A new personal monitoring system for simultaneously measuring airborne dust concentrations and pulmonary ventilation was described. The system consisted of sensors to measure heart rate, ambient dust concentration, body and ambient temperature, and acceleration, which was used as a measure of work related physical activity. The heart rate sensor was a modified electrocardiographic electrode. The dust sensor was a mini real time air monitor that measured mass concentrations by a light scattering detector. The sensors were connected to a data logger that collected the data and inputted it onto computer cards. The computer cards were read into a personal computer that recorded the data on floppy disks. Real time pulmonary ventilation volumes were computed from average heart rates every 30 seconds using a formula that included the time rate of change of heart rate, age, height, and weight. The monitor was evaluated using 34 healthy males, 17 to 62 years old, exercising on a treadmill at 0, 20, 40, 60, 80, and 100% of capacity. Pulmonary ventilation volumes measured by the monitor were compared with those measured by an independent method. The overall error between the ventilation volumes measured by the monitor and those obtained independently was less than 20%. For 25 subjects the difference at each exercise level was less than 10%. The authors conclude that the new monitor can measure pulmonary ventilation volumes more accurately than with other techniques. The electrodes used for measuring heart rate restrict movements slightly, however this can be corrected.