Estimating variation and sources of dust in Puente Jobos, Puerto Rico using a PM₁₀ sensor network

The Puente Jobos community in southern Puerto Rico has multiple sources of inhalable particulate matter less than 10 μm in diameter (PM₁₀), including a nearby coal-fired power plant, a well-traveled road in the center of town, sea spray, and long-range transport of Saharan dust. In this seven-month field study, we evaluated a PM₁₀ optical particle counter (OPC) sensor network in combination with single site filter-based daily federal reference method (FRM) measurements of PM₁₀ mass, black carbon, and trace elements. The OPC PM₁₀ measurement was strongly correlated with the filter-based PM₁₀ concentrations. Sensor performance was improved by using a locally developed correction relying on the sensor internal relative humidity measurement and the concentration in the smallest OPC size bin. PM₁₀ concentrations were statistically significantly elevated in the southern part of the community, closer to coastal areas and the coal-fired power plant. Positive matrix factorization (PMF) was used to identify seven major sources including three associated with coal operations (ash - 9%, stack emissions with elevated sulfur - 9%, and other processes with elevated phosphorous - 17%), sea salt derived (37%), crustal derived (22%), diesel or oil combustion derived (6%), and demolition derived (<1.0%). This study demonstrated the utility of lower-cost OPCs to complement FRM measurements of PM₁₀ composition to identify the sources and the spatial and temporal variation of PM₁₀ in a community.