Fig. 4
From: Clinical validation of controlled exposure to birch pollen in the Environmental Exposure Unit (EEU)
Decrease in PNIF reported by birch allergic and non-allergic participants during the EEU challenge visit. Birch allergic participants experienced a reduction in their peak nasal inspiratory flow (PNIF) compared to baseline, which was sustained for the duration of the exposure period (up to 240 min time point) and peaking at a mean reduction of 28.6 % at 210 min. The PNIF gradually decreased following the challenge but did not return to baseline values by the 480 min time point. Non-allergic participants reported wide variation in their PNIF but with no statistically significant change from baseline values throughout the duration of the study (one-way repeated measures ANOVA with Tukey’s correction). NB: four participants did not complete the PNIF section of the diary cards they took home (270 min time point to 480 min) and were excluded from this analysis