This document discusses indoor air pollution and solutions. It notes that Delhi has very polluted air that poses health risks. Often, indoor air is more polluted than outdoor air due to materials used in buildings. Sick building syndrome describes health issues that occur in tightly sealed modern buildings due to indoor pollutants. A HEPA filter can remove 99.97% of particles like dust, pollen, mold and bacteria by using mechanisms like inertial impaction, diffusion and interception. HEPA filters are constructed of pleated borosilicate fibers and an activated carbon pre-filter helps capture larger particles and odors. Testing a homemade air purifier with HEPA and carbon filters could help reduce indoor air pollution.

1. By:
Shaikh Maaz
Zubair Sayyed
Mohammad Faiz
MHSSCOE

2.  According to WHO delhi is one of
the most polluted cities in the world,
with people on risk of respiratory
disease.
 Often the air quality inside a
building is worse than the air quality
outside
 Harmful compounds can be found in
carpets, building materials, paints
and furniture – especially when they
are new
 Air pollution can cause serious
health problems, especially for
people who are very young, very old,
or who have heart or lung problems.

3. Sick-Building Syndrome
 Sick-building syndrome is a set of symptoms,
such as headache, fatigue, eye irritation, and
dizziness, that may affect workers in modern,
airtight office buildings.
 Sick-building syndrome is believed to be caused by
indoor air pollutants.
 Sick-building syndrome is most common in hot
places where buildings are tightly sealed to keep
out the heat.

4. What is a HEPA FILTER?
 HEPA is an acronym for “High Efficiency Particulate Air”
 This type of air filter can remove at least 99.97% of dust,
pollen, mold, bacteria and any airborne particles with a size
of 0.3 micrometres (μm)
• Human Hair: 50150 microns
• Household dust and lint: 0.01100 micron
• Pollen: 10110 microns
• Mold: 150 microns
• Pet dander: 0.110 microns
• Tobacco Smoke: 0.011 micron
• Viruses and Bacteria: 0.00110 microns

5. Construction:
 HEPA filter is constructed of borosilicate
microfibres in the form of pleated sheet
 Sheet is pleated to increase the overall filtration
surface area.
 The pleats are separated by serrated aluminum
baffles or stitched fabric ribbons, which direct
airflow through the filter
 This combination of pleated sheets and baffles
acts as filtration medium.

6. HEPA FILTER

7. Filtration mechanisms:
 1. Inertial Impaction :
 larger particles are filtered due to the impaction
mechanism.
 Larger particles have higher mass and are harder to
turn than smaller particles due to inertia. Because of
this inertial effect, the particles continue to travel in a
somewhat straight line even though the airstream is
turning to move past the fiber.
 Once the particle comes in contact with the fiber, it
becomes attached and is “filtered” from the airstream

8. Filtration mechanisms:
 2. Diffusion:
 it is the most difficult air filtration mechanism to imagine
or explain.
 Very small particles come in contact with fibers due to
diffusive effects.
 The particles collide with air molecules and are “pushed
around.” This effect is called Brownian motion. Because of
Brownian motion, small particles don’t precisely follow the
airstream, but instead “vibrate” or move erratically.

9. Filtration mechanisms:
 3.Interception :
 In order to be intercepted, a particle must come within a
distance from a fiber of one radius of itself. Thus, the
particle makes contact with the fiber and becomes
attached.
 The interception mechanism can be contrasted with the
impaction mechanism in that a particle which is
intercepted is smaller and its inertia is not strong enough
to cause the particle to continue in a straight line.

10. Overall Design
There’s also the powerful combination of an activated carbon
pre-filter. That’s double the precaution and filtration. Nothing
gets through, dust, gases, or smells. Activated carbon filters or
anti bacterial filters are rarely used alone to clean the air, but as
a helper they work wonders!

11. Function of Pre-filters
 Having pre-filters inbuilt into purifiers is a hefty
advantage over cleaners that don’t. This is the first step
in the filtration process where the pre-filters job is to
capture large particles the main filter usually can’t, or
particles that get stuck to it.
 It prevents debris getting into the main filter, and this
is why pre-filters come in handy as an additional
strength in filter technology.

12. Anti Bacterial Filters
 Anti bcterial filter are special in a few ways. similar
kind is activated carbon filter.
 Activated carbon is also called activated charcoal
which goes through a process with oxygen to open up
the pores between atoms.
 The main function of activated charcoal is to adsorb
the odors or colored substances from liquids or gases.

13. PROPOSAL FOR PROJECT (B)
 The model consist of a powerful fan placed in a timber or
plastic frame and installing pre-filter, HEPA filter and
carbon filter in front of the fan the edges of the unit will be
tape with duct tape to ensure that air will properly flow
through the filters and the fan.
Proposed
Design.

14.  Testing of the model will
be done on respiratory dust
sampler machine in the
environment lab of the
college.
 The output of HEPA filter
can be connected on the
outside plate of sampler
along with the filter paper
to test out the concentration
of particulate matter
removed by HEPA filter in
the room.
A typical dust sampler
at environment lab of
MHSSCOE