Personal Exposure Studies Research Articles

Exposure to air pollutants in Vietnam: Assessing potential risk for tourists

Tourism can form an important component of a nation's GDP, and Vietnam is among the most visited countries in Southeast Asia. Most studies on personal exposure focus on the general population, or occupational cohorts with exposure to specific pollutants. However, short-term exposure to air pollutants while visiting regions with high levels of air pollution can lead to acute health effects. A personal exposure study was conducted across three cities in Vietnam to estimate exposure to particulate matter (PM2.5) and black carbon for tourists. Measurements were conducted during the wet season in 2014 in Ho Chi Minh City, Da Lat and Nha Trang using portable instrumentation. Average 24-hr PM2.5 and BC exposures were estimated as 18.9±9.24 and 3.41±1.33μg/m3 and among the three cities, Ho Chi Minh was found to have the highest PM2.5 concentrations. Environmental tobacco smoke, commuting and street food stands were found to contribute to highest levels of exposure to PM2.5 and BC across all cities.

Assessing Exposure to Household Air Pollution: A Systematic Review and Pooled Analysis of Carbon Monoxide as a Surrogate Measure of Particulate Matter.

Background:Household air pollution from solid fuel burning is a leading contributor to disease burden globally. Fine particulate matter () is thought to be responsible for many of these health impacts. A co-pollutant, carbon monoxide (CO) has been widely used as a surrogate measure of in studies of household air pollution.Objective:The goal was to evaluate the validity of exposure to CO as a surrogate of exposure to in studies of household air pollution and the consistency of the relationship across different study settings and conditions.Methods:We conducted a systematic review of studies with exposure and/or cooking area and CO measurements and assembled 2,048 and CO measurements from a subset of studies (18 cooking area studies and 9 personal exposure studies) retained in the systematic review. We conducted pooled multivariate analyses of associations, evaluating fuels, urbanicity, season, study, and CO methods as covariates and effect modifiers.Results:We retained 61 of 70 studies for review, representing 27 countries. Reported correlations (r) were lower for personal exposure (range: 0.22–0.97; ) than for cooking areas (range: 0.10–0.96; ). In the pooled analyses of personal exposure and cooking area concentrations, the variation in ln(CO) explained 13% and 48% of the variation in ln(), respectively.Conclusions:Our results suggest that exposure to CO is not a consistently valid surrogate measure of exposure to . Studies measuring CO exposure as a surrogate measure of PM exposure should conduct local validation studies for different stove/fuel types and seasons. https://doi.org/10.1289/EHP767

Inter-comparison of personal monitors for nanoparticles exposure at workplaces and in the environment

Personal monitors based on unipolar diffusion charging (miniDiSC/DiSCmini, NanoTracer, Partector) can be used to assess the individual exposure to nanoparticles in different environments. The charge acquired by the aerosol particles is nearly proportional to the particle diameter and, by coincidence, also nearly proportional to the alveolar lung-deposited surface area (LDSA), the metric reported by all three instruments. In addition, the miniDiSC/DiSCmini and the NanoTracer report particle number concentration and mean particle size. In view of their use for personal exposure studies, the comparability of these personal monitors was assessed in two measurement campaigns. Altogether 29 different polydisperse test aerosols were generated during the two campaigns, covering a large range of particle sizes, morphologies and concentrations. The data provided by the personal monitors were compared with those obtained from reference instruments: a scanning mobility particle sizer (SMPS) for LDSA and mean particle size and a ultrafine particle counter (UCPC) for number concentration. The results indicated that the LDSA concentrations and the mean particle sizes provided by all investigated instruments in this study were in the order of ±30% of the reference value obtained from the SMPS when the particle sizes of the test aerosols generated were within 20–400nm and the instruments were properly calibrated. Particle size, morphology and concentration did not have a major effect within the aforementioned limits. The comparability of the number concentrations was found to be slightly worse and in the range of ±50% of the reference value obtained from the UCPC. In addition, a minor effect of the particle morphology on the number concentration measurements was observed. The presence of particles >400nm can drastically bias the measurement results of all instruments and all metrics determined.

