October 18, 1984 Appeal from the Workers' Compensation Board. In 1967, claimant developed acute pharyngitis and bronchitis. The condition did not cause him to lose any time from work between that date and 1973. In 1973, claimant's employer changed from a "wet" manufacturing process of cement to a "dry" process which produced exceptionally fine, powdery cement. This change caused the working environment to become extremely dusty and claimant was exposed to this condition nearly constantly throughout