Personal Protective Equipment
Your employer must provide personal protective equipment (PPE) to you free of charge. You must use this correctly, and follow the training and instruction you've been given.
In some jobs, failure to use PPE properly can be grounds for disciplinary action or even dismissal. However, you can refuse to wear PPE if it puts your safety at risk (eg PPE of the wrong size could put you at risk because of its poor fit). Ask your employer or the firm's safety representative for the right size (which must be provided free of charge).