RESUMEN
Ozone reacts readily with many indoor materials, as well as with compounds in indoor air. These reactions lead to lower indoor than outdoor ozone concentrations when outdoor air is the major contributor to indoor ozone. However, the products of indoor ozone reactions may be irritating or harmful to building occupants. While active technologies exist to reduce indoor ozone concentrations (i.e, in-duct filtration using activated carbon), they can be cost-prohibitive for some and/or infeasible for dwellings that do not have heating, ventilating, and air-conditioning systems. In this study, the potential for passive reduction of indoor ozone by two different clay-based interior surface coatings was explored. These coatings were exposed to occupied residential indoor environments and tested bimonthly in environmental chambers for quantification of ozone reaction probabilities and reaction product emission rates over a 6-month period. Results indicate that clay-based coatings may be effective as passive removal materials, with relatively low by-product emission rates that decay rapidly within 2 months.
Asunto(s)
Contaminación del Aire Interior/análisis , Contaminación del Aire Interior/prevención & control , Silicatos de Aluminio/química , Ozono/análisis , Arcilla , Materiales de Construcción , Monitoreo del Ambiente/métodos , Filtración , Pintura , VentilaciónRESUMEN
This study involved the development of a model for evaluating the potential costs and benefits of ozone control by activated carbon filtration in single-family homes. The modeling effort included the prediction of indoor ozone with and without activated carbon filtration in the HVAC system. As one application, the model was used to predict benefit-to-cost ratios for single-family homes in 12 American cities in five different climate zones. Health benefits were evaluated using disability-adjusted life-years and included city-specific age demographics for each simulation. Costs of commercially available activated carbon filters included capital cost differences when compared to conventional HVAC filters of similar particle removal efficiency, energy penalties due to additional pressure drop, and regional utility rates. The average indoor ozone removal effectiveness ranged from 4 to 20% across the 12 target cities and was largely limited by HVAC system operation time. For the parameters selected in this study, the mean predicted benefit-to-cost ratios for 1-inch filters were >1.0 in 10 of the 12 cities. The benefits of residential activated carbon filters were greatest in cities with high seasonal ozone and HVAC usage, suggesting the importance of targeting such conditions for activated carbon filter applications.
Asunto(s)
Filtros de Aire/economía , Contaminación del Aire Interior/economía , Carbono/análisis , Filtración/economía , Vivienda , Ozono/análisis , Aire Acondicionado/economía , Contaminación del Aire Interior/análisis , Contaminación del Aire Interior/prevención & control , Ciudades , Análisis Costo-Beneficio , Filtración/instrumentación , Humanos , Material Particulado/análisis , Años de Vida Ajustados por Calidad de Vida , Estaciones del AñoRESUMEN
UNLABELLED: People spend approximately one-third of their lives sleeping, where they can be exposed to a myriad of particle-bound biological agents and chemical pollutants that originate within mattresses and bedding, including allergens, fungal spores, bacteria, and particle-phase semi-volatile organic compounds. Full-scale particle resuspension experiments were conducted in an environmental chamber, where volunteers performed a prescribed movement routine on an artificially seeded mattress. Human movements in bed, such as rolling from the prone to supine position, were found to resuspend settled particles, leading to elevations in airborne particle concentrations. Resuspension rates were estimated for the size fractions of 1-2 µm, 2-3 µm, 3-5 µm, 5-10 µm, and 10-20 µm, and were in the range of 10(-3) to 10(1) h(-1). Particle size had the most significant impact on the resuspension rate, whereas dust loading, volunteer body mass, and ventilation rate had a much smaller impact. Resuspension increased with the intensity of a movement, as characterized by surface vibrations, and decreased with repeated movement routines. Inhalation exposure was characterized with the intake fraction metric. Intake fractions increased as the particle size and ventilation rate decreased and ranged from 10(2) to 10(4) inhaled particles per million resuspended, demonstrating that a significant fraction of released particles can be inhaled by sleeping occupants. PRACTICAL IMPLICATIONS: Full-scale chamber experiments with human volunteers demonstrate that body movements in bed can resuspend settled particles from mattresses, leading to elevated airborne particle concentrations in both the breathing zone and bulk air of the chamber. Numerous variables influence resuspension, including particle size and intensity of a specific body movement. The results suggest that human-induced resuspension in the sleep microenvironment may play an important role in contributing to our inhalation exposure to mattress dust pollutants.
