keep clean traffic sign on blue sky

maintain hygiene stay neat tidy preserve cleanliness spotless sanitary clean dirtfree sanitation sterile purified purity hygienic untainted tidiness unsoiled unpolluted unsullied spotlessness unblemished sterility uncontaminated unadulterated unpollutedness uninfected unstained neatness unspoiled unmarked unsoiledness cleancut state uncontaminatedness unstainedness pure unsmudged cleanly