Custom Air Alt

I'm trying to make a block that behaves like air that gives you a status effect when you walk through it. I want it to be replaceable, but if you place and break a block that used to be occupied with this air, then the air is deleted. I need it so that

• You can place and break blocks freely within the air
• If you place and break a block inside the air it won't be destroyed
• The air doesn't spread everywhere