An electrostatic aerosol collector comprising: a collector housing; an aerosol entry port that provides an inlet for air to flow from outside of the collector housing to the inside of the housing; a sample substrate receiving area within the collector housing for receiving a sample substrate including a collection area upon which particulates are collected; a passageway between the aerosol entry port and the sample substrate receiving area; a charging device having an electrode, the electrode having a tip that extends into the passageway; a high voltage power source coupled to the charging device; wherein: the tip of the electrode creates an electric field defining a charging point in the passageway through which the air passes; the sample substrate is held at an electric potential that is different from the electric potential of the charging point during particulate collection; characterised in that the collector comprises a spraying device having a spray nozzle that extends into the passageway between the tip of the electrode and the sample substrate receiving area, wherein the spraying device sprays a fluid from the spray nozzle over the collection area of the sample substrate, where the fluid is specifically selected to prepare the collected sample for subsequent evaluation. a collector housing; an aerosol entry port that provides an inlet for air to flow from outside of the collector housing to the inside of the housing; a sample substrate receiving area within the collector housing for receiving a sample substrate including a collection area upon which particulates are collected; a passageway between the aerosol entry port and the sample substrate receiving area; a charging device having an electrode, the electrode having a tip that extends into the passageway; a high voltage power source coupled to the charging device; wherein: the tip of the electrode creates an electric field defining a charging point in the passageway through which the air passes; the sample substrate is held at an electric potential that is different from the electric potential of the charging point during particulate collection; characterised in that the collector comprises a spraying device having a spray nozzle that extends into the passageway between the tip of the electrode and the sample substrate receiving area, wherein the spraying device sprays a fluid from the spray nozzle over the collection area of the sample substrate, where the fluid is specifically selected to prepare the collected sample for subsequent evaluation. the tip of the electrode creates an electric field defining a charging point in the passageway through which the air passes; the sample substrate is held at an electric potential that is different from the electric potential of the charging point during particulate collection; characterised in that the collector comprises a spraying device having a spray nozzle that extends into the passageway between the tip of the electrode and the sample substrate receiving area, wherein the spraying device sprays a fluid from the spray nozzle over the collection area of the sample substrate, where the fluid is specifically selected to prepare the collected sample for subsequent evaluation.