Grade

Preparation

Remark

A (in B background)

Sterile starting materials and components

(Unless subjected to sterilization or filtration through a microorganism retaining filter later in the process)

A (in B background)

Preparation of solutions (if not to be sterile filtered later)

A (in B background)

Handling and filling of aseptically prepared products,

A (in B background)

Handling of exposed sterile equipment

A (in B background)

Transfer of partially closed containers, before complete stoppering

E.g. in freeze drying

(Grade B environment if in sealed transfer trays)