Portable microbiological air samplers for sampling air biocontaminants within critical environments such as cleanrooms, food production areas, fermentation rooms, hospitals and treatment plants to quantify the presence of micro-organisms. Comply with ISO 14698-1 requirements. Comprise disinfectable, polyurethane pump housing/controller with push-on, autoclavable, anodised aluminium or stainless steel, perforated sampling head which holds either 60mm diameter contact plates or 90mm diameter petri dishes. The internal surfaces of the sampling chamber  are coated  with antibacterial  silver ions. A rechargeable,  battery-operated  pump allows portability and operation for up to 4 hours. The controller allows manual, sequential and programmed (1 to 2000 litres) sampling, delayed start, preset sampling flow rates, memory storage of up to 99 sampling procedures, graphical display with a choice of languages, USB interface and low battery alarm. The housing design allows horizontal or vertical operation and the unit can be switched on or off remotely using an infra-red control.