Glossary of common terms

Glossary of common I.H. & Env. terms

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Terminology	Brief description
AED	Aerodynamic diameter (of particles) usually expressed in microns.
Aerosol	A finely divided material suspended in air or other gaseous environment
Air monitoring	Sampling for pollutants in the air using a variety of means such as sorbent tubes, bags, filters and sampling conventions.
Air Pollutant	Any substance in air that could, in high enough concentration, harm man, other animals, vegetation, or material. Pollutants may include almost any natural or artificial composition of airborne matter capable of being airborne. They may be in the form of solid particles, liquid droplets, gases, or in combination.
Air Pollution	The presence of contaminant or pollutant substances in the air that do not disperse properly and interfere with human health or welfare, or produce other harmful environmental effects.
Air quality monitoring	Sampling, measurement/analysis of airborne pollutants.
Air quality standards	The level of pollutants prescribed by regulations that are not to be exceeded during a given time in a defined area.
Airborne particulates	Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Airborne particulates include: windblown dust, emissions from industrial processes, smoke from the burning of wood and coal, and motor vehicle or non-road engine exhausts.
Alveoli	The tiny sacs of air in the lungs where gaseous exchange takes place. Oxygen is taken into the body and carbon dioxide is expelled.
Ambient air	Any unconfined portion of the atmosphere: open air, surrounding air.
Ambient temperature	Temperature of the surrounding air or other medium.
Aromatic	A type of hydrocarbon, such as benzene or toluene, added to gasoline in order to increase octane. Some aromatics are toxic.
Asbestos	A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled.
Asbestosis	A disease associated with inhalation of asbestos fibers. The disease makes breathing progressively more difficult and can be fatal.
Aspirated	Forced airflow over or through a sensor.
Asthma	A condition marked by labored breathing, constriction of the chest, coughing and gasping usually brought on by allergies
Back pressure	The differential pressure drop across a restriction, such as a filter in a cassette, normally measured in inches of water.
Black globe temperature	The temperature within a matt black, hollow sphere. It measures the radiant temperature of the ambient air.
Breathing zone	The volume within about 8 inches of the operator’s mouth or nose.
BSI	British Standards Institute in the UK.
Carbon absorber	An add-on control device that uses activated carbon to absorb volatile organic compounds from a gas stream. (The VOCs are later recovered from the carbon.).
Carcinogen	Any substance that can cause or aggravate cancer.
Celsius scale	A range of temperatures over a 100-degree range expressed as 0 degrees at the freezing point and 100 at the boiling point for pure water at standard atmospheric pressure.
Centigrade scale	A range of temperatures over a 100-degree range expressed as 0degrees at the freezing point and 100 at the boiling point for pure water at standard atmospheric pressure. Now more commonly referred to as the Celsius scale.
Chronic effect	An adverse effect on a human or animal in which symptoms recur frequently or develop slowly over a long period.
Chronic exposure	Multiple exposures occurring over an extended period of time or over a significant fraction of an animal's or human's lifetime (Usually seven years to a lifetime.)
Climate change (also referred to as 'global climate change')	The term 'climate change' is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, 'climate change' has been used synonymously with the term, 'global warming'; scientists however, tend to use the term in the wider sense to also include natural changes in climate.
Compliance monitoring	Collection and evaluation of data, including self-monitoring reports, and verification to show whether pollutant concentrations and loads contained in permitted discharges are in compliance with the limits and conditions specified in the permit.
Compound	Chemical combination of different elements to form a substance where the compound atoms cannot be separated by physical means. Such compounds are not necessarily stable and may decay into other simpler compounds.
Contaminant	Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil.
Contamination	Introduction into water, air, and soil of microorganisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the medium unfit for its next intended use. Also applies to surfaces of objects, buildings, and various household and agricultural use products.
Cyclone sampling head	A device that uses centrifugal force to remove large and heavier particles from polluted air. The smaller size particles pass up the cavity and are deposited on the filter membrane. Cyclones are designed to separate out the respirable size particles.
