The first images from NASA's new space-borne air pollution sensor reveal how levels of toxic pollutants change within a day across the United States.

New sensors being installed on the roofs of tall buildings in Kensington, Chelsea and another as yet undecided location will reveal the days and times when pollution levels are at their highest.

Flow ($179), developed by Paris-based Plume Labs SAS, is a portable pollution sensor that’s encased in aluminum punched with a pattern of asymmetric holes for “360 air intake.” ...