Why the prevalence and incidence of hearing loss for all industries combined did not change much during 1981-2010 (about 1-2%), but the adjusted risk decreased significantly (46%)?

Question Description

Instructions:

Please read a NIOSH study “Trends in worker hearing loss by industry sector, 1981-2010”, published in the American Journal of Industrial Medicine (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4557728/pdf/nihms718189.pdf).

Using your own words and critical thinking skills, discuss

1. (15 points) Why the prevalence and incidence of hearing loss for all industries combined did not change much during 1981-2010 (about 1-2%), but the adjusted risk decreased significantly (46%)?
2. (15 points) Why the prevalence for hearing loss among workers in Healthcare and Social Assistance were increasing, and what factors may have contributed to?