Levels Of Airborne Particulate Matter Research Articles

Concentrations and Size Distributions of Airborne Particulate Matter and Bacteria in an Experimental Aviary Laying-Hen Chamber

<abstract> <bold><sc>Abstract.</sc></bold> High levels of airborne particulate matter (PM) and bacteria may exist in animal housing, which can be detrimental to the health of animals and workers. The sizes of these bioaerosols determine their aerial transport behaviors and depositions in the respiratory tracts of animals and humans. However, little is known regarding the size distribution of airborne PM and bacteria in livestock houses, especially in alternative animal housing systems that aim to enhance animal welfare, such as aviary hen-housing systems. The study reported here was therefore conducted to characterize the concentrations and size distributions of airborne bacteria (in count) and PM (both in count and in mass) in a pilot-scale aviary laying-hen chamber. Thirty-four laying hens were kept in the environmentally controlled aviary chamber (L × W × H = 2.2 × 2.3 × 2.4 m) for three months. The hens were given a 16L:8D photoperiod (lights on at 6:00 h and off at 22:00 h) and access to the litter floor from 12:00 h to 22:00 h daily. Airborne bacteria and PM were simultaneously sampled for 15 min at 1.5 m above the litter floor every fourth day at 5:45 h, 9:45 h, 13:45 h, 17:45 h, and 21:45 h. Concentrations of airborne bacteria at six size ranges (0.65 to 1.1 μm, 1.1 to 2.1 μm, 2.1 to 3.3 μm, 3.3 to 4.7 μm, 4.7 to 7.1 μm, and >7.1 μm) and PM concentrations (0.523 to 20.535 μm) were determined. The daily mean (±SD) concentrations of PM count, PM mass, and airborne bacteria were 1.70 (±0.66) × 10⁷ particles m^-3, 1.12 (±0.47) mg m^-3, and 3.39 (±2.38) × 10⁵ cfu m^-3, respectively. Concentrations of airborne PM and bacteria during the litter-access period (12:00 to 22:00 h) were significantly higher than those during the rest of the day when the hens were off the floor (p < 0.05). Median diameter and geometric standard deviation (GSD) for the PM count (0.523 to 20.535 μm) were 2.11 and 2.34 μm, respectively. Median diameter and GSD for the PM mass (0.523 to 20.535 μm) were 7.45 and 4.58 μm, respectively. PM <10 μm accounted for more than 95% of the total PM count, whereas PM >2.5 μm accounted for more than 90% of the total PM mass, in the size range of 0.523 to 20.535 μm. The majority (>95%) of the airborne bacteria were carried by particles >3.3 μm. Airborne bacteria count concentration was positively related to PM mass concentration (p < 0.05) with a slope of 3.84 (±2.70) × 10⁵ cfu mg^-1 PM. Results of the study are useful for improving understanding of transport behaviors of aerosols in aviary hen systems, assessing potential respiratory risks to humans and animals, and exploring mitigation techniques.

Temporal Variations in Airborne Particulate Matter Levels at an Indoor Bus Terminal and Exposure Implications for Terminal Workers

This study investigates temporal variations in PM levels in Taipei bus terminal and assesses exposure levels for bus terminal workers. Measurement results show that temporal variations in PM levels in the waiting room and on the platform of this indoor bus terminal were strongly associated with bus traffic volume. The PM10, PM2.5, and ultrafine particle (UFP) levels on the bus platform were 1.9, 2.0, and 1.2 times higher than those inside the waiting room, respectively. Additionally, PM10 and PM2.5 levels on the platform were approximately 2.3 and 2.8 times higher than those at an ambient monitoring station, respectively. Measurement results indicate that the major PM source inside this bus terminal is diesel buses and that PM can be trapped in this semi-confined bus terminal to a far greater extent than in typical open-air bus stations. Daily PM exposure levels for station ticket inspectors who check passenger tickets in the waiting room and manage arriving and departing buses on the bus platform are assessed. Daily PM exposure levels for station ticket inspectors during different shifts are calculated based on average PM levels and working time spent in the waiting room and on the platform. Based on observational results, station ticket inspectors spend approximately 80–85% and 15–20% of their working time in the waiting room and on the platform, respectively. Daily PM10 and PM2.5 exposure levels for station ticket inspectors were approximately 1.3–1.5 and 1.6–1.8 times higher than those in the outdoor atmosphere, respectively. Additionally, daily UFP exposure levels for station ticket inspectors were approximately 5.6–7.2 times higher than those in the urban background. Measurement results demonstrate that potential health risk induced by PM is high for station ticket inspectors who work for long periods at this indoor bus terminal.

