Ultrafine particle pollution : reduction potential using vegetation, sampling strategies, and agricultural occupational exposure assessment
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Fecha
2016
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en
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
La contaminación por material particulado, y específicamente por material particulado
ultrafino (UFP en Inglés, PUF en Español), es un problema para la salud humana,
tanto dentro de hogares como en el ambiente. Por esto, reducir la exposición y
concentraciones de PUF en zonas pobladas es un tema de investigación importante.
El primer objetivo de este estudio fue determinar la efectividad de diferentes plantas
para reducir las concentraciones de PUF en viviendas. Los resultados de esta primera
parte del trabajo abordan la necesidad de soluciones accesibles, económicas y
amigables con el medio ambiente para la grave contaminación del aire que existe en
Santiago de Chile. Este trabajo evaluó la eficacia de diferentes especies vegetales
disponibles en el comercio en Santiago para reducir el material PUF. Estos resultados
entregan potenciales soluciones para descontaminar el aire de partículas ultrafinas en
ambientes interiores.
Para lograr esto, se midieron las concentraciones de material PUF durante tres horas
dentro y fuera de una cámara de policarbonato, con y sin una planta en su interior,
mediante un contador de partículas de condensación (P-TRAK). Se comparó la
reducción de los niveles de material PUF dentro de la cámara entre blancos y tratados
con 11 especies de plantas usando factores de infiltración (Finf). En general los
resultados muestran que la presencia de la mayoría de las plantas se relaciona con
una disminución del material PUF, con reducciones pequeñas pero significativas.
Nueve de los 11 tipos de planta redujeron el material PUF dentro de la cámara. La
planta Juniperus chinensis, San José, alcanzó la mayor disminución de PUF por planta
(5.5%). Se estableció una relación lineal entre el número de plantas Juniperos dentro
de la cámara y el porcentaje de reducción PUF (R2=0.95), alcanzando con cuatro
plantas la disminución mas grande del estudio – Finfp=19.9%. Sorprendentemente, la
planta Dracaena deremensis compacta incrementó las concentraciones de PUFs,
adémas, Schefflera arboricola ‘Variegata’ no afectó los niveles del contaminante. El área superficial de las plantas se relaciona con reducciones en PUFs (R2=0.85)
cuando se comparan los resultados significativos. La temperatura y la humedad
dentro de la cámara no afectaron los resultados significativamente. Se calculó la
disminución de PUF en viviendas utilizando las plantas Juniperos, estimada en un
11%. Los resultados muestran que las plantas pueden disminuir el material PUF en
viviendas en pequeña cantidad pero de forma significativa. Además la presencia de
plantas dentro de casas pueden llevar otros beneficios.
El segundo objetivo de este estudio fue determinar con precisión la exposición al
carbono negro (CN). Las partículas de carbono negro están usualmente en el rango
de tamaño, y por lo tanto son consideradas PUFs en la atmósfera y se relacionan
con efectos negativos para la salud humana y el clima. El método de referencia
estándar para medir la exposición al CN es caro, requiere el servicio de un laboratorio
certificado, y no es capaz de aislar exposiciones muy altas. Por lo tanto, este trabajo
se completó para determinar si un monitor en tiempo real y fácil de utilizar como
microAeth® (MA), puede ser sustituido por el método estándar de referencia (método
NIOSH 5040) para determinar la exposición al CN con precisión. El método 5040 mide
carbón elemental, carbón orgánico y carbón total, pero comparamos carbón elemental
(CE) al CN dado su correlación.
Para lograr esto, se hizo experimentos en una cámara que contenía contaminación de
gases de escape diésel. Este bi-producto estaba hecho fresco por el momento de los
experimentos. También se realizaron experimentos en terrenos agrícolas. Se
compararon mediciones con el método estándar y con MA para cada caso. Durante
ambos tipos de experimentos, los dos filtros estaban contiguos y midieron de forma
simultánea. Se realizó un tercer grupo de experimentos donde se comparó los dos
MAs en el terreno.
Los dos métodos se correlacionaron linealmente, y todos los experimentos en los
cuales el MA se estableció a la velocidad de flujo de 50 ml/min mostraron subestimar
los valores del MA respecto a las concentraciones CE del método estándar en un 20% (R2=0.99).
