Overview

• On August 14, Apple released iOS 18.6.1 and watchOS 11.6.1 to reintroduce blood-oxygen monitoring for US Apple Watch Series 9, Series 10, and Ultra 2 models that lacked the feature
• The redesign keeps watch sensors active but moves measurement processing to the paired iPhone, presenting results in the Respiratory section of the Health app
• Only US units with part numbers ending in "LW/A" qualify for the redesigned feature, while devices purchased before the import ban or outside the US retain on-device calculations
• After installing the OS updates, an over-the-air asset download—triggered by opening the Health app or taking an ECG—may be required to activate the restored feature
• The underlying legal battle with Masimo remains unresolved with appeals pending, and the workaround’s longevity depends on potential court decisions or licensing outcomes