If you live in a very dusty/dirty area, then you definitely want to make sure you keep a fresh coat of a paint sealant and/or a wax on it. This will both protect the finish, and make it easier to keep clean. With that much dust, the only thing to do is wash it because if you try just wiping it down with a quick detailer, you’ll just scratch the finish. There are rinseless wash options and here is a link to a good article on that topic.