Local authorities, health and environment
WHO/EURO Home page


Monet Thames

Pollutants in the air can create smog(1) and acid rain, cause respiratory or other serious health illnesses, damage the protective ozone layer in the upper atmosphere, and contribute to climate change. Air pollutants can be particularly harmful to people belonging to high - risks groups such as children and the elderly.
It is estimated that 30 - 40% of Europeans living in cities are exposed to average concentrations of air pollutants such as sulphur dioxide and nitrogen dioxide that are above WHO or European Union (EU) guidelines (EEA, 1997). However, not everyone who lives in such areas will have health problems. Level, extent, and duration of exposure, age, individual susceptibility, and other factors play a significant role in determining whether or not someone will experience pollution-related health problems.
Air pollution is a general term used to describe the mixture of substances that are naturally or artificially introduced into the air. The most well-documented of these substances (and those usually monitored on a routine basis) include sulphur dioxide (SO2), nitrogen oxides (NOx, including NO and NO2), carbon monoxide (CO), ozone (O3), lead (Pb), and total suspended particles (TSP) also known as suspended particulate matter (SPM) or black smoke (BS).

The air we breathe
An active person inhales 10,000-20,000 litres of air each day - about 7-14 litres per minute, although a person taking strenuous physical exercise (e.g. jogging) may inhale up to 50 litres of air per minute. A 3 year old child at rest inhales twice as much air per unit body weight than an adult; thus as their airways are narrower, and their lungs still developing, problems as a result of breathing in pollutants are likely to be more serious and longer lasting.

Air composition
Air is a mixture of gases in the lower atmosphere. Dry air at sea level is composed in volume of nitrogen (78.08%), oxygen (20.95%), argon (0.93%), carbon dioxide (0.03%), together with very small amounts of other gases. Water vapour is found in variable concentrations.

The major sources of these pollutants are the combustion of fossil fuels (for energy generation, industrial processes and transportation), and of solid fuels, such as coal and wood, for domestic purposes. Air pollution is different from other forms of pollution in that, once the pollutants are in the air, exposure cannot be easily avoided. If high levels of outdoor air pollution are occurring in a city, it may be expected that a large proportion of the population will be exposed.
Levels of air pollution may vary markedly even at the local level, especially in the case of ground-level emissions (e.g. from road transport). Short-term variations in pollution levels will also occur due to variations in emission activity. The level of total human exposure will vary depending on the proportion of time one spends outdoors, the ability of the individual pollutants to enter the indoor environment and the levels of pollutants generated indoors from cookers, paints, furnishings and building materials. Most people spend a much larger proportion of their life indoors than outdoors. Therefore indoor air pollution is a significant public health problem, especially for children.

(1) smog= smoke and fog


Document Actions