The effects of air pollution

Most air pollutants are capable of affecting human and animal health and of damaging plant life and materials. The incurred effects depend on the nature of the compounds, their concentration and exposure times.

Effects on human health generally include risks linked to "pollution peaks", periods of high concentrations localised in time and space, effects linked to chronic pollution (background pollution) i.e. prolonged exposure to pollutants at lower concentrations. Certain organisms are more susceptible than others, in particular people with chronic respiratory disorders, and young children and the elderly.

In Auvergne, when weather conditions are particularly unfavourable, concentration peaks can approach or exceed certain regulatory thresholds. The most common acute effects mainly trigger eye, nose or throat irritations resulting in respiratory and bronchial difficulties, and often lead to asthma attacks.

The severity of chronic effects is still widely debated and a number of epidemiological studies have agreed on the existence of a risk factor due to urban pollution breathed on a daily basis (impaired respiratory function, increase in the risks of cardio-vascular mortality, and cancer).

The effects of air pollution on plant life are mainly visible as lower yield rates. Several studies have quantified the harmful effects of oxidising atmospheres containing high concentrations of ozone and other photochemical pollutants. In addition, the chemical transformation of certain gaseous pollutants (nitrogen and sulphur oxides in particular) in the presence of moisture increases rainfall acidity, thereby contributing to forest decline.

Materials, and therefore all buildings, monuments or building facades are subject to significant damage linked to air pollution, in particular due to acid rain (erosion of building stones, damage to paintings, corrosion of zinc roofing materials, etc.) and the deposition of particulate matter (blackening). When this damage is not irreparable, it results in major heritage restoration efforts and resurfacing of facades.

On a larger scale, there is the problem of the probable increase in the greenhouse effect, which is currently the subject of a great deal of incertitude on the future of the climate. While carbon dioxide, which by the way is not in itself a toxic substance, is the main culprit, ozone and other substances produced indirectly via photochemical reactions also play a major role in the process.