Personal Monitoring Study Research Articles

User-Centred Design of a Final Results Report for Participants in Multi-Sensor Personal Air Pollution Exposure Monitoring Campaigns.

Using low-cost portable air quality (AQ) monitoring devices is a growing trend in personal exposure studies, enabling a higher spatio-temporal resolution and identifying acute exposure to high concentrations. Comprehension of the results by participants is not guaranteed in exposure studies. However, information on personal exposure is multiplex, which calls for participant involvement in information design to maximise communication output and comprehension. This study describes and proposes a model of a user-centred design (UCD) approach for preparing a final report for participants involved in a multi-sensor personal exposure monitoring study performed in seven cities within the EU Horizon 2020 ICARUS project. Using a combination of human-centred design (HCD), human–information interaction (HII) and design thinking approaches, we iteratively included participants in the framing and design of the final report. User needs were mapped using a survey (n = 82), and feedback on the draft report was obtained from a focus group (n = 5). User requirements were assessed and validated using a post-campaign survey (n = 31). The UCD research was conducted amongst participants in Ljubljana, Slovenia, and the results report was distributed among the participating cities across Europe. The feedback made it clear that the final report was well-received and helped participants better understand the influence of individual behaviours on personal exposure to air pollution.

AI-Enabled Wearable and Flexible Electronics for Assessing Full Personal Exposures

Research on the exposome has been extended to personal exposures, and full assessment of personal exposures is of great significance for personal health monitoring and epidemiological studies. Compared with static measurement instruments, wearable sensors are more suitable for dynamic personal exposures assessment. The development of flexible wearable sensors with the features of being physically comfortable and easy to use can be a promising solution for the measurement of personal exposures. With the support of big data and AI, large-scale personal exposures assessment could foster the transition from population-based to individual-based epidemiological studies and upgrade the intelligence level of medical services.

Modeling Exposure Reduction for Personal Level Interventions

Through the APIC-ESTEE (Air Pollution Impacts on Cardiopulmonary Disease in Beijing: An integrated study of Exposure Science, Toxicogenomics and Environmental Epidemiology) project, we have developed a model for the reduction of personal exposures to air pollution to assess the health impacts of interventions such as face mask wearing and use of indoor air purifiers. The model accounts for population level time activity patterns and micro-environmental concentrations. A preliminary analysis for Beijing used data on time activity patterns based on Chinese exposure factors; indoor and outdoor fine particulate (PM2.5) concentrations came from residential home studies, a study of public indoor environments, and a feasibility personal monitoring study. In-transit concentrations were estimated as 110% of ambient concentrations. Three intervention scenarios were modelled – wearing a highly effective or a poorly effective facemask whenever a person is outdoors or in transit and use of an air purifier in the home environment. The effects of these interventions were modelled assuming ‘average’ (84 µg/m3) and high (396 µg/m3) outdoor PM2.5 concentrations. Data for potential exposure reduction for the face mask scenario came from a study of total inward leakage in a volunteer trial with diesel exhaust exposure. Data for the air purifier scenario came from a literature review. Use of a highly effective mask reduced 24-hr average personal exposure by 27% over the baseline scenario of no intervention, while the air purifier reduced exposure by 29% for the average ambient condition. For the high ambient concentration scenario, the highly effective mask reduced exposure by 26% compared to 25% for the air purifier. With a poorly effective mask, the personal exposure reduction under average and high ambient concentrations was 11%. The model will be further developed in a probabilistic form for modelling population level exposure interventions and health impacts.

