a

ADMS

Atmospheric Dispersion Modelling System

AURN

Automatic Urban and Rural (air quality monitoring) Network, managed by contractors on behalf of Defra.

Accuracy

A measure of how well a set of data fits the true value.

Adjustment

Robust correction of modelled results to account for uncertainties in the model.

Air Quality Action Plan (AQAP)

Air Quality Action Plans provide the mechanism by which local authorities, in collaboration with national agencies and others, state their intentions for working towards the air quality objectives using the powers they have available.

Air Quality Annual Status Report (ASR)

A document produced by local authorities in the UK to report on air quality within their jurisdiction. These reports are part of the LAQM framework and are required under the Environment Act 1995.

Air Quality Assessment (AQA)

A comprehensive evaluation of the levels and sources of air pollution in a specific area, to determine whether air quality meets established health and environmental standards. These assessments are crucial for informing policy decisions, planning new developments, and protecting public health and the environment.

Air Quality Management Area (AQMA)

An Air Quality Management Area (AQMA) is declared for an area where a local air quality is unlikely to meet the Government’s national air quality objectives. Once an AQMA has been declared, the local authority has to carry out further work to monitor the air quality in the area and identify what action can be taken to improve it.

Air Quality Neutral (AQN)

A term for developments that do not contribute to air pollution beyond allowable benchmarks.

Air Quality Objective (AQO)

Policy target generally expressed as a maximum ambient concentration to be achieved, either without exception or with a permitted number of exceedances within a specific timescale (see also air quality standard).

Air Quality Standard

The concentrations of pollutants in the atmosphere which can broadly be taken to achieve a certain level of environmental quality. The standards are based on the assessment of the effects of each pollutant on human health including the effects on sensitive subgroups (see also air quality objective).

Ambient Air

Outdoor air in the troposphere, excluding workplace air.

Ambient Sound (as used in BS4142:2014)

The sound that comprises the total sound for a specific situation and time (e.g. distant road traffic + wildlife + air conditioning unit)

Annoyance

Loss of amenity due to dust, odour or pollution often related to people making complaints, but not necessarily sufficient to be a legal nuisance.

Annual Average Daily Traffic (AADT)

The traffic flow for a 24-hour period, averaged over a year.

Annual Average Weekday Traffic (AAWT)

The total volume of vehicle traffic, weekdays only, on a road or motorway for a year divided by the number weekdays in the year; a measurement of how busy a road is during the working week.

Annual Mean

The average (mean) of the concentrations measured for each pollutant for a specific year.

b

BS4142:2014

A British Standard that provides guidance when assessing sound of an industrial or commercial nature.

BS8233:2014

A British Standard that provides guidance for the control of noise in and around buildings. This guide suggests criteria such as suitable sleeping/resting conditions, and proposes noise levels that normally satisfy these criteria for most people.

Background Sound (as used in BS4142:2014)

The sound level that is exceeded by the residual sound for 90% of the time.

Building Research Establishment Environmental Assessment Method (BREEAM)

The methodology which sets the world standard for rating systems of building and works as an environmental assessment method.

c

C

A spectral correction applied to Rw values to account for specific noise sources.

A “C” correction is used for living activities (talking, music, radio, tv), children playing, railway traffic at medium and high speeds, highway road traffic > 80km/h, jet aircraft at short distances and factories emitting mainly medium and high frequency noise.

Cambridge Environmental Research Consultants (CERC)

Provides environmental software and services for air pollution problems for cities, industries and airports.

Character (of an odour)

Odour character or quality is essentially what the odour smells like. It identifies that odour and differentiates it from another odour of equal intensity.

Clean Air Zone (CAZ)

Area where certain types of vehicles cannot enter without meeting set emission standards or paying a charge / penalty.

Concentration

The amount of a substance present in a given volume of air. Typically expressed either as the volume of that compound per unit volume of air (e.g. ppm or ppb) or the mass of that compound per unit volume of air (e.g. mg/m³ or µg/m³). For odours (which may comprise a mixture of compounds), concentration is measured in European Odour Units (ouE/m³).

Conservative

Tending to over-predict the impact rather than under-predict; robust.

Ctr

A spectral correction applied to Rw values to account for specific noise sources.

A “Ctr” correction is used for urban road traffic, railway traffic at low speeds, propeller driven aircraft, jet aircraft at large distances and factories emitting mainly low and medium frequency noise.

d

Data Capture

The percentage of all the possible measurements for a given period that were validly measured.

Decibel (dB)

The standard unit for defining sound pressure levels. The decibel is a logarithmic quantity reflecting the human perception of changes in sound pressure levels. The lower threshold of normal hearing is around 0dB and 130dB is the upper threshold of pain. A change of 1dB in sound pressure levels is barely perceptible and 3dB is normally the minimum audible difference. A change of 5dB is clearly audible to the average listener. A change of 10dB roughly corresponds to a subjective ‘halving’ or ‘doubling’ of loudness.

