Is the incidence of occupational asthma reduced by 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	Hannu 2007	6/9 initially assessed as suitable to continue work with powered RPE able to continue beyond 6 months (out of 34 cases)
burgeps	Fukakusa 2011	Does really answer thgis question, but shows that those with respiratory symptoms were less likely to use RPE
burgeps	Jones, 2014	Retrospective observational study