Mobile Phones, Wireless Technologies and Cognitive and Behavioural Outcomes in the SCAMP Adolescent Cohort

Introduction: Scientists remain uncertain as to whether children’s developing brains are more vulnerable than those of adults to radiofrequency (RF) waves emitted from mobile phones and other wireless devices. The Study of Cognition, Adolescents and Mobile Phones (SCAMP) is a three-year prospective cohort study of adolescents across London, UK which aims to investigate whether children’s use of mobile phones and other wireless devices influences their neurocognitive/behavioural development. Methods: Data on cognitive function, wireless device use and lifestyle are collected at baseline and follow-up via school-based computerised assessments and optional parent/pupil home-based questionnaires. Parents are invited to consent to linkage of their child’s assessment data with routine records (e.g. health and educational records, mobile traffic data), thus allowing for comparisons between self-reported and objective mobile phone use. Biological samples (e.g. urine, saliva) are being collected to provide additional information about potential confounders such as puberty. A RF personal monitoring study is also being conducted in a subset of the cohort to gain an in-depth understanding of children’s personal RF exposure and the relative contribution of each RF source. Pupils are asked to carry a personal exposimeter with integrated GPS tracking for 48 hours, complete a smartphone activity diary and a paper questionnaire, and provide a urine and saliva sample. Results: Baseline data have been collected from 5,504 pupils (53.2% female, mean age 12.0 (SD 0.4); 42.3% White, 20.3% South Asian, 15.9% Black, 11.5% Mixed, 9.9% Other). Preliminary analysis shows that over 80% of participants own a mobile phone. To date, personal monitoring study data have been collected from 40 pupils. Conclusions: SCAMP will improve our understanding of children’s RF exposures and cognitive function and will provide an evidence base to inform public health policy in this area.

A68 Inhalation of traffic-related air pollution using personal monitoring and wearable technology

Abstract Background Many studies indicate that air pollution can lead to both acute and chronic health effects. From a husband/wife study (Dons et al., Atmos Environ, 2011), we know that the time-activity pattern is important in determining exposure to air pollution with a difference of up to 30% in exposure between partners. Exposure in the transport microenvironment contributed 20% to cumulative exposure; whereas only 6% of the time is spent travelling. Moreover, when accounting for breathing rates, time in transport can contribute up to a third of the total inhaled particles. Until now, estimation of inhaled concentration is usually based upon literature values or on cumbersome rather than convenient wearable personal health monitors. Methods A personal monitoring study on 40 test persons in Antwerp (Belgium) was set up measuring black carbon (BC), time-activity patterns, geo-location, and physical activity through accelerometry (ExpoApp) and health markers. Activity types and transport modes were annotated based on GPS, accelerometry and physical activity data. Several sensors that register energy expenditure and cardiovascular function (Sensewear armband, Zephyr BioHarness) are being applied for seven consecutive days on these volunteers while inhalation of BC is calculated. Four different methods to calculate minute ventilation where applied: (1) based on activity classification and minute ventilation estimates from literature; (2) based on heart rates; (3) based on breathing rates; (4) based on METs – metabolic equivalents of work, energy expenditure, and oxygen consumption. Currently a larger multicentre study is ongoing within the framework of the European FP7 PASTA project, including Barcelona and London. Results Initial results based on the activity classification provided by the Sensewear Armband, show that volunteers (all office workers) were sleeping for 28% of the time, and at rest for 58% of the time. Volunteers were travelling for 8% of the day. Seven-day average exposure to BC was 1142 ±165 ng/m³. Average daily inhaled BC concentrations accumulated close to 20 µg; depending on the calculation method, inhaled concentrations differed considerably (14±7%), with method (1) giving the highest values. Only while sleeping, the estimation method does not seem to influence the results. Conclusions Especially for traffic-related air pollution, exposure away from home (while travelling and in other non-home microenvironments) is a significant confounder in exposure assessment. In future epidemiological studies it is key to estimate personal exposure and inhaled dose rather than concentrations on fixed locations; using mobile sensors and wearables this comes within reach.

Measurement Error in Spatial Exposure Models: Study Design Implications.

Measurement Error in Spatial Exposure Models: Study Design Implications.

