Abstract

BLANCO-BECERRA, Luis Camilo; GAFARO-ROJAS, Aurora Inés  and  ROJAS-ROA, Néstor Yezid. Influence of precipitation scavenging on the PM_2.5/PM₁₀ ratio at the Kennedy locality of Bogotá, Colombia. Rev.fac.ing.univ. Antioquia [online]. 2015, n.76, pp.58-65. ISSN 0120-6230.  https://doi.org/10.17533/udea.redin.n76a07.

Objective: To establish whether the scavenging effect reduces the PM_2.5/PM₁₀ ratio in rainy periods in comparison with dry periods, at the Kennedy locality of Bogotá, Colombia. Materials and methods: Relationships among hourly and daily PM₁₀, PM_2.5, PM_2.5/PM₁₀ 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/PM₁₀ ratio was 0.36 (SD= ± 0.12), with an hourly maximum of 0.96. In rainy hours, the PM_2.5/PM₁₀ 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/PM₁₀ 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 significant. Conclusions: Precipitation reduces PM_2.5 concentrations at a lower extent than it reduces PM₁₀ 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.

Keywords : Precipitation; PM_2.5/PM₁₀ ratio; air pollution; scavenging.

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