Air Pollution
What is Air Pollution?
A pollutant emitted directly from a source into the atmosphere (e.g., CO, SO2).
Key formula / rule: Plume Rise (Holliday-Stack Formula - Simplified)
Key points
- Identify major air pollutants and their sources.
- Understand the formation and dispersion of air pollutants.
- Analyze the health and environmental impacts of air pollution.
- Evaluate different air pollution control technologies.
Common exam trap
Confusing primary and secondary pollutants.
Definitions
- Term
Primary Pollutant
- Meaning
A pollutant emitted directly from a source into the atmosphere (e.g., CO, SO2).
- Term
Secondary Pollutant
- Meaning
A pollutant formed in the atmosphere through chemical reactions involving primary pollutants and other atmospheric constituents (e.g., Ozone, acid rain).
- Term
Particulate Matter (PM)
- Meaning
A complex mixture of extremely small solid particles and liquid droplets suspended in the air.
- Term
Smog
- Meaning
A type of air pollution formed when emissions react with sunlight, typically a mixture of smoke and fog.
- Term
Acid Rain
- Meaning
Rainfall made sufficiently acidic by atmospheric pollution (mainly sulfur dioxide and nitrogen oxides) to damage buildings, forests, and lakes.
Learning objectives
Identify major air pollutants and their sources.
Understand the formation and dispersion of air pollutants.
Analyze the health and environmental impacts of air pollution.
Evaluate different air pollution control technologies.
Comprehend relevant air quality standards.
Formulae
- Name
Plume Rise (Holliday-Stack Formula - Simplified)
- Note
Δh = Plume rise, F = Buoyancy flux parameter, Q = Heat emission rate, u = Wind speed, H = Stack height. This is a simplified representation; actual formulas are more complex.
- Expression
Δh = (1.6 * F * Q) / (u * H0.5)
- Name
Concentration of Pollutant from Point Source (Gaussian Plume Model - Simplified)
- Note
C = Concentration, Q = Emission rate, u = Wind speed, H = Stack height, σx, σy, σz = Dispersion coefficients (depend on atmospheric stability and distance x). This is a simplified form for ground-level concentration at (x,0,0) when z=0.
- Expression
C(x,y,z) = (Q / (2 * π * u * σz * σx)) * exp(-y2 / (2 * σy2)) * exp(-(z-H)2 / (2 * σz2))
Prerequisites
Basic Chemistry (combustion, chemical reactions)
Physics (gas laws, atmospheric phenomena)
Environmental Science fundamentals
Common mistakes
Confusing primary and secondary pollutants.
Underestimating the health impacts of PM2.5.
Not considering indoor air pollution sources.
Overlooking the role of meteorological factors in pollutant dispersion.
Keywords
Air Pollution
Primary Pollutants
Secondary Pollutants
Particulate Matter
SO2
NOx
CO
Ozone
Smog
Acid Rain
Emission Control
Dispersion Models
NAAQS
Practice preview
In the context of atmospheric stability, a condition where the Environmental Lapse Rate (ELR) is less than the Adiabatic Lapse Rate (ALR) is termed as:…
easy
Calculate the effective stack height (H) if the physical stack height (h) is 80 m, the plume rise (delta h) is 15 m, and the wind speed at the stack top is 5 m/s.…
medium
Identify the INCORRECT statement regarding the working principle of an Electrostatic Precipitator (ESP):…
medium