The California TEAM study: Breath concentrations and personal exposures to 26 volatile compounds in air and drinking water of 188 residents of Los Angeles,Antioch, and Pittsburg,CA

The U.S. EPA carried out a study of personal exposures to 26 volatile organic chemicals in the air, drinking water, and exhaled breath of 188 California residents in 1984. Sixteen chemicals were often found above quantifiable limits in the personal air samples, but only the four trihalomethanes were often found in drinking water. The highest exposures were to 1,1,1-trichloroethane, para-dichlorobenzene, xylenes, benzene, and tetrachloroethylene. Indoor air concentrations generally exceeded outdoor air concentrations, particularly at the higher percentiles. Breath concentrations of eight chemicals showed significant correlations with preceding personal air concentrations in the two visits to Los Angeles. Smoking, employment, and automobile-related activities were identified as important sources of personal exposure to a number of target compounds.     

Comparison of breath CO,CO exposure,and Coburn model predictions in the U.S. EPA Washington-Denver (CO) study

The U.S. EPA studied the carbon monoxide (CO) exposures and resulting breath CO concentrations of 625 non-smoking persons in Washington, D.C., and 454 non-smokers in Denver, CO, in the winter of 1982–83. Mean population-weighted breath concentrations were 5.1 ± 0.2 (SE) ppm in Washington and 7.2 ± 0.2 ppm in Denver. These values were correlated with the preceding personal air CO exposures (Spearman rank correlation coefficient r_s > 0.5, P < 0.0001) but not with the outdoor concentrations (r_s < 0.2). However, the breath measurements did not agree very closely with the personal exposures according to the current (Coburn) model relating alveolar CO to ambient CO. One reason for the discrepancy may have been the slight observed negative bias displayed by the personal monitors. A method of using the breath measurements to arrive at an improved estimate of personal exposures has been developed and applied. The method leads to an upward revision of exposure estimates: about 10% of the Washington target population of 1.22 million non-smokers are estimated to have exceeded the EPA 8-h ambient standard of 9 ppm during the winter of 1982–83, well above the 3.5% indicated by the personal monitor measurements.     

Continuous emissions monitoring using spark-induced breakdown spectroscopy

A new technology for monitoring airborne heavy metals on aerosols and particulates based on spark-induced breakdown spectroscopy (SIBS) was evaluated at a joint U.S. Environmental Protection Agency (EPA)/U.S. Department of Energy test at the rotary kiln incinerator simulator (RKIS) facility at EPA/Research Triangle Park, NC, in September 1997. The instrument was configured to measure lead and chromium in a simulated combustion flue gas in real time and in situ at target levels of 15 and 75 micrograms/dry standard cubic meters. Actual metal concentrations were measured during the tests using EPA Reference Method (RM) 29. The SIBS technology detected both lead and chromium at the low- and high-level concentrations. Additionally, the hardware performed without failure for more than 100 hr of operation and acquired data for 100% of the RM tests. The chromium data were well correlated with concentration increases resulting from duct operations and pressure fluctuations that are known to entrain dust.     

Continuous Emissions Monitoring Using Spark-Induced Breakdown Spectroscopy

ABSTRACT

A new technology for monitoring airborne heavy metals on aerosols and particulates based on spark-induced breakdown spectroscopy (SIBS) was evaluated at a joint U.S. Environmental Protection Agency (EPA)/U.S. Department of Energy test at the rotary kiln incinerator simulator (RKIS) facility at EPA/Research Triangle Park, NC, in September 1997. The instrument was configured to measure lead and chromium in a simulated combustion flue gas in real time and in situ at target levels of 15 and 75 u, g/dry standard cubic meters. Actual metal concentrations were measured during the tests using EPA Reference Method (RM) 29.

The SIBS technology detected both lead and chromium at the low- and high-level concentrations. Additionally, the hardware performed without failure for more than 100 hr of operation and acquired data for 100% of the RM tests. The chromium data were well correlated with concentration increases resulting from duct operations and pressure fluctuations that are known to entrain dust.     

