Air Pollution

Meteorology

The scientific study of the atmosphere.

Atmospheric Medium

The medium through which all air pollutants are released.

Wind Movement

The movement of air (wind) plays a crucial role in atmospheric processes.

Heat Exchange

Processes like convection and radiation contribute to the exchange of heat in the atmosphere.

Fate of Pollutants

Atmospheric processes determine the destiny of pollutants, including transport, dispersion, transformation, and removal.

Air Pollution Meteorology

The field that focuses on understanding how atmospheric processes impact the behavior of pollutants.

Temperature Inversion

A deviation from the normal change of an atmospheric property with altitude, where air temperature increases with an increase in altitude.

Smog

An effect of temperature inversion, where warm air forms a layer over cold air.

Natural Sources of Air Pollutants

• Dust blown by wind

• Pollutants from wildfires and volcanoes

• Volatile organics released by plants

• Withdrawing groundwater

Human Sources of Air Pollutants

• Stationary sources

• Mobile sources

Primary Pollutants

Pollutants directly emitted into the atmosphere.

Secondary Pollutants

Pollutants formed through chemical reactions in the atmosphere.

Effects of Air Pollution

Acid rain, photochemical smog, ozone layer depletion, global warming, and various short-term and long-term health effects.

Atmospheric Dispersion

The process by which air pollutants disperse in the atmosphere.

Plume rise

Influenced by exit gas mass, exit velocity, and exit gas temperature

Effective stack height

Plume rise, along with stack height, is known as

Downwind Distance

Greater distance from discharge to receptor increases air volume for dilution.

Wind Speed and Direction

Determines the contaminated gas stream's movement across terrain.

Stability

More unstable atmosphere enhances dilution power. Non-ground-based inversions limit vertical dilution

Dispersion Modeling

The mathematical description of meteorological transport and dispersion of air pollutants.

Point Source Gaussian Dispersion Model

A model used to estimate air pollutant concentrations based on source and meteorological parameters.

Air Pollution Prevention

Strategies such as renewable energy production, energy conservation, eco-friendly transportation, and green building to reduce air pollution.

Renewable fuel and clean energy production

The most basic solution for air pollution is to move away from fossil fuels, replacing them with alternative energies like solar, wind, and geothermal.

Energy conservation and efficiency

Producing clean energy is crucial. But equally important is to reduce our consumption of energy by adapting responsible habits and using more efficient devices.

Eco-friendly transportation

Shifting to electric vehicles and hydrogen vehicles and promoting shared mobility (i.e., carpooling, and public transports) could reduce air pollution.

Green building

From planning to demolition, green building aims to create environmentally responsible and resource-efficient structures to reduce their carbon footprint.

Particulate Matter Pollutants Control

Methods like Settling Chambers, Inertial Separator or Cyclone, Electrostatic Precipitators, Bag House and Filter.

Gaseous Pollutants Control

Methods like absorption, adsorption, combustion, and flue gas desulfurization to control gaseous pollutants.

Control of Air Pollution from Mobile Sources

Technologies like positive crankcase ventilation valves, exhaust gas recirculation valves, charcoal canisters, and catalytic converters to control air pollution from vehicles.

Positive crankcase ventilation valves

Direct crankcase blowby emissions into the engine.

Exhaust gas recirculation valves

Reduce NOx formation during fuel combustion.

Charcoal canisters

Sequester volatile hydrocarbons for later burning in the engine.

Catalytic converters

Designed to oxidize partially combusted hydrocarbons and CO to CO2.

Short-term Health Effects

Headache, Coughing, Pneumonia, Bronchitis, Skin Irritation

Long-term Health Effects:

Central Nervous System Diseases, Cardiovascular Diseases, Respiratory Diseases, Impacts on Liver, Impacts on Reproductive System

Looping

Strong lapse condition

Coning

Weak lapse condition

Fanning

Inversion condition

Lofting

Inversion below, lapse aloft

Fumigation

Lapse below, inversion aloft

Trapping

Weak lapse below, inversion aloft

Gasoline

1 kg of this needs about 15 kg air for complete combustion. Incomplete combustion results in emissions of carbon monoxide and hydrocarbons.

Diesel Engine

Operates at a higher air-to-fuel ratio. Well-designed (blank) emit less CO and hydrocarbons but have higher NOx emissions due to higher operating temperatures.