| Description |
Air pollution is an important factor both for global climate change and human health. Exposure to particulate matter pollution smaller than 2.5 micrometers (PM2.5) has been linked to increases in cardiopulmonary disease, premature mortality, and asthma diagnoses. PM2.5 also contributes to impaired visibility and changes in the global radiative balance. Temperature inversions, or persistent cold air pools (PCAPs), trap pollutants in mountain valleys such as the Salt Lake Valley. In fact, Salt Lake County frequently exceeds EPA's 24- hour PM2.5 ambient air quality standard during wintertime PCAP events. Secondary particulate matter, including ammonium nitrate, ammonium sulfate, and ammonium chloride, contribute to over half of the PM2.5 mass during wintertime inversions. Furthermore, heterogeneous atmospheric reactions have been observed between secondary aerosols, including those listed previously, and primary combustion particles, including diesel soot. This study investigates the particle interactions between laboratory simulated secondary and primary PM2.5: ammonium sulfate salt and reference diesel soot. This is intended to serve as a model of the interactions that occur in Salt Lake County during PCAP events. Particle interactions were observed using a scanning mobility particle sizer (SMPS) and scanning transmission electron microscope (STEM). The methods outlined in this paper could be used in order to prepare secondary aerosol salt and soot mixtures for use in a toxicological study. |
