, treatment with elastase alone produced a constellation of pulmonary functional and structural changes that were pathognomonic of emphysema. Exposure to 2R1 but not 2A1 cigarette smoke significantly augmented the emphysematous changes produced by PPE.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2006

The effect of biomass burning on respiratory symptoms and lung function in rural Mexican women.

BACKGROUND: The use of biomass as a cooking fuel is commonplace in developing countries and has been associated with chronic bronchitis and obstructive airway disease. METHODS: A cross-sectional survey was done in the village of Solis, close to Mexico City. Lifelong nonsmoking women 38 yr of age or older (n=841) completed a questionnaire on respiratory symptoms and illnesses and on cooking fuel use, and performed spirometry in their homes. Particulate matter concentration was measured with a nephelometer in the kitchen for 1 h, while the subject was cooking. RESULTS: The peak indoor concentration of particulate matter (PM10, particles with a diameter of 10 microm or less) often exceeded 2 mg/m3. Compared with those cooking with gas, current use of a stove burning biomass fuel was associated with increased reporting of phlegm (27 vs. 9%) and reduced FEV1/FVC (79.9 vs. 82.8%). Levels of FEV1 were 81 ml lower and cough was more common (odds ratio, 1.7; 95% confidence interval, 1.0-2.8) in women from homes with higher PM10 concentrations. All women found with moderate airflow obstruction (Global Initiative for Chronic Obstructive Lung Disease stage II and above) were cooking with biomass stoves. CONCLUSION: Women cooking with biomass fuels have increased respiratory symptoms and a slight average reduction in lung function compared with those cooking with gas.

Adult↗

PubMed2000

Characterization of indoor particle sources: A study conducted in the metropolitan Boston area.

An intensive particle monitoring study was conducted in homes in the Boston, Massachusetts, area during the winter and summer of 1996 in an effort to characterize sources of indoor particles. As part of this study, continuous particle size and mass concentration data were collected in four single-family homes, with each home monitored for one or two 6-day periods. Additionally, housing activity and air exchange rate data were collected. Cooking, cleaning, and the movement of people were identified as the most important indoor particle sources in these homes. These sources contributed significantly both to indoor concentrations (indoor-outdoor ratios varied between 2 and 33) and to altered indoor particle size distributions. Cooking, including broiling/baking, toasting, and barbecuing contributed primarily to particulate matter with physical diameters between 0.02 and 0.5 microm [PM((0.02-0.5))], with volume median diameters of between 0.13 and 0.25 microm. Sources of particulate matter with aerodynamic diameters between 0.7 and 10 microm [PM((0.7-10))] included sautéing, cleaning (vacuuming, dusting, and sweeping), and movement of people, with volume median diameters of between 3 and 4.3 microm. Frying was associated with particles from both PM((0.02-0.5)) and PM((0.7-10)). Air exchange rates ranged between 0.12 and 24.3 exchanges/hr and had significant impact on indoor particle levels and size distributions. Low air exchange rates (< 1 exchange/hr) resulted in longer air residence times and more time for particle concentrations from indoor sources to increase. When air exchange rates were higher (> 1 exchange/hr), the impact of indoor sources was less pronounced, as indoor particle concentrations tracked outdoor levels more closely.

Activities of Daily Living↗

PubMed2005

Local variations in CO and particulate air pollution and adverse birth outcomes in Los Angeles County, California, USA.

We extended our previous analyses of term low birth weight (LBW) and preterm birth to 1994-2000, a period of declining air pollution levels in the South Coast Air Basin. We speculated that the effects we observed previously for carbon monoxide, particulate matter < 10 microm in aerodynamic diameter (PM10), and traffic density were attributable to toxins sorbed to primary exhaust particles. Focusing on CO, PM10, and particulate matter < 2.5 microm in aerodynamic diameter (PM2.5), we examined whether varying residential distances from monitoring stations affected risk estimates, because effect attenuation may result from local pollutant heterogeneity inadequately captured by ambient stations. We geocoded home locations, calculated the distance to the nearest air monitors, estimated exposure levels by pregnancy period, and performed logistic regression analyses for subjects living within 1-4 mi of a station. For women residing within a 1-mi distance, we observed a 27% increase in risk for high (> or = 75th percentile) first-trimester CO exposures and preterm birth and a 36% increase for high third-trimester pregnancy CO exposures and term LBW. For particles, we observed similar size effects during early and late pregnancy for both term LBW and preterm birth. In contrast, smaller or no effects were observed beyond a 1-mi distance of a residence from a station. Associations between CO and PM10 averaged over the whole pregnancy and term LBW were generally smaller than effects for early and late pregnancy. These new results for 1994-2000 generally confirm our previous observations for the period 1989-1993, again linking CO and particle exposures to term LBW and preterm birth. In addition, they confirm our suspicions about having to address local heterogeneity for these pollutants in Los Angeles.