Arsenic contaminated site at an abandoned copper smelter plant: waste characterization and solidification/stabilization treatment

A preliminary survey of an arsenic contaminated site from an abandoned copper smelting facility and feasibility study of using solidification/stabilization (S/S) process to treat the contaminant waste were undertaken. It was found that the waste, located in the three-flue gas discharge tunnels, contained 2-40% arsenic. The pH of the contaminated waste is extremely low (ranging from 1.8 to 3.6). The X-ray diffraction evidence indicates that the arsenic particles present in the flue gas mainly exist as As(III), or As(2)O(3). The total amount of arsenic contaminated waste is estimated to be 700 ton in the studied area. About 50% of the particle sizes are less than 2 mm. Arsenic is easily extracted from wastes with a variety of leaching solutions. In order to meet the arsenic leaching standard of the toxicity characteristic leaching procedure (TCLP), an extremely high cement dosage is required in the S/S process (cement/waste weight ratio>6). The waste with lower particle size having higher specific surface area exhibits somewhat positive effect on the S/S performance. The use of fly ash from municipal waste incinerators, in conjunction with the reduced amount of cement, is able to meet the TCLP arsenic and lead standards. The use of lime alone could meet the TCLP arsenic standard, but lead leaching concentrations exceeded leaching Pb standard. The results of semi-dynamic leaching tests of some solidified samples indicate higher accumulated arsenic leaching concentrations after only a few leachant renewals.     

Outdoor/Indoor/Personal ozone exposures of children in Nashville, Tennessee

An ozone (O3) exposure study was conducted in Nashville, TN, using passive O3 samplers to measure six weekly outdoor, indoor, and personal O3 exposure estimates for a group of 10- to 12-yr-old elementary school children. Thirty-six children from two Nashville area communities (Inglewood and Hendersonville) participated in the O3 sampling program, and 99 children provided additional time-activity information by telephone interview. By design, this study coincided with the 1994 Nashville/Middle Tennessee Ozone Study conducted by the Southern Oxidants Study, which provided enhanced continuous ambient O3 monitoring across the Nashville area. Passive sampling estimated weekly average outdoor O3 concentrations from 0.011 to 0.O30 ppm in the urban Inglewood community and from 0.015 to 0.042 ppm in suburban Hendersonville. The maximum 1- and 8-hr ambient concentrations encountered at the Hendersonville continuous monitor exceeded the levels of the 1- and 8-hr metrics for the O3 National Ambient Air Quality Standard. Weekly average personal O3 exposures ranged from 0.0013 to 0.0064 ppm (7-31% of outdoor levels). Personal O3 exposures reflected the proportional amount of time spent in indoor and outdoor environments. Air-conditioned homes displayed very low indoor O3 concentrations, and homes using open windows and fans for ventilation displayed much higher concentrations.     

Assessing the relationship between personal particulate and gaseous exposures of senior citizens living in Baltimore, MD

We conducted a multi-pollutant exposure study in Baltimore, MD, in which 15 non-smoking older adult subjects (> 64 years old) wore a multi-pollutant sampler for 12 days during the summer of 1998 and the winter of 1999. The sampler measured simultaneous 24-hr integrated personal exposures to PM2.5, PM10, SO4(2-), O3, NO2, SO2, and exhaust-related VOCs. Results of this study showed that longitudinal associations between ambient PM2.5 concentrations and corresponding personal exposures tended to be high in the summer (median Spearman's r = 0.74) and low in the winter (median Spearman's r = 0.25). Indoor ventilation was an important determinant of personal PM2.5 exposures and resulting personal-ambient associations. Associations between personal PM2.5 exposures and corresponding ambient concentrations were strongest for well-ventilated indoor environments and decreased with ventilation. This decrease was attributed to the increasing influence of indoor PM2.5 sources. Evidence for this was provided by SO4(2-) measurements, which can be thought of as a tracer for ambient PM2.5. For SO4(2-), personal-ambient associations were strong even in poorly ventilated indoor environments, suggesting that personal exposures to PM2.5 of ambient origin are strongly associated with corresponding ambient concentrations. The results also indicated that the contribution of indoor PM2.5 sources to personal PM2.5 exposures was lowest when individuals spent the majority of their time in well-ventilated indoor environments. Results also indicate that the potential for confounding by PM2.5 co-pollutants is limited, despite significant correlations among ambient pollutant concentrations. In contrast to ambient concentrations, PM2.5 exposures were not significantly correlated with personal exposures to PM2.5-10, PM2.5 of non-ambient origin, O3, NO2, and SO2. Since a confounder must be associated with the exposure of interest, these results provide evidence that the effects observed in the PM2.5 epidemiologic studies are unlikely to be due to confounding by the PM2.5 co-pollutants measured in this study.     

