Biomedical subjects

Barbara J Turpin

Publications and source records attributed to Barbara J Turpin.

12 recordsLinked to original sources

PubMed2006

Evidence for oligomer formation in clouds: reactions of isoprene oxidation products.

Electrospray ionization mass spectrometry (ESI-MS) was used to investigate product formation in laboratory experiments designed to study secondary organic aerosol (SOA) formation in clouds. It has been proposed that water soluble aldehydes derived from aromatics and alkenes, including isoprene, oxidize further in cloud droplets forming organic acids and, upon droplet evaporation, SOA. Pyruvic acid is an important aqueous-phase intermediate. Time series samples from photochemical batch aqueous phase reactions of pyruvic acid and hydrogen peroxide were analyzed for product formation. In addition to the monomers predicted by the reaction scheme, products consistent with an oligomer system were found when pyruvic acid and OH radical were both present. No evidence of oligomer formation was found in a standard mix composed of pyruvic, glyoxylic, and oxalic acids prepared in the same matrix as the samples analyzed using the same instrument conditions. The distribution of high molecular weight products is consistent with oligomers composed of the mono-, oxo-, and di-carboxylic acids expected from the proposed reaction scheme.

Aldehydes↗

PubMed2006

Source proximity and outdoor-residential VOC concentrations: results from the RIOPA study.

Ambient volatile organic compound concentrations outside residences were measured in Elizabeth, New Jersey as part of the Relationship of Indoor, Outdoor, and Personal A:r (RIOPA) study to assess the influence of proximity of the residences to known ambient emissions sources. The closest distances between the outdoor samplers and emission sources were determined using Geographic Information Systems (GIS)techniques. Multiple regression models were developed for residential ambient concentrations of aromatic hydrocarbons (BTEX), methyl tert butyl ether (MTBE), and tetrachloroethylene (PCE). The natural log transformed ambient concentrations of BTEX were inversely associated with distances to major roadways with high traffic densities and gasoline stations, atmospheric stability, temperature, and wind speed. Ambient MTBE levels were associated with inverse distance to gas stations and interstate highways. Residential ambient PCE concentration was inversely associated with distance to dry cleaning facilities, atmospheric stability, temperature, wind speed, and relative humidity. The linear regression models that include proximity to emission sources and meteorological variables explained 16-45% of the overall variation of ambient residential VOC concentrations. Meteorological conditions, especially atmospheric stability and temperature, explained 60-90% of the total variation in the regression models. The residential ambient air concentrations were 1.5-4 times higher than the urban background levels outside homes very close (<50 m) to ambient emission sources where approximately 7% of the population live. However, the relative increase of risk for disease is small and variations in air concentration in the background urban atmosphere are greater than those from the proximity to roadways.

Air Pollutants↗

PubMed2005

PM2.5 of ambient origin: estimates and exposure errors relevant to PM epidemiology.

Epidemiological studies routinely use central-site particulate matter (PM) as a surrogate for exposure to PM of ambient (outdoor) origin. Below we quantify exposure errors that arise from variations in particle infiltration to aid evaluation of the use of this surrogate, rather than actual exposure, in PM epidemiology. Measurements from 114 homes in three cities from the Relationship of Indoor, Outdoor and Personal Air (RIOPA) study were used. Indoor PM2.5 of outdoor origin was calculated as follows: (1) assuming a constant infiltration factor, as would be the case if central-site PM were a "perfect surrogate" for exposure to outdoor particles; (2) including variations in measured air exchange rates across homes; (3) also incorporating home-to-home variations in particle composition, and (4) calculating sample-specific infiltration factors. The final estimates of PM2.5 of outdoor origin take into account variations in building construction, ventilation practices, and particle properties that result in home-to-home and day-to-day variations in particle infiltration. As assumptions became more realistic (from the first, most constrained model to the fourth, least constrained model), the mean concentration of PM2.5 of outdoor origin increased. Perhaps more importantly, the bandwidth of the distribution increased. These results quantify several ways in which the use of central site PM results in underestimates of the ambient PM2.5 exposure distribution bandwidth. The result is larger uncertainties in relative risk factors for PM2.5 than would occur if epidemiological studies used more accurate exposure measures. In certain situations this can lead to bias.

