This paper presents the measures that can help to achieve the reduction of harmful gases produced by otto engines. Gases that are formed during the incomplete combustion of the fuel are listed and their impact on the human health is described. Exhaust emissions are regulated by Euro standards that limit emissions of toxic gases. There are several technical measures to specifically reduce harmful gases at otto engine; the paper describes the technical procedures that contribute to the largest reduction of pollution and some new technology. The use of alternative fuels for motor vehicles is one of the possible ways to reduce harmful emissions from vehicles. Economic measures are a good example of measures to reduce exhaust emissions, because they encourage people by giving them subsidies to the procurement of environmentally friendly road motor vehicles on alternative fuel. In Croatia, The Croatian Government, The Ministry of Environmental and Nature Protection and The Environmental Protection and Energy Efficiency Fund are trying to reduce the steady growth of emissions, by giving incentives for electric, hybrid and plug-in vehicles, and initiate the use of motor vehicles on alternative fuels.