Environmental
Health Foundation Study
on the BioGuard 1000
Figure 1 shows the particle removal efficiency of the BioGuard. The efficiency was found to be essentially the same for different particle sizes within the measurement range (0.3 to 3 _m).
It is seen that the BioGuard removed more than half of the aerosol particles from the chamber's air during the first 15 minutes, 80% of the particles during 30 minutes, and about 90% of the particles during 40 minutes. When operating continuously beyond 40 minutes, the efficiency remained between 90% and about 100%.
Figure 2 shows the result of similar tests conducted with the Sharper Image Ionic Breeze Personal Air Purifier. It is seen that the experimental points representing different particle sizes are somewhat scattered. The data show that the particle removal efficiency curve for the Sharper Image Ionic Breeze Personal Air Purifier is not as steep as the one for the BioGuard.
The particle removal efficiency of the former is about 25% after 15 minutes (compared to about 50% for the BioGuard), 40-50% after 30 minutes (compared to 80% for the BioGuard ), about 60% after 40 minutes (compared to 90% for the BioGuard ), and 70% after one hour (when almost all the airborne particles are removed by the BioGuard). Thus, the difference between the BioGuard and the Sharper Image wearable unit may be due to the difference in their ion emission rates.
Figure 3 shows the SILA 10-31 performance. No air cleaning (in addition to the natural decay due to sedimentation) was detected with this unit operating during one hour. We attribute this to the very low ion emission rate produced by the SILA unit.