A multiple linear regression model was developed for the prediction of ozone, sulphur dioxide and carbon monoxide concentrations in Hyytiälä Forestry Field Station. Each parameter is expressed as a linear function of values from model. Coefficients of linear functions are calculated by minimizing the sum of the squares of the distances from each data point to the plane in multidimensional space. Mean relative reduction of RMSE (root mean square error) of ozone concentrations is 10%, mean relative reduction of RMSE of carbon monoxide concentration is 60% , mean relative reduction of RMSE of sulphur dioxide is 12%.