Asunto(s)
Contaminación del Aire Interior/análisis , Lechos , Material Particulado , Peso Corporal , Humanos , Exposición por Inhalación , Movimiento , Tamaño de la Partícula , VentilaciónRESUMEN
Retail buildings have a potential for both short-term (customer) and long-term (occupational) exposure to indoor pollutants. However, little is known about volatile organic compound (VOC) concentrations in the retail sector and influencing factors, such as ventilation, in-store activities, and store type. We measured VOC concentrations and ventilation rates in 14 retail stores in Texas and Pennsylvania. With the exception of formaldehyde and acetaldehyde, VOCs were present in retail stores at concentrations well below health guidelines. Indoor formaldehyde concentrations ranged from 4.6 ppb to 67 ppb. The two mid-sized grocery stores in the sample had the highest levels of ethanol and acetaldehyde, with concentrations up to 2.6 ppm and 92 ppb, respectively, possibly due to the preparation of dough and baking activities. Indoor-to-outdoor concentration ratios indicated that indoor sources were the main contributors to indoor VOC concentrations for the majority of compounds. There was no strong correlation between ventilation and VOC concentrations across all stores. However, increasing the air exchange rates at two stores led to lower indoor VOC concentrations, suggesting that ventilation can be used to reduce concentrations for some specific stores.
Asunto(s)
Acetaldehído/análisis , Contaminantes Atmosféricos/análisis , Contaminación del Aire Interior/análisis , Formaldehído/análisis , Compuestos Orgánicos Volátiles/análisis , Comercio , Pennsylvania , Texas , VentilaciónRESUMEN
The health effects associated with exposure to ozone range from respiratory irritation to increased mortality. In this paper, we explore the use of three green building materials and an activated carbon (AC) mat that remove ozone from indoor air. We studied the effects of long-term exposure of these materials to real environments on ozone removal capability and pre- and post-ozonation emissions. A field study was completed over a 6-month period, and laboratory testing was intermittently conducted on material samples retrieved from the field. The results show sustained ozone removal for all materials except recycled carpet, with greatest ozone deposition velocity for AC mat (2.5-3.8 m/h) and perlite-based ceiling tile (2.2-3.2 m/h). Carbonyl emission rates were low for AC across all field sites. Painted gypsum wallboard and perlite-based ceiling tile had similar overall emission rates over the 6-month period, while carpet had large initial emission rates of undesirable by-products that decayed rapidly but remained high compared with other materials. This study confirms that AC mats and perlite-based ceiling tile are viable surfaces for inclusion in buildings to remove ozone without generating undesirable by-products. PRACTICAL IMPLICATIONS The use of passive removal materials for ozone control could decrease the need for, or even render unnecessary, active but energy consuming control solutions. In buildings where ozone should be controlled (high outdoor ozone concentrations, sensitive populations), materials specifically designed or selected for removing ozone could be implemented, as long as ozone removal is not associated with large emissions of harmful by-products. We find that activated carbon mats and perlite-based ceiling tiles can provide substantial, long-lasting, ozone control.
Asunto(s)
Contaminación del Aire Interior/prevención & control , Materiales de Construcción , Ozono/aislamiento & purificación , Acetona/análisis , Aire/análisis , Benzaldehídos/análisis , Carbón Orgánico/química , AmbienteRESUMEN
UNLABELLED: More than 30 years after the First International Indoor Climate Symposium, ten researchers from the USA, Slovakia, Sweden, and Denmark gathered to review the current status of indoor environmental research. We initiated our review with discussions during the 1-day meeting and followed that with parallel research and writing efforts culminating with internal review and revision cycles. In this paper, we present our choices for the most important research findings on indoor environmental quality from the past three decades followed by a discussion of the most important research questions in our field today. We then continue with a discussion on whether there are research areas for which we can 'close the book' and say that we already know what is needed. Finally, we discuss whether we can maintain our identity in the future or it is time to team up with new partners. PRACTICAL IMPLICATIONS: In the early years of this field, the accumulated knowledge was small and it was possible for any researcher to acquire a complete understanding. To do so has become impossible today as what we know has grown to exceed the learning capacity of any person. These circumstances challenge us to work collectively to synthesize what we do know and to define clearly what remains to be learned. If we fail to do these things well, we risk repeating research without memory, an inefficiency that we cannot afford.