Defra

Department for Environment, Food and Rural Affairs

Defra Trip End Model Presentation Program (TEMPro)

Software, including guidance documents, used for viewing the National Trip End Model (NTEM) datasets.

Detailed Assessment

Using a detailed dispersion model to determine if particular emissions source(s) are likely to significantly impact local air quality.

DfT

Department for Transport

Disamenity

The Oxford English Dictionary defines disamenity as “the unpleasant quality or character of something.” Defra has described disamenity as nuisance caused by an activity such as noise, odour, litter, vermin, visual intrusion and associated perceived discomfort, however, the use of ‘annoyance’ may be preferred, with ‘nuisance’ having certain legal connotations.

Dispersion modelling

The mathematical computation of the dispersal of emissions as they travel through the ambient atmosphere.

Dn,e,w

A single-number quantity that describes the sound insulation of ventilators.

DnT,w (Weighted standardized level difference)

A single-number quantity that describes airborne sound insulation between rooms, “corrected” to a reference reverberation time of 0.5 s for dwellings.

Dust Management Plan (DMP)

A comprehensive document designed to control and minimize dust emissions from various activities, particularly in construction and industrial operations. These plans are essential for protecting the health and safety of employees, the community, and the environment.

Dust soiling

The effect of deposited dust which can lead to annoyance.

Dw (Weighted level difference)

A single-number quantity that describes airborne sound insulation between rooms, but which is not adjusted to reference conditions.

dBA (A-weighted decibel)

A-weighted decibels have been corrected using a frequency weighting that corresponds to the frequency sensitivity of the human auditory system. Measurements of noise in dBA are generally used for assessing human perception of noise.

e

EPUK

Environmental Protection (UK)

EQS

Environmental Quality Standard

Emission Rate / Emission Factor

The quantity of a pollutant released from a source over a given period of time.

Emissions Factor Toolkit (EFT)

A tool produced by Defra that allows users to calculate road vehicle NO_x, PM₁₀ and PM_2.5 emission rates for a specified year, road type, vehicle speed and vehicle fleet composition.

Environment Agency (EA)

An executive non-departmental public body, sponsored by Defra, working to create better places for people and wildlife, and support sustainable development.

Environmental Impact Assessment (EIA)

A process through which an environmental impact of a proposed development is evaluated. The aim of an EIA is to protect the environment by ensuring that a local planning authority, when deciding whether to grant planning permission for a project which is likely to have significant effects on the environment, does so in the full knowledge of the likely significant effects, and takes this into account in the decision-making process.

Exceedance

A period of time where the concentration of a pollutant is greater than, or equal to, the appropriate air quality standard.

f

FIDOL factors

The perception of the impact of odour involves its Frequency, Intensity, Duration and Offensiveness (the unpleasantness at a particular intensity) and the Location of the receptor(s).

Facade-level

A measurement taken in close proximity (e.g. 1m) to a reflective surface (other than ground) such as a building facade. It is generally accepted that reflections from the surface will increase the measured noise levels by around 3 dB compared to free-field levels, i.e. free-field levels = facade levels – 3 dB.

Free-field

A sound field determined at a point away from reflective surfaces other than the ground with no significant contributions due to sound from other reflective surfaces. Generally as measured outside and away from buildings.

Frequency

How often an individual is exposed to a stressor.

Fugitive emissions

Unintended or irregular (non-point-source) emissions, from industrial, construction, and odour activities.

g

GIS

Geographical Information Systems, software used to analyse and visualise geographical data.

GLA

Greater London Authority, the devolved regional governance body for Greater London.

Ground-borne Vibration

Vibration transmitted through the ground. Can cause disturbance or annoyance if at sufficient levels. Usually measured as Vibration Dose Values (VDVs).

h

Heavy Duty Vehicle (HDV)

Goods vehicles + buses >3.5t gross vehicle weight

Heavy Goods Vehicle (HGV)

Any vehicle with a total weight >3.5t including the cargo.

Hz (Hertz)

Hz is the unit of frequency, equal to one cycle per second. Frequency of sound waves refers to the number of pressure fluctuations per second. Frequency is related to the pitch of a sound.

i

IAQM

Institute of Air Quality Management

Impacts

Changes in environmental conditions due to a development.

Indoor Air Quality Plan (IAQP)

A strategic document designed to ensure a healthy indoor environment by managing and improving air quality within buildings.

Intensity (of an odour)

How strong an odour is perceived to be.

k

Kerb

In the context of LAQM, the kerb is defined as the edge of the carriageway adjacent to traffic.

l

LA10,T

The A-weighted level of noise exceeded for 10% of the specified measurement period (T). It gives an indication of the upper limit of fluctuating noise and is commonly used to describe road traffic noise levels.

