Particulate matter modeling in Puerto Rico during wet and dry season episodes

A modeling study was performed in order to understand particulate matter pollution behavior in a tropical urban environment in the San Juan metropolitan area on the island of Puerto Rico. Air quality simulations using the chemistry transport model Weather Research and Forecast Chemistry (WRF-CHEM) were performed to study mass concentrations of fine particulates (PM2.5 or less) on the island. The simulations were performed for the months of January and July of 2009. These months represent the minimum and the maximum respectively of particulate pollution in the island and the San Juan metro area and will provide a comparison between dusty and dust free conditions and the effects dusty air masses have on locally generated pollution. The results from the model were compared with data collected in the island by the Puerto Rico Environmental Quality Board for regulatory purposes. Preliminary observations of the available data shows an increase in the average concentrations of PM 2.5 for the month of July in comparison to concentrations in January. The average concentrations were 5.7 µg/m3 and 8.6 µg/m3 respectively. Similar trends are observed in the coarse particulate matter (PM 10). The presence of a dusty air mass (Saharan Dust) was confirmed by satellite observations for the week of July 28 to August 4 in which PM 10 concentrations rose over 80 µg/m3 on July 28. The results of this project could be of use to policy and decision makers by helping them evaluate current and future air quality regulations for the improvement of air quality standards and emissions controls for criteria air pollutants.