Out study was designed to investigate the levels of air pollutants in the environment of Bejaia (Algeria) and the effects of meteorological factors. The present investigation includes measurements of carbon monoxide, nitrogen monoxide and sulphur dioxide during the period of March 2005 to December 2006. The measurements were realized near six polluting areas: a heavy traffic area, a public discharge and 4 factories (wood, tar, cork, ceramic). We measured simultaneously the emissions of the three pollutants at chimney exits and at different distances from the sources. The regression between concentration and distance is an exponential decrease. The amount of pollution in the chimney and in the immediate environment sometimes exceeds the thresholds dictated by regulations. Meteorological effects are also studied. Pollutant levels have an inverse relationship to wind speed. Also, the relationship of humidity with SO₂ and NO indicate the ability of the acid gases to form sulphuric acid and nitric acid in the atmosphere of Bejaia. The increase in ambient temperature causes a decrease of CO level and an increase of NO and SO₂ levels. The diurnal and seasonal variations of air pollution showed that measured concentrations are strongly correlated with industrial activity and heavy traffic in the centre of Bejaia city. Applying the Box-Jenking method to the measured pollutant concentrations during 2006, we established a forecasting model for the following year.