North American playas are large dust emitters. Dotting the deserts of the Southwestern United States, these dry lake beds are highly saline from the concentration of salts following evaporation. These salt deposits can become entrained in the air when winds scour the dried lakebed. The resulting saline dust has a high fraction of halogenated compounds, primarily those containing chlorine. When the chlorine-containing aerosols (the dust that remains suspended in the atmosphere) mix with nitrogen oxides (primarily dinitrogen pentoxide), a gas called nitryl chloride (ClNO2) is produced. Sunlight interacts with ClNO2, breaking it apart into chlorine radicals that participate in the formation of tropospheric ozone.
In 2015 the United States (US) Department of State launched an Air Quality Monitoring Program with the primary goals of protecting US personnel and their families, obtaining sound data to reduce exposure, evaluating the Department’s enterprise risk, advancing scientific understanding, and highlighting US technology and leadership. This effort has contributed air quality reporting at many embassies and consulates around the world. Volunteer on-site Air Quality Fellows provide the scientific expertise behind this program. Air Sciences’ Dr. Katheryn Kolesar recently returned from such a trip to Cairo, Egypt.
To track emissions at the national level, the United States Environmental Protection Agency (EPA) requires Oregon (and other states) to conduct statewide inventories from all sources of air pollution. These data collected from across the country are used for making new rules and modeling air pollution.
A few years in the making, Cleaner Air Oregon (CAO) addresses this need and is already affecting many companies in the state. As of November 2018, all permitted facilities should have already submitted emissions inventories for their sources to the Oregon Department of Environmental Quality (DEQ).