Paragraph from a
Flight Global article on the Dutch F-35s.
Since the Dutch air force will use hardened aircraft shelters for its F-35s, the first deployment has also been used to trial operations from these types of hangars. In the USA, the aircraft are operated from sun shelters or larger hangars, and the confined space in a smaller shelter increases the sound and vibration levels placed on the airframe. Emission levels from the Pratt & Whitney F135 engine also needed to be monitored, to ensure ground crews can perform their work safely.
Somewhat surprised that it is only now that the effects of HAS operations are being checked-out.