Suffice it to say that the outdoor air becomes a veritable concentration of allergens.
Why does drying your laundry outside make the symptoms worse?

When you leave your clothes or sheets outside to dry, they act like pollen magnets . The pollen, naturally sticky, attaches itself to the fabric fibers during the hours of exposure.
As a result, once you’re back inside, the pollen invites itself into your home… and onto your skin, hair, and sheets. It’s therefore not surprising to see your symptoms intensify for no apparent reason.
It’s a bit like leaving your laundry in the middle of a flowery field during pollen season , before bringing it back to your room.