All you need to know about Particulate Matter - PM2.5

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Particulate Matter PM2.5
All you need to know about...

All you need to know about Particulate Matter PM2.5
PM2.5 are complex mixture of solid and aerosols with
diameter of 2.5 μm or less. These fine inhalable
particles are composed various chemical species
like organic compounds, inorganic ios, metallic
compounds, elementary carbon, etc.
They are more than 100 times thinner than a human
hair and can penetrate deeper into the human
respiratory tract when inhaled.
PM2.5 in the atmosphere consists of toxic organic compounds and heavy metals released
from various sources. Once released, they stay in the air for a long time i.e. days or weeks
and can travel hundreds of miles.
WHAT IS PM2.5?

All you need to know about Particulate Matter PM2.5SOURCES
Particulate matter PM2.5 are either directly emitted from a source - Primary PM or are
formed through the chemical reactions of gases such as oxides of sulfur (SOx), nitrogen
oxides (NOx), organic compounds, etc. in the atmosphere - Secondary PM.
Natural sources: wind-blown dust from open land, pollen, spores, mold, dirt, soil erosion,
and forest fires.
Anthropogenic Sources:
● Burning fossil fuels such as gasoline, oil, diesel or wood, etc.
● Waste burning, agricultural burning, etc.
● Emission from motor vehicle exhaust
● Emission from energy supply and industrial combustion processes
● Metal and steel production, specifically smelting and processing of metals

All you need to know about Particulate Matter PM2.5
The breakpoints concentrations describing the quality of air based on the PM2.5 concentrations
(μg/m3) for different countries are:
India (24-hr) US (24-hr) China (24-hr) EU (8-hr)
AQI Category
Break point
concentration
AQI Category
Break point
concentration
AQI Category
Break point
concentration
AQI Category
Break point
concentration
Good 30 Good 35 Excellent 15 Very low 10
Satisfactory 60 Moderate 75 Good 35 Low 20
Moderately
polluted
90
Unhealthy for
sensitive
115
Lightly
Polluted
65 Medium 30
Poor 150 Unhealthy 150
Moderately
Polluted
150 High 60
Very Poor 250
Very
Unhealthy
250
Heavily
Polluted
250 Very high 60+
Severe 250+ Hazardous 250+
Severely
Polluted
250+
The Air quality guidelines by the World Health Organization suggests a 24-hr mean of 25
μg/m3.
Source: National Ambient Air Quality Index, CPCB (Oct 2014)
PERMISSIBLE LIMITS

All you need to know about Particulate Matter PM2.5ADVERSE IMPACTS
HEALTH IMPACTS OF PM2.5
● PM2.5 particles travel deep into the lungs through the
respiratory tract inducing tissue damage, and lung
inflammation and may lead to premature death
● Initially it causes irritation to eyes, nose, throat, and upper
respiratory tracts, coughing, sneezing, and shortness of breath
aggravating already present respiratory diseases. Prolonged
exposure causes permanent respiratory diseases such as
asthma, chronic bronchitis, heart diseases and reduce lung
function growth in children.
Increase in PM2.5 have been linked to an increase in deaths due to viruses such as novel
coronavirus disease (COVID-19). Harvard University, in one of its studies has claimed that an
increase in the PM2.5 values by 1 µg/m3, corresponded to 8% increase in the COVID-19
deaths.

All you need to know about Particulate Matter PM2.5ADVERSE IMPACTS
ENVIRONMENTAL IMPACTS OF PM2.5
● PM2.5 alters the absorption and scattering of light in
the atmosphere affecting visibility. They are major
precursors of smog.
● Settling of PM on plant, soil and water ecosystems
have negative impact.
● The metal and organic compounds reduce plant
growth and yield while the deposition of PM into
water bodies affects its quality and clarity.
● Some components of PM such as black carbon promote climate warming while
some components such as sulfates and nitrates have cooling properties.

All you need to know about Particulate Matter PM2.5CORRECTIVE MEASURES
The primary action is PM2.5 monitoring to identify the areas with high particulate levels or
areas where air quality does not meet the PM2.5 national standards. In addition to this, the
following corrective measures can be taken:
● Limit outdoor activities and close windows and vents during times of high air
pollution.
● Avoid keeping your vehicle idle for long.
● Avoid areas with traffic congestions, construction activities, or unpaved roads.
Breathing such polluted air daily also leads to health effects in the long run.
● Eliminate the use of the fireplace, wood stove, gas-powered lawn, or garden
equipment.
● Eliminate open burning of leaves, trash or other materials.

All you need to know about Particulate Matter PM2.5MONITORING METHODS
High-volume Gravimetric Method
The PM2.5 monitors based on the gravimetric principle
takes in the ambient air for 24 hours at a constant flow
rate through a size-selective inlet that only allows
particulate matter with an aerodynamic diameter of 2.5
µm or less to pass through.
PM2.5 present in the ambient air is collected on a pre
weighted and pre-conditioned filter which is weighted
again after 24-hours to determine the mass of PM
collected which is proportional to the PM concentration.

Beta Attenuation Monitor (BAM)
The PM2.5 monitoring based on the BAM principle
measures the particle mass density using beta radiation
attenuation.
The particulates in the ambient air drawn into the PM2.5
monitor are deposited on a paper-band filter and exposed
to beta rays (i.e. electrons with energies in the 0.01 to 0.1
MeV range) which get attenuated as a function of the
particulate mass. The beta count reduces with an increase
in the PM2.5 mass and is recorded by the detector and
converted to concentration.

Laser Scattering
The PM2.5 monitor based on the physical principle of
light scattering, also known as optical particle counter
(OPC), measures dust particles illuminated by laser
light at a 90° angle.
The light scattered from each particle is collected at
approximately 90° by a mirror and detected by a
photodiode and fed into a multi-channel size classifier
where a pulse height analyzer is used to classify the
pulse that is proportional to the particle size PM2.5. The
counts in the PM2.5 channel are converted to
concentration.

All you need to know about Particulate Matter PM2.5OIZOM’S PRINCIPLE
Oizom’s DUSTROID is an online particulate
monitoring system that measures the
concentration of various particulate matter with
size ranging from 1 micron to 100 microns such
as PM1, PM2.5, PM10, and PM100 in the ambient air.
The sensor that measures PM2.5 work on active
sampling method of laser scattering that
counts particulate matter using a highly
accurate laser beam.
Real-time monitoring of PM2.5 levels helps in
calculating air quality index to deliver health
advisories as well as formulating an action plan
to meet standards.

All you need to know about Particulate Matter - PM2.5

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All you need to know about Particulate Matter - PM2.5