An apparatus for generating and collecting particulate matter derived from combusting a carbon-containing fuel in oxidizing gas includes a fuel burner housed in a container. The container has a gas inlet, a gas outlet; the gas outlet connects with a conduit for transporting the gas to atmosphere which is associated with means for forcing gas to flow from the gas inlet via the container and the conduit to atmosphere. Located within the conduit is a station for collecting particulate matter from gas flowing through the conduit. The gas flow-forcing means is controlled in response to a detected gas flow rate at the gas inlet to ensure the rate of gas flow at the gas inlet is maintained at a desired rate, thereby to promote particulate matter formation. A method for collecting particulate matter derived from combusting carbon-containing fuel employs the apparatus.