The purpose of fans that blow air on you when you enter/exit a mall or a supermarket.

Oh, an air curtain. The doors are opening all the time, and spending some electricity making a vertical column of air saves a lot of money over letting all that air conditioned air out. I believe some of those open-air coolers use the same effect so they can be open-air yet cool.

Not so sure about with supermarkets, but industrial warehouses have them on pretty much all large external doors. They are air curtains, and they are intended to keep bugs and birds and other such flying pests out of the warehouse.

Large buildings try to maintain a positive pressure (higher air pressure inside) so that air always blows out when the doors open.

This is done so that dirt and bugs and birds and leaves and snow and whatever else gets blown away instead of drawn in.

Receiver for a major grocery warehouse here. We also have these setup on smaller openings as well as some internal areas to keep bugs from flying in

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