Stephen T. Ferguson

URBAN AIR PARTICULATE INHALATION ALTERS PULMONARY FUNCTION AND INDUCES PULMONARY INFLAMMATION IN A RODENT MODEL OF CHRONIC BRONCHITIS

Epidemiological studies have reported increased morbidity in human populations following inhalation of elevated levels of urban particulate matter. These responses are especially prevalent in populations with chronic obstructive pulmonary diseases, including chronic bronchitis. Toxicological studies have reported altered pulmonary function and increased pulmonary inflammation following particulate inhalation in the laboratory setting. However, most of these studies have utilized artificial particles that may not accurately mimic outdoor air pollutant conditions. Few studies have utilized actual urban air particle samples in inhalation studies. In the present study, the effects of inhaled concentrated urban air particulates on pulmonary function and pulmonary inflammation are addressed. Normal rats and rats with chronic bronchitis induced by approximately 200 ppm SO(2) for 6 wk were subsequently subjected to filtered air or concentrated air particles (CAPs). Twelve rats per group in 4 groups (48 rats total) were exposed for 5 h/day for 3 consecutive days. The CAPs aerosol levels were 206, 733, and 607 microg/m(3) (MMAD = 0.18 microm, sigma(g) = 2.9) on days 1, 2, and 3, respectively. Following the final day of exposure, pulmonary function parameters, including peak expiratory flow (PEF), tidal volume (TV), respiratory frequency (RF), and minute volume (MV), were measured and compared to preexposure baseline levels. Twenty-four hours following the final day of exposure, bronchoalveolar lavage was performed for total cell counts, differential cell counts, and total lavage protein levels. Pulmonary responses to CAPs in chronic bronchitic animals indicated a significant increase in tidal volume as well as peak expiratory flow. In CAPs-exposed animals without underlying bronchitis, significantly increased tidal volume was observed. Significant pulmonary inflammation was observed in the CAPs-exposed animals, particularly those with chronic bronchitis. Significant increases in neutrophils, lymphocytes, and total lavage protein were observed. These results suggest two distinct mechanistic responses to inhaled particles: a stress-type pulmonary function response marked by increases in flow and volume, that is, deeper breathing; and acute pulmonary inflammation marked by cellular influx, particularly neutrophils. From these data it is concluded that inhaled urban air particles alter pulmonary breathing parameters and increase pulmonary inflammation.

Development of a High Volume Cascade Impactor for Toxicological and Chemical Characterization Studies

This paper presents the design and development of a compact high volume cascade impactor (HVCI). The HVCI operates at a flow rate of 900 l/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup filter. The backup filter is placed downstream of the fourth stage and is used to collect the ultrafine particles ( d p < 0.1 w m). The major feature of this novel sampler is its ability to collect relatively large amounts of particles (mg-g levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected particles per cm 2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found not to be significant. Particles can be easily recovered from the foam substrates using aqueous extraction. The impactor was calibrated using polydisperse particles. The 50% cutpoints of the 4 stages were 9.90, 2.46, 1.0, and 0.1 w m, respectively. Interstage losses of ultrafine and fine particles were < 10% and for coarse particles were < 20%. The pressure drop across the 4 stages and the backup filter were 0.25, 0.75, 1.25, 19.9, and 3.3 kPa, respectively.

Fine particle concentrators for inhalation exposures—effect of particle size and composition

This paper presents the development and evaluation of ambient fine particle concentrators for conducting animal and human exposure studies. These systems utilize the technology of virtual impactors to concentrate particles in the range 0.15--2.5 μm. Ambient particles are first drawn at 5000 1m -1 through a preselective inlet that removes particles above 2.5 μm. Subsequently, the remaining aerosol is drawn through a series of virtual impactors, which increase particle concentration by a factor of about 10 and 30, for human and animal exposures, respectively. Results from the experimental characterization of the concentrators showed that the concentration enrichment process occurs without any distortion in the size distribution and chemical composition of the sampled ambient aerosols. Furthermore, labile constituents of fine particles, such as volatile ammonium nitrate are preserved during this process.

