As the US’s network for monitoring air pollution deteriorates, a Floodlight investigation has found that the chemical industry is going state-to-state to restrict one of the few options citizens have left for holding polluters accountable: low-cost air sensors.

Over the past two years, the non-profit investigative newsroom determined, lawmakers in Louisiana, Kentucky and Ohio have passed strikingly similar laws barring regulators from acting on air-quality data that communities collect themselves – unless it comes from Environmental Protection Agency (EPA)-approved equipment that typically costs tens of thousands of dollars. Similar legislation has repeatedly been introduced in West Virginia.