An historical experiment: Los Angeles smog evolution observed by blimp.

Unlabelled: Observations of smog over the Los Angeles Basin (LAB) links high oxidant mixing ratios with poor visibility, sometimes <5 km. By the 1970s, investigators recognized that most of the aerosol affecting visibility was from gaseous oxidation products, sulfate, nitrate, and organic carbon. This led to the 1972-1973 Aerosol Characterization Experiment (ACHEX), which included observations at the ground and from aircraft.

Air quality measurements-From rubber bands to tapping the rainbow.

Unlabelled: It is axiomatic that good measurements are integral to good public policy for environmental protection. The generalized term for "measurements" includes sampling and quantitation, data integrity, documentation, network design, sponsorship, operations, archiving, and accessing for applications. Each of these components has evolved and advanced over the last 200 years as knowledge of atmospheric chemistry and physics has matured.

Precursor reductions and ground-level ozone in the Continental United States.

Unlabelled: Numerous papers analyze ground-level ozone (O₃) trends since the 1980s, but few have linked O₃trends with observed changes in nitrogen oxide (NOx) and volatile organic compound (VOC) emissions and ambient concentrations. This analysis of emissions and ambient measurements examines this linkage across the United States on multiple spatial scales from continental to urban. O₃concentrations follow the general decreases in both NOx and VOC emissions and ambient concentrations of precursors (nitrogen dioxide, NO₂; nonmethane organic compounds, NMOCs).