Personal exposure monitoring wearing protocol compliance: An initial assessment of quantitative measurement

Personal exposure sampling provides the most accurate and representative assessment of exposure to a pollutant, but only if measures are implemented to minimize exposure misclassification and reduce confounders that may cause misinterpretation of the collected data. Poor compliance with personal sampler wearing protocols can create positive or negative biases in the reported exposure concentrations, depending on proximity of the participant or the personal sampler to the pollutant source when the monitor was not worn as instructed. This paper presents an initial quantitative examination of personal exposure monitor wearing protocol compliance during a longitudinal particulate matter personal exposure monitoring study of senior citizens of compromise health in North Carolina. Wearing compliance varied between participants because of gender or employment status, but not longitudinally or between cohorts. A minimum waking wearing compliance threshold, 0.4 for this study of senior citizens, is suggested to define when personal exposure measurements are representative of a participant's exposure. The ability to define a minimum threshold indicates data weighting techniques may be used to estimate a participant's exposure assuming perfect protocol compliance.

Occupational and environmental exposure to extremely low frequency-magnetic fields: a personal monitoring study in a large group of workers in Italy

An inaccurate evaluation of exposure is considered a possible cause for the inadequate conclusiveness of epidemiological research on adverse effects of extremely low frequency-magnetic fields (ELF-MF). The objective of this study is to provide an evaluation of current ELF-MF exposure in workers, the specific contribution of occupational exposure to overall 24-h exposure, and the representativeness of a job exposure matrix (JEM). ELF-MF exposure was monitored in 543 workers for 2 days using personal meters. Time-weighted average (TWA) levels at work, at home and outside the home were calculated. A JEM based on the 1988 International Standard Classification of Occupations (ISCO 88) was created. Median exposure at work, at home and outside the home were 0.14, 0.03 and 0.05 μT, respectively. Occupational exposure accounted for about 60% of 24-h exposure. In the JEM, about 50% of the classified occupations included significantly different individual TWAs. Occupational exposure to ELF-MF appeared low. Median exposure levels at home and outside were 20-28% of the occupational level, giving a minor contribution to overall day-to-day exposure. The frequent occurrence of workers with different TWA included under the same job title highlights the risk of misclassification in epidemiological studies on ELF-MF effects based on JEM.

Gender Differences in Chronic Exposure to Traffic-Related Air Pollution—A Simulation Study of Working Females and Males*

The objective of this study was to identify spatial variability in exposure to outdoor traffic-related air pollution with specific emphasis on comparing exposure estimates for working females and males across a metropolitan area. A spatial exposure simulation model was used to estimate annual average exposure to traffic-related nitrogen dioxide for males and females reporting regular work in census tracts other than that of their residence, in Vancouver, British Columbia. The model produced estimates of annual average exposure in six microenvironments (home indoor, work indoor, other indoor, outdoor, in-vehicle to work, and in-vehicle other) using time-activity patterns and work flow data, for males and females in each of 382 census tracts. This allowed for the identification of spatial variations in exposure estimates for each gender, due to mobility within the study region. Indoor sources of nitrogen dioxide were not included in the simulation. No significant differences in estimated total exposure were found between working females and males in general. Small but observable spatial differences, however, were found between working females and males at the 90th percentile of the exposure distributions associated specifically with the work indoor microenvironment. These were highest in suburban areas (+3 μ g/m3 for females, relative to total exposures in the range of 26 to 37 μ g/m3 annual average hourly nitrogen dioxide). These results identify specific geographic locations in the study area where personal monitoring studies might be warranted and suggest that the inclusion of workplace locations in multivariate modeling could be useful to further understand differences in estimated exposures.