Personal exposures to particles and their relationships with personal activities for chronic obstructive pulmonary disease patients living in Boston

An exposure study of 18 subjects with chronic obstructive pulmonary disease (COPD) living in the Boston, MA, area was conducted. The objective was to examine determinants of personal exposures to particulate matter (PM) with aerodynamic diameters of less than 2.5 microm (PM2.5), less than 10 microm (PM10), and between 2.5 and 10 microm (PM2.5-10). In a previous publication, the analyses of the longitudinal individual-specific relationships among indoor, outdoor, and personal levels showed that the relationships varied by subject and by particle size fraction. In the present paper, statistical and physical models were used to examine personal PM2.5, PM10, and PM2.5-10 exposure covariates. Results indicated that time-weighted indoor concentrations were significant predictors of personal PM2.5, PM10, and PM2.5-10 exposures. Also, time-weighted outdoor concentrations, time spent near smokers, and time spent during transportation were important predictors for PM2.5 but not for personal PM2.5-10 exposures. In turn, time spent cleaning contributed to all size-fraction personal exposures, whereas cooking affected only personal PM2.5-10 exposures. The findings showed that the relationship between personal PM2.5 exposures and the corresponding ambient concentrations was influenced by home air exchange rates (or by ventilation status). Because the particle properties or components causing the health effects are unknown, it is not certain to what extent the risk posed by ambient particles can be reduced by controlling any one of these factors.     

Organochlorine pesticides in elementary school yards along the Texas-Mexico border

A reconnaissance study was undertaken to determine potential contaminant exposures to children through soil from elementary school playgrounds. Soil samples were collected from areas along the Texas-Mexico border, inland areas (soils from elementary school yards in cities/towns within the state of Texas), and three National Parks (one on the border, one in Tennessee, and one in Washington). The present study focused on organochlorine (OC) pesticides as the potential contaminants of concern because of their historical (and possibly current) use, and their importance as persistent organic pollutants (POPs). DDE and heptachlor were the most frequently detected OCs (69 and 63%, respectively), although heptachlor concentrations in soil never exceeded 5 ppb. Relatively higher concentrations of DDE were observed in agricultural areas along the border (50-60 ppb in soils from McAllen, Palmview, and San Benito) than in other soils. However, a school yard in Lubbock, TX had the highest OC concentration observed (70 ppb dieldrin). These results may be due to historical agriculture activity prior to the banning of OC pesticides such as DDT in the early 1970s, as well as the more recent use of DDT in Central and South America for malaria control.     