Density	A measure of how heavy a solid, liquid, or gas is for its size.
Dew point	The temperature at which the water vapor in the air first starts to condense. Typically expressed in degrees Fahrenheit or Celsius.
Diffraction	Radiation being bent or curved from its original course, for example light as it passes through a narrow slit.
Diffusion tubes	An inert tube of plastic or stainless steel that contains an absorbing matrix capable of collecting specific target air pollutants. The tubes are used for ambient air monitoring and sent to a laboratory for analysis.
Dry bulb temperature	The temperature reported by a thermometer shielded from the direct rays of the sun or other radiant sources that measures the temperature of the local air.
Dust	Solid particles, usually produced by a mechanical process, with a range of particle diameters from 0.1 to 100 microns. Dust can also include fumes that condense from the vapor state usually from the volatilization of molten metals, high boiling liquids or combustion.
EC	The European Community.
Ecosystem	The interacting system of a biological community and its non-living environmental surroundings.
EPA	The Environmental protection Agency in the USA.
Epidemiology	Study of the distribution of disease, or other health-related states and events in human populations, as related to age, sex, occupation, ethnic, and economic status in order to identify and alleviate health problems and promote better health.
Equivalent method	Any method of sampling and analyzing for air pollution which has been demonstrated to the relevant regulators satisfaction to be, under specific conditions, an acceptable alternative to normally used reference methods.
EU	The European Union.
Exceedance	A measured quantity that is greater than an allowed limit.
Extractive monitoring	Measurement made on a sample that is taken from a stream or flow.
Fahrenheit scale	A range of temperatures over a 180-degree range expressed as 32 degrees at the freezing point and 212 at the boiling point for pure water at standard atmospheric pressure.
Filter cassette	A mechanical container designed to minimize the handling of the delicate filters used in sampling for particulates.
Filters	Can be made from glass fiber (GF/A) or mixed cellulose ester (MCE). Used to collect the particulates in the air when performing sampling conventions. Usually used in 25 or 37 mm diameter sizes.
Flow meter	A device used to verify the flow rate of a personal sampling pump used for sampling conventions to ensure stable and well-known conditions.
Gas	Material that is in the gaseous phase under the surrounding conditions.
Globe temperature	The temperature reported by a thermometer mounted inside a small matt black globe that measures the radiant heat in an area.
Gravimetric analysis	The determination of the mass concentration using pre and post weighed filters.
Heat exhaustion	A heat related illness characterized muscular weakness, distress, nausea, vomiting, dizziness, pale clammy skin and fainting.
Heat stress	The physiological strain caused by an increase in core body temperature above safe levels where the individual is at risk of overheating.
HSE	Health and Safety Executive (UK Agency)
Indoor air	The breathing air inside a habitable structure or conveyance.
Indoor air pollution	Chemical, physical, or biological contaminants in indoor air.
IR	Infrared radiation beyond the limit of normal human sight.
ISO	The International Standards Organization.
Isokinetic sampling	Sampling velocity equal to local gas velocity. Usually considered inside chimney stacks and other such locations.
Maximum exposure limit	These are the statutory limits that should not normally ever be exceeded. MELs are particularly applied to substances known to be carcinogenic.
Micron	A unit of length. One millionth of a meter or one thousandth of a millimeter. One micron equals 0.00004 of an inch.
Monitoring	Periodic or continuous surveillance or testing to determine the level of compliance with statutory requirements and/or pollutant levels in various media or in humans, plants and animals.
MSHA	The Mine Safety and Health Administration in the USA.
Natural wet bulb temperature	The temperature reported by a thermometer that has a wet wick over it supplied continuously with water from a reservoir.
Nephelometer	Optical measurement device based upon the scattering effect of light by particulate.
NIOSH	National Institute of Occupational Safety and Health in the USA.
Occupational exposure limits	8 hour time weighted average levels for each material under consideration. Limits are published by such bodies as OSHA, HSE etc. in each country.
