1-13 Intro to air pollution

APES 2024

Air pollution

Air pollution

The introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings, or to alter ecosystems

Natural emissions of pollution include

• volcanoes

• lightning

• forest fires

• plants, both living and dead

Natural emissions of pollution all

release compounds that can be classified as pollutants

Anthropogenic sources include

on-road vehicles, power plants, industrial processes, waste disposal (incinerator)

Anthropogenic

human-caused

Residence time

the time a pollutant stays in the atmosphere

Pollutants with brief residence times exert

localized impacts over short time periods

ex. Particulate matter, automobile exhaust

Pollutants with long residence times exert

regional or global impacts (Pollutants causing climate change or ozone depletion)

The EPA sets nationwide standards for

emissions and concentrations of toxic pollutants

States monitor

air quality and the EPA takes over enforcement if plans are inadequate

Criteria pollutants

pollutants that pose especially great threats to human health

Criteria pollutant examples

• Carbon monoxide

• sulfur dioxide

• nitrogen dioxide,

• tropospheric ozone

• particulate matter

• lead

Carbon monoxide

• common emission in vehicle exhaust

• can be a significant component of air pollution in urban areas

• Problem in developing countries where people may cook with manure, charcoal or kerosene indoors

• Incomplete combustion of any kind

Sulfur dioxide (SOx)

• A corrosive gas that comes primarily from combustion of fuels, ex. coal, oil, gasoline

• A respiratory irritant and can adversely affect plant tissue

• Also released in large quantities during volcanic eruptions and in much smaller quantities, during forest fires

Nitrogen Oxides (NOx)

• Motor vehicles and stationary fossil fuel combustion are primary anthropogenic
  sources

• Respiratory irritant, increases susceptibility to respiratory infection

• An ozone precursor, leads to formation of photochemical smog

• Converts to nitric acid in atmosphere, is harmful to aquatic life and some vegetation

• Contributes to over-fertilizing terrestrial and aquatic systems.

Ozone (O3)

• Secondary pollutant

• formed when heat and sunlight cause chemical reactions between oxides of
  nitrogen (NOX) and Volatile Organic Compounds (VOCs), also known as Hydrocarbons

• reaction can occur both near the ground and high in the atmosphere.

Types of ozone

• Tropospheric ozone – bad ozone

• Stratospheric ozone – good ozone

How does ozone smell?

sweet

Particulate matter (PM)

Solid or liquid particles suspended in air

Types of particulate matter

• PM 2.5 – diameter less than 2.5 micrometers (fine particles)

• PM 10 – diameter less than 10 micrometers

Particulate matter comes from

• Burning of coal, oil, diesel, biofuels

• Agriculture, road construction

Particulate matter can be

natural or anthropogenic

Particulate matter in the atmosphere ranges considerably in size and can

absorb or scatter light, creates a haze and reduces the light that reaches the surface of Earth

Lead

• A gasoline additive, also found in oil, coal, and old paint

• Impairs central nervous system

• At low concentrations, can have measurable effects on learning and ability to concentrate

Carbon dioxide (CO2)

• released by burning fossil fuels has led to
  its becoming a major concern

• Appears naturally from respiration, decomposition and volcanic eruptions

• Not a criteria pollutant

• Is a greenhouse gas and does lead to Earth’s warming

CO2 recently exceeded a concentration of

400 parts per million (ppm) in the atmosphere and appears to be steadily increasing each year

Volatile organic compound (VOC)

• An organic compound that evaporates or sublimates at room temperatures

• Formed by evaporation of fuels, solvents, paints, and improper combustion of fuels such as gasoline

• A precursor to ozone formation

Volatile organic compound (VOC) examples

• formaldehyde and gasoline

• Trees are a natural source of VOCs