Cuando se midió el efecto de carga de los filtros en la cámara de diesel usando el MA,
se observó un efecto pequeño. Los filtros usados previamente subestimaron el método
estándar en un 7% más que los filtros nuevos (R2=0.99). Se probó un segundo monitor
MA y éste subestimó aún más el método estándar que el MA original, sin embargo,
ambos MAs mantuvieron alta correlación (R2=0.99) entre ellos. Un factor de corrección
se presenta basado en los resultados de los experimentos de cámara cuando el MA
original fue utilizado con filtros nuevos. El tercer objetivo fue cuantificar la exposición ocupacional de agricultores a CN. Se
midieron las concentraciones de CN durante 20 días de cosecha normales,
mediante el uso del MA por 16 agricultores, en Iowa, EE.UU. Se promediaron muestras
tomadas cada 30-segundos a una velocidad de flujo de 50 ml/min. Los registros de las
actividades y los tiempos fueron tomados por un observador externo. Las
concentraciones promedio según actividad y ponderadas en el tiempo (TWCtasks),
fueron analizadas en 13 tipos de actividades identificadas.
Se observó una diferencia significativa en las concentraciones promedio de CN entre
las actividades de los agricultores (p<0.001). En ambos análisis la exposición del
agricultor a las emisiones de tractores, cosechadoras y otros vehículos grandes que
se encontraran encendidos o lo hubieran estado recientemente, en el exterior o en
recintos cerrados, resultaron en las exposiciones más altas a CN (GM=13.15 por el
actividad, GSD=3.31 µg/m3
). Las concentraciones diarias de CN y las exposiciones
más altas fueron analizadas, con un promedio diario que oscila entre 0-11 µg/m3 (AM)
y un promedio de exposición total diaria de 2.29 µg/m3 incluyendo todas las visitas.
Las exposiciones más altas registraron desde 100 µg/m3 y ocurrieron frecuentemente
(en el 40% de las visitas). Considerando que el estado de EE.UU con las concentraciones de CN más altas (2.5
µg/m3
) tiene niveles comparables a los que estan expuestos los agricultores de este
estudio, ser agricultor debería ser considerado como una ocupación en que se
evaluen las exposiciones a CN más extensamente, y donde se realicen estrategias de
prevención a exposiciones mayores.
En resumen, este trabajo busca resolver las piezas que faltan en la literatura sobre
calidad del aire, evaluando sistemas de remediación del aire contaminado de bajo
costo, proponiendo un factor de corrección basado en el método estandar actual para
un equipo monitor de CN, y finalmente reportando por primera vez las grandes
concentraciones de CN a las que están expuestos los agricultores. El objetivo de
este estudio es facilitar y proveer información para el mejoramiento del calidad del aire,
e identificar y caracterizar, actividades con riesgo de exposiciones altas en una población
expuesta.
Particle pollution, specifically ultrafine particle (UFP) pollution, is a human-health concern both indoors and outdoors. Reducing ambient UFP exposure and concentrations in populated areas is therefore an important research topic. The first research aim of this study was to assess the effectiveness of plants to decrease UFP concentrations in indoor environments. The results of this work address the need for accessible, cheap, and environmentally friendly solutions to indoor air contamination in the heavily polluted city of Santiago, Chile. This work tests the efficiency of various commercially available vegetative species in removing ultrafine particle pollution. Results provide potential air remediation to treat indoor ultrafine particles. To achieve this aim, ambient UFP concentrations were measured for three hours within and outside of a polycarbonate chamber with and without plants using a condensation particle counter (P-TRAK). Reductions in in-chamber UFP levels within the chamber between controls and treatments of 11 plant species were compared using infiltration factors (Finfs). The presence of most plants resulted in in-chamber UFP reductions, with typically small but significant results. Nine out of 11 plants led to reductions in UFPs. The Juniperus