LA90,T

The A weighted noise level exceeded for 90% of the specified measurement period (T). It is commonly used to define “background” noise level, i.e. the underlying noise level in the absence of intermittent or short-duration noises.

LAeq,T (equivalent continuous noise level)

The sound level of a notionally steady sound having the same energy as the A-weighted fluctuating sound over the measurement period (T). The A-weighted equivalent continuous noise level (LAeq) is commonly used to describe the “average” noise level in a given environment over the measurement period.

LAmax (maximum noise level)

The highest A-weighted noise level recorded during the measurement period. Unless described otherwise, it is generally measured using the ‘fast’ sound level meter response.

Land Use Planning & Development Control: Planning for Air Quality (LUPDC)

Guidance from EPUK and the IAQM for the consideration of air quality within the land-use planning and development control processes.

Light Duty Vehicle (LDV)

Cars and small vans <3.5t gross vehicle weight.

Local Air Quality Management (LAQM)

The process by which local authorities carry out their duties under the Environment Act 1995, the Environment (Northern Ireland) Order 2002, and subsequent regulations.

Local Air Quality Management Technical Guidance (TG22)

Guidance to support local authorities in the UK in carrying out their duties under various environmental regulations. The TG22 document provides detailed instructions and methodologies for assessing air quality, identifying pollution sources, and implementing measures to improve air quality. It aims to ensure that local authorities have the necessary tools and information to protect public health and the environment.

Local Nature Reserve (LNR)

Area of natural heritage that are at least locally important.

London Air Pollution Exposure Criteria (APEC)

A set of guidelines used to assess and manage air pollution exposure in London. The APEC categories help planners and developers ensure that new projects do not exacerbate air quality issues and that residents are protected from harmful pollution levels.
APEC-A: Locations where air quality is considered acceptable, and no specific air quality measures are required.
APEC-B: Locations where air quality is borderline, and mitigation measures are recommended to reduce exposure.
APEC-C: Locations where air quality is poor, and significant mitigation measures are required to make the development acceptable.
APEC-D: Locations where air quality is very poor, and development is generally not recommended due to the high levels of pollution.

London Atmospheric Emissions Inventory (LAEI)

The key tool for air quality analysis and policy development in London. It is a regularly updated database of pollutant emissions and sources including geographically referenced data and maps.

Low Emissions Zone (LEZ)

Where certain types of vehicles cannot enter without meeting set emission standards or paying a charge / penalty.

L′nT,w (Weighted standardized impact sound pressure level)

A single-number quantity that describes the impact sound insulation of floors over a range of frequencies. Impact sound is caused by physical impacts (such as footfall) on the floor. Impact sound insulation is quantified by placing a ‘tapping machine’ on top of the floor and measuring the resultant noise levels in rooms below. LnTw is the sound level difference “corrected” to a reference reverberation time (0.5 seconds unless stated otherwise).

m

MVHR - Mechanical Ventilation with Heat Recovery

A system that provides fresh air to a building while capturing heat from the outgoing stale air to reduce energy loss.

Multi-Agency Geographic Information for the Countryside (MAGIC)

A website providing authoritative geographic information about the natural environment from across government. The information covers rural, urban, coastal and marine environments across Great Britain.

n

NAEI - National Atmospheric Emissions Inventory

Estimates annual pollutant emissions from 1970 to the most current publication year for the majority of pollutants.

NO₂

Nitrogen dioxide

NOₓ

Nitrogen oxides – both NO₂ and nitrogen oxide (NO)

NR (Noise Rating)

Noise rating is a method for assigning a single number level to a noise spectrum. It is typically used to specify allowable noise emissions from mechanical ventilation systems in buildings. For a typical noise spectrum the NR level is approximately equivalent to the dBA level minus 6, i.e. NR ≈ dBA – 6.

NRMM - Non-Road Mobile Machinery

Mobile machines and equipment that is not made for transporting goods or passengers on roads.

National Nature Reserve (NNR)

Key place for wildlife and natural features in England, established to protect the most significant areas of habitat and of geological formations.

National Planning Policy Framework (NPPF)

A framework setting out the government’s economic, environmental and social planning policies for England and how these are expected to be applied.

Noise

Sound that causes disturbance or annoyance. Noise is assessed in terms of sound pressure levels.

Nuisance

Something that causes inconvenience or annoyance. Please note that there are very specific definitions in law therefore this definition should not be used in a general sense.

o

Octave-band or third-octave band (1/1 or 1/3)

The spectrum of audible frequencies can be separated into proportional ‘bands’ to facilitate ease of computation and analysis (the bandwidth being proportional to the band centre-frequency). Third-octave bands (1/3-octave) split each octave into 3 bands, which allows greater accuracy.