Researcher and institutional review board perspectives on the benefits and challenges of reporting back biomonitoring and environmental exposure results

As the number of personal exposure studies expands and trends favor greater openness and transparency in the health sciences, ethical issues arise around reporting back individual results for contaminants without clear health guidelines. Past research demonstrates that research participants want their results even when the health implications are not known. The experiences of researchers and institutional review boards (IRBs) in studies that have reported personal chemical exposures can provide insights about ethical and practical approaches while also revealing areas of continued uncertainty. We conducted semi-structured interviews with 17 researchers and nine IRB members from seven personal exposure studies across the United States to investigate their experiences and attitudes about the report-back process. Researchers reported multiple benefits of report-back, including increasing retention and recruitment, advancing environmental health literacy, empowering study participants to take actions to reduce exposures, encouraging shifts in government and industry practices, and helping researchers discover sources of exposure through participant consultation. Researchers also reported challenges, including maintaining ongoing contact with participants, adopting protocols for notification of high exposures to chemicals without health guidelines, developing meaningful report-back materials, and resource limitations. IRB members reported concern for potential harm to participants, such as anxiety about personal results and counterproductive behavior changes. In contrast, researchers who have conducted personal report-back in their studies said that participants did not appear overly alarmed and noted that worry can be a positive outcome to motivate action to reduce harmful exposures. While key concerns raised during the early days of report-back have been substantially resolved for scientists with report-back experience, areas of uncertainty remain. These include ethical tensions surrounding the responsibility of researchers to leverage study results and resources to assist participants in policy or community-level actions to reduce chemical exposures, and how to navigate report-back to vulnerable populations.

Opportunistic mobile air pollution monitoring: A case study with city wardens in Antwerp

The goal of this paper is to explore the potential of opportunistic mobile monitoring to map the exposure to air pollution in the urban environment at a high spatial resolution. Opportunistic mobile monitoring makes use of existing mobile infrastructure or people’s common daily routines to move measurement devices around. Opportunistic mobile monitoring can also play a crucial role in participatory monitoring campaigns as a typical way to gather data.A case study to measure black carbon was set up in Antwerp, Belgium, with the collaboration of city employees (city wardens). The Antwerp city wardens are outdoors for a large part of the day on surveillance tours by bicycle or on foot, and gathered a total of 393 h of measurements. The data collection is unstructured both in space and time, leading to sampling bias. A temporal adjustment can only partly counteract this bias. Although a high spatial coverage was obtained, there is still a rather large uncertainty on the average concentration levels at a spatial resolution of 50 m due to a limited number of measurements and sampling bias. Despite of this uncertainty, large spatial patterns within the city are clearly captured.This study illustrates the potential of campaigns with unstructured opportunistic mobile monitoring, including participatory monitoring campaigns. The results demonstrate that such an approach can indeed be used to identify broad spatial trends over a wider area, enabling applications including hotspot identification, personal exposure studies, regression mapping, etc. But, they also emphasize the need for repeated measurements and careful processing and interpretation of the data.

Using Global Positioning Systems (GPS) and temperature data to generate time-activity classifications for estimating personal exposure in air monitoring studies: an automated method.

BackgroundPersonal exposure studies of air pollution generally use self-reported diaries to capture individuals’ time-activity data. Enhancements in the accuracy, size, memory and battery life of personal Global Positioning Systems (GPS) units have allowed for higher resolution tracking of study participants’ locations. Improved time-activity classifications combined with personal continuous air pollution sampling can improve assessments of location-related air pollution exposures for health studies.MethodsData was collected using a GPS and personal temperature from 54 children with asthma living in Montreal, Canada, who participated in a 10-day personal air pollution exposure study. A method was developed that incorporated personal temperature data and then matched a participant’s position against available spatial data (i.e., road networks) to generate time-activity categories. The diary-based and GPS-generated time-activity categories were compared and combined with continuous personal PM2.5 data to assess the impact of exposure misclassification when using diary-based methods.ResultsThere was good agreement between the automated method and the diary method; however, the automated method (means: outdoors = 5.1%, indoors other =9.8%) estimated less time spent in some locations compared to the diary method (outdoors = 6.7%, indoors other = 14.4%). Agreement statistics (AC1 = 0.778) suggest ‘good’ agreement between methods over all location categories. However, location categories (Outdoors and Transit) where less time is spent show greater disagreement: e.g., mean time “Indoors Other” using the time-activity diary was 14.4% compared to 9.8% using the automated method. While mean daily time “In Transit” was relatively consistent between the methods, the mean daily exposure to PM2.5 while “In Transit” was 15.9 μg/m3 using the automated method compared to 6.8 μg/m3 using the daily diary.ConclusionsMean times spent in different locations as categorized by a GPS-based method were comparable to those from a time-activity diary, but there were differences in estimates of exposure to PM2.5 from the two methods. An automated GPS-based time-activity method will reduce participant burden, potentially providing more accurate and unbiased assessments of location. Combined with continuous air measurements, the higher resolution GPS data could present a different and more accurate picture of personal exposures to air pollution.

