What evidence is there for the benefit of the enhanced use of respiratory protective equipment?

The following references have been associated with this question by users of this website. They do not form part of the BOHRF occupational asthma guidelines.

burgeps	Dressel 2007	Education + RPE in farmers mainly with cow or pig occupational asthma. Increased use of RPE from 62-76% associated with some reduced symptoms and reduced FeNO, but only in those in whom it was raised beforehand
burgeps	Feary 2019
burgeps	Ilgaz 2019	This study clearly shows the limited role of high-level RPE in the control of occupational asthma from metalworking fluids in those already sensitised. The ABC plot from the Oasys system was used to compare pre and post RPE with airfed helmets donned and removed outside the workplace. Source control is more likely to work.