Particulates Matter in Atmosphere

Page | 1 Submitted To : Prof. Murad Sir of Chemistry Deptt GPGC-MARDAN

Introduction To Particulate Matter (PM): 1. What is Particulate Matter (PM)?

Particulate matter is the sum of all solid and liquid particles suspended in air many of which are hazardous. This complex mixture includes both organic and inorganic particles, such as dust, pollen, soot, smoke, and liquid droplets. These particles vary greatly in size, composition, and origin.

Particles in air are either: directly emitted, for instance when fuel is burnt and when dust is carried by wind, or Indirectly formed, when gaseous pollutants previously emitted to air turn into

particulate matter. 2. Facts About Particulate Matter (PM)?

PM is one of the six EPA (Environmental polluted air) “criteria pollutants”. PM has no fixed composition:

1) PM may consist of either only one chemical. E.g. sulphate, sulphuric acid, lead oxide, carbon oxide. 2) PM may consist of numbers of pollutants. E.g. organic chemicals, metals, organics compounds dust.

US reported first time in 1969 that “it’s a mixture of mixture”. PM is among the most harmful air pollutants.

3. Why does particle size matter?

The aerodynamic properties of particles determine how they are transported in air and how they can be removed from it. These properties also govern how far they get into the air passages of the respiratory system. Additionally, they provide information on the chemical composition and the sources of particles. On the basis of the particulate matter can be classified as:

Coarse Particles (PM10 - PM2.5).

Fine Particle (PM2.5).

Ultra-Fine Particle (0.1 µm).

Particulates Matter in Atmosphere

Page | 2 Submitted To : Prof. Murad Sir of Chemistry Deptt GPGC-MARDAN

1) Coarse Particles (PM10 - PM2.5). They are formed by the mechanical break up of larger solid particles.

CHARACTERISTICS OF CAORSE PARTICALES :

They can be produced from roads dust, agricultural process, uncovered soil, or mining

operations, as well as non-combustible material when burning of fossil fuel occurs. Pollen grain, mould spores, and plants insect’s parts can also contribute to coarse particle. Finally, evaporation of sea-spray can produced large particle near coast. Undergoes rapid sedimentation. Bypass the body defenses in the nose and throat & enter into the lungs.

2) Fine Particle (PM2.5). They are largely formed by the nucleation of gases in which is the initial stage in which the gas becomes a particle. When additional gas condensates on the particles, or through coagulation, when two or more particles combine to form a larger particle. Particles produced by the intermediate reactions of gases in the atmosphere are also called secondary particles.

CHARACTERISTICS OF FINE PARTICALES :

Combustion of fossil fuels such as coal, oil, and petrol can produce fine particles from the

condensation of materials vaporized during combustion. They are emitted from power plants, industries, & automobiles. They remain suspended in the air, and can extremely travel up to long distance with air. They penetrate into lungs and damage the lungs tissue.

3) Ultra-Fine Particle (0.1 µm). They are formed by the atmospheric reactions of sulphur oxides and nitrogen oxides initially released as gases.

CHARACTERISTICS OF ULTRA- FINE PARTICALES :

The very sensitive & toxic particles among all in the atmosphere. They consist of primarily of inorganic ions, mostly hydrocarbon, and some metals. They remain suspended in the air, and can extremely travel up to long distance with air. They passed from lungs tissue and enter to the blood stream. They circulate like oxygen molecule in the, circulatory system.

Particulates Matter in Atmosphere

Page | 3 Submitted To : Prof. Murad Sir of Chemistry Deptt GPGC-MARDAN

4. Which materials are the main components of particulate matter?

On average, the two main components of particulate matter in Europe are sulphate and

organic matter. This is true both for fine particles (PM2.5) and for coarse and fine particles Combined (PM10).

However, near roads mineral dust is also a main component of PM10. Soot, also referred to as black carbon, and makes up 5 to10% of fine particles and somewhat

less of coarse particles; near certain roads the proportion of soot can reach 15 to 20%.

5. Main Sources of Particulate Matter?

Natural Sources: They originate from natural sources such as:

volcanos, dust storms, forest, grassland fires, living vegetation

and sea spray.

