The Politics of Air Pollution
It is a fact that many things that are regarded as important to modern life also produce significant and potentially life shortening air pollution - petrol and diesel engines, industrial processes, burning of all kinds from domestic solid fuel stoves and fires, garden bonfires, to waste incinerators.
This presents a seemingly intractable dilemma for politicians at all levels who seem incapable of squaring the circle of how society currently functions versus how the consequent pollution affects our health.
National and International Standards for Air Pollution
There are UK, EU and WHO limit values, international standards, for the currently recognised forms of air pollution.
Whilst the WHO speaks of "guidelines" in its rather dated document on air pollution at http://www.who.int/mediacentre/factsheets/fs313/en/, the UK DEFRA document from the early 2000s talks of "targets" and objectives", see https://uk-air.defra.gov.uk/assets/documents/Air_Quality_Objectives_Update.pdf, it is only the EU document that sets out "targets" followed up by legal limit values (which are currently binding on the UK but for how long?) See http://ec.europa.eu/environment/air/quality/standards.htm .
The Reality ...
Local authorities are required to (or, at least, should ...) declare AQMAs, air quality management areas, where areas under their jurisdiction consistently exceed the EU air pollution limits. But the reality is that the exceedances are sometimes gross, and the local authority is simply incapable of bringing things back into compliance. DEFRA's reports such as https://uk-air.defra.gov.uk/library/annualreport/ are mostly hand wringing, and the press drives home the reality https://www.theguardian.com/environment/2017/jan/06/london-breaches-toxic-air-pollution-limit-for-2017-in-just-five-days
Like radiation from radioactivity or x-rays, there are many who say there is no safe lower limit for the health effects of air pollution. A WHO report in the International Journal of Public Health admits this when it sets the lower threshold at the lowest background levels of PM2.5 that one might expect anywhere in Europe (5.8µg/m3). See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480843/ which also says " The Naess et al. (2007) paper shows a generally linear relationship between NO2 and mortality among 71–90 year olds, in the 20–60 µg/m3 range. Figure 1 in that paper actually shows a steeper CRF (concentration response function) in the 0–20 µg/m3 range, [but] with wider confidence intervals due to the smaller numbers of participants at such low exposures. The Cesaroni et al. (2013) paper continued to show a linear decline below 20 µg/m3, although again with wider confidence intervals."
A WHO report "Air Quality Guidelines" from as far back as 2005 says
This is backed up by the COMEAP reports issued by the UK Government - see https://www.gov.uk/government/publications/comeap-mortality-effects-of-long-term-exposure-to-particulate-air-pollution-in-the-uk
These levels should be compared to the EU limit value for PM2.5 particulates of 25µg/m3 with targets to reduce to 20µg/m3 and eventually 18µg/m3 as the annual average exposure, but note in the UK document that Scotland has set an annual limit of 10µg/m3. Note that there are no limits for shorter term exposure other than for PM10 which has a 24 hour limit of 50µg/m3. Note also that I am concentrating on particulates for reasons that will be clear in the section on Citizen Science, but similar arguments will apply for NO2.
Besides mortality, there are studies which suggest links between air pollution, particularly particulates, and alzheimer's disease, mental health, birth defects, and early birth. Links will be in the biography, and I will expand this section at some point.
So - the politics breaks both ways and is presented with a dilemma between the stability of business-as-usual, growth, etc, versus the real and increasingly quantifiable consequences of air pollution.