Some compounds are allergenic, while others, like indoor volatile
organic compounds (VOC), cause irritation of mucous membranes
[131]. Moreover, the contaminant sources can be active or passive:
active sources are those associated with heat sources, such as CO2
from occupants; passive sources are not linked with heat sources,
such as VOC from building materials [133]. DV can remove active
sources more efficiently than the passive sources [133]. However,
there may have even a risk of airborne cross infection in a room
with only vertical low-velocity ventilation [129]. Table 7 shows the
comparison of application of ventilation methods with different
contaminants. Besides these classified methods, two control strategies
are recommended to control the indoor air quality: ventilation
control (demand control) and contamination protection
(monitoring with sensors) [135