Anthropogenic Sources: They originates from human activities such as:

The burning of fossil fuel, incinerating wastes, metal-

smelting, large power generation, wood burning,

construction/demolition, vehicles emissions, dirty roads dust.

Particulates Matter in Atmosphere

Page | 4 Submitted To : Prof. Murad Sir of Chemistry Deptt GPGC-MARDAN

Coarse particle: they are limited to upper respiratory tract of air passage way.

Fine particle: they penetrate deeper into the lungs and reach to terminal bronchioles and

alveoli. Stay here, for longer period and affect lung to lead cancer.

Ultra-fine particle: enter into blood, and travel throughout the body.

6. Types of Particulate Matter?

a) Primary Particulate:

Primary particulate matters are those which are directly emitted

from the source concerned to particulate matter, such as:

pollution from industries, automobiles, wood & coal burning, dry cleaner, volcanos

gas-stations, etc.

b) Secondary Particulate:

Secondary particulate are formed in the atmosphere as a result of

the interaction of chemicals in the environment such as:

SO2, NOX, and VOCS, with other compounds in the air.

7. Precursor of Particulate Matter?

Mobile Source: vehicles, NOX, and VOCS make the PM.

Stationary Sources: power plants, factories, SO2, NO2.

Area Sources: dry-cleaner, gas-stations, VOCS.

Natural Sources: grass-land & forest fires, volcanoes eruption.

Particulates Matter in Atmosphere

Page | 5 Submitted To : Prof. Murad Sir of Chemistry Deptt GPGC-MARDAN

8. Environmental impact of Particulate Matter?

a) IMAIRMENT OF VISIBILTY: the fine particles reduced the visibility.

b) DEAMAGE TO ENVIRONMENT: particles can carried over long distance by wind and settle

on ground or water. They make lakes & streams acidic, deplete nutrients in the soils, and damage

the sensitive forest and farms crops.

c) ASTHETIC EFFECT: settling particles on statues and monuments can stain or, damage stone

and other particles in the environment.

9. Adverse Health Effect of Particulate Matter?

Irritate the eyes, nose & throat.

Inflammation of lungs tissue.

Decreased the lungs functions.

Caused chronic lungs diseases.

Severity of “asthma” attack on children.

Pre-term birth & low birth weight.

Pre-mature death in people with heart & lungs diseases.

Mobile Sources

(Vehicles) VOCs, NO

2, PM

Stationary Sources (Power plants, factories)

NO2, SO

2, PM

Area Sources

(Drycleaners, gas stations) VOCs

Natural Sources (Forest fires, volcanoes)

PM

Particulates Matter in Atmosphere

Page | 6 Submitted To : Prof. Murad Sir of Chemistry Deptt GPGC-MARDAN

10. Anthropogenic PM long Term Exposure to Health?

Asthma.

Bronchitis.

Chronic obstructive pulmonary diseases (COPD).

Pneumonia.

Upper respiratory tract or, lower respiratory tract disorder.

Lungs cancer.

11. Control of Particulate Matter (from industrial sources)?

The following methods were used to control the particulate matter from factory zones.

FABRIC FILTER (Bag House): fabric material is used to capture particles from air.

I. They can achieve very high efficiency.

II. Can used for a wide variety of dust.

III. Especially useful for very small diameter.

CYCLONE: particles are impacted against of a cone shape and deposited in hopper below.

I. Can achieve very high efficiency.

II. Especially used with larger diameter of dust.

III. Can be used for pre-treatment to high efficiency devices.’

IV. Product recovery (flour, coffee dust).

ELECTROSTATIC PRECIPITATION: A high voltage charged is used electrically to attract

particles out of exhaust streams.

I. Can achieve very high efficiency.

II. Very energy sufficient.

III. Depend on resistivity of particles (i.e. composition).

IV. Required very high voltage.

V. Generate ground level ozone.

WET SCRUBBER: impaction and interception of particles by scrubbing of liquid such as water.

GRAVITATIONAL SETLING CHAMBER: A low velocity is used for particles to allow

large particles settle down by force of gravity and collect as solid particles.

The End!!!