Intake fraction distributions for benzene from vehicles in the Helsinki metropolitan area

The intake fraction (iF) gives a measure of the portion of a source's emissions that is inhaled by an exposed population over a defined period of time. This study examines spatial and population-based iF distributions of a known human carcinogen, benzene, from a ubiquitous urban source, local vehicular traffic, in the Helsinki Metropolitan Area using three computational methods. The first method uses the EXPAND model (EXPosure to Air pollution, especially to Nitrogen Dioxide and particulate matter), which incorporates spatial and temporal information on population activity patterns as well as urban-scale and street canyon dispersion models to predict spatial population exposure distributions. The second method uses data from the personal monitoring study EXPOLIS (Air Pollution Exposure Distributions of Adult Urban Populations in Europe) to estimate the intake fractions for individuals in the study. The third method, a one-compartment box model provides estimates within an order-of-magnitude or better for non-reactive agents in an urban area. Population intake fractions are higher using the personal monitoring data method (median iF 30 per million, mean iF 39 per million) compared with the spatial model (annual mean iF 10 per million) and the box model (median iF 4 per million, mean iF 7 per million). In particular, this study presents detailed intake fraction distributions on several different levels (spatial, individual, and generic) for the same urban area.

Estimation of ambient and non-ambient components of particulate matter exposure from a personal monitoring panel study

To provide additional insight into factors affecting exposure to airborne particulate matter and the resultant health effects, we developed a method to estimate the ambient and nonambient components of total personal exposure. The ambient (or outdoor) component of total personal exposure to particulate matter (PM) (called ambient exposure) includes exposure to the ambient PM concentration while outdoors and exposure while indoors to ambient PM that has infiltrated indoors. The nonambient component of total personal exposure to PM (called nonambient exposure) refers to exposure to PM generated by indoor sources and an individual's personal activity. We used data collected from a personal monitoring study in Vancouver, Canada to demonstrate the methodology. In this study, ambient PM(2.5) exposure was 71% of the measured ambient PM(2.5) concentration and was responsible for 44% of the measured total personal PM(2.5) exposure. Regression analysis of the pooled data sets for ambient and total exposure against outdoor concentrations yielded similar slopes (0.76 for ambient and 0.77 for total) but a higher coefficient of determination for ambient exposure (R(2)=0.62) than for total exposure (R(2)=0.072). As expected, the nonambient exposure was not related to the ambient concentration (R(2)<10(-6)). For longitudinal analyses of the relationship between measured personal exposure and ambient concentrations for individual subjects, the correlation of total personal exposure with ambient concentration yielded values of Pearson's r from 0.83 to -0.68 with an average of 0.36. The relationship was statistically significant for only five of the 16 subjects. In contrast, the correlation of the estimated ambient exposure with ambient concentration yielded values of Pearson's r from 0.92 to 0.77 with an average of 0.88; 14 were significant. An example, taken from an epidemiologic analysis using the exposure data from this paper, demonstrates the usefulness of separating total exposure into its ambient and nonambient components.

Outdoor, indoor, and personal exposure to VOCs in children.

We measured volatile organic compound (VOC) exposures in multiple locations for a diverse population of children who attended two inner-city schools in Minneapolis, Minnesota. Fifteen common VOCs were measured at four locations: outdoors (O), indoors at school (S), indoors at home (H), and in personal samples (P). Concentrations of most VOCs followed the general pattern O ≈ S < P ≤ H across the measured microenvironments. The S and O environments had the smallest and H the largest influence on personal exposure to most compounds. A time-weighted model of P exposure using all measured microenvironments and time–activity data provided little additional explanatory power beyond that provided by using the H measurement alone. Although H and P concentrations of most VOCs measured in this study were similar to or lower than levels measured in recent personal monitoring studies of adults and children in the United States, p-dichlorobenzene was the notable exception to this pattern, with upper-bound exposures more than 100 times greater than those found in other studies of children. Median and upper-bound H and P exposures were well above health benchmarks for several compounds, so outdoor measurements likely underestimate long-term health risks from children’s exposure to these compounds.

Assessment of indoor fine aerosol contributions from environmental tobacco smoke and cooking with a portable nephelometer.

