Air pollution horizon-scanning: Seven potential risks of relevance to the UK

Horizon scanning is used to help identify potentially significant societal, economic or
technological shifts which if they occurred would have major impacts on society.
AQEG generally approaches the science and technology of air pollution either through
retrospective analyses – what has happened to air quality and why, - or via future
projections. These future projections are generally short to medium term and bounded by
well-established science, but it is alsoA QEG’s role to identify evidence gaps that include
uncertainties. It is valuable to periodically look beyond established evidence, towards
emerging science to identify potential perturbations and assess risks that might plausibly
lead to unexpected and large future air quality changes, for example those arising from
climatological, technological and behavioural shifts.
Since atmospheric chemistry is often non-linear in the generation of secondary pollutants
and has dependencies on weather and climate, there exists the potential also for chemical
and physical tipping points that may amplify changes in air quality (either positively or
negatively). Often unanticipated air quality outcomes occur not because of a single large
event but instead through the accumulation or interaction of multiple smaller changes.A ir
quality outcomes are closely linked to policy and regulation but also to hard-to-predict public
choices around transport, diet and lifestyle. A possible impact from these types of future
changes can be difficult to capture and often requires in-depth knowledge of the science
field.A lso noteworthy is that the chemical nature of air pollution is not fixed; it changes over
time as sources change reflecting wider regulatory, technological and social trends.
New perspectives can also arise from new scientific knowledge. The history of air pollution
science is littered with events and discoveries that revealed new risks and required rapid
evolution of regulation and policy. Examples include the great smog of London in 1952 and
the Clean Air Act of 1956, the discovery of the pervasive harm from lead additives in fuel
and the measurement campaigns of the 1970s that revealed that photochemical ozone was
not just confined to warmer climates but affected air quality in western Europe too. On the
health front research from the 1990’s revealed that the health-harm from long-term
exposure was far greater than that from short-term smog events laying the foundations for
modern air quality regulation.
AtA QEG meeting 66 a round-table discussion on the long-term future for air quality in the
UK was undertaken. Members each highlighted up to three areas of possibly underrecognised
significance in a horizon scanning context. The focus of the discussion was on
events, changes and processes that required specialist knowledge of the air pollution
science field to discern rather than more generalised high impact and extreme events on air
quality such as war and terrorism, chemical, biological, radiological or nuclear releases
(CBRN) or major chemical accidents. These latter types of events are already identified in
Defra Futures Team horizon scanning activities and more broadly are well-captured in the
Cabinet Office National Risk Register. A wide range of issues related to atmospheric
emissions, novel materials, human behaviours, monitoring, regulation, atmospheric
processes and social factors were discussed.
A number of consensus themes emerged which are summarised in this short note.