Asunto(s)
Contaminantes Atmosféricos/historia , Contaminación del Aire Interior/historia , Salud Ambiental/historia , Contaminantes Atmosféricos/efectos adversos , Contaminantes Atmosféricos/análisis , Contaminación del Aire Interior/efectos adversos , Contaminación del Aire Interior/prevención & control , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Investigación/historia , Investigación/tendenciasRESUMEN
UNLABELLED: Chronic human exposure to formaldehyde is significantly increased by indoor sources. However, information is lacking on why these exposures appear to persist in older homes with aging sources. We use data from the Relationships of Indoor, Outdoor, and Personal Air study to evaluate 179 residences, most of which were older than 5 years. We assess the dependence of indoor formaldehyde concentrations (C(in)) on building type and age, whole-house air exchange rate, indoor temperature, and seasonal changes. Indoor formaldehyde had mean and median concentrations of 17 ppb, and primarily originated from indoor sources. The factors we analyzed did not explain much of the variance in C(in), probably because of their limited influence on mechanisms that control the long-term release of formaldehyde from aging pressed-wood products bound with urea-formaldehyde (UF) resins. We confirmed that the mitigating effects of ventilation on C(in) decrease with time through the analysis of data for new homes available in the literature, and through models. We also explored source control strategies and conclude that source removal is the most effective way to decrease chronic exposures to formaldehyde in existing homes. For new homes, reducing indoor sources and using pressed-wood with lower UF content are likely the best solutions. PRACTICAL IMPLICATIONS: Formaldehyde concentrations in homes due to indoor sources appear to persist throughout the lifetime of residences. Increases in ventilation rates are most effective in decreasing indoor concentrations in new homes where formaldehyde levels are high or when homes are tight. Consequently, other alternatives need to be promoted such as decreasing the amount of pressed-wood products with urea-formaldehyde (UF) resins in homes or reducing the UF content in these materials.
Asunto(s)
Contaminantes Atmosféricos/análisis , Contaminación del Aire Interior/análisis , Materiales de Construcción/análisis , Monitoreo del Ambiente , Formaldehído/análisis , Vivienda , Madera , Contaminantes Atmosféricos/química , Contaminación del Aire Interior/prevención & control , Humanos , Humedad , Estaciones del Año , Temperatura , Factores de Tiempo , VentilaciónRESUMEN
The House Observations of Microbial and Environmental Chemistry (HOMEChem) study is a collaborative field investigation designed to probe how everyday activities influence the emissions, chemical transformations and removal of trace gases and particles in indoor air. Sequential and layered experiments in a research house included cooking, cleaning, variable occupancy, and window-opening. This paper describes the overall design of HOMEChem and presents preliminary case studies investigating the concentrations of reactive trace gases, aerosol particles, and surface films. Cooking was a large source of VOCs, CO2, NOx, and particles. By number, cooking particles were predominantly in the ultrafine mode. Organic aerosol dominated the submicron mass, and, while variable between meals and throughout the cooking process, was dominated by components of hydrocarbon character and low oxygen content, similar to cooking oil. Air exchange in the house ensured that cooking particles were present for only short periods. During unoccupied background intervals, particle concentrations were lower indoors than outdoors. The cooling coils of the house ventilation system induced cyclic changes in water soluble gases. Even during unoccupied periods, concentrations of many organic trace gases were higher indoors than outdoors, consistent with housing materials being potential sources of these compounds to the outdoor environment. Organic material accumulated on indoor surfaces, and exhibited chemical signatures similar to indoor organic aerosol.
