Application Note – Bioaerosol N.25 – European Standard for biological Agents Monitoring in workplace atmosphere
The European Standard EN 14042, April 2003 “Workplace atmospheres – Guide for application and use of procedures for the assessment of exposure to chemical and biological agents” 6.3 “Measurement of airborne micro-organisms and endotoxin”, 6.3.1. “Methods using an impactor as sampler” presents the Table.
| CHARACTERISTICS | COMMENTS |
| Operating principles | A measured volume of air is drawn through a sampler such that airborne micro-organisms are caused to leave the air stream and impact onto e semi solid (typically an agar culture medium) or solid surface. Semi solid media thus directly inoculated are incubated to develop colonies from viable, culturable micro-organisms |
| Typical measurement task | Measurements near an emission source; periodic measurements |
| Typical measurement range | 101 to 105 Colony Forming Units per 1 m3 of air |
| Response time/Averaging time | 1 minute to 30 minutes depending on bio-aerosol concentration |
| Selectivity | Dependent on subsequent analysis |
| Influence of environmentalParameter: Pressure | No |
| Influence of environmentalParameter: Temperature and humidity | Both can affect viability / culturability of bio-aerosol; could cause dehydration of semisolid collection substrates leading to reduction in collection efficiency |
| Influence of environmentalparameter: Air speed | Effect on inlet efficiency |
| Influence of environmentalParameter: Vibration | No |
| Calibration | Calibrate inlet air flow rate before each sampling |
| Limitations | Short sampling time for high bio-areosol concentrations to avoid overloading. In general can only be used for culturable analysis. High sampler costs. Static (area) sampling only. Many samplers available poorly characterised for inlet efficiency compared to ISO /CN convention |