Air Pollutants↗

PubMed2005

Isoprene forms secondary organic aerosol through cloud processing: model simulations.

Isoprene accounts for more than half of non-methane volatile organics globally. Despite extensive experimentation, homogeneous formation of secondary organic aerosol (SOA) from isoprene remains unproven. Herein, an incloud process is identified in which isoprene produces SOA. Interstitial oxidation of isoprene produces water-soluble aldehydes that react in cloud droplets to form organic acids. Upon cloud evaporation new organic particulate matter is formed. Cloud processing of isoprene contributes at least 1.6 Tg yr(-1) to a global biogenic SOA production of 8-40 Tg yr(-1). We conclude that cloud processing of isoprene is an important contributor to SOA production, altering the global distribution of hygroscopic organic aerosol and cloud condensation nuclei.

Aerosols↗

PubMed2005

Influence of ambient (outdoor) sources on residential indoor and personal PM2.5 concentrations: analyses of RIOPA data.

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to investigate residential indoor, outdoor and personal exposures to several classes of air pollutants, including volatile organic compounds, carbonyls and fine particles (PM2.5). Samples were collected from summer, 1999 to spring, 2001 in Houston (TX), Los Angeles (CA) and Elizabeth (NJ). Indoor, outdoor and personal PM2.5 samples were collected at 212 nonsmoking residences, 162 of which were sampled twice. Some homes were chosen due to close proximity to ambient sources of one or more target analytes, while others were farther from sources. Median indoor, outdoor and personal PM2.5 mass concentrations for these three sites were 14.4, 15.5 and 31.4 microg/m3, respectively. The contributions of ambient (outdoor) and nonambient sources to indoor and personal concentrations were quantified using a single compartment box model with measured air exchange rate and a random component superposition (RCS) statistical model. The median contribution of ambient sources to indoor PM2.5 concentrations using the mass balance approach was estimated to be 56% for all study homes (63%, 52% and 33% for California, New Jersey and Texas study homes, respectively). Reasonable variations in model assumptions alter median ambient contributions by less than 20%. The mean of the distribution of ambient contributions across study homes agreed well for the mass balance and RCS models, but the distribution was somewhat broader when calculated using the mass balance model with measured air exchange rates.

Air Pollutants↗

PubMed2005

Relationship of Indoor, Outdoor and Personal Air (RIOPA) study: study design, methods and quality assurance/control results.

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) Study was undertaken to evaluate the contribution of outdoor sources of air toxics, as defined in the 1990 Clean Air Act Amendments, to indoor concentrations and personal exposures. The concentrations of 18 volatile organic compounds (VOCs), 17 carbonyl compounds, and fine particulate matter mass (PM(2.5)) were measured using 48-h outdoor, indoor and personal air samples collected simultaneously. PM2.5 mass, as well as several component species (elemental carbon, organic carbon, polyaromatic hydrocarbons and elemental analysis) were also measured; only PM(2.5) mass is reported here. Questionnaires were administered to characterize homes, neighborhoods and personal activities that might affect exposures. The air exchange rate was also measured in each home. Homes in close proximity (<0.5 km) to sources of air toxics were preferentially (2:1) selected for sampling. Approximately 100 non-smoking households in each of Elizabeth, NJ, Houston, TX, and Los Angeles, CA were sampled (100, 105, and 105 respectively) with second visits performed at 84, 93, and 81 homes in each city, respectively. VOC samples were collected at all homes, carbonyls at 90% and PM(2.5) at 60% of the homes. Personal samples were collected from nonsmoking adults and a portion of children living in the target homes. This manuscript provides the RIOPA study design and quality control and assurance data. The results from the RIOPA study can potentially provide information on the influence of ambient sources on indoor air concentrations and exposure for many air toxics and will furnish an opportunity to evaluate exposure models for these compounds.

Air Movements↗

PubMed2005

Relationships of Indoor, Outdoor, and Personal Air (RIOPA). Part I. Collection methods and descriptive analyses.

