funny and not funny em5 sensor cleaning story

I have 3 lenses for my em5 the kit 12-50 ,the zuiko digital 12 f2 and my tamron 18-250 with an nikon s to m43 dadptor

It happen to me that had changed a lot of times  between all the lenses

I just take a picture a picture of a white wall and looking in the monitor founded circular grey dots

just in case I have an hand punp for dust sensor cleaning .so I took out the lens and started pumping air into the em5 sensor but no matter what I did the grey dots a the monitor just stay unchanged

frustrated beacause nex week I will be in the snowish Prague and need a clean sensor

Just started to think where can  I  take my camera for a pro quick sensor cleaning

But , one moment !!! ,   I started  to laughing beacause I just undesrtood  what was the reason:

MY ADDED TRANSPARENT MONITOR PROTECTOR WAS WITH MANY MANY AIR BUBLES INSIDE !!

the sensor was clean before and super clean now:-)

end of the cleaning story

By the way can some one tell me the best way to shot in snow ?