5. An employer must not undertake work in demolition, maintenance or any other work which exposes or is liable to expose employees of that employer to asbestos in respect of any premises unless either—
(a)that employer has carried out a suitable and sufficient assessment as to whether asbestos, what type of asbestos, contained in what material and in what condition is present or is liable to be present in those premises; or
(b)if there is doubt as to whether asbestos is present in those premises, that employer—
(i)assumes that asbestos is present, and that it is not chrysotile alone, and
(ii)observes the applicable provisions of these Regulations.