Ten year follow up of farmers with farmer's lung.

Twenty-nine patients previously diagnosed as having suffered from farmer's lung in or before 1970 were asked whether the condition had recurred and what measures they had taken to avoid such recurrence. Those who had retired from farming had been least affected by recurrence, while those who continued to farm had been protected by making silage instead of hay or by wearing protective respirators. To be effective, a respirator should be worn on every occasion that farm dust is encountered and must be properly maintained.