Animal production is a main source of NH3 emission into the environment and a significant producer of other polluting gases. Most of the best available techniques (BAT) that could be used today are not very widely applied in the field because of costs, especially in existing livestock buildings. Industrial applications show that TiO2 catalytic paint can be used to transform NH3 into N-2, N2O or NO and water. Field experiments aimed at determining effects on indoor air quality and NH3 and polluting gas emissions into the environment of coating pig house walls with TiO2 catalytic paint and to assess the potential efficiency of this simple painting technique as a low cost BAT technique for animal farmers. The trial was performed in two identical mechanical ventilated farrowing rooms in a swine farm in Northern Italy. Environmental parameters, ventilation rate and gas concentrations were continuously monitored in the two units throughout a 28 day production cycle. NH3, N2O, CO2, CH4 average concentrations of 5.41, 1.18, 6.28 and 2109.38 mg m(-3) (reference unit without treatment) and 3.76, 1.13, 5.32 and 1881.64 mg m(-3) (experimental unit) were, respectively, recorded during a full farrowing cycle. Pollutant emissions, expressed on a Livestock Unit (LU, i.e., 500 kg live weight) basis, were 16.33, 3.57, 18.96 and 6365.01 kg y(-1) LU-1 (reference unit) and 11. 37, 3.43, 16.11 and 5695.58 kg y(-1) LU-1 (experimental unit), respectively. Significantly higher pollutant concentrations and emissions were found in the untreated reference unit, under similar environmental conditions and with identical numbers of sows and piglets per unit. (c) 2007 Elsevier Ltd. All rights reserved.