Hello everyone. In this video,
we will talk about the sources of Bioaerosols.
Bioaerosols, enter a building in many ways.
One of which is throught the air stream as bioaerosols are small and light.
When contaminated air passes through heating, ventilation,
air conditioning - a HVAC system,
bioaerosols contaminate the system along with construction dust and debris.
The fluctuation efficiency of a HVAC system is thus affected.
Besides, after entering a building,
bioaerosols tend to occupy surfaces with
high humidity level, such as areas affected by water leakage, floods and spills.
When indoor relative humidity level which is 70% or above,
materials containing carbon may
absorb enough moisture to support the growth of bioaerosols.
When bioaerosols become visible, which is called microbial contamination,
it indicates a high concentration of bioaerosols indoors.
From this graph, it is clear that increasing the relative humidity level,
raises fungi concentration in an indoor environment.
As a result, the humidification is important to prevent the growth of the bioaerosols,
especially for a place where the ambient relative humidity is high.
Bacteria and fungi may germinate on the interior surfaces,
cooling coil and filter of a ventilation system.
When the ventilation system shuts down,
it becomes a perfect environment for bacteria and fungi to grow.
Therefore, when you turn on
the ventilation system, those bacteria and fungi spread to the indoor environment.
The indoor concentration of bacteria and fungi thus increase.
But after a period of time, with the operation of the filter,
the indoor concentration of bacteria and fungi reduce gradually.
In addition, people are a main source of bioaerosols.
Whenever we move, the outer dead layers of our skin are shed due to friction.
Those skin scales usually contaminated with bioaerosols, become airborne.
Coughing and sneezing also contribute bioaerosols to the indoor air.
People bring in contaminants on their clothes such as dust,
pet dander that become airborne.
Therefore, the number of people inside
a room affects the potential for disease transmission.
To conclude, in this video,
we introduced the sources of bioaerosols
which are primarily from the HVAC system and people.