Effectiveness of In-Room Air Filtration and Dilution Ventilation for Tuberculosis Infection Control

Abstract

Tuberculosis (TB) is a public health problem that may pose substantial risks to health care workers and others. TB infection occurs by inhalation of airborne bacteria emitted by persons with active disease. We experimentally evaluated the effectiveness of in-room air filtration systems, specifically portable air filters (PAFs) and ceiling-mounted air filters (CMAFs), in conjunction with dilution ventilation, for controlling TB exposure in high-risk settings. For each experiment, a test aerosol was continuously generated and released into a full-sized room. With the in-room air filter and room ventilation system operating, time-averaged airborne particle concentrations were measured at several points. The effectiveness of in-room air filtration plus ventilation was determined by comparing particle concentrations with and without device operation. The four PAFs and three CMAFs we evaluated reduced room-average particle concentrations, typically by 30% to 90%, relative to a baseline scenario with two air-changes per hour of ventilation (outside air) only. Increasing the rate of air flow recirculating through the filter and/or air flow from the ventilation did not always increase effectiveness. Concentrations were generally higher near the emission source than elsewhere in the room. Both the air flow configuration of the filter and its placement within the room were important, influencing room air flow patterns and the spatial distribution of concentrations. Air filters containing efficient, but non-high efficiency particulate air (HEPA) filter media were as effective as air filters containing HEPA filter media.     

Metal oxides remove hydrogen sulfide from landfill gas produced from waste mixed with plaster board under wet conditions

Hydrogen sulfide (H2S) is a major odorant in landfills. We have studied H2S production from landfill residual waste with and without sulfur-containing plaster board, including the influence of the water content in the waste. The laboratory experiments were conducted in 30-L polyethylene containers with a controlled water level. We also studied how different materials removed H2S in reactive layers on top of the waste. The organic waste produced H2S in concentrations of up to 40 parts per million (ppm) over a period of 80 days. When plaster board was added, the H2S concentration increased to 800 ppm after a lag period of approximately 40 days with a high water level, and to approximately 100 ppm after 50 days with a low water level. The methane (CH4) concentration in the initial experiment was between 5 and 70% after 80 days. The CH4 concentration in the second experiment increased to nearly 70% in the container with a high water level, slowly declining to approximately 60% between days 20 and 60. The CH4 concentrations during the experiments resembled normal landfill concentrations. Metallic filter materials were very efficient in removing H2S, whereas organic filter materials showed poor H2S removal.     

Estimated hourly personal exposures to ambient and nonambient particulate matter among sensitive populations in Seattle, Washington

Epidemiological studies of particulate matter (PM) routinely use concentrations measured with stationary outdoor monitors as surrogates for personal exposure. Despite the frequently reported poor correlations between ambient concentrations and total personal exposure, the epidemiologic associations between ambient concentrations and health effects depend on the correlation between ambient concentrations and personal exposure to ambient-generated PM. This paper separates personal PM exposure into ambient and nonambient components and estimates the outdoor contribution to personal PM exposures with continuous light scattering data collected from 38 subjects in Seattle, WA. Across all subjects, the average exposure encountered indoors at home was lower than in all other microenvironments. Cooking and being at school were associated with elevated levels of exposure. Previously published estimates of particle infiltration (Finf) were combined with time-location data to estimate an ambient contribution fraction (alpha, mean = 0.66+/-0.21) for each subject. The mean alpha was significantly lower for subjects monitored during the heating season (0.55+/-0.16) than for those monitored during the nonheating season (0.80+/-0.17). Our modeled alpha estimates agreed well with those estimated with the sulfur-tracer method (slope = 1.08; R2 = 0.67). We modeled exposure to ambient and nonambient PM with both continuous light scattering and 24-hr gravimetric data and found good agreement between the two methods. On average, ambient particles accounted for 48% of total personal exposure (range = 21-80%). The personal activity exposure was highly influenced by time spent away from monitored microenvironments. The median hourly longitudinal correlation between central site concentrations and personal exposures was 0.30. Although both alpha and the nonambient sources influence the personal-central relationship, the latter seems to dominate. Thus, total personal exposure may be poorly predicted by stationary outdoor monitors, particularly among persons whose PM exposure is dominated by nonambient exposures, for example, those living in tightly sealed homes, those who cook, and children.     