Measurement Error in Spatial Exposure Models: Study Design Implications.

Measurement Error in Spatial Exposure Models: Study Design Implications.

Daily Activity Patterns and Time Spent for Exposure Assessment:

Recently in the field of personal exposure studies, the individual daily activity and time spent have been greatly concerned. The information about daily activity and time use patterns provide benefit on the analysis of environmental pollutant within microenvironment. Comprehensive studies for daily activity with time spent as a basis for estimates of personal exposure have been conducted few times in Korea. The primary objective of this research, therefore,is to present activity patterns and time spent of individuals especially for University students. University campus is unique area where students decide activities and spend time respect to them on campus. This activity and time spent will be a basis of estimating number of activity population by time of day at a certain building or place on campus. Activity population estimated will help to assessment individual exposure in micro-environmental pollutants. The Dongnam University conducted a student activity survey. A random 500(10%) students, sample of students representing the total Dongnam University student population, was selected and they were asked to complete a activity diary for one school day between April 4 and 30, 2012. The questions included demographic information and activity-time use patterns. The activities consist of 7 major classifications: Work(class, lab, etc), Study(personal), Excise, Recreation, Club, Other, and Travel. We focus on the school hours from 6AM to 24PM and present the statistics of activity frequency, duration, and travel time by activity patterns. Further, based on the activity-time spent data, we develop activity profile by hourly segmentation at individual building level on campus and construct a statistical model for estimating activity profile. This will be basis of estimates of activity population for exposure at environmental pollutant. Findings will indicate whether theactivity-time spent estimates have great potential of personal exposure studies with indoor pollutant.

Simulating real-world exposures during emergency events: studying effects of indoor and outdoor releases in the Urban Dispersion Program in upper Manhattan, NY

A prospective personal exposure study, involving indoor and outdoor releases, was conducted in upper Midtown Manhattan in New York City as part of the Urban Dispersion Program (UDP) focusing on atmospheric dispersion of chemicals in complex urban settings. The UDP experiments involved releases of very low levels of perfluorocarbon tracers (PFTs) in Midtown Manhattan at separate locations, during two seasons in 2005. The study presented here includes both outdoor and indoor releases of the tracers, and realistic scripted activities for characterizing near source and neighborhood-scale exposures using 1-min and 10-min duration samples, respectively. Results showed that distributions of individual tracers and exposures to them within the study area were significantly influenced by surface winds, urban terrain, and movements of people typical of urban centers. Although in general, PFT levels returned quickly to zero in general after cessation of the emissions, in some cases, the concentrations stayed at higher levels after the releases stopped. This is likely due to accumulation of the PFTs in some buildings, which then serve as "secondary sources" when outside levels are lower than indoor levels. Measurements of neighborhood-scale PFT concentrations (up to distances of several blocks away from the release points) provided information needed to establish a baseline for determining how different types of releases could affect exposures both to the general public and to emergency responders. These data highlight the factors impacting the toxic threat levels following releases of hazardous chemicals and provide supporting information for evaluating and refining protocols for emergency event response.

Determinants of Respirable Silica Exposure in Stone Countertop Fabrication: A Preliminary Study

A preliminary study of personal exposure to respirable quartz was conducted in four shops that used a variety of wet and dry methods to fabricate countertops from granite and quartz-containing synthetic stone-like materials. Full-shift time-weighted average (TWA) exposures exceeded the ACGIH threshold limit value of 0.025 mg/m3 for all workers who used dry fabrication methods, even for very limited time, during any part of the work shift (n = 15 person-days). The geometric mean of exposures for workers who used dry methods extensively was about 1 mg/m3 (n = 12 person-days). Workers who operated only automated or remotely controlled stone cutting or shaping equipment had calculated TWA exposures of approximately 0.02 mg/m3 (n = 3 person-days). Task-specific geometric mean exposures for various wet and dry manual operations were ranked based on estimated concentrations extracted from multi-task partial-shift sample results using a linear algebra procedure. Limited use of dry methods was observed in shops that had previously reported using only wet methods. These results suggest that even shops that report using only wet methods might, in fact, resort to brief use of dry methods for specific operations. Therefore, there may be reason for concern over potential overexposure to respirable quartz in all stone countertop shops.

