July 11, 2024
AUTHOR(S):
Teresa Moreno1, Stefanos Agathokleous1, Carlos Casado 2, Amaya Manso3, Katie Kedwell4, Martin Lehmann4
(1 CSIC, 2 CARTIF, 3 AUVASA, 4 M+H)
In AeroSolfd we are measuring the exposure levels of air pollutants at semi-indoor sites such as bus transportation depots and metro stations. For this we are looking at concentration levels of main pollutants such as inhalable particulate matter (PM), however, to investigate the contribution of specific airborne particle sources, such as brake wear and its associated trace metals, the chemical composition of PM is also needed.
Illustration of CSIC measuring equipment (grey machines front left) and M+H air purifiers (black & white square machines) at AUVASA bus depot. Note that the filtration is not part of this deliverable and will be published later.
The key questions we want to address are (1) what is the air quality (AQ) within semi-enclosed transport-related working microenvironments and why does it vary? (2) can metalliferous emissions from non-exhaust sources such as brakes and tyres be recognised in the AQ data? (3) what can be done to improve AQ and thus benefit the workers? In our deliverable D3.2 “Contribution of brake emissions to measured exposure at specific, closed demo sites derived” we report on AQ inside the AUVASA bus depot in Valladolid in north-western Spain. Understanding the background inhalable particle concentration levels and chemistry within the bus depot area is the first step to improving air quality within this semi-enclosed public transportation micro-environment. AUVASA bus depot is 5 km south of the city centre and can accommodate up to 154 buses (28 diesel, 46 liquid petroleum gases, 51 compressed natural gas, 18 hybrid and 11 electric). During this air quality study, no exceptional construction or other engineering tasks occurred, just regular vehicle maintenance work associated with oil changing, air filter cleaning, tyres, brakes, and sheet metal work involving sanding and use of fillers, primers and paints.
Daily distribution of baseline (BL) PM2.5 at AUVASA bus depot and outdoor (Vega Sicilia air quality official monitoring station) environment. The dots represent the average.
Our results show that (1) daily AQ inside the bus depot is highly variable; (2) ambient inhalable particle mass concentrations are usually higher at the start of the working day soon after 07:00 when a “rush hour” bus traffic peak is common; (3) peaks in ambient PM concentrations are common during the night/early morning, probably due at least in part to emissions released during maintenance work; (4) the presence of inhalable particles released from brakes is strongly suggested by close correlations between classic “brake-related” elements, notably Fe, Cu, Sb, Cr and, to a lesser extent, Ba; (5) the presence of particles released from tyres is suggested by transient peaks in the concentration of Zn but no other metals; (6) improvements in ventilation and/or use of air purifiers, especially during rush hour peaks and when maintenance work is being performed, are the most obvious ways to improve AQ in the working environment for the depot employees.
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Read the full report here:
