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<\/p>\nJust as air quality varies depending on where you are in the world, so to do the air quality standards. In this blogpost we\u2019ll talk about the different standards in effect around the globe, how they compare, and who in the world has the toughest standards (as well as the weakest).<\/p>\n
What is an air quality standard?<\/h2>\n
An ambient air quality standard (AAQS) simply put is a limit on the amount of a given pollutant in the air. These standards are usually enshrined in national (or federal) law and are legally binding. The standards are designed to protect people\u2019s health and have been calculated to allow a margin for people most at risk e.g. the young and old and people with pre-existing health problems.<\/p>\n
Looking around the world, most AAQS cover a handful of key pollutants that are collectively referred to as \u2018criteria pollutants’:\u00a0 ozone, particulate matter, sulphur oxides, nitrogen oxides, carbon monoxide, and lead. Although countries often have standards for the same types of air pollutants, the limits themselves are quite different.<\/p>\n
Limits, targets and averages<\/h2>\n
An air quality standard may state a limit i.e. the level of pollutant x must not exceed amount y. Alternatively a standard may stipulate a target i.e. by year z the level of pollutant x must not exceed amount y. In some cases the air quality standards will have a mix of both.<\/p>\n
To further complicate matters, standards are under periodic review and the limits or targets may be reduced. This\u00a0link<\/a> shows how the US EPA\u2019s ozone standard has changed over the years, and a further reduction is now under review.<\/p>\n The other thing you will notice looking at international standards is that they contain a mix of averages and units. For example the US favours stating standards in part per million (ppm) whereas in the EU they state values in\u00a0\u00b5g\/m3. In some cases the limits are stated as an average over 1 hour, 8 hours or even 24 hours.\u00a0This variability makes inter-comparison more difficult.<\/p>\n The ambient air quality standards most often compared include those of the European Union, the United States, and the WHO. The WHO air quality standards are not legally binding; they are there as a guideline for countries who may or may not choose to adopt them. China\u2019s standards have also come under close scrutiny<\/a> in recent years.<\/p>\n The best comparison we have seen comes courtesy of the National Environmental Research Institute of Denmark<\/a>. In this analysis the AAQS of the EU, US and WHO are compared to those found in China, Japan, and Switzerland. A link to the complete analysis can be found here<\/a>.<\/p>\n A more succinct comparison has been produced by the David Suzuki Foundation. Their comparison chart is reproduced below with thanks.<\/p>\nHow do international standards compare?<\/h2>\n
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