If the windscreen wipers begin to move while you are changing the wiper blades, you can be trapped by the wiper arm.
If the windscreen wipers start moving when the bonnet is open, you could be trapped by the wiper linkage.
If the wiper blades are worn out, they will no longer wipe the windscreen properly. Replace the wiper blades twice a year, preferably in spring and autumn.
Driver's side: long wiper blade
Front passenger side: short wiper blade