chinensis 'San Jose' resulted in the highest per-plant UFP reduction (5.5%). A linear relationship between number of plants and percent UFP reduction was proven (R2=0.95) for Juniper plants, with four plants reaching a maximum Finfp reduction (19.9%). Surprisingly, the Dracaena deremensis compacta resulted in increased concentrations of UFPs, and the Schefflera arboricola ‘Variegata’ resulted in virtually no changes in concentrations. %). Plant surface area was associated with UFP reduction (R2=0.85) when comparing significant results. Humidity and temperature did not significantly influence reduction. Household estimation of UFP reduction was assessed using Juniper plants (11%). Results indicate that plants may provide a significant, yet small UFP reduction in homes with the co-benefit of greening the indoor environment. The aim of the second study was to accurately quantify black carbon exposure. Black carbon (BC) particles are typically in the size range of, and therefore exist as, UFPs in the atmosphere and are implicated in producing negative human-health and climatological effects. The standard reference method used to assess BC exposure is expensive, requires sample shipment, and does not isolate peak exposures. Therefore, this work was completed to determine whether an easily deployed real-time monitor, the microAeth® (MA), could be substituted for the standard reference method (NIOSH method 5040) for accurately determining BC exposures. To address this, experiments in a chamber with fresh diesel exhaust and experiments in agricultural settings were carried out. This involved side-by-side comparisons of the standard method results to those produced by the MA in both settings; additionally, a third set of experiments took place, comparing the results of two MAs in the field. Both methods were linearly correlated, and all experiments with the MA at flow-rate 50 ml/min showed the MA to underestimate the standard method’s EC concentrations by 21% (R2=0.99). When comparing the filter loading effect in the diesel chamber using the MA, a small effect was seen – previously used filters underestimated the standard method by 5.6% more than new filters (R2=0.99). A second MA underestimated levels reported by the original MA, however both MAs were highly correlated (R2=0.99). A correction factor is presented based on chamber experiments using new filters in the original MA. The third aim was to quantify BC personal exposures in 16 farmers, measured over 20 sampling days using a MA during harvest. 30-second averaged samples were taken at a flow-rate of 50 ml/minute as task-types and times were recorded by a third-party observer. Average task-based and time-weighted concentrations were analyzed from 13 identified task-types. A significant difference was found in average BC concentrations between tasks (p<0.001). In both analyses, farmers’ exposure to tractor, combine, or loader-tractor’s exhaust from a recently or currently running machine in/outdoor resulted in the highest BC exposure (task-based GM=13.15, GSD=3.31 µg/m3 ). Additionally, daily BC concentrations and peak exposures were analyzed, with daily arithmetic means ranging from 0-11 µg/m3 , and an average total daily exposure of 2.29 µg/m3 ; peak exposures ≥100 µg/m3 occurred frequently (40% of visits). Considering that New Jersey, which maintains the highest spatially weighted concentrations of BC has comparable levels (2.5 µg/m3 ), farming should be considered as an occupation to be studied further in BC exposure assessments, and exposure prevention strategies during peak exposures should be explored. In summary, this work seeks to address current gaps in air quality literature by assessing low-cost filtration systems, by providing a correction factor for a valuable BC monitor based on the current standard method, and finally, by demonstrating for the first time the exposure to BC which farmers experience. The aim of this work is to more readily provide information aimed to improve air quality, and to identify and characterize high-exposure activities in an exposed population.