Personal exposure to PM2.5 and element composition—A comparison between outdoor and indoor workers from two Mexican cities

Many individuals work outdoors in the formal and informal economy of the large urban areas in developing countries, where they are potentially exposed for long periods to high concentrations of ambient airborne particulate matter (PM). This study describes the personal exposures to PM of 2.5 μm aerodynamic diameter and smaller (PM_2.5) for a sample of outdoor and indoor workers in two cities, Mexico City and Puebla, in central Mexico.Thirty-six workers in Mexico City and 17 in Puebla were studied. Thirty were outdoor workers (i.e., taxi and bus drivers, street vendors, and vehicle inspectors) and 23 were indoor (office) workers. Their personal exposures to PM_2.5 were monitored for a mean 19-h period. In Mexico City, the street vendors and taxi drivers overall exposures were significantly higher than indoor workers were. In Puebla, bus drivers had a higher overall exposure than vehicle inspectors or indoor workers. Most of the exposures were above the 65 μg m⁻³ 24-h Mexican standard.In Mexico City, exposures to Si, Ti, Cr, Mn, Fe, Ni, Cu, Mo and Cd were higher for outdoor than for indoor workers. In Puebla, exposures to Si, S, K, Ca, Ti, V, Mn, and Zn also were higher for outdoor workers. In Mexico City outdoor workers exposures to Cu, Pb, Cr, Se and Mo were 4 or more times higher than for Puebla outdoor workers, while Puebla outdoor workers’ exposures to V, Si, Fe and Ca were 3 or more times higher than Mexico City outdoor workers.These results suggest that for these outdoor workers the elevated local ambient air PM concentrations and an extended period spent outside are more important contributors to total exposures than indoor concentrations. These workers could be at particular risk of increased morbidity and mortality associated with ambient PM.     

Methylmercury, fish consumption, and the precautionary principle

This paper considers several broad issues in the context of probabilistic assessment of the benefits of curtailing mercury (Hg) emissions from U.S. coal-fired power plants, based on information developed from recent literature and epidemiology studies of health effects of methylmercury. Exposure of the U.S. population is considered on the national scale, in large part because of recent questions arising from survey and experimental data about the relative importance of local deposition of airborne Hg. Although epidemiological studies have provided useful information, safe levels of Hg exposure remain uncertain, in part because of other dietary considerations in the populations that were studied. For example, much of the seafood consumed in one of the major studies was also contaminated with polychlorinated biphenyls, as are fish taken from some U.S. fresh waters. The primary epidemiological approach involves cross-study comparisons in relation to mean exposures, rather than detailed critiques of individual effects reported in each study. U.S. exposures are seen to be well below the levels at which adverse health effects are reported. This analysis supports the conclusion that unilateral reduction of Hg emissions from U.S. coal-fired power plants alone is unlikely to realize significant public health benefits.     

Microenvironmental characteristics important for personal exposures to aldehydes in Sacramento,CA, and Milwaukee,WI

Oxygenated additives in gasoline are designed to decrease the ozone-forming hydrocarbons and total air toxics, yet they can increase the emissions of aldehydes and thus increase human exposure to these toxic compounds. This paper describes a study conducted to characterize targeted aldehydes in microenvironments in Sacramento, CA, and Milwaukee, WI, and to improve our understanding of the impact of the urban environment on human exposure to air toxics. Data were obtained from microenvironmental concentration measurements, integrated, 24-h personal measurements, indoor and outdoor pollutant monitors at the participants' residences, from ambient pollutant monitors at fixed-site locations in each city, and from real-time diaries and questionnaires completed by the technicians and participants. As part of this study, a model to predict personal exposures based on individual time/activity data was developed for comparison to measured concentrations. Predicted concentrations were generally within 25% of the measured concentrations. The microenvironments that people encounter daily provide for widely varying exposures to aldehydes. The activities that occur in those microenvironments can modulate the aldehyde concentrations dramatically, especially for environments such as “indoor at home.” By considering personal activity, location (microenvironment), duration in the microenvironment, and a knowledge of the general concentrations of aldehydes in the various microenvironments, a simple model can do a reasonably good job of predicting the time-averaged personal exposures to aldehydes, even in the absence of monitoring data. Although concentrations of aldehydes measured indoors at the participants' homes tracked well with personal exposure, there were instances where personal exposures and indoor concentrations differed significantly. Key to the ability to predict exposure based on time/activity data is the quality and completeness of the microenvironmental characterizations for the chemicals of interest. Consistent with many earlier studies, personal exposures are difficult to predict using data from regional outdoor monitors.     

