Indoor, outdoor, and personal exposure monitoring of particulate air pollution: the Baltimore elderly epidemiology-exposure pilot study

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Abstract

A 17-day pilot study investigating potential PM exposures of an elderly population was conducted near Baltimore, Maryland. Collection of residential indoor, residential outdoor, and ambient monitoring data associated with the subjects living at a common retirement facility was integrated with results from a paired epidemiological pilot study. This integration was used to investigate the potential pathophysiological health effects resulting from daily changes in estimated PM exposures with results reported elsewhere. Objectives of the exposure study were to determine the feasibility of performing PM exposure assessment upon an elderly population and establishing relationships between the various exposure measures including personal monitoring. PM2.5 was determined to be the dominant outdoor size fraction (0.83 PM2.5/PM10 mass ratio by dichot monitoring). Individual 24-h PM1.5 personal exposures ranged from 12 to 58 μg m−3. Comparison of data from matched sampling dates resulted in mean daily PM1.5 personal, PM2.5 outdoor, and PM1.5 indoor concentrations of 34, 17, and 17 μg m−3, respectively. Activity patterns of the study population indicated a generally sedentary population spending a mean of 96% of each day indoors. Future studies would benefit from the use of a consistent sampling methodology across a larger number of PM measurement sites relevant to the elderly subjects, as well as a larger personal PM exposure study population to more successfully collect data needed in matched epidemiological-exposure studies.

Introduction

During the last decade, numerous epidemiological studies have reported an association between potential exposure to particulate matter air pollution at concentrations below the current national air quality standard and excess mortality and morbidity. A review of the reported statistical association in these studies has been extensively discussed in the US EPA's report, Air Quality Criteria for Particulate Matter (US EPA, 1996a) with subsequent reviews or consideration (US EPA, 1996b, US EPA, 1996c, US EPA, 1996d, US EPA, 1997a, US EPA, 1997b, US EPA, 1998). Studies summarized in these reports indicate that individuals over the age of 65 years old may be 1.5–3 times more susceptible than younger individuals to various health effects related to potential ambient PM10 exposure. As an example, Schwartz (1995) reported that those 65+ had a relative risk of 1.08 for hospital admissions caused by a respiratory illness linked with ambient PM10 concentrations.

The US EPA is conducting a series of combined human exposure/human epidemiological studies to address important research needs relating to ambient PM exposure and potential health effects. The first of these studies was a 17-day pilot study conducted upon an elderly population in Towson, Maryland during January–February 1997. A pilot study was needed to address a large number of epidemiology and exposure research unknowns. These unknowns included the feasibility of recruitment and retention of elderly subjects for health effects and personal monitoring measurements. Likewise, procedures and techniques were not established concerning type and placement of PM monitoring equipment within retirement communities or upon elderly subjects in the case of personal exposure monitoring. Results from this study would establish these procedures and provide information on what improvements would be necessary in future study designs.

The overall objective of the pilot study was to evaluate the feasibility of conducting a combined human exposure/human epidemiological study on an elderly population and develop recommendations as to what changes in the study design would be needed for future studies. Detailed descriptions of the epidemiological study design and results have been presented elsewhere (Liao et al., 1999). The epidemiological study design suggested that indoor, outdoor, and ambient PM2.5 mass concentrations should be the focus of the exposure measures. This decision affected the selection and placement of PM instrumentation. Epidemiological results indicated that daily variation in certain indoor and outdoor PM2.5 mass concentrations correlated to a number of cardiovascular health effects in subjects having a compromised medical status. This report also indicated that while the constrained exposure study design was successful in supporting the health effects research, future linked studies would greatly benefit from expanded PM exposure measurements (greater number of measurement days or sampling completeness) and enhanced personal exposure monitoring.

Specific objectives for the exposure component of the pilot study were therefore based upon the constraints imposed upon it by the epidemiological data needs. These objectives were:

  • to provide PM mass concentration data that could be associated with the health effect measurements from indoor, outdoor and ambient measurement sites of significance to the elderly population being studied;

  • to measure personal exposure to PM and evaluate the relationship of this measure to indoor residential, outdoor residential, and ambient site measurements; and

  • to collect information on housing characteristics and personal activities of the elderly.

