Applications
Regulations applicable to outdoor ambient air
In terms of ambient air quality, different levels of regulations may apply: international, union of states (e.g., Europe, USA, etc.), national, or local. However, all these regulations share the same objectives:
Evaluate population and vegetation exposure to pollution,
Evaluate the effectiveness of actions taken by various authorities to limit pollution,
Inform the population about air quality.
At the international level:
Several international agreements have been concluded over the past five decades. These include:
The Geneva Convention on Long-Range Transboundary Air Pollution (1979),
The Montreal Protocol on Substances that Deplete the Ozone Layer (1987),
The Oslo Protocol on the Further Reduction of Sulfur Emissions (1994),
Protocols on heavy metals and persistent organic pollutants (POPs) adopted in Aarhus, Denmark, on June 24, 1998,
The Rio Convention on Climate Change (1992), followed by the Kyoto Protocol (1997), ratified by 141 countries in 2010, and the Paris Agreement ratified by 183 countries (2016).
Note: The Copenhagen Conference (December 2009) was intended to renegotiate an international climate agreement to follow the Kyoto Protocol, whose commitments ended in 2012. No strong consensus on the post-2012 climate regime could be reached. Negotiations are ongoing.
An international comparison of existing ambient air quality standards for six main atmospheric pollutants—ozone, particulates, sulfur oxides, nitrogen oxides, carbon monoxide, and lead—is presented in Table 1.
Pollutant | World Health Organization | European Union | Australia | United States | Canada | China (Class 1 / Class 2)* |
|---|---|---|---|---|---|---|
Ozone, O3 (\(µg/m^3\)) 8-hour Average | 100 | 120 | 160 | 160 | 130 | 100/160 |
Particles with an Aerodynamic Diameter < 10 µm, PM10 (\(µg/m^3\)) 24-hour Average | 25 | 50 | 25 | 65 | 30 | 40/70 |
Sulfur Dioxide, SO2 (\(µg/m^3\)) 24-hour Average | 21 | 125 | 208 | 365 | 300 | 50/150 |
Nitrogen Dioxide, NO2 (\(µg/m^3\)) 24-hour Average | 40 | 40 | 57 | 100 | 100 | 40/40 |
Carbon Monoxide, CO (\(µg/m^3\)) 8-hour Average | 10000 | 10000 | 10000 | 10000 | 15000 | - |
Lead, Pb (\(µg/m^3\)) Annual Average (in the \(PM_{10}\) fraction) | - | 0,5 | 0,5 | 1,5 | - | 0,5 |
Note : A dash (-) indicates that there is no regulation or guideline value associated with the specific pollutant. Class 1 standards apply to specific regions and national parks. Class 2 standards apply to all other areas, including urban and industrial zones. | ||||||
In Europe:
The first European directives date back to the early 1980s (Directive 80/779/EEC, known as the “SO2/Dust Directive”; Directive 82/884/EEC setting a maximum value for lead; and Directive 92/72/EEC on ozone).
In 1996, a framework for assessing and managing ambient air quality within the European Community, aimed at building a common strategy, was defined. The main objectives of this strategy are as follows:
Define and set ambient air quality objectives in the Member States (EU-28),
Obtain information on air quality in Member States based on common methods and criteria,
Preserve good ambient air quality where it exists and improve it in other cases.
The current directives on air quality include:
Directive 2004/107/EC of the European Parliament and Council amended on December 15, 2004, concerning arsenic, cadmium, mercury, nickel, and polycyclic aromatic hydrocarbons in ambient air (amended August 28, 2015);
Directive 2008/50/EC of the European Parliament and Council amended on May 21, 2008, on ambient air quality and cleaner air for Europe (amended August 28, 2015). This directive sets out monitoring requirements for various pollutants such as SO2, NO2, PM10 and PM2.5, O3, Pb, benzene.
The various guideline values and thresholds established for ambient air quality in EU Member States are presented in the following tables.
