The Pathogen Control Engineering Group has a wide range of facilities and expertise at its disposal to carry out projects ranging from simple lab based microbial testing of products and devices to complex research studies involving site sampling, targeted lab experiments and numerical modelling. Please view our research case studies to see how we have investigated different problems.

Laboratory Studies

Laboratory based research is carried out using either small bench-scale tests rigs or the group's aerobiology test chamber to replicate the conditions in a full-sized ventilated room. We have a fully equipped microbiology laboratory capable of handling microorganisms up to hazard category two. One of the group's major strengths is its expertise in combining microbiology techniques with the problem solving skills gained in an engineering environment. This means we have significant experience in designing custom testing environments to investigate a wide range of problems and device. For example we have two test-rigs, designed in-house, for examining the susceptibility of both static and aerosolised microorganisms to ultraviolet light.

The "barbeque" test rig for exposing microorganisms on agar plates or in static water to UV-C irradiation

The laminar flow test rig for exposing aerosolised microorganisms to a controlled UV-C dose (a) Central UV chamber, (b) Creating the bioaerosol with a Collison nebuliser, (c) Sampling exposed microorganisms with a 6-stage Anderson sampler

The aerobiology test chamber is a 32m 3 , mechanically ventilated, hazard category two room designed for carrying out experiments on bioaerosols. The room is climatically controlled with a ventilation rate between 2 and 12 AC/h and a choice of two ventilation regimes. Aerosolised microorganisms can be introduced to the room via a tube attached to an external nebuliser, and the concentration in the air sampled remotely via one of five sample ports, and an appropriate air sampler. The facility can be used for a wide range of experiments from fundamental research to understand how microorganisms survive in indoor environments to testing the efficacy of disinfection devices.

Aerobiology test chamber (a) External view showing air handling equipment, (b) Internal view showing bioaerosol supply tube and device testing, (c) Ante-room with washing facilities and access to sample ports.

This paper describing one of our projects demonstrates how many of these facilities are utilised in practice: UV's role in hospital infection control.

Site Sampling

In addition to laboratory based experiments, the group has significant experience of carrying out sampling studies in different environments. Bioaerosol sampling is a particular speciality and we have a wide range of samplers available including 2 six-stage Anderson samplers, a Burkard CM90 Cyclone sampler and a hand held SAS single stage impactor. These have been used in several environments from hospital wards to outdoor composting sites to sample both bacteria and fungi. We also have a laser particulate counter, two air ion analysers and UV meters for more specialist studies.

Numerical Modelling

One of the group's unique aspects is the combination of experimental capability with significant expertise in mathematical modelling. We use a range of tools, from custom programs to model ventilation and infection risk to state-of-the-art computational fluid dynamics (CFD) software to model the airflow and bioaerosol distributions within buildings. The group has experience in using a range of modelling tools including CFX, Fluent and Flow3d CFD software packages and several programming environments.

CFD modelling of Aerobiology test chamber (a) Airflow pattern, (b) Bioaerosol distribution in the presence of a UV device.