The Acute and Long-Term Effects of Middle East Sand Particles on the Rat Airway Following a Single Intratracheal Instillation

Military personnel deployed in the Middle East have emphasized concerns regarding high levels of dust generated from blowing desert sand and the movement of troops and equipment. Airborne particulate matter levels (PM10; PM < 10 μm) in the region may exceed 1500 μg/m3, significantly higher than the military exposure guideline (MEG) of 50 μg/m3. Increases in PM10 have been linked to a rise in incidences of asthma, obstructive pulmonary disease, lung cancer, and cardiovascular diseases. Male Sprague-Dawley rats received a single intratracheal (IT) instillation of 1, 5, or 10 mg of Middle East PM10 collected at a military occupied site in Kuwait, silica (positive control), or titanium dioxide (TiO2; negative control) suspended in 400 μl sterile saline, or saline alone (vehicle control). Twenty-four hours, 3 d, 7 d and 6 mo postexposure (n = 15/group), organs including lung were evaluated for histopathological changes and for particle contaminants. Bronchoalveolar fluid (BALF) was also analyzed for cellular and biochemical parameters, including cytokines and chemokines. Instillation of silica resulted in early, pronounced, sustained inflammation indicated by significant increases in levels of total protein and neutrophils, and activities of lactate dehydrogenase activity and β-glucuronidase activity. Lower magnitude and transient changes using the same markers were observed in animals exposed to TiO2 and Middle East PM10. The results suggest that for acute exposures, this Middle East PM10 is a nuisance-type dust with relatively low toxicity. However, since average deployment of military personnel to the Middle East is 180 d with potential for multiple follow-on tours, chronic exposure studies are needed to fully understand the pulmonary effects associated with Middle East PM exposure.

Susceptibility to Inhaled Flame-Generated Ultrafine Soot in Neonatal and Adult Rat Lungs

Over a quarter of the U.S. population is exposed to harmful levels of airborne particulate matter (PM) pollution, which has been linked to development and exacerbation of respiratory diseases leading to morbidity and mortality, especially in susceptible populations. Young children are especially susceptible to PM and can experience altered anatomic, physiologic, and biological responses. Current studies of ambient PM are confounded by the complex mixture of soot, metals, allergens, and organics present in the complex mixture as well as seasonal and temporal variance. We have developed a laboratory-based PM devoid of metals and allergens that can be replicated to study health effects of specific PM components in animal models. We exposed 7-day-old postnatal and adult rats to a single 6-h exposure of fuel-rich ultrafine premixed flame particles (PFPs) or filtered air. These particles are high in polycyclic aromatic hydrocarbons content. Pulmonary cytotoxicity, gene, and protein expression were evaluated at 2 and 24 h postexposure. Neonates were more susceptible to PFP, exhibiting increased lactate dehydrogenase activity in bronchoalveolar lavage fluid and ethidium homodimer-1 cellular staining in the lung in situ as an index of cytotoxicity. Basal gene expression between neonates and adults differed for a significant number of antioxidant, oxidative stress, and proliferation genes and was further altered by PFP exposure. PFP diminishes proliferation marker PCNA gene and protein expression in neonates but not adults. We conclude that neonates have an impaired ability to respond to environmental exposures that increases lung cytotoxicity and results in enhanced susceptibility to PFP, which may lead to abnormal airway growth.

Premature Mortality in the Kingdom of Saudi Arabia Associated with Particulate Matter Air Pollution from the 1991 Gulf War

ABSTRACT The State of Kuwait oil fires and military operations associated with the 1991 Gulf War resulted in substantially increased levels of airborne particulate matter (PM) in the Kingdom of Saudi Arabia (KSA) during 1991 and 1992. Using quantitative risk assessment methodology, this article estimates the increase in premature deaths in citizens of the KSA associated with the Gulf War–related increase in PM air pollution levels. Meta-analysis of daily time-series studies of non-accidental mortality associated with increased PM10 levels using two alternative methodologies yielded exposure-response relative risk functions of 2.7% and 3.5% per 50 μ g/m3 increase in PM10 concentration. Combining these exposure-response functions with estimates of the magnitude and duration of the increased PM10 exposure, the size of the exposed population and baseline mortality rates provided an estimate of approximately 1,080 to 1,370 excess non-accidental deaths of Saudi citizens during 1991–1992 associated with the Gulf War–related increase in PM levels.

A refined biomonitoring study of airborne particulate matter pollution in Rome, with magnetic measurements onQuercus Ilextree leaves

SUMMARY Elevated levels of airborne particulate matter (PM) are a current problem for air quality in many major metropolitan areas. Many European cities have tightened the PM limits in the air, due to advances in monitoring PM levels. In order to establish guidelines for monitoring and curbing anthropogenic PM output, a better understanding of its origin, composition and diffusion is required. Biomonitoring of magnetic properties of tree leaves has been suggested previously to be a good approach to measure pollution levels in cities both in space and time. We report on a magnetic biomonitoring study of PM in the city of Rome, conducted from 2005 October to December. We collected approximately 180 different sample sets of tree leaves of Quercus ilex, an evergreen oak widely distributed in Rome, at 112 different locations. Specific magnetic susceptibility χ of the leaf is used as a fast, easy and cost-effective proxy to assess levels of primary anthropogenic airborne PM pollution. Highly polluted areas correlate with high traffic areas, with an average susceptibility value of χ = 3.2 × 10 −7 m 3 kg −1 .L ow traffic zones are characterized by values more than an order of magnitude lower at χ = 1.4 × 10 −8 m 3 kg −1 , and the background magnetic susceptibility is around χ = 2.6 × 10 −9 m 3 kg −1 . The data show that distance dependence from the source is the most significant factor for the concentration of magnetic PM, and that pollution levels and sources can be reliably delineated by measuring magnetic susceptibility values on tree leaf samples of Q. ilex. A new protocol for magnetic susceptibility measurements is proposed, in order to account for changes due to water evaporation in the leaves as a function of time after collection of the samples. Additional magnetic analyses, such as acquisition of artificial remanences and hysteresis properties, were used to characterize the mineralogy and grain size of the magnetic PM. The results indicate that the population of ferrimagnetic phases have a homogenous composition and grain size throughout the investigated area.