Measurement of personal and integrated exposure to particulate matter and co-pollutant gases

Personal exposure measurement can serve as an effective tool to understand the effect of exposure to air pollutants. Alternatively, exposure assessment using pollutant concentrations in different microenvironments and accurate time-activity information for the subjects can provide good information regarding human integrated exposure. A panel of 18 healthy students of Indian Institute of Technology (IIT) Kanpur in the age group of 18 to 30 years participated in the personal exposure measurements for particulate matter, CO, NO(2) and VOC during post-monsoon and pre-monsoon seasons. Overall, 432 h person exposure data was collected in this study. The major sources of particulate and gaseous co-pollutants were identified. These directly obtained personal exposure values were then compared to the indirectly estimated integrated exposure values. Personal and integrated exposures gave statistically similar results. Through this study, we have shown that integrated exposure values could closely estimate the personal exposure values for particulate matter that can significantly reduce time and cost involved in personal exposure studies. The lung parameters for all the subjects measured during the pre-monsoon and post-monsoon seasons showed statistically significant reduction during pre-monsoon. This was attributed to the high levels of coarse particles during pre-monsoon.

Defining indoor heat thresholds for health in the UK

It has been recognised that as outdoor ambient temperatures increase past a particular threshold, so do mortality/morbidity rates. However, similar thresholds for indoor temperatures have not yet been identified. Due to a warming climate, the non-sustainability of air conditioning as a solution, and the desire for more energy-efficient airtight homes, thresholds for indoor temperature should be defined as a public health issue. The aim of this paper is to outline the need for indoor heat thresholds and to establish if they can be identified. Our objectives include: describing how indoor temperature is measured; highlighting threshold measurements and indices; describing adaptation to heat; summary of the risk of susceptible groups to heat; reviewing the current evidence on the link between sleep, heat and health; exploring current heat and health warning systems and thresholds; exploring the built environment and the risk of overheating; and identifying the gaps in current knowledge and research. A global literature search of key databases was conducted using a pre-defined set of keywords to retrieve peer-reviewed and grey literature. The paper will apply the findings to the context of the UK. A summary of 96 articles, reports, government documents and textbooks were analysed and a gap analysis was conducted. Evidence on the effects of indoor heat on health implies that buildings are modifiers of the effect of climate on health outcomes. Personal exposure and place-based heat studies showed the most significant correlations between indoor heat and health outcomes. However, the data are sparse and inconclusive in terms of identifying evidence-based definitions for thresholds. Further research needs to be conducted in order to provide an evidence base for threshold determination. Indoor and outdoor heat are related but are different in terms of language and measurement. Future collaboration between the health and building sectors is needed to develop a common language and an index for indoor heat and health thresholds in a changing climate.

Factors influencing variability in the infiltration of PM2.5 mass and its components

The infiltration of particles into homes can vary seasonally, between homes in a community and between communities. However, few studies have examined the day to day variability across multiple homes. We used continuous data collected from a 2-year (2005–2006) personal exposure study conducted in Windsor, ON to estimate daily infiltration factors (Finf) for fine particulate matter (PM2.5), Black Carbon (BC), and ultrafine particles (UFP) as well as the ambient personal exposure factor (Fpex) for PM2.5. In addition, the daily ambient and non-ambient generated components of indoor and personal concentrations were estimated.Median daily Finf estimates ranged from 0.26 to 0.36 across seasons for PM2.5; from 0.28 to 0.59 for BC; and from 0.15 to 0.26 for UFP. Median daily Fpex estimates ranged from 0.24 to 0.31 across seasons. Daily PM2.5 and UFP Finf and Fpex estimates were higher in summer than winter, although BC showed the opposite trend. Predictors of daily infiltration were typically related to window-opening behaviours, air conditioning, meteorological variables, and home age. In addition, use of electrostatic precipitators and stand alone air cleaners was associated with significantly reduced infiltration factors, indicating that these devices may provide a cost effective mechanism of reducing human exposures to particles of ambient origin.The majority of indoor PM2.5 (median 57–73%) and indoor BC (median 90–100%) was of ambient origin across seasons, while both personal PM2.5 and indoor UFPs had significant non-ambient contributions (median 60–65%). Factors that were found to increase non-ambient particle concentrations were typically related to cooking, candle use, supplemental heating, cleaning, and number of people in the home. Factors that were found to decrease non-ambient particle concentrations were open windows, and air cleaner use.This work has several implications to both epidemiologic studies and risk management. A better understanding of the factors influencing Finf and Fpex can improve exposure assessment and contribute to reduced exposure misclassification in epidemiologic studies. Furthermore, by increasing our knowledge of non-ambient and ambient exposures, risk associated with PM exposure can be managed more effectively.

