; and (bb) may publish the proposed national primary drinking water regulation described in item (aa) concurrently with the publication of the determination to regulate the perfluoroalkyl or polyfluoroalkyl substance or class of perfluoroalkyl or polyfluoroalkyl substances. (II) Deadline (aa) In general Not later than 1 year after the date on which the Administrator publishes a proposed national primary drinking water regulation under clause (i)(I) and subject to item (bb), the Administrator shall take final action on the proposed national primary drinking water regulation. (bb) Extension The Administrator, on publication of notice in the Federal Register, may extend the deadline under item (aa) by not more than 6 months. (H) Health advisory (i) In general Subject to clause (ii), the Administrator shall publish a health advisory under paragraph (1)(F) for a perfluoroalkyl or polyfluoroalkyl substance or class of perfluoroalkyl or polyfluoroalkyl substances not subject to a national primary drinking water regulation not later than 1 year after the later of— (I) the date on which the Administrator finalizes a toxicity value for the perfluoroalkyl or polyfluoroalkyl substance or class of perfluoroalkyl or polyfluoroalkyl substances