A satellite constellation launches a new era of air quality monitoring

Growing up in South Korea, Heesung Chong was acutely aware of air quality. “The aerosol pollution is relatively severe in South Korea. On bad days, you could feel it,” he says. The air on such days not only was fouled with the tiny drops of liquid and solid particles but was contaminated with high concentrations of other pollutants such as NO2, SO2, and ground-level ozone. All are health hazards.As a child, Chong had not considered pursuing atmospheric science. In fact, he went into college for a degree in chemical engineering which he received in 2015. But when he discovered an atmospheric science laboratory at his university as a senior trying to figure out what to study in graduate school, he thought, “This is it.” “Working in that field seemed really interesting, scientifically, and also important,” Chong says. His choice was serendipitous. Chong entered the field at the dawn of a new era of space-based air quality measurement. Through the course of his PhD and post-graduate studies, he has worked on the world’s first two geostationary air quality monitoring satellites. One watches pollution develop over North America and the other monitors air quality in Asia. A third will launch this summer to observe air pollutants in Europe and complete the constellation planned to watch the northern hemisphere. For decades, scientists and community members relied on ground-based air quality monitors to understand air pollution. Each monitoring station gives a hyperlocal point measurement of pollutant concentrations. But the further away a person is