Objective: To determine if air conditioning might mitigate summer reductions in semen quality.
Design: Prospective study of semen quality in summer and winter.
Setting: Normal human volunteers were studied in the setting of a fertility laboratory.
Patients, participants: Two groups of volunteers were selected from the vicinity of New Orleans: 64 men who worked indoors during the summer in air-conditioned environments and 76 others who worked outdoors.
Interventions: None.
Main outcome measures: Parameters of manual semen analysis were examined for seasonal and group differences.
Results: Remarkably similar reductions in semen quality during summer as compared with winter were observed in both indoor and outdoor workers, respectively, with regard to the following parameters of semen quality: 19% and 19% in sperm concentration, 25% and 27% in total sperm per ejaculate, 17% and 20% in motile sperm concentration, 13% and 15% in percent sperm with normal morphology, and 23% and 23% in concentration of morphologically normal motile sperm.
Conclusions: These findings do not support the hypothesis that the heat of the summer is detrimental to male reproductive capacity. The available evidence suggests instead a possible role of photoperiod in causing the seasonal changes in semen quality.