Near real-time information on air quality data and ozone forecast by UBA

• Agglomeration: means a zone with a population of more than 250.000 inhabitants or, where the population is 250.000 inhabitants or less, a population density per km² exceeding a Member State specific threshold. The threshold is to be defined by the Member States so that it justifies the need for air quality to be assessed and managed.
• Alert threshold: means a level above which there is a risk to human health from brief exposure. The Member States have to take immediate steps as laid down in Directive 96/62/EC.
• Ambient air: means air in the troposphere, excluding work places.
• AOT40 (accumulated exposure over a threshold of 40 ppb): means the sum of the differences between hourly concentrations greater than 80 µg/m³ (= 40 parts per billion) and 80 µg/m³ over a given period using only the 1 hour values measured between 8:00 and 20:00 (Central European Time) each day. The value is expressed in µg/m³×h.
• Assessment: means any method used to measure, calculate, predict or estimate the level of pollutants in ambient air.
• Assessment threshold: A distinction is drawn between
  • Upper assessment threshold: means a level below which a combination of measurements and modelling techniques may be used to assess ambient-air quality.
  • Lower assessment threshold: means a level below which modelling or objective estimation techniques alone may be used to assess ambient-air quality.
• Emission: means any air pollution originating from an installation (cf. Immission).
• Emission inventory: documentation of emissions
• Exposure: means exposure of humans or the environment to pollution. An exposure does not necessarily result in sickness, but can be the cause of damage or disease.
• Fixed measurements: means measurements by measuring instruments in fixed measurement facilities. In contrast to fixed measurements, mobile measurements are carried out using road vehicles.
• Immission: means any air pollution which affects human beings, animals, plants, soil, water, the atmosphere or cultural objects and other material goods (cf. Emission).
• Level: means the concentration of a pollutant in ambient air or the deposition thereof on surfaces in a given period.
• Limit value: means a level fixed on the basis of scientific knowledge, with the aim of avoiding, preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained within a given period and not to be exceeded once attained.
• Long-term objective: means the concentration of a pollutant in ambient air below which, according to current scientific knowledge, direct adverse effects on human health and/or the environment as a whole are unlikely. This objective is to be attained in the long term. The required measures should be proportionate to their contribution to the environmental objective.
• Margin of tolerance: means the margin by which the limit value for a pollutant may be exceeded, subject to the conditions laid down in Directive 96/62/EC. The margins of tolerance are reduced annually and apply in the European Member States until the limit values become mandatory.
• Oxides of nitrogen: means the sum of nitric oxide (NO) and nitrogen dioxide (NO₂) added as parts per billion and expressed as nitrogen dioxide in micrograms per cubic meter.
• Ozone precursors: are defined as substances, which contribute to the formation of ground level ozone. Ozone precursors include nitrogen oxides (NO_x) and volatile organic compounds (VOC).
• Particles: dust particles.
• Particulate matter (PM₁₀): means dust particles which pass through a size-selective inlet with a 50 % efficiency cut-off at 10 µm aerodynamic diameter.
• Pollutant: means any substance, which is emitted directly or indirectly by man into the ambient air and likely to have harmful effects on human health and/or the environment as a whole.
• Pollutant formation:
  • Primary pollutant: directly emitted from natural (for example formation of dust after volcanic eruptions) or anthropogenic sources.
  • Secondary pollutant: formed from precursor substances (e.g. ozone).
• Reference method: means a method recommended for measurement. Any other measuring method must demonstrate equivalence with the reference method.
• Target value: means a level fixed with the aim of avoiding long-term harmful effects on human health and/or the environment as a whole, to be attained where possible in a given period.
• Volatile organic compounds (VOC): means all organic compounds from anthropogenic and biogenic sources, with the exception of methane, which are capable of producing photochemical oxidants by reactions with nitrogen oxides in the presence of sunlight. EU Directive 2002/3/EC recommends a number of these compounds for measurement for the purpose of gaining a better understanding of ozone formation and precursor dispersion processes.
• Zone: means part of the territory of a Member State delimited by it.

Abbreviations

Units

Air pollutants

Organisations

List of volatile organic compounds recommended for measurement (Directive 2002/3/EC)