A good physical sunscreen would be a first start. Use one that has Zinc Oxide on the label towards the top, or gives a percentage of at least 15% and up.
For dust, the best thing you can do is rinse often, if you can. Not cold or hot water. Just room temperature. Then if your skin is dry feeling just apply a tiny bit of Olive Oil or other oil of your choice onto your face. This will help to keep the sand from getting too much in your pores of your face.
I hope you do understand this as I am not sure where you are located and what your main language.