RESUMEN
A nested chamber design was constructed for the purpose of studying parameters that affect indoor air chemistry. Experiments were conducted in this system to investigate the effects of three surface types (Teflon, wallpaper, and carpet) and two levels of relative humidity (50% and 70% RH) on the formation of gas-phase nitrous acid (HONO) through the heterogeneous reaction of nitrogen dioxide (NO2) with sorbed water vapor. The results of this investigation show that, compared with Teflon surfaces, carpet made of synthetic fibers increased the NO2 surface removal rate by nearly an order of magnitude and resulted in higher peak HONO concentrations. The results also suggest that the capacity of a surface to sorb water will determine if HONO is released from that surface after the NO2 source has been turned off and the heterogeneous reaction between NO2 and sorbed water is no longer significant. Vinyl-coated wallpaper was found to release HONO for prolonged periods of time after the NO2 source was turned off at both 50% and 70% RH whereas Teflon was found to do so only at 70% RH. The results of this investigation also demonstrate the utility of the nested chamber design in investigating indoor air chemistry.
Asunto(s)
Contaminación del Aire Interior/análisis , Modelos Teóricos , Ácido Nitroso/química , Humedad , Dióxido de Nitrógeno/química , Ácido Nitroso/análisis , Volatilización , Agua/químicaRESUMEN
The 1990 Clean Air Act mandated oxygenation of gasoline in regions where carbon monoxide standards were not met. To achieve this standard, methyl tertiary butyl ether (MTBE) was increased to 15% by volume during winter months in many locations. Subsequent to the increase of MTBE in gasoline, commuters reported increases in symptoms such as headache, nausea, and eye, nose, and throat irritation. The present study compared 12 individuals selected based on self-report of symptoms (self-reported sensitives; SRSs) associated with MTBE to 19 controls without self-reported sensitivities. In a double-blind, repeated measures, controlled exposure, subjects were exposed for 15 min to clean air, gasoline, gasoline with 11% MTBE, and gasoline with 15% MTBE. Symptoms, odor ratings, neurobehavioral performance on a task of driving simulation, and psychophysiologic responses (heart and respiration rate, end-tidal CO(2), finger pulse volume, electromyograph, finger temperature) were measured before, during, and immediately after exposure. Relative to controls, SRSs reported significantly more total symptoms when exposed to gasoline with 15% MTBE than when exposed to gasoline with 11% MTBE or to clean air. However, these differences in symptoms were not accompanied by significant differences in neurobehavioral performance or psychophysiologic responses. No significant differences in symptoms or neurobehavioral or psychophysiologic responses were observed when exposure to gasoline with 11% MTBE was compared to clean air or to gasoline. Thus, the present study, although showing increased total symptoms among SRSs when exposed to gasoline with 15% MTBE, did not support a dose-response relationship for MTBE exposure nor the symptom specificity associated with MTBE in epidemiologic studies.
Asunto(s)
Contaminantes Atmosféricos/farmacología , Gasolina , Éteres Metílicos/farmacología , Manifestaciones Neuroconductuales/efectos de los fármacos , Enfermedades Respiratorias/inducido químicamente , Adulto , Anciano , Estudios de Casos y Controles , Método Doble Ciego , Exposición a Riesgos Ambientales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Encuestas y CuestionariosRESUMEN
Little information currently exists regarding the occurrence of secondary organic aerosol formation in indoor air. Smog chamber studies have demonstrated that high aerosol yields result from the reaction of ozone with terpenes, both of which commonly occur in indoor air. However, smog chambers are typically static systems, whereas indoor environments are dynamic. We conducted a series of experiments to investigate the potential for secondary aerosol in indoor air as a result of the reaction of ozone with d-limonene, a compound commonly used in air fresheners. A dynamic chamber design was used in which a smaller chamber was nested inside a larger one, with air exchange occurring between the two. The inner chamber was used to represent a model indoor environment and was operated at an air exchange rate below 1 exchange/hr, while the outer chamber was operated at a high air exchange rate of approximately 45 exchanges/hr. Limonene was introduced into the inner chamber either by the evaporation of reagent-grade d-limonene or by inserting a lemon-scented, solid air freshener. A series of ozone injections were made into the inner chamber during the course of each experiment, and an optical particle counter was used to measure the particle concentration. Measurable particle formation and growth occurred almost exclusively in the 0.1-0.2 microm and 0.2-0.3 microm size fractions in all of the experiments. Particle formation in the 0.1-0.2 microm size range occurred as soon as ozone was introduced, but the formation of particles in the 0.2-0.3 microm size range did not occur until at least the second ozone injection occurred. The results of this study show a clear potential for significant particle concentrations to be produced in indoor environments as a result of secondary particle formation via the ozone-limonene reaction. Because people spend the majority of their time indoors, secondary particles formed in indoor environments may make a significant contribution to overall particle exposure. This study provides data for assessing the impact of outdoor ozone on indoor particles. This is important to determine the efficacy of the mass-based particulate matter standards in protecting public health because the indoor secondary particles can vary coincidently with the variations of outdoor fine particles in summer.
