When used in dusty environments, such as livestock houses, the current EU reference sampler for ambient dust (PM10 and PM2.5) with an impaction pre-separator (IPS) is expected to become overloaded, because of the low dust-retaining capacity of the greased impaction plate in the IPS. The two objectives of this study were (1) to verify this by regularly replacing the loaded greased plates by clean ones, and (2) to evaluate a sampler with a cyclone pre-separator (CPS) as an alternative dust sampler in ambient environments and in livestock houses (fattening pig, broiler, and dairy) following the EU standard procedure. Results showed that PM10-IPS did not become overloaded in 24 h measurements in layer houses, whereas PM2.5-IPS became overloaded within 1 h. PM2.5-CPS did not become overloaded during 48 h sampling in a layer house. Both PM10- and PM2.5-CPS showed good precision and comparability with IPS in less dusty environments. In pig and broiler houses with high dust loads, PM10-CPS could give comparable results with IPS by introducing a correction factor. It is concluded that PM2.5-IPS is not suitable for use in livestock houses, and that PM2.5-CPS is very resistant to high dust load. For PM10 sampling, both IPS and CPS can be used. (C) 2009 Elsevier Ltd. All rights reserved.