Dynamics and measurement of ultrafine aerosols Table 3. 219 Subjects 1 3 5 6 7 Vital capacity Vc(I.) 4.81 4.37 6.1 5.6 4.9 Experimental residual volume V~, (1.) 0.85 1.26 1.62 1.26 1.8 Residual volume V, (I.) 1.43 1.7 1.33 2.04 2.0 Forced experimental volume FEV t (1.) 4.05 3.53 5.5 4.88 4.23 in 1 sec FEVt/V c 0.84 0.81 0.89 0.87 0.88 /cm H20\ Airway resistance R~kI.--~ ) 1.32 1.35 0.74 1.78 1.I0 Aerosol persistence tn (sec) 24.5 22.5 23 32 20 during breath-holding d = 0.55 ~m ; Vt = 1 I. Total deposition DE d = 0.55 #m 0.11 0.10 0.11 0.07 0.17 Vf = 1 I.; f = 15min -t d = 1.0gm 0.16 0.14 0.15 0.10 0.20 Aerosol recovery following RCto t tp = 0 sec 0.89 0.90 0.91 0.90 0.88 single breath inhalation RCt~ tp = 0sec 0.82 0.81 0.81 0.85 0.73 d = 0.55 gm ; RC,,, tp = 0 sec 0.085 0.11 0.12 0.06 0.20 Vt= 11. RCtt dtp ~ 12sec 0.17 0.19 0.18 0.16 0.22 Definition of abbreviations : t n - half-life of a monodisperse aerosol during breath-holding; Vf - tidal volume; f- breathing frequency ; tp - period of breath-holding; d - particle diameter; RCtot, RCtl d and RCr, , - aerosol recovery in total exhaled, tidal and reserve air. STUDIES ON LOCAL AEROSOL DEPOSITION IN THE HUMAN RESPIRATORY TRACT B. HAIDER and L. T. COLLINS GeseUschaft fiir Strahlen- und Umweltforschung mbH Miinchen, D-8042 Neuherberg, West Germany A pulse inhalation apparatus has been built in order to obtain information on the local distribution of aerosol particles deposited in the human lung. A person is breathing at the inhalation apparatus through a mouth piece. The measuring system consists of a laser light scattering photometer, a system of hot film probes and a fast electrically driven valve. The aerosol concentration and the air flow are measured both during inhalation and exhalation. The valve connects the mouth piece to one of three air channels: the filtered air line and aerosol line for inhalation, and the exhalation line. A PDP l I computer collects all data and synchronizes the valve with the breathing pattern. The subject starts an experiment by breathing filtered air. After a preselected number of breathing cycles the computer inserts one aerosol pulse into the inhalation phase. The beginning and the end of the pulse are defined by preset volumes. The leading and trailing edges of the pulse are typically 10 msec. This procedure is repeated several times. The evaluation of the experiments starts with the calibration of the flow and aerosol concentration. Then the tidal volume, the amount of aerosol and its deposition in the respiratory tract are calculated. The measured inhaled and exhaled aerosol patterns will be compared with data obtained from a computerized lung deposition model. This model describes the lung as a system of tubes and bifurcations. A Monte Carlo program calculates the geometry of the tubes and the bifurcations, the flow distribution, and the pathway of a single particle and its deposition using probability distributions. The calculations are carried out for a large number of aerosol particles to obtain reliable results. A fit with the experimental data is obtained by changing different parameters of the model. CONTRIBUTION TO THE DOSE-RESPONSE RELATIONSHIP OF CO WERNER RESCH, HELGER HAUCKand MANFREDNEUBERGER Institut f'dr Medizinische Physik and lnstitut fiir Umwelthygiene, Universitiit Wien, Austria In 1972 the World Health Organisation (WHO) proposed Air Quality Standards for carbonmonoxide based not only on theoretical considerations but also on experimental studies about effects of relatively low CO- concentrations on man. Frequently the latter ones have been criticized by experts pointing out some weak aspects of data and experimental performance. So COHlyconcentrations have been determined using inappropriate methods or merely estimated, CO-concentrations the volunteers were exposed to did not match the actual immission