If a person has in his possession a substance immediately before the date on which it is declared to be a Group I or a Group III hazardous substance in terms of section 2, he may, notwithstanding the provisions of subsection (1) of this section, sell, lease, use, operate, apply or install or keep installed on any premises, as the case may be, that substance-
(a) at any time during a period of 180 days calculated from the date on which it was so declared to be such a substance; and
(b) if, before the expiry of the period mentioned in paragraph (a), an application was made in terms of section 4 for a licence which would authorize such sale, lease, use, operation, application or installation, at any time until
such application has been finally refused in terms of this Act.