Do you let your baby play in the sand pit? I believe they are very unhygienic.

I think you shouldn't overthink things. In that case, pretty much everything else is unhygienic -- playgrounds, the seaside and schools. Plenty of children play in sandpits around the world and they are fine. If I were you, I'd let baby play in sandpit and supervise him or her to make sure that baby does not get injured or eat anything that he or she shouldn't. And when we get home, I'll make sure that baby gets a thorough bath and shower.