Aircraft engine makers must now measure all exhaust pollution, not just visible smoke

US regulators have finalized new rules requiring aircraft engine manufacturers to measure all particulate matter in exhaust, not just visible smoke. This means engine makers must now certify their products against a new standard for invisible pollution.

For decades, aircraft engine pollution rules focused on visible smoke. This change means regulators can now track the full range of particulate emissions, including the tiny, invisible particles that are a major health concern. It forces engine manufacturers to design for a new kind of clean, which could eventually lead to cleaner air around airports.