Pollutant | Limit Value | Alert Threshold | Critical Load |
|---|---|---|---|
Nitrogen Dioxide, \(NO_2\) | Annual Average: 40 µg/m³ Hourly Average: 200 µg/m³, not to be exceeded more than 18 hours per year | 400 µg/m³ exceeded for 3 consecutive hours | |
Nitrogen Oxides, NOx | Annual Average (as \(NO_2\)) : equivalent): 30 µg/m³ (for vegetation protection) | ||
Sulfur Dioxide, \(SO_2\) | Annual Average (for human health protection): 125 µg/m³, not to be exceeded more than 3 days per year 24-hour Average (for human health protection): 350 µg/m³, not to be exceeded more than 24 hours per year | 1-hour Average: 500 µg/m³ exceeded for 3 consecutive hours | Annual & Winter Average (for vegetation protection): 20 µg/m³ |
Lead, Pb | Annual Average (in \(PM_{10}\) fraction): 0.5 µg/m³ | ||
Particles with an Aerodynamic Diameter < 10 µm, \(PM_{10}\) | Annual Average: 40 µg/m³ 24-hour Average: 50 µg/m³, not to be exceeded more than 35 days per year | ||
Carbon Monoxide, CO | Maximum Daily 8-hour Average: 10,000 µg/m³ | ||
Benzene, \(C_6H_6\) | Annual Average: 5 µg/m³ |
Pollutant | Target Value | Long-term Objective | Recommendation and Information Thresholds | Alert Threshold |
|---|---|---|---|---|
Ozone, O3 | Human Health Protection: 8-hour average: 120 µg/m³, not to be exceeded more than 25 days per calendar year on average over 3 years Vegetation Protection: AOT40* from May to July, 8 a.m. to 8 p.m.: 18,000 µg/m³·h (average over 5 years) | Human Health Protection: Maximum daily 8-hour average: 120 µg/m³ per calendar year Vegetation Protection: AOT40* from May to July, 8 a.m. to 8 p.m.: 6,000 µg/m³·h | 1-hour Average: 180 µg/m³ | Information: 240 µg/m³ 1-hour average Mandatory Actions: 240 µg/m³ for 3 consecutive hours |
*AOT40 (expressed in (μg/m³)∙hour) refers to the sum of the differences between hourly concentrations exceeding 40 parts per billion (40 ppb, equivalent to 80 µg/m³), during a given period, using only 1-hour values measured daily between 8 a.m. and 8 p.m. (CET). | ||||
Pollutant | Limit Value | Target Value | Exposure Reduction Objective Relative to the AEI (Average Exposure Indicator)** 2011 | Exposure Concentration Obligation | |
|---|---|---|---|---|---|
Particles with a Maximum Aerodynamic Diameter of 2.5 µm, \(PM_{2,5}\) | Human Health Protection: Annual Average: Phase 1: 27.9 µg/m³ for 2011, decreasing annually to reach 25 µg/m³ in 2015 Phase 2: 20 µg/m³ by 2020* | Human Health Protection: Annual Average: (to be achieved by 2010): 25 µg/m³ | Initial Concentration: | Percentage Reduction Target: | 20 µg/m³ by AEI** 2015 |
≤ 8,5 µg/m³ | 0% | ||||
≥ 8,5 and < 13 µg/m³ | 10% | ||||
≥ 13 and <18 µg/m³ | 15% | ||||
≥ 18 and <22 µg/m³ | 20% | ||||
≥ 22 µg/m³ | All appropriate measures to achieve 18 µg/m³ | ||||
*To be reviewed by the European Commission in 2013 based on available information on health and environmental impact, technical feasibility, and experience gained from the target value in Member States. AEI: Average Exposure Indicator, defined as the three-year average of PM₂.₅ concentrations (e.g., AEI 2011 is the annual average concentration for the years 2009, 2010, 2011). | |||||
Pollutants | Target Value to be achieved by December 31, 2012* |
|---|---|
Arsenic, As | 6 ng/m³ |
Cadmium, Cd | 5 ng/m³ |
Nickel, Ni | 20 ng/m³ |
Benzo(a)pyrene (used as a marker for the carcinogenic risk of Polycyclic Aromatic Hydrocarbons - PAHs): 1 ng/m³ | 1 ng/m³ |
*Annual average of the total content in the PM₁₀ fraction. | |