Influence of precipitation scavenging on the PM2.5PM10 ratio at the Kennedy locality of Bogotá, Colombia

Abstract

ABSTRACT:Objective: To establish whether the scavenging effect reduces the PM 2.5 /PM 10 ratio in rainy periods in comparison with dry periods, at the Kennedy locality of Bogotá, Colombia. Materials and methods: Relationships among hourly and daily PM 10 , PM 2.5 , PM 2.5 / PM 10 ratio, temperature, relative humidity and precipitation records from the Kennedy air quality station from January 2007 to September 2011 were analyzed. Results: The hourly mean PM 2.5 /PM 10 ratio was 0.36 (SD= ± 0.12), with an hourly maximum of 0.96. In rainy hours, the PM 2.5 /PM 10 ratio was 0.41 (SD= ± 0.13) and was reduced to 0.36 (DE= ± 0.12) in dry hours. On the other hand, the daily mean PM 2.5 /PM 10 ratio was 0.36 (SD= ± 0.09) with a daily maximum of 0.79. The daily mean on rainy days was higher (0.39; SD= ± 0.09) than that recorded on dry days (0.34; SD= ±0.08). All these differences were statistically signifi cant. Conclusions: Precipitation reduces PM 2.5 concentrations at a lower extent than it reduces PM 10 concentrations. The analysis was not conclusive about the effect of precipitation on PM 2.5 concentrations, so it is not possible to assert that precipitation reduces the risk associated with the exposure to airborne particulate matter. To deepen our knowledge about the effect of precipitation on particulate matter pollution, it is recommended to apply additional techniques such as particle counting and particulate matter chemical characterization. RESUMEN :Objetivo: Establecer si el efecto barrido disminuye el valor de la relación PM 2.5 /PM 10 en horas o días lluviosos, en comparación con periodos secos, en la localidad de Kennedy de Bogotá, Colombia. Material y métodos: Se analizaron relaciones entre los registros horarios y diarios de PM 10 , PM 2.5 , relación PM 2.5 /PM 10 , temperatura, humedad relativa y precipitación, de la estación del sistema de vigilancia de calidad del aire de la localidad de Kennedy en Bogotá durante el periodo de enero de 2007 a septiembre de 2011. Resultados: La media horaria de la relación PM 2.5 /PM 10 fue de 0,36 (DE= ± 0,12), con un máximo horario de 0,96. En horas lluviosas, la relación PM 2.5 /PM 10 fue de 0,41 (DE= ± 0,13), disminuyendo a 0,36 (DE= ± 0,12) en horas secas. Por otra parte, la media diaria de la relación fue de 0,36 (DE= ± 0,09), con una media máxima diaria de 0,79. La media diaria en días lluviosos fue mayor (0,39; DE= ± 0,09), que la encontrada en días secos (0,34; DE= ± 0,08). Todas las diferencias de medianas fueron estadísticamente signifi cativas. Conclusiones: La precipitación disminuye las concentraciones de PM 10 , y en menor proporción las de PM 2.5 , lo cual tiene como resultado un leve aumento de la relación PM 2.5 /PM 10 con la precipitación. El análisis no es concluyente en cuanto a la reducción de PM 2.5 , por lo cual no es posible afi rmar que la precipitación reduce el riesgo a la salud asociado a la exposición a material particulado en el aire ambiente. Con el fi n de profundizar sobre el conocimiento del efecto de la precipitación sobre la contamin...

Spatial and Temporal Variability of the PM2.5/PM10 Ratio in Wuhan, Central China

“…In addition, only the arithmetic mean of PM 2.5 /PM 10 ratio is used in the data analysis, while other robust statistics, e.g., median, various percentiles, and Theil-Sen trend analysis, which are not sensitive to non-normal distributions and to extreme values in both tails of the distributions, can be applied to better understand the variability of the ratios (Munir, 2016). Finally, the PM 2.5 /PM 10 ratio varies at space and time as a consequence of PM fluctuation, but many other factors, such as meteorological condition, affect its value and variability (Blanco-Becerra et al, 2015;. The influencing factors and their relationship with the PM 2.5 / PM 10 ratio can be taken into consideration in further work.…”

“…Compared with numerous studies demonstrating the variability of PM concentrations (Eeftens et al, 2012;Hu et al, 2014;Akinlade et al, 2015;Ghim et al, 2015;Huang et al, 2015;Zhang and Cao, 2015;Zhou et al, 2015;Xu et al, 2016a), few studies have reported on the spatio-temporal variability of the PM 2.5 /PM 10 ratio (Blanco-Becerra et al, 2015;Zhang and Cao, 2015;Munir, 2016;Zhou et al, 2016). The goal of this study is to investigate the spatiotemporal variability of the PM 2.5 /PM 10 ratio at a city scale systematically and comprehensively.…”

“…Since fine and coarse particles come from diverse sources and perform different physic-chemical properties, the PM 2.5 /PM 10 ratio can provide crucial information relating to the particle origin, its formation process and its effects on human health (Speranza et al, 2014;Blanco-Becerra et al, 2015). Higher ratios of PM 2.5 /PM 10 attribute particle pollution to anthropogenic sources and smaller ratios indicate considerable involvement of coarse particles, which might be related to natural sources, e.g.…”

Análisis de componentes principales funcionales para el estudio de material particulado (pm10) en la ciudad de Bogotá

“…At the same time, Bautista (2010) and Vargas & Rojas (2009) made a description of the chemical and physical characteristics of the PM10 and PM2.5 concluding that they are a health risk because of the high presence of metals in them. This conclusion is also supported by the high correlation that exists between these two pollutants as Galvis & Rojas (2005) and Blanco-Becerra et al (2015) pointed this out.…”

The impact of crop residue burning (CRB) on the diurnal and seasonal variability of the ozone and PM levels at a semi-urban site in the north-western Indo-Gangetic plain

“…For more detailed information about the temporal variation of the emission sources in the area, a monthly variation of the PM 2.5 /PM 10 ratios and their impact on ozone concentrations along with error bars with one standard deviation are presented in figure 4. The ratio varies more greatly at the study site and indicates more complex and changing PM sources (Blanco-Becerra et al 2015). The proportion of fine particles in PM 10 also shows great variability ranges from 10% to 42% with an average value of 25% on a monthly basis.…”