This document discusses bioaerosols and droplet nuclei. It defines bioaerosols as small airborne biological material, either attached to particulate matter or not, including microorganisms, their byproducts, and fragments. Bioaerosols can be viable, such as living bacteria and viruses, or non-viable, like toxins and proteins. Droplet nuclei are small aerosols formed from the evaporation of respiratory droplets smaller than 5 micrometers that can transmit diseases through airborne transmission. Common sources of bioaerosols include outdoor environmental sources, indoor materials and occupants, and human activities like coughing or talking. Exposure to some bioaerosols is associated with respiratory illnesses, but others may benefit immune

1. BIOAEROSOL AND DROPLET
NUCLEI
MUSKAN
M.Sc. (Microbiology)

2. Bioaerosol
• Bioaerosols are small, airborne biological material either
attached to particulate matter or not.
• They are ubiquitous in the environment comprised of
aerosols originated biologically such as live or dead
microorganism and their metabolites, toxins, or
fragments that exist widely in the environment.

4. Type of bioaerosols
• Viable.
•Non-viable.

5. Viable bioaerosols
•The viable forms include bacteria, fungi, viruses
and algae.
•The non-viable forms include endotoxins and
proteins.
•The adverse health effects caused by viable
bioaerosols could be attributed to their ability to
grow, multiply and produce toxic substances.

6. Non- viable bioaerosols
•Non-viable bioaerosols are not currently
alive and, therefore, cannot multiply; aerosolized
pollen, animal dander and saliva, and insect
excreta are all forms of non-viable bioaerosols.
• In contrast, viable bioaerosols are living
organisms that demonstrate microbiological
activity and have the potential to multiply.

7. Sources of bioaerosols

8. Transport mechanism of bioaerosols
• Ejection of bioaerosols into the atmosphere.
• Small scale transport via clouds.
• Large scale transport via dust plumes.
• Community dispersal.

9. Disease by Bioaerosols
• The sources of indoor bioaerosol pollution include outdoor sources (passing through
windows, doors, and ventilation); building materials; furnishings; occupants; pets;
house plants; and organic wastes.
• Regular or ordinary human activities (e.g., coughing, washing, toilet flushing, talking,
walking, sneezing, and sweeping floors) are also capable of generating bioaerosols .
• However, basic environmental conditions, such as temperature and moisture content,
can considerably influence the extent of their formation and dispersion due to their
controlling effect on the formation of microorganisms .
• Consequently, the prevalence of bioaerosols can be associated with certain human
diseases, such as pneumonia, influenza, measles, asthma, allergies, and gastrointestinal
illness.
• However, under certain circumstances, exposure to some microbes is beneficial for
health in terms of developing a healthy immune system and protect children from
developing allergies and asthma.

11. Droplet Nuclei
• Droplet nuclei are aerosols formed from the evaporation of respiratory
droplets.
• They are generally smaller than 5 μm in diameter. Droplet nuclei are
formed by the "dried residua of larger respiratory droplets".
• These particles are "the vehicle for airborne respiratory disease
transmission, which are the dried-out residual of droplets possibly
containing infectious pathogens".Diseases such
as tuberculous and COVID-19 can be transmitted via droplet nuclei.

13. • Airborne droplet nuclei develop when the fluid of pathogenic droplets (1-5
µm in size; micrometre = one-thousandth of a millimetre) evaporates.
• They are so small and light they may remain suspended in the air for several
hours. Thus, they may also infect persons entering a room which has been
left by a patient long ago.
• Also, airborne droplet nuclei can be widely dispersed by air currents.
Tuberculosis, chickenpox, measles and possibly also influenza may be
transmitted this way.

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