1. Ambient air - air in the troposphere, with the exception of the jobs, as defined by Government Decision no. 1.091 / 2006 on the minimum safety and health requirements for the workplace, where the public has no access rule for which the provisions on health and safety at work (Law 104/2011 on ambient air quality)

2. Pollutant - any substance present in ambient air and likely to have harmful effects on human health and / or the environment as a whole (Law 104/2011 on ambient air quality)

3. Level - concentration of a pollutant in ambient air or the deposition thereof on surfaces in a given period of time (Law 104/2011 on ambient air quality)

4. Evaluation - any method used to measure, calculate, predict or estimate levels (Law 104/2011 on ambient air quality)

5. Limit value - the level set based on scientific knowledge in order to avoid and prevent the occurrence of events and reducing harmful effects on human health and the environment as a whole, which is reached in a given period and not to be exceeded once was reached (Law 104/2011 on ambient air quality)

6. Critical level - the level set based on scientific knowledge, which if exceeded direct adverse effects may occur on some receptors, such as trees, plants or natural ecosystems but not on humans (Law 104/2011 on ambient air quality )

7. Margin of tolerance - the percentage of the limit value by which that value may be exceeded under the conditions set out in this law (Law 104/2011 on ambient air quality)

8. Air quality plans - plans setting out measures to achieve the limit values or target values (Law 104/2011 on ambient air quality)

9. Target value - the level set in order to avoid and prevent the occurrence of events and reducing harmful effects on human health and the environment as a whole, which should be achieved as far as possible in a given period (Law 104/2011 on ambient air quality)

10. Alert threshold - the level which, if exceeded, there is a risk to human health from brief exposure to the population in general and the need to act immediately (Law 104/2011 on ambient air quality)

11. Information threshold - the level which, if exceeded, there is a risk to human health from brief exposure for particularly sensitive sections of the population and for which immediate and appropriate information is necessary (Law 104/2011 on ambient air quality )

12. Upper assessment threshold - the level below which to assess ambient air quality, you can use a combination of fixed measurements and modeling techniques and / or indicative measurements (Law 104/2011 on ambient air quality)

13. Lower assessment threshold - the level below which to assess ambient air quality is sufficient to use modeling techniques or objective estimation (Law 104/2011 on ambient air quality)

14. The long term goal - the level which must be achieved in the long term, unless this is not achievable through proportionate measures in order to ensure effective protection of human health and the environment (Law 104 / 2011 on ambient air quality)

15. Contributions from natural sources - emissions of pollutants not caused directly or indirectly by human activities, including natural events such as volcanic eruptions, seismic activities, geothermal activities, wild land fires, storms, marine aerosols resuspension or transport atmosphere of natural particles originating from dry regions (Law 104/2011 on ambient air quality)

16. Zone - part of the national territory delimited in order ambient air quality assessment and management (Law 104/2011 on ambient air quality)

17. Agglomeration - area that is a conurbation with a population of over 250,000 inhabitants or, where the population is less than or equal to 250,000 inhabitants, with a population density per km2 more than 3,000 inhabitants (Law 104/2011 on ambient air quality)

18. PM10 - particulate matter which passes through a hole the size selection, as defined in the reference method for sampling and measurement of PM10, SR EN 12341 with a 50% efficiency cut aerodynamic diameter 10 micrometers (Law 104/2011 on ambient air quality)

19. PM2.5 - particulate matter which passes through a hole the size selection, as defined in the reference method for sampling and measurement of PM2.5; SR EN 14907 with a 50% efficiency cut-off aerodynamic diameter of 2.5 micrometers (Law 104/2011 on ambient air quality)

20. The average exposure indicator - the average level determined on the basis of measurements at urban background locations throughout the country and offers clues on population exposure. It is used to calculate the national exposure reduction target and the exposure concentration obligation on (Law 104/2011 on ambient air quality)

21. The obligation on the exposure concentration - the level set on the basis of the average exposure indicator with the aim of reducing harmful effects on human health, to be attained in a given period (Law 104/2011 on ambient air quality)

22. The national target for reducing exposure - the percentage reduction of the average exposure of the population, set for the reference year with the aim of reducing harmful effects on human health, which must be attained where possible over a given period ( Law 104/2011 on ambient air quality)

23. Locations urban background - places in urban areas where levels are representative of the exposure in general urban population (Law 104/2011 on ambient air quality)

24. Nitrogen oxides - the amount of volume concentrations (ppbv) of nitrogen monoxide (nitric oxide) and nitrogen dioxide expressed in units of mass concentration of nitrogen dioxide (micrograms / cubic meters) (Law 104/2011 on ambient air quality )

25. Fixed Measurements - measurements taken at fixed sites either continuously or by random sampling to determine the levels in accordance with the relevant data quality objectives (Law 104/2011 on ambient air quality)

26. Indicative measurements - measurements which meet data quality objectives that are less strict than those required for fixed measurements (Law 104/2011 on ambient air quality)

27. Volatile organic compounds VOC - organic compounds from anthropogenic and biogenic sources, other than methane, which can produce photochemical oxidants by reaction with nitrogen oxides in the presence of sunlight (Law 104/2011 on ambient air quality)

28. Ozone precursor substances - substances that contribute to the formation of ozone at ground level (Law 104/2011 on ambient air quality)

29. Total deposits or gained - the total amount of pollutants which is transferred from the atmosphere to surfaces such as soil, vegetation, water, buildings, etc., to a certain area in a certain time (Law 104/2011 on quality ambient air)

30. Arsenic, cadmium, nickel and benzo (a) pyrene - the total amount of these elements and compounds contained in PM10 fraction (Law 104/2011 on ambient air quality)

32. Polycyclic aromatic hydrocarbons - organic compounds consisting entirely of carbon and hydrogen, composed of at least two fused aromatic rings (Law 104/2011 on ambient air quality)

33. The total gaseous mercury - elemental mercury and mercury gaseous radicals, for example water soluble mercury compounds which have a sufficiently high vapor pressure to exist in the gas phase (Law 104/2011 on ambient air quality)

34. The protection zone - the area of land surrounding the point where metering is fixed, so any activity defined within it, then installation of measuring equipment, do not affect the representativeness of ambient air quality data for which it was location (Law 104/2011 on ambient air quality)

35. Holder of activity - any natural or legal person who operates, controls or is delegated decisive economic power on an activity with potential impact on ambient air quality (Law 104/2011 on ambient air quality)

36. Fugitive emissions - emissions unguided released into the ambient air through windows, doors and other openings, ventilation systems or opening that normally falls in the category routed sources of pollution (Law 104/2011 on ambient air quality)

37. Emissions from stationary sources - emissions released into the ambient air equipment, installations, including ventilation in construction activities from other works that produce or fixed through which discharged pollutants (Law 104/2011 on ambient air quality)

38. emissions from mobile sources of pollution - emissions released into the ambient air from transport by road, rail, sea and air, non-road mobile machinery fitted with internal combustion engines (Law 104/2011 on ambient air quality)

39. Releases from diffuse sources of pollution - emissions released into the ambient air undirected emission sources of air pollutants, such as sources of fugitive emissions, natural sources of emissions and other sources not specifically defined (Law 104/2011 on quality ambient air)