Occurrence of farmer's lung disease is relevant to meteorological conditions: a 20-year follow-up field survey analysis.

BACKGROUND

A field survey on farmer's lung disease (FLD) in a dairy farming community in the northernmost district of Japan has been in progress since 1978.

METHODS

The correlation between the number of FLD occurrences year by year and dairy farming conditions and meteorological data were compared.

RESULTS

Thirty-four FLD cases had occurred in a 20 years period. Average number of days below freezing during the harvest season the year prior to FLD occurrence were significantly smaller than other years (2.1 +/- 0.7 [SE] days, 4.6 +/- 0.7 days, P < 0.05, respectively). Average annual sum of the sunlight hours in the years before the years with FLD occurrence was significantly smaller than those without FLD occurrence (1457.1 +/- 114.0 hr, 1811.3 +/- 97.7 hr, P < 0.05, respectively) and was also significantly smaller for the sunlight hours during a harvest season (821.9 +/- 60.2 hr, 1023.2 +/- 52.7 hr, P < 0.05, respectively).

CONCLUSIONS

Temperature and sunlight hours closely associated with the FLD occurrence.