Urban PM2.5 concentrations in a small Colombian city and the impact associated with particle emissions generated by small-scale lime production

Abstract

The stricter guidelines for fine particles PM2.5 recently published by the World Health Organization motivates also smaller cities to assess the exposure levels. In this study PM2.5 was assessed in the municipality of Vijes, an important center for lime production in the Cauca River Valley, Colombia. The main objective was to determine PM2.5 concentration levels in the urban background in the city and to estimate the contribution from the industrial sources located west of the urbanized area. Four low-cost optical sensors and a meteorological tower were installed during two separate campaigns. The PM2.5 measurements were analyzed with the support of meteorological data and dispersion modeling. Mean levels of PM2.5 in the urban background were found to be well below the Colombian limit value, in the range of 14 to 19 µg m-3 and with lower levels in the city center. The monitor located in the westernmost urban area, closest to the industrial plants, registered a high 24h mean level close to the national limit value. The industrial contribution to long-term PM2.5 concentrations in the urban background of Vijes was estimated to be of the order of maximum 6 µg m-3, i.e., a minor fraction of the monitored mean PM2.5 levels in the urban background. The dominating part were attributed to other anthropogenic sources within or east of Vijes, as well as originating from the regional background concentration characterizing the Cauca River Valley to the east of Vijes, where pre-harvest sugar cane burning is common.
 This assessment of PM2.5 concentrations in a city without fixed air quality monitors and infor-mation on emission sources, was designed to be expedient and possible to perform with a very restricted budget. The methodology can be used as a first step for smaller cities to know how critical the situation is in terms of fine particulate matter. Future studies, preferably involving also an analysis of the composition of PM2.5 are needed to understand in more detail the contri-butions of different local sources that are present inside the city.