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Respiratory function of a random sample of a previously studied class of seminary students was evaluated once each week on 27 occasions between October and May in order to determine the relationship of variation in function with environmental factors. A statistical method is presented for systematic sorting of meaningful significant correlations. The best correlation was found between fraction of predicted functional residual capacity and ambient temperature. Although "spot" measurements (paper tape-soiling index) made a significant contribution, no meaningful relationship could be demonstrated for respiratory function and other measured air pollution or meteorological parameters. The significant environmental-respiratory function interaclions demonstrated occurred in some but not an subjects. Airway resistance levels in subjects with a history of asthma, but presently asymptomatic, were significantly higher, but there was no obvious difference in their relationship to the measured environmental factors.

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The resistances to flow in the upper (Ruaw) and lower (Rlaw) airway of human lungs were measured simultaneously with total airway resistance (Raw) and the volume of thoracic gas (Vtg) using the plethysmographic method and lateral pressure taps at the tracheal and oral levels. Ruaw is found to decrease slightly in a curvilinear fashion with increasing Vtg while its reciprocal, Guaw, is linearly related to Vtg with a negative Vtg intercept in normal subjects. Lower airway conductance (Glaw) is linearly related to Vtg with a slope of approximately 1.0 liters/sec per cm H2O per liter. From the partitioned resistances it is deduced that total airway conductance (Gaw) is curvilinear but approximately linear over the majority of the Vtg. A method of calculating resistance and conductance in the upper and lower airways from Raw versus Vtg data is presented using the equation Raw = Vtg/(A @#X002B; B Vtg) where B2/A @#X003D; dGlaw/ dVtg. Three hundred and sixty-two records of Raw versus Vtg data from 22 normal, asthmatic, and bronchitic subjects are then evaluated by this method and the results compared to those obtained by direct measurement. intrathoracic or lower airway conductance; intrathoracic or lower airway resistance; extrathoracic or upper airway conductance; extrathoracic or upper airway resistance Submitted on November 8, 1963