Asunto(s)
Microbiología del Aire/normas , Contaminantes Atmosféricos/análisis , Contaminación del Aire Interior/análisis , Monitoreo del Ambiente/métodos , Vivienda/normas , Material Particulado/análisis , Aerosoles , Aire Acondicionado , Filtros de Aire , Culinaria , Gases , Humanos , Tamaño de la PartículaRESUMEN
Epomediol (EPO) is a synthetic terpenoid compound shown to be active in increasing bile flow and some enzymatic activities of liver plasma membranes in the rat. The possible effect of EPO treatment in the ethinyl-estradiol (EE) induced cholestasis in the rat was investigated by measuring the hepatic transport of sulfobromophthalein (BSP) (plasma clearance and biliary secretion) and bile flow. Liver plasma membrane fluidity was also determined by the steady state fluorescence polarization (P) of diphenylhexatriene (DPH). EE administration (5 mg/kg s.c. for 5 days) was followed by a significant, comparable reduction (P less than 0.001) in BSP plasma clearance and biliary excretion and in bile flow. Intraperitoneal administration of EPO (100 mg/kg) to EE-treated rats restored both parameters of BSP transport, as well as bile flow, to control values. Liver plasma membrane fluidity was markedly (P less than 0.01) decreased by EE administration with a concomitant reduction (P less than 0.01) in Na+/K+-ATPase activity. EPO administration significantly increased membrane fluidity to values higher either to cholestatic (P less than 0.05) or control (P less than 0.05) animals. On the contrary, EPO did not influence Na+/K+-ATPase activity in either EE-treated or control animals. These data indicate that EPO fully reverses the impairments of BSP transport and bile flow induced by EE, possibly by reversing the decrease in liver plasma membrane fluidity induced by the synthetic estrogen. On the contrary, the EE-mediated decrease in Na+/K+-ATPase activity was not reversed by EPO.
Asunto(s)
Colagogos y Coleréticos/farmacología , Colestasis/inducido químicamente , Etinilestradiol/antagonistas & inhibidores , Hígado/efectos de los fármacos , Fluidez de la Membrana/efectos de los fármacos , Terpenos/farmacología , Animales , Bilis/efectos de los fármacos , Compuestos Bicíclicos Heterocíclicos con Puentes , Membrana Celular/efectos de los fármacos , Membrana Celular/enzimología , Colestasis/prevención & control , Hígado/enzimología , Masculino , Ratas , Ratas Endogámicas , ATPasa Intercambiadora de Sodio-Potasio/análisisRESUMEN
Deltorphins are naturally occurring peptides with high affinity and selectivity for delta-opioid receptors. They share with dermorphin, another mu-selective opioid agonist, the same N-terminal tripeptide Tyr-D-Xaa-Phe, where D-Xaa is a D-Ala or a D-Met residue. This common sequence appears to be essential for the best fitting of the peptides to both mu- or delta-opioid sites. We studied the changes in receptor affinity and selectivity and in biological potency of deltorphins due to shortening of the sequence, C-terminal deamidation or single amino acid substitutions. The results support the view that a code addressing the molecule towards delta-opioid sites is expressed in the C-terminal region of these peptides. This addressing domain confers high delta-selectivity to the ligand in the following two ways: (i) increased affinity for delta-sites; (ii) decreased affinity for mu-sites. The sequence of the C-terminal tripeptide appears to be responsible for the high delta-affinity of the molecules. Negatively charged side chains inhibit mu-binding and enhance delta-selectivity.
