If an employer identifies that higher PPE spec is required for BAME employees undertaking a particular task, is it necessary to increase the spec for all employees working in that area?
It is. If you assess a risk and identify a control measure then fail to deploy it, then you are breaching your legal duties under HASWA and potentially committing a criminal offence. So if you decide for example that N95 respirators have to be used by everyone, you have a duty to provide them.
So the short answer is yes.