This paper reports only on the methods and the results of the exposure monitoring component of the pilot study and exposure-related recommendations for future linked epidemiology-exposure studies.

The pilot study was conducted in Towson, MD, an unincorporated community in central Baltimore County. It is an urban residential area with few industrial sources; thus, ambient PM in this area should be mainly influenced by regional rather than local sources. PM2.5 was expected to be the predominant size fraction (70–90% by mass) of the total ambient PM10 and similar in magnitude and composition relative to similar areas in other eastern US cities. A daily ambient PM10 range of 10–70 μg m−3 would be expected during a January–February study period based upon historical eastern US concentration monitoring (AIRS (1997) database).

Residential exposure monitoring was conducted at one retirement facility. The retirement center was a predominantly brick, three-story facility having two main sections interconnected via staircases and elevators. The older main section of the facility held administrative offices, dietary preparation, dining, laundry, social, and living quarters for some of the residents. This section of the facility contained approximately 150 small domiciles that were typically less than 74 m2 in floor size, and each consisted of a combination living room/bedroom, and a bathroom. The second section of the facility held nearly 90 more recently built apartments. Apartments were 93–112 m2 in size and consisted of separate kitchens, dining rooms, living rooms, bedrooms and bathrooms. No attempt was made to determine how spatially equivalent PM mass concentrations were relative to the different residences within the facility (apartments versus domiciles). Neither dander-producing animals nor tobacco smoking were permitted inside the facility.

Central HVAC systems were operated in the different sections of the building. In the winter, both systems used a common natural gas boiler to produce hot water from which heated air was exchanged and supplied throughout the facility. Low efficiency (⩽40% atmospheric dust spot rating) fiber particle filters were used in both HVAC systems. The recently built apartments (most were <4 yr old in 1997) also had supplemental electric baseboard heaters in each room. The retirement facility was in a residential neighborhood (∼1.6 km away from I-695) and surrounded by a multi-acre green-belt of grass, plants, and trees.

Twenty-six non-smoking subjects participated in the health monitoring component of the study. Detailed demographic data for these subjects have been reported elsewhere (Shy et al., 1998; Liao et al., 1999). The 26 subjects had a mean age of 81 years, ranging from 65 to 89. They were predominantly white and female (96 and 73%, respectively). Eighteen (69%) of the subjects had a reported medical condition such as hypertension or coronary heart disease (Liao et al., 1999) and were classified as having a compromised health status based upon study inclusion criteria.

The study was conducted over a 17-day period from 22 January to 7 February, 1997. The planned monitoring scheme is outlined in Table 1. Monitoring included a combination of 24-h integrated gravimetric methods, as well as continuous (microbalance) measurements. Elemental analysis (by XRF) was performed on filters collected at the residential outdoor site to obtain data on important PM constitutents such as sulfate.

Monitoring was conducted at three fixed site locations: an ambient monitoring platform, outdoors at the retirement facility, and indoors at a central hallway site in the facility. The outdoor residential site was on the open parking deck of the retirement center. Automobile traffic in the parking deck was light, as few residents drove vehicles. The indoor residential site was located in the first floor hallway of the older main section of the facility. This location was near the rooms where health measurements were taken and which contained the small domiciles. Samplers at this site were placed in an alcove where there was little foot traffic. The ambient monitoring site was located on the Clifton Park Golf Course approximately 4 km north of the Baltimore harbor area and 8 km south-southeast of the retirement center. Monitoring at these sites was scheduled for all study days.