A combined analysis of backward trajectories and aerosol chemistry to characterise long-range transport episodes of particulate matter: The Madrid air basin, a case study

This study has investigated the influence of synoptic weather patterns and long-range transport episodes on the concentration levels of airborne particulate matter (TSP, PM10 and PM2.5) and some major ions (SO 4 2−, NO 3 − and NH 4 +) at a background rural station in central Spain. Air mass back-trajectories arriving at the site in 1999–2005 have been analysed by statistical methods. First, cluster analysis was used to group trajectories into 8 clusters depending on their direction and speed. Meteorological scenarios associated to each cluster have been obtained and interpreted. Then, the incidence of different air mass transport patterns on particle concentrations and composition recorded at this station was evaluated. This evaluation included PM10 and PM2.5 concentrations and chemical composition data, obtained at three representative sites of the Madrid air basin during sampling campaigns carried out in the course of the 1999–2005 period. Finally, a residence time analysis of trajectories was also performed to detect remote sources and transport pathways. Significantly elevated concentrations of TSP and PM10 were observed for Northern African flows as a consequence of the transport of mineral dust. Significant inter-cluster differences were also observed for PM2.5 and secondary inorganic compounds, with the highest concentrations associated with low baric gradient situations and Southern European flows. The residence time analysis confirmed that current TSP and PM10 concentrations in central Spain are likely to be influenced significantly by long-range transport of desert dust from different desert regions in North Africa. Furthermore, emissions from continental Europe with a high time of residence in the western and central areas of the Mediterranean basin, seem to significantly influence PM2.5 and secondary inorganic aerosol concentrations in this region.

Pollution and Genetic Structure of North American Populations of the Common Dandelion (Taraxacum Officinale)

Assessing the genetic structure of natural populations differentially impacted by anthropogenic contaminants can be a useful tool for evaluating the population genetic consequences of exposure to pollution. In this study, measures of genetic diversity at variable-number-tandem-repeat loci in six dandelion populations (3 urban and 3 rural) showed patterns that may have been influenced by exposure to environmental contaminants. Mean genetic similarity among individuals within a population was significantly and positively correlated with increasing levels of airborne particulate matter (< or = 10 microm, PM10) and soil concentrations of four metals (Cd, Fe, Ni and Pb). In addition, mean genetic similarity was always significantly higher at the urban sites compared to rural sites. There was a significant negative correlation between the number of genotypes at a site and increasing amounts of PM10, concentrations of five soil metals (Cd, Cu, Fe, Ni and Pb), leaf tissue levels of Fe and a significant positive correlation between the extent of clonality at a site and levels of PM10 and soil concentrations of five metals (Cd, Cu, Fe, Ni and Pb). Although, this study does not directly establish a causal link between the specific contaminants detected at the study sites and differences in genetic diversity, our data are consistent with the hypothesis that pollution-induced selection has contributed in some fashion to the lower genetic diversity found at the urban sites.

Effects of Ambient Air Pollutants on Asthma Medication Use and Wheezing among Fourth-Grade School Children from 12 Southern California Communities Enrolled in The Children's Health Study

To investigate the effects of 12 monthly average air pollution levels on monthly prevalence of respiratory morbidity, the authors examined retrospective questionnaire data on 2034 4th-grade children from 12 Southern California communities that were enrolled in The Children's Health Study. Wheezing during the spring and summer months was associated with community levels of airborne particulate matter with a diameter < or = 10 microm (PM10) (odds ratio (OR) = 2.91; 95% confidence interval (CI) = 1.46-5.80), but was not associated with community levels of ozone, nitrogen dioxide, PM2.5 (diameter < or = 2.5), nitric acid, or formic acid. Logistic regression was performed on data stratified into two seasonal groups, spring/summer and fall/winter. Among asthmatics, the monthly prevalence of asthma medication use was associated with monthly levels of ozone, nitric acid, and acetic acid (OR = 1.80 [95%CI = 1.19-2.70]; OR = 1.80 [95%CI = 1.23-2.65]; OR = 1.57 [95% CI = 1.11-2.21]; respectively). Asthma medication use was more prevalent among children who spent more time outdoors--with consequential exposure to ozone--than among children who spent more time indoors (OR = 3.07 [95%CI = 1.61-5.86]; OR = 1.31 [95%CI = 0.47-2.71]; respectively). The authors concluded that monthly variations in some ambient air pollutants were associated with monthly respiratory morbidity among school children.