On-site measurement

Traditionally exposure measurements of chemical compounds are carried out in two steps. In step one, the compounds in air are sampled. Aerosols are sampled by sucking air through a filter to collect the particles using a pump. Gaseous compounds are samples either by sucking air through an adsorbent or chemosorbent using a pump or passively using a diffusive sampler. In the second step, the samples are analysed in a laboratory to identify and quantify the compounds in the sample and calculate the concentration of the compounds in the air. 

With on-site measurements both sampling and analysis are carried out on-site and the results are obtained almost immediately. Today there are numerous direct reading instruments available for this purpose. Physical parameters such as temperature, humidity, air pressure are exemples of such measurements. There is also portable instruments for certain gases, e.g., carbon monoxide, carbon dioxide and for airborne particles. At Fenix Environmental we have developed a method for on-site measurements of aerosols and metals. This method can be combined with other measurements for assessment of the air quality. Work is now i progress to increase the applicability by combining these methods with video technology (PIMEX) so the exposure "can be seen" on a video film simultaneously with the exposed person in action.

With on-site measurements one can use the monitoring for new applications. One can, e.g., measure directly during short time exposure. One can directly assess the effect of various exposure preventive measures. One can directly compare different work patterns for a specific work task. The quick feed-back makes on-site measurements suitable for education but also for different optimisation of preventive measures.  The rapid measurements makes it possible to perform more measurements during short times, which can give better basis for decisions of improvements.

References
Nygren O, Aspman O. Validation and application of wipe sampling and portable XRF analysis as an on-site screening method for assessment of deposited aerosols on workplaces, Aust J Chem 37 (2004), 1021-28.
Nygren O. Wipe sampling as a tool for monitoring aerosol deposition in workplaces. J Environ Monit, 8 (2006), 49 - 52.