Will connecting MS Access kill my SQL Server?

I am working as a DBA and have been told some customer who use access need to connect to some tables in a SQL Server Database (some of these tables a containng 1 million rows+)

MY concern is does a query written access use the SQL Server Engine or does it just do a full table scan, pull all data and then get rid of what it does not need? My concern is will this connection put a load on my server and possible screw up my database? Note – they only need READ ONLY.

Really appreicate help on this