Assessment of Integrated Aerosol Sampling Techniques in Indoor, Confined and Outdoor Environments Characterized by Specific Emission Sources

Laura Borgese,Donatella Placidi,Elisabetta Comini,Roberto Lucchini,Laura E Depero,Dario Zappa,Angelo Finco,Stefania Federici,Anne Wambui Mutahi,Ahmad Assi,Maria Chiesa,Elza Bontempi,Claudio Marchesi,Claudio Carnevale,Marialuisa Volta,Giacomo Gerosa,Franko Kasemi

doi:10.3390/app11104360

Abstract

This paper highlights advantages and drawbacks due to the use of portable and low-cost devices for aerosol sampling, showing their performances during an aerosol monitoring campaign with the parallel use of the gravimetric sampling reference method and a cascade impactor. A specific monitoring campaign was held running all instruments in parallel in indoor, confined, and outdoor environments characterized by local emission sources or particulate matter background concentrations. PM2.5 concentrations were used to compare data emerging from the different instruments adopted. Significant underestimation of PM2.5 emerged when comparing data coming from optical sensors with those estimated by the cascade impactor, whose data resulted in being coherent with gravimetric determination, integrated over the same sampling time. A cause–effect relationship between PM2.5 concentrations and specific emission sources was found when observing the daily patterns of all the real-time sampling devices. It emerged that optical devices are useful for detecting concentration trends, the presence of peak values, or changes in the background value, even if with limited accuracy and precision. The comparison with particle size distributions obtained by the cascade impactor data allowed us to define which particle sizes are not detected by different optical devices, evidencing a low representativeness of optical low-cost sensors for health exposure measurements. The correlations among the specific particle size fractions detected by the cascade impactor and their specific emission sources were particularly high for car emissions in a semi-confined garage area.

Highlights

All the daily patterns collected with KORA and AirVisual Pro along with the specific events that occurred during the monitoring period are reported in the Supplementary Materials (Figures S2 and S3 and Table S1). Both patterns allowed a simple and immediate evaluation of PM2.5 concentration trends, showing peaks corresponding to the presence of identified emission sources
This paper presents an experimental comparison of aerosol sampling methods by means of real-time samplers based on low-cost optical sensors, a cascade impactor, and a PMI for collection of PM2.5 on a Teflon filter membrane
The underestimation of PM2.5 concentration indirectly calculated by low-cost optical sensors with respect to concentrations provided by the PMI, and the good alignment between the latter and the cascade impactor; Different LODs for the optical sensor of the AirVisual Pro (250 nm) and KORA

Summary

Introduction

Aerosol monitoring is extremely important since the respirable suspended particles (hereafter denoted as RSP, commonly referred to as PM10 ) are presently considered one creativecommons.org/licenses/by/ 4.0/). Of the most critical atmospheric pollutants, mainly in urban areas. The health impact of aerosol is scientifically recognized [3,4,5]. For almost 20 years aerosol monitoring has started to focus on particle mass (PM) and on particle number (PN) in order to better assess the health impact due mainly to ultrafine (1–100 nm) and fine (100–1000 nm) particles [8,9]. In urban areas the size distributions of particles present PN peaks

Methods

Results

Conclusion