Development and laboratory performance evaluation of a personal multipollutant sampler for simultaneous measurements of particulate and gaseous pollutants

A personal multipollutant sampler has been developed. This sampler can be used for measuring exposures to particulate matter and criteria gases. The system uses asingle personalsampling pump that operates at a flow rate of 5.2 l/min. The basic unit consists of two impaction-based samplers for PM2.5 and PM10 attached to a single elutriator. Two mini PM2.5 samplers are also attached to the elutriator for organic carbon (OC), elemental carbon (EC), sulfate, and nitrate measurements. For the collection of nitrate and sulfate, the minisampler includes a miniaturized honeycomb glass denuder that is placed upstream of the filter to remove nitric acid and sulfur dioxide and to minimize artifacts. Two passive samplers can also be attached to the elutriator for measurements of gaseous copollutants such as O3, SO2, and NO2. The performance of the multipollutant sampler was examined through a series of laboratory chamber tests. The results showed a good agreement between the multipollutant sampler and the reference methods. The overall sampler performance demonstrates its suitability for personal exposure assessment studies.

Development and Evaluation of a Prototype Ambient Particle Concentrator for Inhalation Exposure Studies

AbstractA number of studies have underlined the importance of the acute and chronic effects of ambient particles on respiratory health. Because fine particles are capable of penetrating deeply into the respiratory system, most of the health studies have focused on the res-pirable portion of the particle size spectrum. Previous studies to examine exposureJ response relationships between particle exposure and adverse respiratory effects have been based on artificial preparations, or collected and resuspended ambient particles, rather than the natural material found in ambient air. Artificial particles may not be representative, and collected particles may be difficult to redisperse. In addition, the chemical and physical characteristics of ambient particles may change upon resuspension. We have developed a new technique that enables us to increase the concentration of ambient particles to levels about 10 times higher (or more, if desirableJ than their ambient values and supply them to an exposure chamber. A...

Laboratory and field evaluation of an improved glass honeycomb denuder/filter pack sampler

Abstract A new and improved glass honeycomb denuder/filter pack sampler has been designed to measure atmospheric particles and gases. The new sampler combines the features of a previously developed glass honeycomb denuder sampler with a new inlet that minimizes loss of sampled gases on the inlet surfaces. Another novelty of the improved design is that the honeycomb denuders are entirely made of glass, instead of consisting of a large number of tubes sealed in an outer glass tube with epoxy resin. The new inlet was designed to reduce the residence time of the air sample as well as the overall surface area available for gas reaction. Although inlets of various materials were tested, the PTFE Teflon coated inlet was found to minimize loss of sampled gases. The honeycomb sampler with the improved inlet was characterized in two different field studies. Outdoor concentrations of nitric acid (HNO 3 ), nitrous acid (HONO), ammonia (NH 3 ), sulfur dioxide (SO 2 ), and fine-particle sulfate (SO 4 2− ), ammonium (NH 4 + ), strong acidity (H + ) and fine particulate mass determined using the honeycomb denuder sampler (HDS) were compared to those determined with a collocated Harvard/EPA annular denuder system (HEADS). The average collection of the HEADS sampler was in excellent agreement (e.g. within ± 10% or less) with that of the honeycomb sampler for all the gas and particle phase species in the comparison studies. Results from the laboratory and field tests suggest that the new honeycomb denuder sampler with the improved inlet is suitable for sampling atmospheric particles and gases. In addition, it has the advantage of being more compact than annular denuder/filter pack systems, which makes the sampler more practical for large-scale monitoring studies.

A Chemical and Toxicological Comparison of Urban Air PM10 Collected During Winter and Spring in Finland.

We have used a new high-volume, low-cutoff inertial impactor (HVLI) in a pilot study on chemical characterization and toxicity testing of ambient air PM10 in Helsinki, Finland. Ambient air PM10 was collected at 1100 L/min in 2- to 4-day periods. Two different PM10 samples were selected to represent wintertime combustion type and springtime resuspension type particulate matter (PM) pollution. The most abundant water-soluble ions and elements were analyzed by ion chromatography and inductively coupled plasma mass spectrometry, respectively. The proinflammatory activation ¡NO and interleukin 6 (IL-6) production] and viability of cultured murine RAW 264.7 macrophages were tested in 24-h incubations with increasing mass doses (30–2000 µg per 106 cells) from the collected PM10 samples. The winter sample had a higher assessed PM2.5 fraction and sulfate content, and lower chloride, sodium, calcium, aluminum, copper, manganese, and especially iron contents than the spring sample. Both PMjo samples induced dose-dependent NO production in murine macrophages, and the springtime PM10 produced also a strong, dose-dependent IL-6 production. In conclusion, the HVLI proved to be a suitable technique for short-term collection of relatively large ambient air PM masses, enabling extensive chemical characterization and toxicity testing from the same samples.