Offensiveness (of an odour)

Used to describe the character and (un)pleasantness of an odour at a particular intensity. It is also used in the context of overall impact in terms of ‘offence to the senses’.

p

PM₁₀

Particulate matter with an aerodynamic diameter of less than 10 micrometres.

PM₂.₅

Particulate matter with an aerodynamic diameter of less than 2.5 micrometres.

Particulate Matter (PM)

A mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.

Pathway

The route that pollution takes from source to receptor.

Plant

Industrial, manufacturing or construction mechanical equipment or vehicles.

Predicted Environmental Concentration (PEC)

The PC plus the concentration of the substance already present in the environment.

Process Contribution (PC)

Concentration of a substance released into air from a specific process.

r

RIBA

Royal Institute of British Architects.

Ramsar site

A wetland site designated to be of international importance under the Ramsar Convention.

Rated Sound LAr,Tr (as used in BS4142:2014)

The specific noise level with adjustment for characteristic features of the noise (i.e. tonality, intermittency or impulsivity)

Re-radiated Noise (or ‘Ground-borne Noise’)

Ground-borne vibration can cause room walls, floors and ceilings to radiate noise in the audible frequencies. This type of noise is often referred to as ground-borne noise. Mechanical plant may also generate structure-borne vibration that is reradiated as noise.

Receptor

Anything that may be sensitive to changes in environmental conditions.

Residual Sound (as used in BS4142:2014)

The sound remaining when the specific sound is inaudible (e.g. distant road traffic + wildlife)

Reverberation

The sound in a room or enclosed space that results from reflections from the room boundaries. The reverberation time (RT) is the time required for the steady sound pressure level in an enclosed space to decay by 60dB.

Risk

The likelihood of an adverse event occurring.

Road link

A broadly uniform length of road, in terms of width, plus traffic volume and speed.

Root Mean Square Error (RMSE)

A measure of the average difference between values predicted by a model and the actual values. It provides an estimation of how well the model is able to predict the target value (accuracy); the lower the value of the RMSE, the better the model is.

Rw (Weighted sound reduction index)

The weighted sound reduction index is a single number laboratory-measured rating used to describe the sound insulation performance of building elements.

R′w (Apparent weighted sound reduction index)

Similar to Rw but measured onsite. R′w normally tends to be lower than the laboratory rated Rw level due to onsite conditions.

s

Site of Special Scientific Interest (SSSI)

A protected area in the United Kingdom and Isle of Man. Sites notified for their biological interest are known as Biological SSSIs and those notified for geological or physiographic interest are Geological SSSIs.

Sniff test

An onsite olfactory survey using the human nose. This gives a semi-quantified measure of odour FIDOL factors and can subsequently be used to inform an assessment of the risk of impacts at receptors.

Sound

The transmission of vibrations through a medium such as air or water.

Sound Absorption

The process whereby sound energy is converted into heat, leading to a reduction in the sound pressure level. Directly related to reverberation in an enclosed space, i.e. more absorption = lower reverberant level and shorter reverberation time.

Sound Insulation

A general term referring to the degree by which a material or separating construction reduces sound energy passing through it.

Special Area of Conservation (SAC)

Protects one or more special habitats and/or species listed in the Habitats Directive.

Special Protection Area (SPA)

Protects one or more rare, threatened or vulnerable bird species listed in Annex I of the Birds Directive, or certain regularly occurring migratory species.

Specific Sound (as used in BS4142:2014)

The sound arising from the source being assessed (e.g. an air conditioning unit).

Street canyon

Narrow streets lined by continuous building facades, generally where the height of buildings on both sides of the road is greater than the road width, leading to the recirculation of air flow that can trap pollutants and limit dispersion.

t

TEMPro - Trip End Model Presentation Programme

Provides factors for the growth of traffic flows of future scenarios.

TVOCs

Total Volatile Organic Compounds.

TfL - Transport for London

The government body responsible for most of the transport network in London.

u

Uncertainty

There are various sources of potential error within the air quality assessment process. Modelling uncertainty may arise from:
• Model uncertainty – due to model formulations;
• Data uncertainty – due to errors in input data, including emissions estimates, background estimates and meteorology; and
• Variability – randomness of measurements used

v

Validation

The general comparison of modelled results against monitoring data carried out by model developers.

Verification

Comparison of modelled results versus any local monitoring data at relevant locations to ensure a robust assessment.

w

World Health Organisation (WHO)

The United Nations agency that connects nations, partners and people to promote health, keep the world safe and serve the vulnerable. The WHO leads global efforts to expand universal health coverage and direct and coordinate the world’s response to health emergencies.

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µg/m³

Microgrammes per cubic metre, a measure of the mass of a pollutant per volume of air.

µg/m³ micrograms per cubic metre

A measure of concentration in terms of mass per unit volume. A concentration of 1µg/m³ means that one cubic metre of air contains one microgram (millionth of a gram) of pollutant.

Glossary

a