Personal exposure levels and microenvironmental concentrations of formaldehyde and acetaldehyde in the Helsinki metropolitan area, Finland

Personal 48-hr exposures to formaldehyde and acetaldehyde of 15 randomly selected participants were measured during the summer/autumn of 1997 using Sep-Pak DNPH-Silica cartridges as a part of the EXPOLIS study in Helsinki, Finland. In addition to personal exposures, simultaneous measurements of microenvironmental concentrations were conducted at each participant's residence (indoor and outdoor) and workplace. Mean personal exposure levels were 21.4 ppb for formaldehyde and 7.9 ppb for acetaldehyde. Personal exposures were systematically lower than indoor residential concentrations for both compounds, and ambient air concentrations were lower than both indoor residential concentrations and personal exposure levels. Mean workplace concentrations of both compounds were lower than mean indoor residential concentrations. Correlation between personal exposures and indoor residential concentrations was statistically significant for both compounds. This indicated that indoor residential concentrations of formaldehyde and acetaldehyde are a better estimate of personal exposures than are concentrations in ambient air. In addition, a time-weighted exposure model did not improve the estimation of personal exposures above that obtained using indoor residential concentrations as a surrogate for personal exposures. Correlation between formaldehyde and acetaldehyde was statistically significant in outdoor microenvironments, suggesting that both compounds have similar sources and sinks in ambient urban air.     

Assessing the Relationship between Personal Particulate and Gaseous Exposures of Senior Citizens Living in Baltimore,MD

ABSTRACT

We conducted a multi-pollutant exposure study in Baltimore, MD, in which 15 non-smoking older adult subjects (>64 years old) wore a multi-pollutant sampler for 12 days during the summer of 1998 and the winter of 1999. The sampler measured simultaneous 24-hr integrated personal exposures to PM₂₅, PM₁₀, SO₄ ^2-, O₃, NO₂, SO₂, and exhaust-related VOCs.

Results of this study showed that longitudinal associations between ambient PM_2.5 concentrations and corresponding personal exposures tended to be high in the summer (median Spearman's r = 0.74) and low in the winter (median Spearman's r = 0.25). Indoor ventilation was an important determinant of personal PM_2.5 exposures and resulting personal-ambient associations. Associations between personal PM₂₅ exposures and corresponding ambient concentrations were strongest for well-ventilated indoor environments and decreased with ventilation. This decrease was attributed to the increasing influence of indoor PM_{2 5} sources. Evidence for this was provided by SO₄ ^2-measurements, which can be thought of as a tracer for ambient PM₂₅. For SO₄ ^2-, personal-ambient associations were strong even in poorly ventilated indoor environments, suggesting that personal exposures to PM_2.5 of ambient origin are strongly associated with corresponding ambient concentrations. The results also indicated that the contribution of indoor PM_2.5 sources to personal PM_2.5 exposures was lowest when individuals spent the majority of their time in well-ventilated indoor environments.

Results also indicate that the potential for confounding by PM_2.5 co-pollutants is limited, despite significant correlations among ambient pollutant concentrations. In contrast to ambient concentrations, PM_2.5 exposures were not significantly correlated with personal exposures to PM_2.5-10, PM_2.5 of non-ambient origin, O₃, NO₂, and SO₂. Since a confounder must be associated with the exposure of interest, these results provide evidence that the effects observed in the PM_2.5 epidemiologic studies are unlikely to be due to confounding by the PM_2.5 co-pollutants measured in this study.     

