Abstract
Long-term monitoring at sites with relatively low particulate pollution could provide an opportunity to identify changes in pollutant concentration and potential effects of current air quality policies. In this study, a 9-year sampling of PM10 (particles with an aerodynamic diameter below 10 µm) was performed in a rural background site in France from February 28, 2012 to December 22, 2020. The Positive Matrix Factorization (PMF) method was used to apportion sources of PM10 based on quantified chemical constituents and specific chemical tracers from collected filters. Oxidative potential (OP), an emerging health-metric that measures PM capability to potentially cause anti-oxidant imbalance in the lung, was also measured using two acellular assays: dithiothreitol (DTT) and ascorbic acid (AA). The contribution of PMF-resolved sources to OP were also estimated using multiple linear regression (MLR) analysis. In terms of mass contribution, the dominant sources are secondary aerosols (nitrate- and sulphate-rich), associated with long-range transport (LRT). However, in terms of OP contributions, the main drivers are traffic, mineral dust, and biomass burning factors. There is also some OP contribution apportioned to the sulphate- and nitrate-rich sources influenced by processes and aging during LRT that could have encouraged mixing with other anthropogenic sources. The study indicates much lower OP values than in urban areas. A substantial decrease (58 % reduction from year 2012 to 2020) in the mass contributions from the traffic factor was found, however, this is not clearly reflected in its OP contribution. Nevertheless, the findings in this long-term study in the OPE site could signal effectiveness of implemented emission control policies, as also seen in other long-term studies conducted in Europe, mainly for urban areas.
Highlights
Particulate matter (PM) is a key factor in various environmental concerns affecting public health and climate
There is some Oxidative potential (OP) contribution apportioned to the sulphate- and nitrate-rich sources influenced by processes and aging during long-range transport (LRT) that could have encouraged mixing with other anthropogenic sources
205 mass concentration of the reconstructed daily PM10 samples ranged from 2 to 51 μg m-3 with an overall average of 9 ± 7 μg m3. These reconstructed PM10 mass concentration only exceeded the PM10 European limit value of 40 μg m3 a few times (n = 3) in the entire measurement period. These values are in the lower range of the concentrations reported for rural areas in Europe, ranging from 3 to 35 μg m-3 (Putaud et al, 2004), and are relatively close to the values found at a remote site in Revin (France, located 165 km away), as described in the SOURCES programme (Weber et al, 210 2019)
Summary
Particulate matter (PM) is a key factor in various environmental concerns affecting public health and climate. Rural sites are of great interest as well because they could represent 35 the regional geochemical background of the atmosphere and potential influence from long-range transport (LRT) of sources Studies at such sites enable the understanding of large-scale processes (Anenberg et al, 2010; Mues et al, 2013; Konovalov et al, 2009), which is necessary to elaborate chemical transport models. The characterization of PM sources and OP in a rural site will enable us to see the large-scale effects of mitigation policies that target reduction of PM mass concentrations This will provide knowledge of efficiency of current air quality guidelines in terms of other emerging health-based metrics of PM exposure. This study investigated long-term trends of emission sources and OP to provide insights in the effectiveness of existing air quality policies 60 both in terms of mass concentration and potential exposure to PM
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