California can't check big trucks from other states for pollution

US environmental regulators are blocking part of California's new heavy-duty truck emissions program. This means California cannot inspect large trucks registered outside the state for compliance with its pollution rules.

California has some of the strictest environmental rules in the US, often setting standards that other states eventually follow. This decision limits California's ability to enforce its own air quality standards on a significant source of pollution. It creates a loophole for out-of-state vehicles, potentially undermining the state's efforts to clean its air.