Occupational exposure standards	These are standards applied to all materials and, in general, exposures below the standard would be regarded as demonstrating adequate compliance with the relevant statutory requirements.
Occupational hygiene	The science associated with the anticipation and recognition of workplace hazards and the evaluation and control of subsequent risks to health.
Organic	This means a substance that is carbon based.
Particulate	Can be an aerosol, mist, fog, dust, fumes or smoke depending upon the source.
Passive sampling	Air sampling without the aid of a sampling pump typically employing diffusion tubes.
Personal sampling	Occupational sampling of airborne contaminants in particulate form with sampling equipment worn by the operator. Measurements are normally taken in the breathing zone of the operator.
PM10	Particulate matter having a mean aerodynamic diameter of 10 microns usually related to ambient air monitoring.
Pressure drop	The differential pressure drop across a restriction, such as a filter in a cassette, normally measured in inches of water.
PUF filters	Porous PolyUrethane Foam filters used for particle size selection when performing air sampling.
Reflection	Relates to the change in direction of a wave after a collision with the surface of an object.
Refraction	The bending effect of light or waves as they pass through a medium of different intensity.
Respirable	The mass fraction of particles with a mean diameter of less than 4 microns.
Rotameter	Same as a flow meter for verifying the flow rate of a sampling pump.
Sampling bag	Used to collect gases and vapors during a measurement. Air is passed through the pump and enters an inert bag where it is collected for later analysis.
Sampling conventions	The size convention of particulate varies and is classified by how far they can travel within the breathing system of humans.
Sensor	A transducer that responds to changes in a certain condition, for example a thermometer that responds to changes in temperature.
Short term exposure limits	A 15 minute short term exposure limit rather like a TWA. If no STEL is quoted for a substance then a level 3 times the 8 hour TWA may be assumed but the total duration of the excursions should not exceed one hour in any 24 hour period.
Sick building syndrome	A widespread occupational health concern that is commonly associated with air conditioning systems in buildings. Symptoms vary but will normally include irritated eyes, nose and throat, headaches and lethargy.
Silicosis	A lung disease caused by excessive inhalation of crystalline silica dust.
Sorbent tubes	Small tubes used to absorb sample gases and vapors. Contain one or more layers of sorbent material whose type depends on the gas/vapor to be sampled. Air to be sampled is drawn through the tube trapping the airborne chemicals. The tube can then be analyzed in a laboratory to determine what substances are present in the sample.
Span	The range of measurement capability in a monitoring instrument from the smallest to the largest value. Sometimes called the dynamic range.
Stack monitoring	The characterization and quantification of emission parameters and components discharged from point (chimney) emission sources.
Static sampling	Monitoring at a fixed location.
Statistical analysis	The classification of the magnitudes of a measured parameter into a cumulative frequency distribution from which various statistical levels can be derived.
Telemetry	The transmission of data sets from a remote monitoring device over large distances to a central readout location. Can be done by radio signals or by telephone modems.
Time weighted average	Occupational exposure limits for a material expressed as an 8 hour time weighted average value (TWA).
Total inhalable fraction	The mass fraction of total airborne particles that are inhaled through the mouth and nose.
Thoracic fraction	The mass fraction of inhalable particles penetrating beyond the larynx
Time weighted average level	The 8 hour time average level for each substance as specified in published standards or recommendations.
Vapor	A liquid or moisture diffused or suspended in air.
VOC	Volatile organic compound.
Volatile	This means a substance is easily converted into a vapor.
WBGT	The wet bulb globe temperature index is a means of specifying a measurable quantity to assess the risk of an operator suffering from heat stroke or other symptoms when working in hot areas. It is an empirical index based upon the relationship between the three different temperatures recorded by thermometers that measure the temperatures of the dry air, the globe and the natural wet bulb in the area where people are working. Corrections are applied depending upon the clothing and work rates to arrive at a safe WBGT temperature for indoors and outdoors.
page last updated - Wednesday May 31, 2006