Particle pollution, specifically ultrafine particle (UFP) pollution, is a human-health concern both indoors and outdoors. Reducing ambient UFP exposure and concentrations in populated areas is therefore an important research topic. The first research aim of this study was to assess the effectiveness of plants to decrease UFP concentrations in indoor environments. The results of this work address the need for accessible, cheap, and environmentally friendly solutions to indoor air contamination in the heavily polluted city of Santiago, Chile. This work tests the efficiency of various commercially available vegetative species in removing ultrafine particle pollution. Results provide potential air remediation to treat indoor ultrafine particles. To achieve this aim, ambient UFP concentrations were measured for three hours within and outside of a polycarbonate chamber with and without plants using a condensation particle counter (P-TRAK). Reductions in in-chamber UFP levels within the chamber between controls and treatments of 11 plant species were compared using infiltration factors (Finfs). The presence of most plants resulted in in-chamber UFP reductions, with typically small but significant results. Nine out of 11 plants led to reductions in UFPs. The Juniperus chinensis 'San Jose' resulted in the highest per-plant UFP reduction (5.5%). A linear relationship between number of plants and percent UFP reduction was proven (R2=0.95) for Juniper plants, with four plants reaching a maximum Finfp reduction (19.9%). Surprisingly, the Dracaena deremensis compacta resulted in increased concentrations of UFPs, and the Schefflera arboricola ‘Variegata’ resulted in virtually no changes in concentrations. %). Plant surface area was associated with UFP reduction (R2=0.85) when comparing significant results. Humidity and temperature did not significantly influence reduction. Household estimation of UFP reduction was assessed using Juniper plants (11%). Results indicate that plants may provide a significant, yet small UFP reduction in homes with the co-benefit of greening the indoor environment. The aim of the second study was to accurately quantify black carbon exposure. Black carbon (BC) particles are typically in the size range of, and therefore exist as, UFPs in the atmosphere and are implicated in producing negative human-health and climatological effects. The standard reference method used to assess BC exposure is expensive, requires sample shipment, and does not isolate peak exposures. Therefore, this work was completed to determine whether an easily deployed real-time monitor, the microAeth® (MA), could be substituted for the standard reference method (NIOSH method 5040) for accurately determining BC exposures. To address this, experiments in a chamber with fresh diesel exhaust and experiments in agricultural settings were carried out. This involved side-by-side comparisons of the standard method results to those produced by the MA in both settings; additionally, a third set of experiments took place, comparing the results of two MAs in the field. Both methods were linearly correlated, and all experiments with the MA at flow-rate 50 ml/min showed the MA to underestimate the standard method’s EC concentrations by 21% (R2=0.99). When comparing the filter loading effect in the diesel chamber using the MA, a small effect was seen – previously used filters underestimated the standard method by 5.6% more than new filters (R2=0.99). A second MA underestimated levels reported by the original MA, however both MAs were highly correlated (R2=0.99). A correction factor is presented based on chamber experiments using new filters in the original MA. The third aim was to quantify BC personal exposures in 16 farmers, measured over 20 sampling days using a MA during harvest. 30-second averaged samples were taken at a flow-rate of 50 ml/minute as task-types and times were recorded by a third-party observer. Average task-based and time-weighted concentrations were analyzed from 13 identified task-types. A significant difference was found in average BC concentrations between tasks (p<0.001). In both analyses, farmers’ exposure to tractor, combine, or loader-tractor’s exhaust from a recently or currently running machine in/outdoor resulted in the highest BC exposure (task-based GM=13.15, GSD=3.31 µg/m3 ). Additionally, daily BC concentrations and peak exposures were analyzed, with daily arithmetic means ranging from 0-11 µg/m3 , and an average total daily exposure of 2.29 µg/m3 ; peak exposures ≥100 µg/m3 occurred frequently (40% of visits). Considering that New Jersey, which maintains the highest spatially weighted concentrations of BC has comparable levels (2.5 µg/m3 ), farming should be considered as an occupation to be studied further in BC exposure assessments, and exposure prevention strategies during peak exposures should be explored. In summary, this work seeks to address current gaps in air quality literature by assessing low-cost filtration systems, by providing a correction factor for a valuable BC monitor based on the current standard method, and finally, by demonstrating for the first time the exposure to BC which farmers experience. The aim of this work is to more readily provide information aimed to improve air quality, and to identify and characterize high-exposure activities in an exposed population.
Notas
Tesis (Doctora en Medicina de la Conservación)
Financial support for the project was given by Universidad Andrés Bello Proyecto Interno, Grant No DI-605-14/I. The BC exposure monitoring study, and processing of NIOSH method 5040 samples was supported in part by the Intramural Research Program of the National Institutes of Health, National Cancer Institute (Z01CP010119).
Financial support for the project was given by Universidad Andrés Bello Proyecto Interno, Grant No DI-605-14/I. The BC exposure monitoring study, and processing of NIOSH method 5040 samples was supported in part by the Intramural Research Program of the National Institutes of Health, National Cancer Institute (Z01CP010119).
Palabras clave
Contaminación Atmosférica, Plantas, Análisis, Agricultura, Aspectos Ambientales