INTRODUCTION

According to the WHO, 3 millions of people die every year under the effect of the air pollution. The real number of the yearly deaths could be located between 1.4 and 6 millions.

Mortality by asthma increased practically in all countries of the world. In USA, it increased 118% enters 1980 and 1993. The hospitalization for asthma increased in practically all western countries. The prevalence of the asthma increased in the countries of North Africa in realized studies these last 20 years.

Important interactions exist between the genetic and environmental factors in allergic diseases. Among the environmental factors, the atmospheric pollution and the modifications of the life style occupy a non negligible place currently.

SOURCES OF POLLUTION

Oxides of nitrogen and the ozone: 70% of the carbon monoxide comes from the automotive circulation. The ozone comes from the processes of photooxydation. The tips of pollution corresponding in the cities to good weather

Dioxide of sulfur SO2: comes of the combustion of containing fossil fuels of sulfur (heavy fuel, coal, diesel). In presence of humidity, it forms the sulphuric compounds that contribute to the acidic rains and the deterioration of the fabrication stone. It is a good indicator of a complex "acido-particulate pollution."

Particles in suspension: It is a complex of organic or mineral substances. We distinguishes the "fine particles" (PM10, PM2.5) coming from the combustion (diesels) or of condensed industrial steams and the" big" particles coming from the pavements or other industrial dismissals.

Carbon monoxide results from the incomplete combustion of the fuels used in the vehicles, when the motor turns in an enclosed space or when there is a concentration of vehicles that rolls slow-motion in the covered spaces

Volatile organic compounds (VOC) are recovered in the hydrocarbons coming from the oil ferries of storage, at the time of the replenishment of the automotive reservoirs or at the time of some industrial processes or organic compounds given out by agriculture and the natural habitat. They intervene in the process of ozone formation in the low atmosphere.

ASSESSMENT OF THE IMPACT

The most vulnerable people to the pollution are already people, asthmatic or allergic, the children of less than 3 years and the aged people. 2 types of pollution exist according to their impact

The assessment of this impact can make itself by short-term or long-term studies:

Several scorers of the effect of the air pollution are used as well to the epidemiological level (Respiratory mortality, cost of cares, exacerbations of the asthma) that to the experimental level (broncho-pulmonary inflammation, change of the pulmonary morphology, change of the defense systems)

EPIDEMIOLOGICAL STUDIES

A big European Survey having interested more 25 millions of inhabitants during 14 years showed an interrelationship between the level of pollution (ozone, fine particles and dioxide of nitrogen) and the respiratory symptoms in particular between the admissions in emergency for respiratory symptoms and the exacerbations of the asthma. Another survey having interested 7500 schoolchildren in Germany and having compared 18 sites to dense circulation and 16 to middle or weak traffic put in evidence a meaningful interrelationship between the intensity of the traffic and the symptoms of the asthma. A meaningful interrelationship has also been noted between the risk of atopy, the bronchial hyperreactivity degree and the proximity of a zone polluted in a transverse survey having interested a cohort of 670 children.

Other studies analyzed each of the pollutants and its role in the asthmatic disease in particular the fine particles, the dioxide of nitrogen and the ozone among asthmatic subjects or having a vulnerable land predisposing to the asthma with setting in evidence of a positive interrelationship between the level of these pollutants and the exacerbation of the symptoms, the deterioration of the respiratory function or the accentuation of the bronchial hyperreactivity

EXPERIMENTAL STUDIES

Several studies were about the action of the pollutants on inflammatory cells, cellular interaction, mediators, the epithelium respiratory and that show a relation between the exposition to the pollutants and the modification of the these parameters. Other studies were interested in the interaction pollen-pollutant and showed the role of pollutants in particular the particles of diesel in the increase of the allergenic power of different types of pollen.

CONCLUSION

The outdoor pollution seems to aggravate the respiratory symptoms among the atopic subjects. The acute and chronic exposition to pollutants as the NO2, l‘O3, and PM increase the response to the aeroallergens among predisposed subjects. The pollutants can themselves to modify the allergenic potential of the pollens.

création: décembre 2006