This study on the relationships of indoor, outdoor, and personal air (RIOPA) was undertaken to collect data for use in evaluating the contribution of outdoor sources of air toxics and particulate matter (PM) to personal exposure. The study was not designed to obtain a population-based sample, but rather to provide matched indoor, outdoor, and personal concentrations in homes that varied in their proximity to outdoor pollution sources and had a wide range of air exchange rates (AERs). This design allowed examination of relations among indoor, outdoor, and personal concentrations of air toxics and PM across a wide range of environmental conditions; the resulting data set obtained for a wide range of environmental pollutants and AERs can be used to evaluate exposure models. Approximately 100 households with residents who do not smoke participated in each of three cities in distinct locations expected to have different climates and housing characteristics: Elizabeth, New Jersey; Houston, Texas; and Los Angeles County, California. Questionnaires were administered to characterize homes, neighborhoods, and personal activities that might affect exposures. The concentrations of a suite of volatile organic compounds (VOCs) and carbonyl compounds, as well as the fraction of airborne particulate matter with a mass median aerodynamic diameter < or = 2.5 microm (PM2.5), were measured during continuous 48-hour sessions in which indoor, outdoor, and personal air samples were collected simultaneously. During the same 48-hour period, the AER (exchanges/hr; x hr(-1)) was determined in each home, and carbonyl compounds were measured inside vehicle cabins driven by a subset of the participants. In most of the homes, measurements were made twice, during two different seasons, to obtain a wide distribution of AERs. This report presents in detail the data collection methods, quality control measures, and initial analyses of data distributions and relations among indoor, outdoor, and personal concentrations. The results show that indoor sources dominated personal and indoor air concentrations of many measured VOCs and carbonyl compounds. For several measured species, personal concentrations were higher than either indoor or outdoor concentrations, indicating the presence of some sources closely related to personal activities. For some species there were no significant indoor sources in the majority of the homes; thus indoor concentrations were mainly determined by outdoor concentrations in these homes. The range of distributions of air concentrations for the measured VOCs, formaldehyde and acetaldehyde, PM2.5, and AERs were generally consistent with values reported previously in the literature. Thus associations derived from or models based on this data set that may link the influence of outdoor sources with indoor air concentrations of air toxics and PM2.5 can be relevant to other urban settings. The simultaneous measurements of indoor concentrations, outdoor concentrations, AERs, and room volumes allowed the use of a mass balance model, under the steady-state approximation, to mechanistically examine the relative contributions of indoor and outdoor sources to measured indoor concentrations on a home-by-home basis. Estimated indoor source strengths for VOCs and carbonyl compounds varied widely from home to home, consistent with the indoor-outdoor concentration patterns, as shown in scatter plots. The indoor source estimations agreed with published values for PM2.5 and with the general understanding of sources of VOCs and carbonyl compounds. The source strengths reported here, derived from hundreds of homes, are an important contribution to the literature on exposure to air toxics. For the first time for many compounds, these estimates present a cohesive set of measurements across a range of air toxics in paired indoor, outdoor, and personal samples along with AER and questionnaire results that can be used for future analyses of indoor air quality. The estimation of outdoor contributions to measured indoor concentrations provides insights about the relative importance of indoor and outdoor sources in determining indoor concentrations, the main determinant of personal exposure for most of the measured compounds. In this report simple statistical tests mainly of the pooled data were used to analyze differences by sampling site, emission source type, season, home type, and home age. Paired adult-child personal concentrations within the same home were also compared using the pooled data set. These analyses generated some intriguing results that warrant more in-depth investigation in the future.

Air Movements↗

PubMed2004

Chlordanes in the indoor and outdoor air of three U.S. cities.

