The exposure setting used were: 5s Puff, 5s Mix, 180s exposure, 120s purge, and 5s rest. A, shows CO2 / O2 variations; CO2 level did not exceed 0.8 % on highest peak and O2 levels not lower than 19.4 %. B, Temperature was varying ~ 1.5 °C per cycle, and average temperature rose 2 °C over the full 20 cycles. Ambient temperature was 24 °C. C, Relative humidity varies approximately 10% per cycle. 8 cycles shown in each panel.