Annex A2 - Ambient Air Quality Standards

8.1 Background
The huge social and economic costs associated with human exposure to air pollution are now widely recognised. As a consequence, most developed (and many developing) economies now have introduced maximum exposure levels, either a goals or, in some cases, mandatory limits.
A 2005 World Health Organisation (WHO) study confirmed that the developed world is not immune from the consequences of air pollution. The research concluded that exposure to current PM levels reduces the life expectancy of every person in the EU by an average of nine months, and has a direct economic impact of up to €161 billion (US$220 billion) every year. (WHO, 2005-1) Although not mandated in law, the World Health Organisation (WHO) has published guidelines for a range of pollutants (WHO, 2005-2), including recommended maximum exposure levels. In common with the other regulated and recommended limits discussed in this Section, the WHO recommendations are framed as average pollutant concentration over a specified time period (for example micrograms per cubic metre <μg/m3> over a 24-hour period).
In the USA, for instance, standards for ambient air pollution levels are set through the Clean Air Act. The Act is a federal law covering the entire country, but regional governments at both the state and local level required to implement many of the act's requirements. Under the Clean Air Act the US Environmental Protection Agency (EPA) sets limits on a range of air pollutants to help ensure a degree of health and environmental protection to the population.
The Act also gives the EPA powers to intervene at a local level in cases where individual pollution sources such as chemical plants or other industrial activities create an excessively high source of pollution. Although state and local authorities are responsible for implementing much of the activities required under the Act, the EPA may nevertheless intervene and issue sanctions against the state or local agencies, and if necessary can take over enforcement actions in that area.
A set of European Union exposure limits are being phased in over the period 2010 to 2015. They are generally consistent with the approaches taken in other jurisdictions, and also with the WHO
recommendations discussed below.
Actual recommended and mandated exposure limits for each of the above examples are tabulated in Section 8.2 below.
Pollutants tabulated in Section 8.2 are of particular significance because whole populations are
exposed to them in the air we breathe, but it should be noted that many other pollutants are
extremely hazardous and, in circumstances where higher local concentrations occur, can also
represent a severe health risk.
8.2 Air Quality Standards and Regulations


Four pollutants have been identified by the WHO as having the greatest net impact on human health.
These are tabulated below (Table 8.1), together with the recommended guideline limits.

Pollutant Exposure limit Averaging period
Particulate matter (PM10) * 50 μg/m3 24-hour mean
Particulate matter (PM10) 20 μg/m3 annual mean
Particulate matter (PM2.5) ** 25 μg/m3 24-hour mean
Particulate matter (PM2.5) 10 μg/m3 annual mean
Ozone (O3) 100 μg/m3 8-hour mean
Nitrogen Dioxide (NO2) 40 μg/m3 annual mean
Nitrogen Dioxide (NO2) 500 μg/m3 1-hour mean
Sulphur Dioxide (SO2) 20 μg/m3 24-hour mean
Sulphur Dioxide (SO2) 500 μg/m3 10-minute mean
* PM10 means particles with an aerodynamic diameter smaller than 10 microns (μm)
** PM2.5 means particles with an aerodynamic diameter smaller than 2.5 μm
Table 8.1: WHO Exposure Guidelines for Key Pollutants
These guidelines represent recommended exposure limits, but many cities have ambient air PM2.5
levels that exceed the maximum recommended levels by a factor of five or more. Even worse,
measurements taken where wood fires are used for indoor cooking (Park, 2003) found PM2.5
concentrations that sometimes exceeded 8,000μg/m3 – over 300 times higher than the WHO 24-hour
limit. This situation is probably repeated in many regions around the world.
Recognising the damage created by air pollution, in addition to its 2005 legislation the European
Union is now phasing in a new set of legislated exposure limits. Table 8.2 summarises the coverage of some of these Directives, most of which become mandatory over the period 2010 to 2015. (In some instances member states can apply for extensions of up to five years).
More information on the implementation of these regulations can be found at
http://ec.europa.eu/environment/air/quality/standards.htm Pollutant Exposure Limit Averaging period Fine particles (PM2.5) 25 μg/m3 1 year Sulphur dioxide (SO2) 350 μg/m3 1 hour Sulphur dioxide
(SO2) 125 μg/m3 24 hours
Nitrogen dioxide (NO2) 200 μg/m3 1 hour
Nitrogen dioxide (NO2) 40 μg/m3 1 year
PM10 50 μg/m3 24 hours
PM10 40 μg/m3 1 year
Lead (Pb) 0.5 μg/m3 1 year
Carbon monoxide (CO) 10 mg/m3 Max daily 8 hr mean
Benzene 5 μg/m3 1 year
Ozone 120 μg/m3 Max daily 8 hr mean

Polycyclic Aromatic Hydrocarbons 1 ng/m3 1 year
Table 8.2: European Union Air Quality Standards The ambitious targets now being set generate many challenges, as they not only take effect over relatively short lead times, but they also include a broader range of pollutants. Fortunately, many industries now accept that accelerated development of more efficient and lower polluting vehicles,
machinery and industrial processes, using cleaner fuels, is now a business imperative.
The following table summarises the US EPA’s ambient pollution limits established under the Clean Air Act (http://www.epa.gov/air/criteria.html). The limits are generally in line with those promulgated by the European Union (Table 8.2), and those recommended by the WHO (Table 8.1).
Pollutant Level Averaging Time
Carbon Monoxide 9 ppm (10 mg/m3) 8-hour
Carbon Monoxide 35 ppm (40 mg/m3) 1-hour
Lead 0.15 μg/m3 Rolling 3-Month Average
Nitrogen Dioxide 0.053 ppm (100 μg/m3) Annual (Arithmetic Mean)
Particulate Matter (PM10) 150 μg/m3 24-hour
Particulate Matter PM2.5) 15.0 μg/m3 Annual (Arithmetic Mean)
Particulate Matter (PM2.5)[24
hr]
35 μg/m3 24-hour
Ozone [8hr] 0.075 ppm (2008 std) 8-hour
Ozone [1hr] 0.12 ppm 1-hour
Sulphur Dioxide 0.03 ppm Annual (Arithmetic Mean)
Sulphur Dioxide 0.14 ppm 24-hour
Table 8.3: USA Clean Air Act - Ambient Pollutant Limits
Many other countries have similar limits or targets, some of which are based on either the WHO or the US limits.
China, for instance, has air quality standards which generally fall between the WHO and the US
levels. However, the Chinese standards do not include PM2.5, which is one of the most critical
pollutants from a health perspective.
Australia's ambient air quality standards, which were promulgated in June 1998 are legally binding on each level of government, and were required to be met by the year 2008. The latest State compliance reports, tabled in 2006, show generally good progress has been achieved, but many States still reported at least several non-compliance areas. Ozone and PM10 appear to be the pollutants where the greatest level of non-compliance exists.