Updated on August 4, 2021 at 4:39 am NBC Universal, Inc. Bay Area school districts spent millions of dollars on air cleaning systems, which some air quality experts say could endanger students’ health. An NBC Bay Area Investigation reveals why scientists, including those at the Environmental Protection Agency, are now questioning the efficacy and safety of new technology utilized in some devices that are supposed to clean indoor air. Industry experts say fears of the pandemic and a willingness of consumers to pay out big bucks have transformed the air cleaning industry into a sort of Wild Wild West. Online advertisements, which seek to recruit new salespeople to hawk the products, promise six-figures in a single month for those willing to sell air purifiers to school districts.