Adult↗

PubMed1988

Estimation of the diesel exhaust exposures of railroad workers: II. National and historical exposures.

The diesel exhaust exposures of railroad workers in thirteen job groups from four railroads in the United States were used to estimate U.S. national average exposures with a linear statistical model which accounts for the significant variability in exposure caused by climate, the differences among railroads and the uneven distribution of railroad workers across climatic regions. Personal measurements of respirable particulate matter, adjusted to remove the contribution of cigarette smoke particles, were used as a marker for diesel exhaust. The estimated national means of adjusted respirable particulate matter (ARP) averaged 10 micrograms/m3 lower than the simple means for each job group, reflecting the climatic differences between the northern railroads studied and the distribution of railroad workers nationally. Limited historical records, including some industrial hygiene data, were used to evaluate past diesel exhaust exposures, which were estimated to be approximately constant from the 1950's to 1983.

Air Pollutants, Occupational↗

PubMed2003

Pediatric sand aspiration: case report and literature review.

Sand aspiration is a rare but life-threatening event that occurs in the pediatric and adult populations after cave-ins or near drownings. We report the case of a 10-year-old boy who suffered from aspiration of particulate matter after being buried in sand. In addition, we performed a literature review regarding similar cases and their treatment of aspiration of significant amounts of particulate matter. Treatment of the victims ranges from conservative to very aggressive. The treatment employed is dictated by the patient's current condition and the services available to the physician.

Bronchoscopy↗

PubMed2004

Reduction of particulate air pollution lowers the risk of heritable mutations in mice.

Urban and industrial air pollution can cause elevated heritable mutation rates in birds and rodents. The relative importance of airborne particulate matter versus gas-phase substances in causing these genetic effects under ambient conditions has been unclear. Here we show that high-efficiency particulate-air (HEPA) filtration of ambient air significantly reduced heritable mutation rates at repetitive DNA loci in laboratory mice housed outdoors near a major highway and two integrated steel mills. These findings implicate exposure to airborne particulate matter as a principal factor contributing to elevated mutation rates in sentinel mice and add to accumulating evidence that air pollution may pose genetic risks to humans and wildlife.

Air Pollutants↗

PubMedDate not supplied

Design and validation of a high-flow personal sampler for PM2.5.

A high-flow personal sampler (HFPS) for airborne particulate matter has been developed and fully characterised, and validation tests have been carried out. The sampler is a low-cost gravimetric instrument designed to collect particulate matter with a 50% cut point at 2.5 microm aerodynamic equivalent diameter (PM2.5), where size selection is achieved by the use of porous polyurethane foam. Development of a porous foam selector was chosen over a cyclone or impactor due to the lightweight, low-cost, and compact design that could be achieved. The sampler flow rate of 16 1/min is achieved using a portable, flow-controlled pump; this flow rate is far higher than that of conventional personal samplers and the HFPS can therefore be used for personal sampling in the ambient environment over short sampling periods of much less than 24 h. The HFPS is currently being used in a study of particle exposure of urban transport users (cyclists, car drivers, bus and Underground rail passengers) where personal sampling over short time periods representing typical commuter journey times is required. The HFPS was fully characterised in chamber studies with a TSI aerodynamic particle sizer (APS). The sampler was then validated against a co-located U.S. EPA Federal Reference PM2.5 Well Impactor Ninety Six (WINS) and a KTL cyclone, and parallel testing was performed. Initial testing showed some penetration of particles through the porous foam structure; applying an oil coating to the foam eliminated this problem. Chamber testing was carried out on a number of different selector prototypes, with the final design giving a 50% penetration diameter (i.e., d50) of 2.4 microm at 16 1/min. The new sampler exhibited good agreement in three sets of co-located tests with established samplers, and parallel testing showed excellent agreement between paired HFPS samplers.

Air Movements↗