ground-level ozone (O3) has been a serious air pollution problem for several decades and in many metropolitan areas, due to its adverse impact on the human respiratory system. Therefore, to reduce the risks of O3 related damages, developing, maintaining and improving short term ozone forecasting models is needed. This paper presents the results of two prognostic models including gene expression programming (gEP), which is a variant of genetic programming (gP), and multiple linear regression (MLR) to forecast ozone levels in real-time up to 6 hours ahead at four stations in Bilbao, Spain. The inputs to the gEP were meteorological conditions (wind speed and direction, temperature, relative humidity, pressure, solar radiation and thermal gradient), hourly ozone levels and traffic parameters (number of vehicles, occupation percentage and velocity), which were measured in the years of 1993–94. The performances of developed models were compared with observed values and were evaluated using specific performance measurements for the air quality models established in the Model Validation Kit and recommended by the US Environmental Protection Agency. It was found that the gEP in most cases gives superior predictions. Finally it can be concluded on the basis of the results of this study that gene expression programming appears to be a promising technique for the prediction of pollutant concentrations.Zbog štetnog utjecaja na dišni sustav prizemni ozon (O3) već nekoliko desetljeća predstavlja ozbiljan problem u mnogim onečišćenim urbanim područjima. Kako bi se smanjili rizici od oštećenja uzrokovanih ozonom, potrebno je razvijati, održavati i poboljšavati modele kratkoročne prognoze ozona. Ovaj rad prikazuje rezultate dvaju prognostičkih modela, evolucijskog programiranja gena (GEP), koje je varijanta genetskog programiranja (GP), te prognoziranje razina ozona u realnom vremenu višestrukom linearnom regresijom (MLR) do šest sati unaprijed na četiri postaje u Bilbau u Španjolskoj.
Ulazni podaci za GEP su meteorološki uvjeti (brzina i smjer vjetra, temperatura, relativna vlažnost zraka, tlak, sunčevo zračenje i termički gradijent), satne razine ozona i parametri prometa (broj vozila, udio vremena zauzetosti ceste vozilima i njihova brzina), koji su izmjereni u razdoblju 1993–1994. Performanse razvijenih modela ocijenjene su usporedbom s mjerenjima te upotrebom alata za validaciju modela koje je predložila američka Agencija za zaštitu okoliša. Utvrđeno je da GEP u većini slučajeva daje bolje prognoze. Na kraju je zaključeno da je evolucijsko programiranje gena obećavajuća tehnika za prognozu koncentracija onečišćujućih tvari
