Evaluation of Micro-Sensors to Monitor Ozone in Ambient Air

摘要

Micro-sensors are very small sensors with physical dimensions in the sub-micrometer to millimetre range that are used to monitor ozone (O3) in ambient air. They are either based on the variation of the resistance of a semi-conductor or on miniaturized electrochemical cells able to deliver a current varying with the level of the pollutant of interest. In the last years, some technological progress took place and a few commercial sensors are now available in the market. In fact, micro-sensors represent a promising technology in several fields like: monitoring of O3 in ambient air to survey of the limit/target values of the Air Quality Directive, rapid mapping of air pollution over small area, validation of dispersion models, evaluation of exposure of population, emissions monitoring and forest monitoring.However, due to reliability problems there is a hesitancy to apply these sensors for air pollution monitoring. The suitability of these sensors is evaluated in this report. In this study, the response time of micro-sensors is investigated. Moreover, warming time after a cold start, linearity, drift over time and the effect of NO2 interference, wind velocity, temperature and humidity on the response of sensors are presented. The comparison of the response of these samplers versus UV photometry is investigated both under controlled conditions using exposure chamber and under field conditions. All sensors used in the study are commercially available. O3 is determined according to the specifications of the manufacturers, without modification of the model equation proposed by the manufacturers.