Metal Oxides Remove Hydrogen Sulfide from Landfill Gas Produced from Waste Mixed with Plaster Board under Wet Conditions

Abstract

Hydrogen sulfide (H₂S) is a major odorant in landfills. We have studied H₂S production from landfill residual waste with and without sulfur-containing plaster board, including the influence of the water content in the waste. The laboratory experiments were conducted in 30-L polyethylene containers with a controlled water level. We also studied how different materials removed H₂S in reactive layers on top of the waste. The organic waste produced H₂S in concentrations of up to 40 parts per million (ppm) over a period of 80 days. When plaster board was added, the H₂S concentration increased to 800 ppm after a lag period of approximately 40 days with a high water level, and to approximately 100 ppm after 50 days with a low water level. The methane (CH₄) concentration in the initial experiment was between 5 and 70% after 80 days. The CH₄ concentration in the second experiment increased to nearly 70% in the container with a high water level, slowly declining to approximately 60% between days 20 and 60. The CH₄ concentrations during the experiments resembled normal landfill concentrations. Metallic filter materials were very efficient in removing H₂S, whereas organic filter materials showed poor H₂S removal.     

Occurrence of sulfonamide antimicrobials in private water wells in Washington County, Idaho, USA

Samples from six private wells formerly used as sources for drinking water by the residents of Washington County (Weiser, Idaho) were collected to assess the impact of a nearby confined animal feeding operation (CAFO) on the quality of the local groundwater. All six samples were found contaminated by two veterinary antimicrobials, sulfamethazine (at concentrations from 0.076 to 0.22 μg/l) and sulfadimethoxine (at concentrations from 0.046 to 0.068 μg/l). These groundwater samples also contained elevated concentrations of nitrate and ammonium. Three of the sampled wells have nitrate levels that exceeded the maximum contaminant level set by the US Environmental Protection Agency for drinking water, with nitrate concentration as high as 39.1 mg/l. All but one well showed nitrate, which instead contained ammonium at 1.22 mg/l. Analysis of the nitrate and ammonium in these samples by isotopic ratio mass spectrometry indicated δ¹⁵N characteristic of an animal or human waste source. Results from this study underscore the role of CAFO as an important source of antibiotic contamination of groundwater.     

The 1999 Fresno particulate matter exposure studies: comparison of community, outdoor, and residential PM mass measurements

Two collaborative studies have been conducted by the U.S. Environmental Protection Agency (EPA) National Exposure Research Laboratory (NERL) and National Health and Environmental Effects Research Laboratory to determine personal exposures and physiological responses to particulate matter (PM) of elderly persons living in a retirement facility in Fresno, CA. Measurements of PM and other criteria air pollutants were made inside selected individual residences within the retirement facility and at a central outdoor site on the premises. In addition, personal PM exposure monitoring was conducted for a subset of the participants, and ambient PM monitoring data were available for comparison from the NERL PM research monitoring platform in central Fresno. Both a winter (February 1-28, 1999) and a spring (April 19-May 16, 1999) study were completed so that seasonal effects could be evaluated. During the spring study, a more robust personal exposure component was added, as well as a more detailed evaluation of physical factors, such as air-exchange rate, that are known to influence the penetration of particles into the indoor environment. In this paper, comparisons are made among measured personal PM exposures and PM mass concentrations measured at the NERL Fresno Platform site, outside on the premises of the retirement facility, and inside selected residential apartments at the facility during the two 28-day study periods. The arithmetic daily mean personal PM2.5 exposure during the winter study period was 13.3 micrograms/m3, compared with 9.7, 20.5, and 21.7 micrograms/m3 for daily mean overall apartment, outdoor, and ambient (i.e., platform) concentrations, respectively. The daily mean personal PM2.5 exposure during the spring study period was 11.1 micrograms/m3, compared with 8.0, 10.1, and 8.6 micrograms/m3 for the daily mean apartment, outdoor, and ambient concentrations, respectively.