Particulate Matter Dispersion in Urban Environments in Colombia

摘要

Air pollution regulations has been in place in Colombia for about 20 years but progress in improving air quality in urban environments have been slow, mainly due to efforts oriented toward controlling point sources. Construction activities and urban traffic has been identified recently as main culprits of particulate matter high levels in Colombian cities. A classical long-term dispersion model was used to assess air pollution in several cities and regions in Colombia. Meteorological information is supplied by IDEAM (Instituto de Hidrologia, Meteorologia, y Estudios Ambientales), but it has not been designed for air pollution assessment. Wind information is processed to generate 8 wind direction sectors, 6 wind speed categories; stability class information is not available in Colombia. A Joint Frequency Distribution (JFD) has to be estimated using matricial and statistical sampling (i.e. Ibague). Primary data sources for wind like anemograph charts were processed to obtain in those sites where information was available (Coal Mine, Call, and Medellin) To estimate particulate matter from construction activities an emission factor of 400 g/m~2 was obtained using a trial and error approach. Some small point sources with large fugitive dust emissions (brick plants, concrete processing, construction materials processing...) were taken into account as a more permanent construction activity with an emission factor four times larger than for normal construction. Urban traffic was modeled by taking into account yearly vehicle kilometer traveled (VKT). Dispersion of particulate matter in a large open coalmine and port, and two large Colombian cities (Ibague, Call and Medellin) using ISCLT (Industrial Source Complex Long Term) was assessed. Results were very closed to few actual measurements existing in those cities, and managers and local authorities accepted them. Modeling provides an excellent tool for air quality management and monitoring and for implementing adequate controls.