Monitoring portable station for the measurement of fine and ultrafine particle exposure in the PM-CARE project

Background: The PM-CARE project aims at investigating the association between variation of urban-air particulate personal exposure and acute cardio-respiratory effects in cardiac and pulmonary patients, focusing on seasonal and activity-related PM exposure variations. Aim: to set up a mobile air-monitoring unit suitable for personal exposure assessment in the PM-CARE project. Materials and Methods: Three identical measuring units were constructed, consisting of a 0.12 m3 transportable packaged trolley equipped with selected low-weight monitoring devices. The particle number concentrations of PM ranging from 0.02 to 1μm (ultra-fine particles) and from 0.3 to 25μm (fine and coarse fractions) in aerodynamic diameter are continuously detected by two optical counters, whereas the 24h-averaged mass concentrations of PM0.5, PM1, PM2.5 and PM10 are measured through a multistage cascade impactor for gravimetric determination. Carbon monoxide and ozone levels are continuously monitored by continuous recording instruments, while the mean concentration of nitrogen dioxide is measured by passive sampling. Microclimatic probes for temperature and relative humidity complete the equipment set. Results and Discussion: One of the main problems in personal fine and ultrafine PM exposure assessment of patients is to construct a portable monitoring station including complex instruments without excessive burden to the investigated subjects. The instrumental set assembled in the portable trolleys reached the goal of providing a complete measuring station that can be easily moved by the patients at home and during outdoor displacements without failures in performance. The developed station offers a good compromise between accuracy of the PM exposure measurement (including fine and ultrafine particles and mass as well as numerical detection) and light weight, portability and reliability of the instrumental set. Conclusions: The data obtained so far confirmed that the monitoring station fulfils the requirement of the PM-CARE project, since all the subjects under investigations made a proper use of it with a limited technical assistance and the station provided a detailed and reliable picture of personal PM exposure experienced by people in their common daily activities at home and during outdoor movement near their house.