"extra precautions" = visual inspections and bakeout time.
The entire “Wet QD” ops was timelined in order to allow enough time
for a “bake out” prior to ingress, should the EMUs become contaminated
with any leaking ammonia from the QDs.
- EMU = Extravehicular Mobility Unit aka spacesuit
- QD = Quick Disconnect
We know there is ammonia in the area... so they will do a visual
inspection of each other to make sure there is no ammonia ice on their
suits. Once they have concluded that they are clean, that starts a
bake out timer. We do that to make sure we have adequate time for any
hidden ammonia that might be on the suits to evaporate. On a rough
order of magnitude, 30 to 45 minutes is required for that bake out
That clock starts and they will begin their transit back to the
airlock, down the P6 truss. Once they get in the airlock, they will
hook up on umbilicals, they will repress the airlock to 5 psi and
perform a test... a simple way of detecting of how much ammonia might
be in the atmosphere at that 5 psi level. And based on that we'll make
a determination if there is contamination or not. If consumables
permit, they may do a second test. We don't anticipate that to be
ISS Flight Director Norm Knight quoted here http://www.collectspace.com/ubb/Forum30/HTML/001202.html
"What "shutters" are these?"
The ISS windows (at least on the US side) have external shutters most easily seen on the cupola.
From https://images-assets.nasa.gov/image/iss023e042367/iss023e042367~orig.jpg, hand-drawn circles mine.
This image from STS-130 shows all the cupola shutters closed