4.2 Sources of Bioaerosols

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Из курса от партнера The Hong Kong University of Science and Technology

Introduction to Indoor Air Quality

43 оценки

The Hong Kong University of Science and Technology

Introduction to Indoor Air Quality

43 оценки

Course Overview: https://youtu.be/LLVb4FOn4uU This course provides a basic knowledge of an emerging area – Indoor Air Quality (IAQ) in buildings. Learners will realize the importance of maintaining proper IAQ. Characteristics associated with indoor air contaminants (IAC) are demonstrated, such as • Particulate matters (PM2.5, PM10) • Radon • Volatile organic compounds (VOCs) • Asbestos • Bio-aerosols, and more Safe exposure levels, resulting health effects, measurement techniques, mitigate and control measures of these IAC are discussed. Other important areas related to IAQ such as building ventilation systems, indoor flow characteristics, sick building syndrome, and thermal comfort are also covered in this course.

Из урока

Bioaerosols and Asbestos

In the last module of course, we look into the two other major indoor air contaminants - Bioaerosols and Asbestos. Staying in a clean environment does not mean the environment is comfortable. "Thermal Comfort" is also an issue that we need to consider. We also look into "Thermal Comfort" in this module.

4.1 Introduction to Bioaerosols5:42

4.2 Sources of Bioaerosols3:36

4.3 Health Effects of Bioaerosols7:46

4.4 Measuring and Removing Bioaerosols6:15

Познакомьтесь с преподавателями

Christopher Chao
Adjunct Professor
Department of Mechanical and Aerospace Engineering

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.

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