Personal Exposure and Indoor Home Particulate Matter: A Review

This review deals with field studies of particles indoors and exposure to particulate concentrations on recent surveys of homes. The results of indoor and personal exposure concentrations are presented. In addition the effect of other related air pollution factors which might have an effect on exposure to particles are discussed. This paper surveys of particle concentrations and sources in homes from 1981 to 2011. Three major studies which in the USA and a large scale study in Europe that carried out to measure personal exposure and indoor home particle concentrations. A number of small personal exposure studies in homes are also briefly summarized. Personal exposure studies in the USA, EXPOLIS cities and Toronto and others similar studies have documented that the personal exposure to PM concentrations was higher than those measured indoors. Most 2.5 of these studies found a suitable relationship between residential indoor and personal exposure to particulate matter. Personal exposure to respirable particulate matter highly correlated with indoor air. Ambient concentrations obtained from Fixed Site Monitors poorly correlated with total personal exposure to particulate matter concentrations. Some indoor particle source such as smoking, cooking and resuspension of indoor dust may increase subjected to personal exposure and indoor particulate concentrations.

DIFFERENCE IN PERSONAL EXPOSURE TO PARTICULATE AIR POLLUTANTS IN USERS OF DIFFERENT TRANSPORT MODES (AUTOMOBILE, BUS, SUBWAY AND BICYCLE) IN SANTIAGO, CHILE: STUDY DESIGN

Background and Aims: Daily, people can be exposed to high levels of air pollutants during their home-work trips because of their closer proximity to traffic emissions and their exposures may vary according to the mode of transport used (bus, automobile, subway and bicycle). Little is known about exposure to air pollutants in transport´s users in Chile, and even less is known regarding difference in exposure by transport mode. Here, we present a study that compares air pollutant exposures in users of different modes of transport in Santiago, Chile. Methods: (Arial, 8pt, bold) We will conduct a first, observational cross-sectional study of personal exposure to air pollutants in users of different modes of transport in their normal routes. 68 volunteer subjects that have similar home-work routes will be recruited, allocating about 17 subject to each mode (bus, automobile, subway and bicycle). Each participant will perform its morning and evening trips as usual except that they will carry personal monitors to measure particulate air pollutants PM2.5 and ultrafine particles. Additionally, both PM fractions will be measured at a central site in order to separate the contribution of the transport microenvironment from the background. This study will be complemented with a second cross-sectional study where exposure in the different modes will be evaluated in an assigned route (Alameda Street in downtown Santiago) during morning trips. Data will be analyzed using regression models to compare the modes, and determine the effects of environmental factors such as temperature, meteorology, traffic density, and so on, on personal exposure levels. Results: Some preliminary results are expected by the time of the conference. Conclusions: identification of environmental factors that determine increases in pollutant’s exposure may guide actions aimed to reduce people’s exposure to air pollutants during their home-work trip.

Oil Sands Contaminants

Oil Sands Contaminants

Ambient solar UV radiation and seasonal trends in potential sunburn risk among schoolchildren in South Africa

Background. The detrimental effects of excess personal solar ultraviolet (UV) radiation exposure include sunburn, immunosuppression and skin cancer. In South Africa, individuals with minimum natural protection from melanin, including fair-skinned individuals and African albinos, and people spending extended unprotected periods outdoors are at risk of sunburn, a risk factor for skin cancer. Sunburn becomes increasingly likely during the high solar UV radiation hours around midday, and previous studies have shown that children are exposed to potentially high, sunburn-causing solar UV radiation levels while at school. Method. To estimate national potential child sunburn risk patterns, monitored ambient solar UV radiation levels at six sites in South Africa were converted into possible schoolchild solar UV radiation exposures by calculating the theoretical child exposure to 5% of the total daily ambient solar UV radiation as derived from personal child exposure studies. Results. Schoolgoing children with skin types I, II and III were identified as being at greatest risk of sunburn. There were 44 and 99 days in a year when schoolchildren with skin type III (moderately sensitive) living in Durban and De Aar, respectively, would be likely to experience sunburn. Schoolchildren with skin type I (extremely sensitive) were at risk of experiencing sunburn on 166 days in De Aar, and those with skin types I and II were at risk on at least 1 day per year at all six locations. Conclusion. Seasonal patterns show that schoolchildren with sensitive skin types may experience sunburn in spring, summer and autumn months. Differences in child sunburn risk were evident, mainly due to latitude and atmospheric aerosols. Additional factors affecting sunburn risk include schoolchildren’s use of sun protection, sun-exposed activity, and timing and duration of exposure. Understanding risk patterns and obtaining locally relevant information will assist South African skin cancer prevention and sun protection awareness

