Summary

Significant variability in cured-leaf tobacco-specific nitrosamine (TSNA) content is commonly observed when sampling within dark air-curing barns. This variability may be due to inconsistency in the curing environment within different areas of the barn. A study was initiated in 2012, through support from a CORESTA Study Grant, to evaluate if cured-leaf TSNA content is related to microenvironmental conditions in the barn. Low-converter (TRsc) and high-converter (TRHC) selections of TR Madole dark tobacco were air cured in barns near Princeton and Lexington, KY. Temperature and relative humidity were measured with data loggers placed at 27 different locations within each barn for the duration of curing. There were no significant effects of individual data logger placement in either variety selection on hours above 24 °C temperature, hours above 80% relative humidity, or TSNA; therefore, we investigated these data within the 3-dimensional aspects of tier, room, and bent within each barn. There were various effects of tier, room, and bent on temperature, relative humidity, and TSNA. Temperature data followed an understandable pattern across tiers in the barn within each year and location; however, relative humidity and TSNA were more difficult to characterize adequately. There was a significant relationship between hours above 24 °C and TSNA, but not hours above 80% relative humidity. This study has shown that the effect of within-barn position on TSNA cannot be easily predicted.