Consequences of a change in air quality

Human health

Busy City CentreAir Comment on this pagepollution 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.