The most relevant section is Appendix 6 – Selecting RPE for radioactive or biological hazards (page 55) re restrict[ing] exposure to…biological agents defined in COSHH as micro-organisms – bacteria, viruses, fungi…that create a hazard to human health.
Point 6 states you should always use equipment fitted with the highest efficiency filter possible (protection factor of at least 20) to control exposure down to the lowest levels.
Overall, this HSE Guidance includes information on which masks provide the required level of protection, guidance for those with glasses or beards using masks and how often they should be changed. It is a very extensive document.
We anticipate that there may be updated guidance from the HSE with regard to PPE and RPE and will forward this if/once received. In the meantime, we hope the attached guidance is helpful.