Traffic-related Air Pollution and Personal Exposure to Nitrogen Oxides in School Children in Beijing

O-31A6-1 Background/Aims: Several studies have shown association between traffic-related nitrogen oxides (NOx) pollution and adverse health effects in children. Most of these studies, however, used ambient or indoor NOx concentrations as surrogate of personal exposure. The studies on personal exposure to NOx in children are still limited. In this study, we evaluated personal exposure to NOx, nitrogen dioxide (NO2), and nitric oxide (NO) in children from 2 primary schools located in 2 areas in Beijing with different levels of traffic-related air pollution. Methods: A study of personal exposure to NOx, NO2, and NO was conducted in 30 children from a school near a main road with high traffic density (School 1) 4 times from 2007 to 2008, and in 40 children from a school (School 2) located far from the main road in 2008, respectively. Personal exposure to NOx, NO2, and NO were measured with passive samplers. Repeated Measures Test in General Linear model was used to analyze the differences of exposures among the 4 periods in children from School 1. And the differences between 2 schools were analyzed by Mann-Whitney U Rank test. Results: In children from School 1, the highest exposure to NO2 was observed in January 2008, whereas there was no significant difference among the other 3 periods. The lowest and highest exposures to NO and NOx were seen in October and April 2008, respectively. There was no significant difference between the other 2 periods. At the same period of investigation, personal exposure to NO2, NO, and NOx in children from School 1 were 99%, 145%, and 129% higher than those in children from School 2, respectively. Conclusion: Our results suggested that traffic-related air pollution significantly contributed to the personal exposure to NOx, NO2, and NO in school children in Beijing.

Characterization of personal exposure concentration of fine particles for adults and children exposed to high ambient concentrations in Beijing, China

In China, the health risk from overexposure to particles is becoming an important public health concern. To investigate daily exposure characteristics to PM 2.5 with high ambient concentration in urban area, a personal exposure study was conducted for school children, and office workers in Beijing, China. For all participants ( N = 114), the mean personal 24-hr exposure concentration was 102.5, 14.7, 0.093, 0.528, 0.934, 0.174 and 0.703 μg/m c for PM 2.5, black carbon, Mn, Al, Ca, Pb, and Fe. Children's exposure concentrations of PM 2.5 were 4-5 times higher than those in related studies. The ambient concentration of PM 2.5 (128.5 μg/m c) was significantly higher than the personal exposure concentration ( P < 0.05), and exceed the reference concentration (25 μg/m c) of WHO air quality guideline. Good correlation relationships and significant differences were identified between ambient concentration and personal exposure concentration. The relationships indicate that the ambient concentration is the main factor influencing personal exposure concentration, but is not a good indicator of personal exposure concentration. Outdoor activities (commute mode, exposure to heating, workday or weekend travel) influenced personal exposure concentrations significantly, but the magnitude of the influence from indoor activities (exposure to cooking) was masked by the high ambient concentrations.

PAH intermediates: Links between the atmosphere and biological systems

China is now the world's largest emitter of polycyclic aromatic hydrocarbons (PAHs). In addition, PAHs, and their reactive intermediates, undergo trans-Pacific atmospheric transport to the Western U.S. The objectives of our research are to predict, identify and quantify novel PAH intermediates in the atmosphere and biological systems, using computational methods, as well as laboratory and field experiments. Gaussian is used to predict the thermodynamic properties of parent structure PAHs, as well as the associated nitro-, oxy-, and hydroxy-PAH intermediates. Based on these predictions, state-of-the-art analytical chemistry techniques are used to identify and quantify these potential intermediates on Asian particulate matter before and after reaction in a continuous flow photochemical reactor. These same techniques are used to identify the relative proportion of PAH intermediates in PAH source regions (such as Beijing, China) and during long-range atmospheric transport to the Western U.S. PAH personal exposure studies in China and the Confederated Tribes of the Umatilla Indian Reservation in Oregon will be used to assess the similarities and differences in the PAH intermediates in biological systems relative to the atmosphere.