113 Development of a Direct Reading Instrument for Oxidative Potential Measurement in Air

Abstract

Abstract To protect the general population as well as workers, authorities have to identify the most toxic compounds in the particulate aerosol and effectively reduce their concentrations. As the oxidative potential (OP) is suggested to be linked with health effects, it may be more effective to control specific sources of oxidizing particles rather than overall particulate mass. In that case, the use of direct-reading instruments for OP measurement could help to the effective control of noxious air pollutant sources. We present here the development and characterization of a direct-reading instrument based on the acellular ferrous-orange xylenol (FOX) assay, allowing a continuous sensing of ambient oxidizing compounds. The detection principle relies on multiscattering-enhanced absorbance strategy enabling sensitive detection of airborne oxidants (e.g. hydrogen peroxide, hydroxyl radical) with a time resolution of 5 min. Two parallel tasks to improve the reading instrument are underway: 1. A better understanding of the FOX response to the potentially interfering ozone and NOx gases and it relationship with emission sources; 2. Improving the interface for transferring the aerosol in the FOX solution and characterizing the instrument regarding it sensibility, linearity, repeatability and response time. Continuous determination of OP will enable robust epidemiological studies to evidence potential associations with oxidative stress-related and inflammatory disorders. In the future, mapping the average annual OP – together with current PM10, NOx and O3 – will be an essential chemical dimension of the pollution profile.