Asunto(s)
Oligopéptidos/metabolismo , Receptores Opioides/metabolismo , Secuencia de Aminoácidos , Animales , Encéfalo/metabolismo , Cobayas , Íleon/efectos de los fármacos , Íleon/metabolismo , Técnicas In Vitro , Masculino , Ratones , Conformación Molecular , Datos de Secuencia Molecular , Músculo Liso/efectos de los fármacos , Músculo Liso/metabolismo , Plexo Mientérico/efectos de los fármacos , Plexo Mientérico/metabolismo , Oligopéptidos/farmacología , Péptidos/síntesis química , Péptidos/química , Péptidos/metabolismo , Ratas , Receptores Opioides/farmacología , Receptores Opioides delta , Receptores Opioides mu , Relación Estructura-Actividad , Conducto Deferente/efectos de los fármacos , Conducto Deferente/metabolismoRESUMEN
With a cDNA library prepared from skin of Phyllomedusa sauvagei, the sequence of the precursor of dermorphin was elucidated recently. The sequence suggested the existence of another peptide, distantly related to dermorphin. Two variants of this peptide have now been synthesized containing either L- or D-methionine as the second amino acid. The peptide containing the D-methionine exhibited high-affinity and selectivity for delta opioid receptors in the mouse vas deferens and in rat brain homogenates. Moreover, using the synthetic peptide as marker, we could isolate small quantities of the corresponding natural peptide containing D-methionine as the second amino acid from skin extracts of Phyllomedusa sauvagei. The name deltorphin is proposed for this new peptide and its sequence is Tyr-D-Met-Phe-His-Leu-Met-Asp-NH2.
Asunto(s)
Oligopéptidos/metabolismo , Receptores Opioides/metabolismo , Animales , Anuros , Cromatografía Líquida de Alta Presión , Cobayas , Íleon/efectos de los fármacos , Técnicas In Vitro , Ratones , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Narcóticos/farmacología , Ratas , Receptores Opioides delta , Fenómenos Fisiológicos de la Piel , Extractos de Tejidos/análisis , Extractos de Tejidos/farmacologíaRESUMEN
Contaminated tap water is one source of potentially hazardous air pollutants in residential indoor air. Contaminants have been observed to volatilize from household tap water sources, including showers, wash basins, bath-tubs, washing machines, dishwashers, and toilets. A background search of these sources led to the conclusion that more attention should be given to wash basins and tubs, the numerous operating conditions of which yield a significant range of chemical stripping efficiencies. In response, nine laboratory experiments were completed to determine chemical stripping efficiencies and mass transfer coefficients for a kitchen wash basin. Chemical stripping efficiencies ranged from 1.1% to 4.9% for acetone, 13% to 26% for toluene, and 18% to 48% for cyclohexane. The product of overall mass transfer coefficient and interfacial area (KLA) ranged from 0.06 L/min to 0.24 L/min for acetone, 0.7 L/min to 1.9 L/min for toluene, and 0.9 L/min to 3.5 L/min for cyclohexane. Results clearly indicate that chemical properties (e.g., Henry's law coefficient) and system operating conditions (e.g., liquid flow rate and nozzle type) have a significant effect on contaminant stripping efficiency. Furthermore, significant gasphase resistance can occur, even for relatively volatile contaminants, during some operating conditions. The latter observation has important implications with respect to conventional protocols used to extrapolate radon data to other volatile contaminants in drinking water.
Asunto(s)
Contaminación del Aire Interior/análisis , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua/análisis , Humanos , VolatilizaciónRESUMEN
Previous research has indicated that residential washing machines are potential sources of pollution due to the associated use of chemicals found in consumer products, for example, ethanol in laundry detergent and chlorine in bleach. Washing machines may also emit hazardous air pollutants found in contaminated drinking water. To better understand the extent and impact of chemical emissions from tap water, 26 experiments were completed using a residential washing machine and a cocktail of chemical tracers representing a wide range of physicochemical properties. Variable operating conditions for these experiments included water temperature, amount of clothes present in the machine, water volume, and level of washwater agitation. Chemical stripping efficiencies and mass transfer coefficients were determined during each cycle (fill, wash, and rinse) of a normal washing machine event. Headspace ventilation rates were determined using an isobutylene tracer gas. Mass transfer rates were significantly influenced by operating parameters as exhibited by a wide range of chemical stripping efficiencies. Stripping efficiencies ranged from 0.74 to 36% for acetone, 8.2 to 99% for toluene, 10 to 99% for ethylbenzene, and 6.9 to 100% for cyclohexane.
