Seasonal Variation in the Chemical Composition and Oxidative Potential of PM2.5

Abstract

Exposure to fine particulate matter (PM2.5) has well-established systemic human health effects due in part to the chemical components associated with these exposures. Oxidative stress is a hypothesized mechanism for the health effects associated with PM2.5 exposures. The oxidative potential of PM2.5 has recently been suggested as a metric that is more indicative of human health effects than the routinely measured PM2.5 concentration. The purpose of this study was to analyze and compare the oxidative potential and elemental composition of PM2.5 collected at two locations during different seasons. PM2.5 was collected onto PTFE-coated filters (n = 16) along two highways in central Oregon, USA in the Winter (January) and Summer (July/August). PM2.5 was extracted from each filter via sonication in methanol. An aliquot of the extraction solution was used to measure oxidative potential using the dithiothreitol (DTT) assay. An additional aliquot underwent analysis via inductively coupled plasma—mass spectrometry (ICP-MS) to quantify elements (n = 20). Differences in PM2.5 elemental composition were observed between locations and seasons as well as between days in the same season. Overall, concentrations were highest in the winter samples but the contribution to total PM2.5 mass was higher for elements in the summer. Notably, the oxidative potential (nM DTT consumed/µg PM2.5/min) differed between seasons with summer samples having nearly a two-fold increase when compared to the winter. Significant negative correlations that were observed between DTT consumption and several elements as well as with PM2.5 mass but these findings were dependent on if the data was normalized by PM2.5 mass. This research adds to the growing evidence and justification for investigating the oxidative potential and composition of PM2.5 while also highlighting the seasonal variability of these factors.

Size-Resolved Redox Activity and Cytotoxicity of Water-Soluble Urban Atmospheric Particulate Matter: Assessing Contributions from Chemical Components

“…The Spearman’s rho correlation coefficients calculated for OP m DTT and OP v DTT with the corresponding mass and air volume normalized concentrations of chemical compounds of PM are shown in Table S4 . A significant negative correlation (−0.70; p < 0.01) was found between OP m DTT and the mass concentration of PM, in agreement with other studies [ 46 , 47 , 48 ], with a result that certain species that contribute to total PM mass do not contribute significantly to ROS generation capability [ 46 ]. No correlation was found with OP v DTT and PM mass appeared to moderately correlate with OP m DTT (0.41; p < 0.01), nevertheless, no correlation was found with the PM mass concentration suggesting that OP, related to the composition of PM rather than their mass.…”

Short term exposure to low level ambient fine particulate matter and natural cause, cardiovascular, and respiratory morbidity among US adults with health insurance: case time series study

“…We observed geographic differences in the health effects of PM 2.5 , with beneficiaries residing at higher latitudes tending to show higher risk of hospital admissions and emergency department visits for cardiovascular disease associated with exposure to PM 2.5 . We speculate that geographic locations may modify the association between exposure to PM 2.5 and morbidity, possibly through factors such as differences in local temperature,2829 and particle composition contributing to varying levels of oxidative potential 30…”

“…We speculate that geographic locations may modify the association between exposure to PM 2.5 and morbidity, possibly through factors such as differences in local temperature, 28 29 and particle composition contributing to varying levels of oxidative potential. 30 …”

Airborne and Dermal Collection Methods of Gunshot Residue for Toxicity Studies

“…Aliquots of all samples and controls underwent Inductively Coupled Plasma Mass Spectrometry (Thermo Fisher Element XR ICP-MS, Waltham, MA, USA) for elemental quantification of Ag, Ba, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Mn, Ni, P, Pb, Sr, Tl, U, V, and Zn. The calibration curves were generated by Multielement Calibration Standard Solution 2A (Spex Certiprep), and method accuracy was confirmed by the analyzing NIST certified standard reference material 1640a "Trace Elements in Water" as previously described in detail [46]. For the elements representative of GSR, the percent recovery was within ±10% from the actual value of the standard reference material 1640a.…”