Development and Laboratory Performance Evaluation of a Personal Cascade Impactor

Abstract This paper presents the design and laboratory evaluation of a personal cascade impactor. The system is compact, lightweight, and uses a single battery-operated sampling pump. It operates at a flow rate of 5 L/min and consists of four impaction stages, each equipped with slit-shaped acceleration nozzles, and a backup filter. The impactor was calibrated using polydisperse particles. The 50% cut points of the four stages were 9.6, 2.6, 1.0, and 0.5 μm, respectively. The backup filter is placed downstream of the fourth stage and is used to collect the particles with an aerodynamic diameter smaller than 0.5 μm (dp < 0.5 μm). The major feature of this novel sampler is its ability not only to fractionate the particles with an aerodynamic diameter smaller than 10 μm to the various size fractions, but also to collect them onto relatively small polyurethane foam substrates without using adhesives. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found to be insignificant. Interstage losses of particles smaller than 0.5 μm were less than 10%; for fine particles, less than 5%; and for coarse particles, less than 12%. The pressure drop across the four stages and the backup filter were 0.015 kPa (0.153 cm H2O), 0.025 kPa (0.255 cm H2O), 0.274 kPa (2.794 cm H2O), 0.323 kPa (3.294 cm H2O), and 0.370 kPa (3.773 cm H2O), respectively. Particles can be easily recovered from the foam substrates using aqueous extraction.

DEVELOPMENT AND VALIDATION OF A HIGH-VOLUME, LOW-CUTOFF INERTIAL IMPACTOR

A low-cutoff, high-volume conventional impactor has been designed. This sampler uses a slit-shaped acceleration jet and operates at 1100 L/min. The impaction substrate is polyurethane foam (PUF). The impactor collection efficiency was characterized using polydisperse particles, and the 50% size cutoff point was 0.12 ¡m. Losses within the sampler were also characterized and were less than 10%. The use of polyurethane foam (PUF) as a substrate has the following advantages: (I) PUF has a very high particle collection efficiency over a large range of particle sizes, even under conditions of heavy particle loading, as compared to other impaction substrates, such as flat plates and less porous membranes, which typically are subject to significant bounce-off and reentrainment; (2) no oil or grease coating is required, so potential interferences of impurities within such coatings are avoided when chemical, biological, and toxicological tests are performed on the collected particles; (3) PUF itself is chemically inert, minimizing interference with any of these tests; (4) because of the high flow rate of 1100 L/min, a large amount of particles can be collected in a short period of time on a relatively small surface of substrate, facilitating recovery of the collected particles for the different tests; and (5) a large amount of particles can be collected on a relatively small collection surface and easily extracted with small amounts of water or organic solvents. This method will be suitable for the collection of large amounts for toxicological studies and analysis of organic aerosols, which is not possible with other high-volume samplers that utilize large filtration surfaces.

Development of a high-volume concentrated ambient particles system (CAPS) for human and animal inhalation toxicological studies.

A two-stage, high-volume, ambient particle concentrator was developed and characterized. This versatile system, depending on its operational parameters, can be used to fractionate and concentrate particles in three size ranges (PM 10-2.5, PM 10-1, PM 2.5-1) . The performance of this concentrated ambient particle system (CAPS), as well as its individual virtual impaction stages, was investigated as a function of several parameters, including minor-to-total flow ratios and acceleration nozzle Reynolds number. During these laboratory tests, performance parameters such as concentration enrichment factor (CF), particle losses, collection efficiency curves, cutpoint, and pressure drop were measured. The main objective of these investigations was to optimize the ability of the system to concentrate ambient PM 2.5-10 and PM 1-10 particles. PM 2.5-10 particles were concentrated by a factor of 70 to 150. The flow rate of the concentrated aerosol can range between 12.5 and 50 LPM (L/min). Other features of the system include relatively low-pressure drops in the major and minor flows, low particle losses, and a compact design. Performance evaluation of the system also confirmed that separation and concentration of the PM 2.5-10 particles occurred without any significant distortion of the size distribution, during the concentration process. Similar results were obtained for the PM 1-10 size range. For this size range, concentration enrichment was 70 times, and again, no particle size distribution distortion was observed. The overall performance of this versatile system makes it suitable for inhalation toxicological studies.