Asunto(s)
Contaminación del Aire Interior/análisis , Ozono/análisis , Terpenos/análisis , Aerosoles , Ciclohexenos , Exposición a Riesgos Ambientales , Humanos , Limoneno , Compuestos Orgánicos/análisis , Compuestos Orgánicos/farmacocinética , Ozono/farmacocinética , Tamaño de la Partícula , Terpenos/farmacocinéticaRESUMEN
The issue of fine particle (PM2.5) exposures and their potential health effects is a focus of scientific research because of the recently promulgated National Ambient Air Quality Standard for PM2.5. Before final implementation, the health and exposure basis for the standard will be reviewed by the U.S. Environmental Protection Agency within the next five years. As part of this process, it is necessary to understand total particle exposure issues and to determine the relative importance of the origin of PM2.5 exposure in various micro-environments. The results presented in this study examine emissions of fine particles from a previously uncharacterized indoor source: the residential vacuum cleaner. Eleven standard vacuum cleaners were tested for the emission rate of fine particles by their individual motors and for their efficiency in collecting laboratory-generated fine particles. An aerosol generator was used to introduce fine potassium chloride (KCl) particles into the vacuum cleaner inlet for the collection efficiency tests. Measurements of the motor emissions, which include carbon, and the KCl aerosol were made using a continuous HIAC/Royco 5130 A light-scattering particle detector. All tests were conducted in a metal chamber specifically designed to completely contain the vacuum cleaner and operate it in a stationary position. For the tested vacuum cleaners, fine particle motor emissions ranged from 9.6 x 10(4) to 3.34 x 10(8) particles/min, which were estimated to be 0.028 to 176 micrograms/min for mass emissions, respectively. The vast majority of particles released were in the range of 0.3-0.5 micron in diameter. The lowest particle emission rate was obtained for a vacuum cleaner that had a high efficiency (HEPA) filter placed after the vacuum cleaner bag and the motor within a sealed exhaust system. This vacuum cleaner removed the KCl particles that escaped the vacuum cleaner bag and the particles emitted by the motor. Results obtained for the KCl collection efficiency tests show > 99% of the fine particles were captured by the two vacuum cleaners that used a HEPA filter. A series of tests conducted on two vacuum cleaners found that the motors also emitted ultra-fine particles above 0.01 micron in diameter at rates of greater than 10(8) ultra-fine particles/CF of air. The model that had the best collection efficiency for fine particles also reduced the ultra-fine particle emissions by a factor of 1 x 10(3).
Asunto(s)
Contaminación del Aire Interior/efectos adversos , Contaminación del Aire Interior/prevención & control , Tamaño de la PartículaRESUMEN
Exposure to chromium was assessed for 40 children living near chromium waste sites. Sampling was conducted in one Jersey City, New Jersey neighborhood during the summer and fall of 1991. Household dust samples from residences and urine samples from children living near chromium waste sites were collected and analyzed for chromium. During the summer and fall visits when the samples were collected, the children were also interviewed about lifestyle/activity patterns. Comparisons were made with similar samples collected from children and homes in other areas of New Jersey outside of Hudson County with no known chromium waste sites. Household dust masses and chromium loadings and concentrations in the dust showed a significant decline in this Hudson County neighborhood since the area was first sampled in 1990. Interim remediation of neighborhood sites and an active community education program in the interval between the first and second year of sampling may have contributed to the reduction in dust masses and chromium levels in dust. Children's urine chromium concentrations were consistent across the two sampling periods despite reported changes in activity patterns. Chromium concentrations in urine were found to be age-dependent and related to home location. In this sample of Jersey City children less than six years old, time spent playing outdoors was a weak secondary contributor to urine chromium levels.
Asunto(s)
Cromo/orina , Eliminación de Residuos , Niño , Residuos Peligrosos/efectos adversos , Residuos Peligrosos/análisis , Humanos , New JerseyRESUMEN
Hexavalent chromium is a common skin irritant that can cause contact dermatitis in sensitized individuals. Soil samples from two chromium waste sites having different Cr(VI) concentrations were extracted in synthetic sweat solutions over a pH range of 4 to 8 and analyzed for Cr(VI). These extractions were performed to determine the potential availability of Cr(VI) from contaminated soils upon contact with human sweat. The samples were also extracted using the EPA Method 3060 alkaline digestion. Overall, hexavalent chromium was readily extractable from both samples in the solutions tested. One of the samples contained Cr(VI) crystals, known as blooms, and had a Cr(VI) concentration approximately 40 times greater than the sample without blooms. The pH of the synthetic sweat solution had little effect on the Cr(VI) concentration determined for the sample containing blooms, whereas the Cr(VI) concentration determined for the sample without blooms increased with increasing pH. The Cr(VI) extracted in the synthetic sweat solutions was consistently lower than the amount extracted by the EPA 3060 alkaline extraction.