Indoor and outdoor concentrations of six chlordane components (trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, oxychlordane, and MC5) were measured at 157 residences, all of which were inhabited by nonsmoking individuals, in three urban areas during June 1999-May 2000. The analyses were conducted on a subset of 48 h integrated samples collected in Los Angeles County, CA, Houston, TX, and Elizabeth, NJ within the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study. Both particle-bound (PM2.5; quartz fiber filter) and vapor-phase (PUF sorbant) chlordane concentrations were separately measured by GC/EI MS after solvent extraction. The outdoor (gas + particle) total chlordane (trans-chlordane + cis-chlordane + trans-nonachlor + cis-nonachlor) concentrations ranged from 0.036 to 4.27 ng m(-3) in Los Angeles County, from 0.008 to 11.00 ng m(-3) in Elizabeth, and from 0.062 to 1.77 ng m(-3) in Houston. The corresponding indoor total chlordane concentrations ranged from 0.037 to 112.0 ng m(-3) in Los Angeles County, from 0.260 to 31.80 ng m(-3) in Elizabeth, and from 0.410 to 38.90 ng m(-3) in Houston study homes. Geometric mean concentrations were higher in indoor air than outdoor air (1.98 vs 0.58 ng m(-3) in CA; 1.30 vs 0.17 ng m(-3) in NJ; 4.18 vs 0.28 ng m(-3) in TX), which suggests there are significant indoor sources of chlordane species in a subset of homes in each of the three cities. Calculated source strengths relate to home age, with the highest apparent indoor source strengths occurring in unattached single-family homes built during the period from 1945 to 1959. Principle indoor sources of chlordanes likely include volatilization from residues of indoor application of chlordanes and infiltration from subsurface and foundation application of chlordane-containing termiticides during home construction.

Air Pollutants↗

PubMed2002

Origins of primary and secondary organic aerosol in Atlanta: results of time-resolved measurements during the Atlanta Supersite Experiment.

Time-resolved ambient particulate organic (OC) and elemental carbon (EC) data measured in Atlanta, GA, during the Atlanta Supersite Experiment (August3-September 1, 1999) were investigated to determine the temporal trends of atmospheric carbonaceous aerosol and to examine the relative contributions of primary and secondary OC to measured particulate OC. Mean 1-h average concentrations (ranges in parentheses) of PM2.5 OC, EC, and total carbon were 8.3 (3.6-15.8), 2.3 (0.3-9.6), and 10.6 (4.6-24.6) microg of C m(-3), respectively, based on Rutgers University/Oregon Graduate Institute in situ thermal-optical carbon analyzer measurements. Carbonaceous matter (organic material 40%; EC 8%) comprised approximately 48% of PM2.5 mass in Atlanta. Primary and secondary OC concentrations were estimated using an EC tracer method. Secondary OC contributed approximately 46% of measured particulate OC, and 1-h average contributions ranged up to 88%. Vehicle emissions appear to be the dominant contributors to measured EC and primary OC concentrations based on temporal patterns of EC, primary OC, and CO. This research suggests that secondary OC concentrations in Atlanta were influenced by (1) "fresh" secondary organic aerosol formed by photochemical reactions locally in the early afternoons as seen in the Los Angeles air basin and (2) "aged" secondary organic aerosol transported from upwind regions or formed on previous days. Nocturnal peaks in secondary OC and ozone concentrations were observed on several days. The most probable explanation for this is the favorable partitioning of semivolatile organic compounds to the particulate phase driven by temperature decreases and relative humidity increases at night and vertical transport of regional pollutants from above to ground level.

Aerosols↗

PubMed2002

Indoor hydrogen peroxide derived from ozone/d-limonene reactions.

In this pilot study, performed in an office manipulated to resemble an environment with a strong indoor ozone source or a significant influx of outdoor air during a smog event, reactions between ozone and d-limonene produced hydroperoxides. Hydrogen peroxide (H202) presumably constituted the majority of the measured hydroperoxides, although a small amount of organic hydroperoxides (ROOH) may have contributed to the signal. Total hydroperoxides were 1.0-1.5 ppb at low air exchange rates (0.5-4 h(-1)) and 0.6-0.8 ppb at high air exchange rates (12-18 h-1). The net estimated yield ranged from 1.5 to 3.2%, consistent with values reported in the literature. Based on these yields and typical indoor scenarios, peak indoor concentrations of H202 are projected to be comparable with, but not significantly larger than, peak outdoor concentrations. Hygroscopic secondary organic aerosols (SOA; 10-100 microg m(-3)) were simultaneously generated by the ozone/d-limonene reactions; their co-occurrence with H202 provides a mechanism whereby H2O2 can be transported into the lower respiratory tract. The results demonstrate that reduced air exchange rates lead to increased concentrations of H2O2 and SOA as well as a shift in the size-distribution toward larger particles (0.3-0.7 microm diameter), potentially increasing the amount of H2O2 delivered to the lower respiratory region. This study increases our understanding of H2O2 exposures, including exposures to H2O2 associated with co-occurring hygroscopic aerosols. It also re-emphasizes the potential of ozone-driven chemistry to alter indoor environments, often producing products more irritating than their precursors.