Five of the health study participants agreed to wear 24-h-based PM1.5 personal exposure monitors. This limited trial was conducted to evaluate the feasibility of a more intensive effort in the future. Personal monitoring was scheduled to begin on Monday of each week with completion on Saturday (5 periods). No Sunday personal monitoring was performed. Individual start times varied between subjects (8 a.m.–4:30 p.m.) to match their daily health examinations, but were consistent thereafter with respect to this initial schedule. These five individuals also completed time/activity diaries for each day they wore personal monitors. All 26 study participants completed a 32-question daily activity/exposure survey each day.

Section snippets

Personal exposure monitors (PMON)

The PMON unit was manufactured by University Research Glassware, Inc. (URG-2000-15, Carrboro, NC). The mean aerodynamic particle cut-off (dp50) for the inertial impactor-based instrument was 1.5 μm at the 1.7 lpm flow rate used in this study. While a PM2.5-based personal monitor would have been preferable, these were the only monitors available to the investigators. Feasibility of performing these types of measurements upon the elderly was the primary concern and this compromise in size cut-point

Outdoor PM size fraction distribution

Results from residential outdoor dichotomous monitoring are shown in Table 2. A total of 16 days of measurements met the quality assurance objectives. Significant day-to-day PM mass concentration variability was considered essential in the epidemiological study design to increase the likelihood of detecting an exposure-related health effect. PM2.5 concentrations ranged from 7.2 to 32.2 μg m−3 (x̄=15.4). Daily variability as high as 17.7 μg m−3 (x̄=7.0) was observed for this fraction. Coarse (PM

Overall objectives

The integrated epidemiology-exposure study succeeded in its overall goal of providing indoor, outdoor, and ambient measures to estimate the study population's exposure to PM relative to matched health effects in the elderly. Epidemiology results indicated that the indoor PM2.5 measure provided the most valuable measure in detecting potential health effects resulting from daily variations in PM concentrations (Liao et al., 1999). Neither the causal biological mechanism for this effect nor the

Acknowledgements

Federal funding for this research was administered under EPA-NERL contract 68-D2-0134 (QST Environmental, Inc.), which provided logistical field monitoring support, EPA-NERL contract 68-D50049 (ManTech Environmental Technology, Inc.) for XRF analyses, EPA-NHEERL contract 68-D2-0187 (SRA Technologies, Inc.) which assisted in the collection of personal monitoring data, and EPA-NHEERL cooperative assistance agreement #CR-820076 (University of North Carolina-Chapel Hill). The authors acknowledge

References (22)

  • P Lioy et al.

    The personal, indoor, and outdoor concentrations of PM10 measured in an industrial community during the winter

    Atmospheric Environment

    (1990)
  • AIRS (Aerometric Information Retrieval System [database]), 1997. U.S. Environmental Protection Agency. Office of Air...
  • Bahadori, T., 1998. Issues in particulate matter exposure assessment: relationship between outdoor, indoor, and...
  • C Clayton et al.

    Particle total exposure assessment methodology (PTEAM) study: distributions of aerosol and elemental concentrations in personal, indoor, and outdoor air samples in a southern California community

    Journal of Exposure Analysis and Environmental Epidemiology

    (1993)
  • T Dzubay et al.

    A composite receptor method applied to Philadelphia aerosol

    Environmental Science and Technology

    (1988)
  • N Janssen et al.

    Personal sampling of particles in adults: relation among personal, indoor, and outdoor air concentrations

    American Journal of Epidemiology

    (1998)
  • Klepeis, N., Tsang, A., Behar, J., 1996. Analysis of the national human activity pattern survey (NHAPS) respondents...
  • D Liao et al.

    Daily variation of particulate air pollution and poor cardiac autonomic control in the elderly

    Environmental Health Perspectives

    (1999)
  • H Özkaynak et al.

    Personal exposure to airborne particles and metals: results from the particle team study in Riverside, California

    Journal of Exposure Analysis and Environmental Epidemiology

    (1996)
  • J Schwartz

    Short-term fluctuations in air pollution and hospital admissions of the elderly for respiratory disease

    Thorax

    (1995)
  • C Shy et al.

    Cardiovascular responses of elderly persons to particulate air pollution

    Epidemology

    (1998)
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