APES Unit 7 Key Terms

Formaldehyde

A naturally occurring compound that is used as a preservative and as an adhesive in plywood and carpeting.

Evaporate

The process of converting from liquid to a gas or vapor.

Haze

Reduced visibility.

Noise pollution

Unwanted sound that interferes with normal activities that is loud enough to cause health issues including hearing loss.

Smog

A type of air pollution that is a mixture of oxidants and particulate matter.

Catalytic converter

A device that uses chemicals to convert pollutants such as nitrogen oxide and carbon monoxide to nitrogen gas and carbon dioxide.

Vapor recovery nozzle

A device that prevents VOCs from escaping into the atmosphere while a person is fueling their vehicle.

Indoor air pollutants

Compounds that adversely affect the quality of air in buildings and structures.

Base

A substance that contributes hydroxide ions to a solution.

Sulfurous smog (London-type smog; Gray smog; Industrial smog)

Smog dominated by sulfur sulfur dioxide, sulfate compounds, and particulate matter.

pH

The relative strength of acids and bases in a substance. It is a logarithmic scale, meaning that each number on the scale represents a change by a factor of 10.

PM10

Particles smaller than 10 μm are called Particulate Matter-10 and are not filtered out by the nose and throat and can be deposited deep within the respiratory tract.

Radon-222

A radioactive gas that occurs naturally from the decay of uranium and is an indoor air pollutant.

Acid rain (Acid deposition)

Precipitation high in sulfuric acid and nitric acid.

Photochemical oxidant

A class of air pollutants formed as a result of sunlight acting on compounds such as nitrogen oxides and sulfur dioxide.

Primary pollutant

A polluting compound that comes directly out of a smokestack, exhaust pipe, or natural emission source.

PM2.5

Particles of size 2.5 μm and smaller can travel further within respiratory tract and are of even greater health concern.

Sublimate

The process of converting from a solid to a gas or vapor.

Lead (Pb)

A trace metal that occurs naturally in rocks and soils, is present in small concentrations in coal and oil and is a neurotoxin.

Sick building syndrome

A buildup of toxic pollutants in weatherized spaces, such as newer buildings in the developed world.

Sulfur dioxide (SO2)

A corrosive gas that comes primarily from combustion of fuels such as coal and oil, including diesel fuel from trucks.

Thermal inversion

An atmospheric condition in which a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below.

Asbestos

A long, thin, fibrous silicate mineral with insulating properties, which can cause cancer when inhaled.

Photochemical smog (Los Angeles–type smog; Brown smog)

Smog that is dominated by oxidants such as ozone.

Acid

A substance that contributes hydrogen ions to a solution.

Electrostatic precipitator

A device that removes particulate matter by using an electrical charge to make particles coalesce so they can be removed from the exhaust stream.

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.

Secondary pollutant

A primary pollutant that has undergone transformation in the presence of sunlight, water, oxygen, or other compounds.

Inversion layer

The layer of warm air that traps emissions in a thermal inversion.

decibel A scale (dBA)

A logarithmic scale that measure both the loudness of sound and the frequency.

Hydrocarbons

Pollutant compounds that contain carbon-hydrogen bonds, such as gasoline and other fossil fuels, lighter fluid, drycleaning fluid, oil-based paints, and perfumes.

Scrubber

A device that uses a combination of lime and or water to separate and remove particles from industrial exhaust streams.