Asunto(s)
Contaminación del Aire Interior/análisis , Lavandería , Abastecimiento de Agua/análisis , VolatilizaciónRESUMEN
BACKGROUND: The purpose of this study was to evaluate the relationship between duodenal ulcer (DU), Helicobacter pylori (Hp) infection and genetic and enviromental factors, and its influence on treatment and long-term RESULTS. METHOD: In the course of an epidemiological study on the prevalence of esophagogastroduodenal diseases, 1,169 volunteers underwent an endoscopy of the upper part of the gastrointestinal tract. The relationship of incidence rate and size of duodenal ulcers and several risks factors was investigated. RESULTS: A DU was observed in 240 subjects (20.5%), mostly of male gender (64.4% - p<0.0001). The Histological presence of a gastric Hp infection was confirmed in 179 cases (74.6%); it did not influenced the mean size of the ulcers and the presence of gastric intestinal metaplasia, compared to subjects without Hp infection. However, a superficial chronic gastritis was observed in 95.9% of Hp+ subjects and in 83.3% of Hp- (p<0.003), whereas a familiar history of DU was noted in 33.3% of Hp+ subjects and in 50.8% of Hp- (p<0.02). The main risk factor for DU was represented by Hp infection in 119 cases (49.6%), by infective and genetic factors in 60 cases (25%) and only by the genetic factor in 31 cases (12.9%), and was not detected in 30 cases (12.5%). Ulcer recurrence rates, after medical therapy, were 0,5% and 6.5% (p<0.03) at a 2-month follow-up, and 2.2% and 49.1% (p<0.00001) at a 12-month follow-up, among Hp+ and Hp- patients, respectively. CONCLUSIONS: The most common risk factor for DU was a gastric Hp infection, alone or associated to the genetic factor. Since the high incidence of recurrences at a 12-month follow-up, patients affected with a DU but Hp- represented an important therapeutic concern.
Asunto(s)
Úlcera Duodenal/microbiología , Infecciones por Helicobacter/complicaciones , Helicobacter pylori , Adolescente , Adulto , Anciano , Úlcera Duodenal/epidemiología , Femenino , Infecciones por Helicobacter/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Factores de RiesgoAsunto(s)
Encéfalo/metabolismo , Receptores Opioides/clasificación , Animales , Unión Competitiva , Encéfalo/ultraestructura , Encefalina D-Penicilamina (2,5) , Encefalinas/metabolismo , Cinética , Masculino , Membranas/metabolismo , Oligopéptidos/metabolismo , Ratas , Ratas Endogámicas , Receptores Opioides/metabolismo , Receptores Opioides deltaRESUMEN
UNLABELLED: Stand-alone air cleaners may be efficient for rapid removal of indoor fine particles and have potential use for shelter-in-place (SIP) strategies following acts of bioterrorism. A screening model was employed to ascertain the potential significance of size-resolved particle (0.1-2 microm) removal using portable high efficiency particle arresting (HEPA) air cleaners in residential buildings following an outdoor release of particles. The number of stand-alone air cleaners, air exchange rate, volumetric flow rate through the heating, ventilating and air-conditioning (HVAC) system, and size-resolved particle removal efficiency in the HVAC filter were varied. The effectiveness of air cleaners for SIP was evaluated in terms of the outdoor and the indoor particle concentration with air cleaner(s) relative to the indoor concentration without air cleaners. Through transient and steady-state analysis of the model it was determined that one to three portable HEPA air cleaners can be effective for SIP following outdoor bioaerosol releases, with maximum reductions in particle concentrations as high as 90% relative to conditions in which an air cleaner is not employed. The relative effectiveness of HEPA air cleaners vs. other removal mechanisms was predicted to decrease with increasing particle size, because of increasing competition by particle deposition with indoor surfaces and removal to HVAC filters. However, the effect of particle size was relatively small for most scenarios considered here. PRACTICAL IMPLICATIONS: The results of a screening analysis suggest that stand-alone (portable) air cleaners that contain high efficiency particle arresting (HEPA) filters can be effective for reducing indoor fine particle concentrations in residential dwellings during outdoor releases of biological warfare agents. The relative effectiveness of stand-alone air cleaners for reducing occupants' exposure to particles of outdoor origin depends on several factors, including the type of heating, ventilating and air-conditioning (HVAC) filter, HVAC operation, building air exchange rate, particle size, and duration of elevated outdoor particle concentration. Maximum particle reductions, relative to no stand-alone air cleaners, of 90% are predicted when three stand-alone air cleaners are employed.