Asunto(s)
Cromo/análisis , Dermatitis por Contacto/prevención & control , Monitoreo del Ambiente/métodos , Residuos Peligrosos/análisis , Contaminantes del Suelo/análisis , Sudor/química , Humanos , Concentración de Iones de Hidrógeno , New JerseyRESUMEN
A flat surface wipe sampler has been developed to quantitatively measure the concentration (micrograms/g) and surface loading (micrograms/cm2) of dust on flat surfaces. The Lioy-Weisel-Wainman (LWW) Sampler has been tested under conditions that controlled particle deposition in a chamber for two types of particles: road dust and potting soil, and for three different types of surfaces: painted shelving, formica, and wood paneling. The results for replicate analyses demonstrated that the sampler had > 90% efficiency for the capture of deposited dust and had a coefficient of variation of < 20% for replicate samples of the wooden shelving and formica. The wood paneling had a higher coefficient of variation, although it was less than 25%, due to its porosity. Operating procedures are presented and illustrated, and results from a study that used the technique to sample chromium from residential settings are also discussed.
Asunto(s)
Polvo/análisis , Monitoreo del Ambiente/instrumentación , Monitoreo del Ambiente/métodos , Diseño de Equipo , Reproducibilidad de los ResultadosRESUMEN
To determine whether a population living on or adjacent to four sites of chromate production waste was measurably exposed to environmental chromium, spot samples of urine were collected along with wipe samples of household dust and lifestyle/activity interview data. Findings were compared to those from a control population in two communities with no significant chromium use or waste sites. Urine samples were collected and analyzed, employing measures to minimize background chromium contamination. The average Cr mass in dust was 3.7 times that in control houses. The mean creatinine-corrected urine Cr (Cr/c) level of the exposed subgroup residing in households in the 75th percentile of Cr mass in wipe samples was significantly greater than that of the control population. This subgroup was primarily located at a single exposure location. Using lifestyle/activity data, significantly elevated Cr/c urine levels were identified in other exposed subgroups defined by employment location and by outside play time. These data show an association between elevated exposure to chromium in household dust and elevated urine levels of chromium, consistent with residential exposure to chromate production waste. These data also suggest an association between chromium exposure and activities outside the home which are consistent with exposure to chromate production waste.
Asunto(s)
Cromo/análisis , Polvo/análisis , Monitoreo del Ambiente/métodos , Adolescente , Adulto , Cromo/orina , Creatinina/orina , Exposición a Riesgos Ambientales , Femenino , Vivienda , Humanos , Residuos Industriales , Estilo de Vida , Masculino , New JerseyRESUMEN
It is thought that gaseous ammonia in breath neutralizes acidic air pollution and thereby potentially mitigates the pulmonary effects of pollution. The efficacy of breath ammonia depletion methods reported in recent acid aerosol exposure-health response studies was investigated. Fourteen subjects (21 to 54 y of age) performed one or more of the following hygiene maneuvers: (a) acidic oral rinse (pH 2.5); (b) tooth brushing, followed by acidic oral rinse; (c) tooth brushing, followed by distilled water rinse; and (d) distilled water rinse. Initial ammonia levels ranged from 120 to 1,280 ppb (147-1,570 micrograms/m3). Acidic rinsing resulted in an immediate 90% reduction in exhaled ammonia in all subjects, and a return to 50% of baseline levels occurred within 1 h. Depletion that resulted from tooth brushing or distilled water alone was not significant. It was concluded that acidic oral rinsing is an effective method of reducing airway ammonia, but repeated oral rinsing may be required to maintain consistent, low-breath-ammonia conditions during acid aerosol exposure studies.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Amoníaco/análisis , Pruebas Respiratorias , Exposición a Riesgos Ambientales , Antisépticos Bucales/normas , Adulto , Estudios de Evaluación como Asunto , Femenino , Humanos , Concentración de Iones de Hidrógeno , Masculino , Persona de Mediana Edad , Cepillado Dental/normasRESUMEN
The purpose of this study was to identify the significant microenvironments that can lead to chromium exposure in Hudson County, New Jersey residential settings near or on soil contaminated with chromium waste. Measurements were made in indoor air, outdoor air, and house dust. Surface dust was found to be the best index of potential Cr exposure. The values of Cr in Hudson County household dust ranged from 3.25-320 ng/cm2 in wipe samples and 1.0-12 ng/cm2 in vacuum samples. Elevated Cr in household dust was found to be related to residential locations near large chromium waste sites, household cleaning habits, and house renovation activities. Outdoor Cr air levels were similar to those obtained in other urban areas at these seasons of the year, approximately 5-7 ng/m3. Comparisons with measurements of the Cr levels in urine found that the elevated Cr in dust was associated with elevated excretion of Cr. Site-specific Cr differences in household dust suggest different sources and routes of exposure. Within the total group of homes in the present study, Cr in household dust was the major influence on household exposure.