Consequences of a change in Air Quality
Human Health
Air pollution can have short-term and long-term effects on human
health. The size of the effect will vary depending, among other
things, on the concentration of the pollutant(s) and the period and
types of exposure. An individual's exposure to pollutants can vary
greatly. Some people will receive exposure to certain types of air
pollutant while at work; others, such as the elderly and parents
with young children, will receive the majority of their exposure
from pollutants inside the home; whereas for others, who work
predominantly outdoors, exposure to outdoor pollutants will be
particularly relevant. Overall, air pollution is viewed as one of a
number of factors, such as lifestyle choices (e.g. smoking),
respiratory infections, exposure to airborne allergens, 'flu and
extremes of temperature that can affect our health.
For the most part, healthy individuals will not notice or suffer
from any serious or lasting ill effects from levels of pollution
that are commonly experienced in Scotland, even when levels are
described as 'high' or 'very high'. However, it should be borne in
mind that our knowledge of the effects of air pollutants on
individuals as a result of their exposure both in the home and at
work is still incomplete.
People with existing cardiovascular and lung conditions may be
adversely affected by day-to-day changes in the levels of air
pollutants, however, air pollution should be regarded as one of a
number of factors that may affect people with breathing disorders.
In practice, people with asthma are unlikely to know for certain
whether an attack has been triggered by air pollution alone or by a
combination of factors. The number of deaths and hospital
admissions that occur each day varies and both seem to go up when
air pollution levels are high, particularly for individuals with
these conditions and especially among the elderly. On the basis of
current evidence, deaths in such cases are probably brought forward
by a matter of weeks or months rather than years. A report
published by the Committee on the Medical Effects of Air Pollutants
in 2010 suggests that long-term exposure to air pollution is
unlikely to be a direct cause of asthma, but it may exacerbate the
symptoms of existing cases.
Food Production
There is some evidence to suggest that high ozone concentrations
can reduce crop yields; although the precise mechanisms are still
unclear. Effects include visible damage and the early die-back of
leaves (Air
pollution information system).
Ecosystem Health
Although protection of human health is the main focus of air
quality policy in Scotland, air pollution can also have adverse
effects on the natural and built environments. The Air Quality
Strategy sets objectives for nitrogen oxides (NOx) and sulphur
dioxide (SO2) for protection of vegetation and
ecosystems, based on a critical levels approach, i.e.
concentrations of pollutants in air above which damage to sensitive
plants and habitats may occur. Critical loads (the acid deposition
load that will not lead to harmful effects) have been used to
assess the risks to habitats from acidification and eutrophication.
In addition to NOx and SO2, the other main pollutants of
concern for vegetation and ecosystems are ammonia (NH3)
and ozone (O3). Currently, these objectives are being
met across Scotland in the non-built-up areas. They do not apply in
built-up areas.
Cultural Heritage
Historically, high pollutant concentrations in urban areas,
notably black smoke and sulphur dioxide, caused significant damage
to the fabric of buildings. Following the rapid decline in levels
of these pollutants over recent decades, this is no longer a major
issue of concern, although the impacts are still clearly
visible.