Personal monitoring studies have indicated that environmental tobacco smoke (ETS) and cooking are major indoor particulate sources in residential and nonindustrial environments. Continuous monitoring of fine particles improves exposure assessment by characterizing the effect of time-varying indoor sources. We evaluated a portable nephelometer as a continuous monitor of indoor particulate levels. Simultaneous sampling with the nephelometer and PM2.5 impactors was undertaken to determine the relationship between particle light scattering extinction coefficient (sigma(sp)) and particle mass concentration in field and environmental chamber settings. Chamber studies evaluated nephelometer measurements of ETS and particles produced from toasting bread and frying foods. Field measurements were conducted in 20 restaurants and bars with different smoking restrictions, and in five residential kitchens. Additional measurements compared the nephelometer to a different mass measurement method, a piezobalance, in a well-characterized residence where various foods were cooked and ETS was produced. Since the piezobalance provides 2-min average mass concentration measurements, these comparisons tested the ability of the nephelometer to measure transient particle concentration peaks and decay rate curves. We found that sigma(sp) and particle mass were highly correlated (R2 values of 0.63-0.98) over a large concentration range (5-1600 microg/m3) and for different particle sources. Piezobalance and gravimetric comparisons with the nephelometer indicated similar sigma(sp) vs. mass slopes (5.6 and 4.7 m2/g for piezobalance and gravimetric comparisons of ETS, respectively). Somewhat different sigma(sp) vs. particle mass slopes (1.9-5.6 m2/g) were observed for the different particle sources, reflecting the influence of particle composition on light scattering. However, in similar indoor environments, the relationship between particle light scattering and mass concentration was consistent enough to use independent nephelometer measurements as estimates of short-term mass concentrations. A method to use nephelometer measurements to determine particulate source strengths is derived and an example application is described.

Correlations of Personal Exposure to Particles with Outdoor Air Measurements: A Review of Recent Studies

Epidemiological studies have found a correlation between daily mortality and particle concentrations in outdoor air as measured at a central monitor ing station. These studies have been the central reason for the U.S. EPA to propose new tighter particle standards. However, personal monitoring studies have generally found very poor correlations (often approaching 0) between personal exposures and outdoor air concentrations. This has led to questions regarding the scientific basis of the new EPA standard. One reason for the poor correlations noted in the personal monitoring studies is that the correlations were cross-sectional: that is, they included many persons (generally monitored for only 1 or a few days) with no differentiation between persons exposed to high indoor sources (such as smokers) and those with much smaller exposures. Some recent studies have improved on this situation by following persons for a number of days and performing longitudinal correlations on individuals over time. These longitud...

Validation of personal exposure models for sulfate and aerosol strong acidity.

Personal exposure models for sulfates (SO4 =) and aerosol strong acidity (H+) were previously developed using concentration and activity pattern data collected from a personal monitoring study conducted in Uniontown, Pennsylvania, during the summer of 1990. Models were constructed based on time-weighted micro-environmental exposures. For SO4 =, the "best-fit" model included a correction factor, while for H+, it included both a correction factor and a neutralization term. In this paper, we present the validation of these models using data collected in a personal monitoring study conducted in State College, Pennsylvania, during the summer of 1991. Indoor and outdoor concentration and activity pattern data collected in this study were used as inputs for the "best-fit" models for SO4 = and H+. Predicted personal exposures subsequently were compared to the measured personal exposures from State College to determine their accuracy and precision. Predicted personal exposures for both SO4 = and H+ were in excellent agreement with measured personal exposures from State College. The models explained 91 and 62 percent of the variability in personal SO4 = and H+ exposures, respectively, and were able to estimate personal exposures substantially better than outdoor concentrations alone. Validation results suggest that the models' correction and neutralization factors are not site specific and support the models' future application as a technique to assess the personal acid aerosol exposures of children living in similar rural and semi-rural communities.

A personal monitoring study to assess workplace exposure to environmental tobacco smoke.

We enrolled 15 nonsmoking volunteers to evaluate the feasibility of measuring personal exposure to environmental tobacco smoke (ETS) at work and to characterize workplace exposures. During one workshift, we obtained questionnaires on exposure, saliva and urine for cotinine, and personal air samples for respirable particles and nicotine. The levels of cotinine, respirable particles, and nicotine varied widely with self-reports of exposure to ETS, but on average increased with increasing exposure.

