Is the incidence of occupational asthma reduced by controlling exposure?

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	Peters 1977	Descibes rates of sensitisation falling from 40% to 7.2% and disease (asthma and rhinitis) from 15% to nil.
burgeps	Smith 2004
burgeps	Arif 2009	latex no longer a risk factor after 2000
burgeps	Meijster 2009	This paper does not properly address this questions, but is a good longitudinal study of air measurements and their response to a voluntary intervention programme in Holland. There are no clinical outcomes reported. The programme was part of a Dutch covenant for the flour processing industry. The intervention involved information on risk to exposed workers, information on good work practices, a visit from a consultant and distribution of a specific dust control manual including a dust control plan which was completed at each work site. The aim was to reduce exposure to flour and amylase by 50%. The programme has run for 14 years. Reductions in air levels has been very modest (2%/year in flour and 8%/year for amylase in bakery workers, but an increase in >20%/year for general bakery workers. The use of LV increased from negligable to around 40% for industrial bakeries and 60% for flour mills. Despite a plan to remove pressured air hoses for cleaning they remained in use to some extent. Use of liquid enzyme preparations increased from 30-50% of dough makers. The authors conclude that a much more rigorous approach is needed to decrease the exposures
burgeps	Vandenplas 2009	In Belgium powdered latex examination gloves were largely replaced with non-latex gloves with a major reduction in compensation for well documented occupational asthma
burgeps	Baatjies 2014	doesnt really answer the question, but shows that flour levels can be halved by good in store control. This is unlikely to be enough to significantly reduce sensitisation