Aerosols↗

PubMed2002

Polycyclic aromatic hydrocarbons in the indoor and outdoor air of three cities in the U.S.

The indoor and outdoor concentrations of 30 polycyclic aromatic hydrocarbons (PAHs) were measured in 55 nonsmoking residences in three urban areas during June 1999-May 2000. The data represent the subset of samples collected within the Relationship of Indoor, Outdoor, and Personal Air study (RIOPA). The study collected samples from homes in Los Angeles, CA, Houston, TX, and Elizabeth, NJ. In the outdoor samples, the total PAH concentrations (sigmaPAH) were 4.2-64 ng m(-3) in Los Angeles, 10-160 ng m(-3) in Houston, and 12-110 ng m(-3) in Elizabeth. In the indoor samples, the concentrations of sigmaPAH were 16-220 ng m(-3) in Los Angeles, 21-310 ng m(-3) in Houston, and 22-350 ng m(-3) in Elizabeth. The PAH profiles of low molecular weight PAHs (3-4 rings) in the outdoor samples from the three cities were not significantly different. In contrast, the profiles of 5-7-ring PAHs in thesethree citieswere significantlydifferent, which suggested different dominant PAH sources. The signatures of 5-7-ring PAHs in the indoor samples in each city were similar to the outdoor profiles, which suggested that indoor concentrations of 5-7-ring PAHs were dominated by outdoor sources. Indoor-to-outdoor ratios of the PAH concentrations showed that indoor sources had a significant effect on indoor concentrations of 3-ring PAHs and a smaller effect on 4-ring PAHs and that outdoor sources dominated the indoor concentrations of 5-7-ring PAHs.

Air Pollutants↗

PubMed2002

Identification of sources contributing to Mid-Atlantic regional aerosol.

Source types or source regions contributing to the concentration of atmospheric fine particles measured at Brigantine National Wildlife Refuge, NJ, were identified using a factor analysis model called Positive Matrix Factorization (PMF). Cluster analysis of backward air trajectories on days of high- and low-factor concentrations was used to link factors to potential source regions. Brigantine is a Class I visibility area with few local sources in the center of the eastern urban corridor and is therefore a good location to study Mid-Atlantic regional aerosol. Sulfate (expressed as ammonium sulfate) was the most abundant species, accounting for 49% of annual average fine mass. Organic compounds (22%; expressed as 1.4 x organic carbon) and ammonium nitrate (10%) were the next abundant species. Some evidence herein suggests that secondary organic aerosol formation is an important contributor to summertime regional aerosol. Nine factors were identified that contributed to PM2.5 mass concentrations: coal combustion factors (66%, summer and winter), sea salt factors (9%, fresh and aged), motor vehicle/mixed combustion (8%), diesel/Zn-Pb (6%), incinerator/industrial (5%), oil combustion (4%), and soil (2%). The aged sea salt concentrations were highest in springtime, when the land breeze-sea breeze cycle is strongest. Comparison of backward air trajectories of high- and low-concentration days suggests that Brigantine is surrounded by sources of oil combustion, motor vehicle/mixed combustion, and waste incinerator/industrial emissions that together account for 17% of PM2.5 mass. The diesel/Zn-Pb factor was associated with sources north and west of Brigantine. Coal combustion factors were associated with coal-fired power plants west and southwest of the site. Particulate carbon was associated not only with oil combustion, motor vehicle/mixed combustion, waste incinerator/industrial, and diesel/Pb-Zn, but also with the coal combustion factors, perhaps through common transport.

Aerosols↗