Factors Associated with Human Exposures to Polycyclic Aromatic Hydrocarbons

The number and quantities of PAH emitted and accumulated within various environmental media require the development and application of new methods for determining the major routes of exposure to individual and selected compounds. From research that has been conducted on airborne BaP and other selected PAH it appears that they can accumulate indoors as well as outdoors. Smoking seems to be a major contributor for direct and passive inhalation, but the role of cooking and wood burning related to indoor emissions needs to be investigated further. The available data indicate that many PAH will be distributed between both particles and the gas phase. Therefore, new techniques for simultaneously sampling PAH in both phases are required for the indoor environment and personal monitoring studies. These will increase our understanding of the distribution of each component and increase the accuracy of exposure and risk assessments conducted for Total PAH. A strategy (THEES) has been developed for the measurement of BaP exposure from multiple pathways. It should be extended to other PAH, which will assist in quantifying the significance of indoor air related exposures. The inhalation exposures could be derived from indoor combustion sources, penetration of outdoor air indoors, and personal activities, such as cooking and smoking. The reactivity of PAH requires further investigation, since it appears that a number of nitro-PAH will be produced. Some of the resulting compounds will need to be factored into PAH exposure assessments.

Design of surveys for residential and personal monitoring of hazardous substances

This paper reviews survey design methodology for large-scale residential and personal monitoring studies designed to make inferences to target populations. Four monitoring studies conducted recently in the United States that utilized two-phase sampling designs are cited as illustrations of the methodology. Recommendations for efficient statistical design of such monitoring studies are presented.

Estimating human exposure to nitrogen dioxide: Results from a personal monitoring study among housewives

Weekly average personal exposure to nitrogen dioxide (NO 2) was measured in a population of housewives living in Wageningen, The Netherlands, together with weekly average indoor NO 2 concentrations and indoor NO 2 peak concentrations. In part of the population the personal exposure measurements were repeated. The personal exposure and the indoor concentrations were in line with those in other studies in Holland. In general they were higher than the levels found in studies in the United States and Canada, but lower than those reported for Great Britain and Japan. The NO 2 peak concentrations were high, especially in the kitchen. Relationships between personal exposure and indoor concentrations were investigated using bivariate and multiple regression techniques. Indoor concentrations were found to be highly related to personal exposure. The contribution of peak concentrations to the explanation of personal exposure was small. An analysis of variance of the repeated personal exposure measurements showed that due to variation of personal exposure in space and/or time the “error” variance (within persons) was almost as large as the “true” variance (due to differences between persons). Therefore, it will be necessary to repeat personal exposure measurements in order to obtain reliable exposure estimates in health effect studies.

The relationship between indoor nitrogen dioxide concentration levels and personal exposure: a pilot study.

A small, personal monitoring study was performed in a subpopulation (14 families) of a case-control study on the relationship between indoor nitrogen-dioxide exposure and respiratory diseases of schoolchildren. Mothers, schoolchildren and pre-schoolchildren were asked to carry duplicate Palmes diffusion tubes during one week. Simultaneously nitrogen-dioxide concentrations were measured in the kitchen, living room, bedroom, outdoors and--for a few participants--at school and at work. Information on time activity patterns was gathered by means of a self administered diary. Several models for estimating exposure were constructed and tested against measured exposure. The personal exposure of the participants could well be explained by models containing indoor concentrations. Models with time-weighted average concentrations did not explain personal exposure better than models containing indoor concentrations. A calculated time-weighted average exposure was found to underestimate measured personal exposure by an average 20%, probably because the average concentration in a location does not necessarily reflect the actual exposure in that location. Personal exposure of mothers and children was very similar and highly correlated, indicating that the personal exposure of the mother might be a reasonable estimate for the exposure of the child.