The Costco Gas Station hours are usually longer than the Costco Warehouse opening hours, so make sure that you are viewing the Costco Gas Station hours, and not the Store Hours, if you search through an app or with google maps.
All dental hygienists in the United States must be licensed by the state in which they practice, after completing a minimum of two years of school and passing a written board as well as a clinical board exam. State requirements vary by state, and are controlled by state dental boards.
For low-income, rural, and other at-risk populations, and in coordination with local public health agencies and local oral health coalitions, a licensed dental hygienist may perform certain procedures. Refer to RCW 18.29.220 and WAC 246-814.