Asunto(s)
Aire Acondicionado , Contaminación del Aire Interior/prevención & control , Bioterrorismo , Ventilación , Aerosoles , Movimientos del Aire , Contaminantes Atmosféricos/aislamiento & purificación , Bacterias/aislamiento & purificación , Guerra Biológica , Planificación en Desastres , Filtración , Humanos , Tamaño de la PartículaRESUMEN
UNLABELLED: The use of indoor ozone generators as air purifiers has steadily increased over the past decade. Many ozone generators are marketed to consumers for their ability to eliminate odors and microbial agents and to improve health. In addition to the harmful effects of ozone, recent studies have shown that heterogeneous and homogeneous reactions between ozone and some unsaturated hydrocarbons can be an important source of indoor secondary pollutants, including free radicals, carbonyls, carboxylic acids, and fine particles. Experiments were conducted in one apartment and two detached single-family dwellings in Austin, TX, to assess the effects of an ozone generator on indoor secondary organic aerosol concentrations in actual residential settings. Ozone was generated using a commercial ozone generator marketed as an air purifier, and particle measurements were recorded before, during, and after the release of terpenes from a pine oil-based cleaning product. Particle number concentration, ozone concentration, and air exchange rate were measured during each experiment. Particle number and mass concentrations increased when both terpenes and ozone were present at elevated levels. Experimental results indicate that ozone generators in the presence of terpene sources facilitate the growth of indoor fine particles in residential indoor atmospheres. Human exposure to secondary organic particles can be reduced by minimizing the intentional release of ozone, particularly in the presence of terpene sources. PRACTICAL IMPLICATIONS: Past studies have shown that ozone-initiated indoor chemistry can lead to elevated concentrations of fine particulate matter, but have generally been completed in controlled laboratory environments and office buildings. We explored the effects of an explicit ozone generator marketed as an air purifier on the formation of secondary organic aerosol mass in actual residential indoor settings. Results indicate significant increases in number and mass concentrations for particles <0.7 microns in diameter, particularly when an ozone generator is used in the presence of a terpene source such as a pine oil-based cleaner. These results add evidence to the potentially harmful effects of ozone generation in residential environments.
Asunto(s)
Contaminación del Aire Interior/prevención & control , Hidrocarburos/análisis , Oxidantes Fotoquímicos/química , Ozono/química , Aerosoles , Filtración , Vivienda , Humanos , Hidrocarburos/química , Tamaño de la PartículaRESUMEN
This study was carried out using various materials (carpet, gypsum board, upholstery, vinyl and wood flooring, acoustic tiles, and fruit) that were exposed to eight gaseous volatile organic compounds (VOCs) (isopropanol, MTBE, cyclohexane, toluene, ethylbenzene, tetrachloroethene, 1,2-dichlorobenzene, and 1,2,4-trichlorobenzene) in electro-polished stainless-steel chambers. Dynamic responses in VOC concentrations were used to determine linear adsorption and desorption rate coefficients and equilibrium partition coefficients. A linear adsorption/desorption model was used to effectively describe the interactions between VOCs and indoor surface materials for short-term source events (10 h). Relationships between sorption parameters and chemical vapor pressure and the octanol-air partition coefficient were observed. Carpet was identified as the most significant sorptive sink for non-polar VOCs. Virgin gypsum board was observed to be a significant sink for highly polar VOCs. Sorptive interactions between non-polar VOCs and indoor materials were not affected by variations in relative humidity. However, increases in relative humidity were observed to increase the degree of sorption of isopropanol to carpet.