CREATE TABLE table_44091 ("Usage" TEXT, "Class" TEXT, "Performance" TEXT, "Performance test" TEXT, "Particulate size approaching 100% retention" TEXT, "Test Standard" TEXT)

Which Performance has a Test Standard of bs en779, and a Particulate size approaching 100% retention of >2 m, and a Class of f6?
SELECT "Performance" FROM table_44091 WHERE "Test Standard" = 'bs en779' AND "Particulate size approaching 100% retention" = '>2µm' AND "Class" = 'f6'
SELECT "Performance" FROM "table_44091" WHERE "Class" = 'f6' AND "Particulate size approaching 100% retention" = '>2µm' AND "Test Standard" = 'bs en779'