Costas Sioutas

Rationale: Particulate matter ⩽2.5 μm in aerodynamic diameter (PM2.5) is an established cause of lung cancer, but the association with ultrafine particulate matter (UFP; aerodynamic diameter < 0.1 μm) is unclear. Objectives: To investigate the association between UFP and lung cancer overall and by histologic subtype. Methods: The Los Angeles Ultrafines Study includes 45,012 participants aged ⩾50 years in southern California at enrollment (1995–1996) followed through 2017 for incident lung cancer (n = 1,770). We estimated historical residential ambient UFP number concentrations via land use regression and back extrapolation using PM2.5. In Cox proportional hazards models adjusted for smoking and other confounders, we estimated associations between 10-year lagged UFP (per 10,000 particles/cm3 and quartiles) and lung cancer overall and by major histologic subtype (adenocarcinoma …

In this study, two online monitoring systems were developed for measuring total organic carbon (TOC) and water-soluble organic carbon (WSOC) in fine and coarse airborne particles. The performance of these monitoring systems was assessed through field experiments to confirm their capability for real-time measurement. For collecting fine airborne particles, a versatile aerosol concentration enrichment system (VACES) coupled with an aerosol-into-liquid sampler (AILS) were utilized. On the other hand, the collection of coarse particles was conducted by two virtual impactors (VIs) in tandem with a modified BioSampler. These particle collection setups were connected to a Sievers M9 TOC analyzer to provide hourly readings of TOC and WSOC levels in water-based samples. Hourly average concentrations of TOC in fine and coarse particles were found to be 5.17±2.41 µg/m³ and 0.92±0.29 µg/m³, respectively. A …

Objective To characterize the molecular underpinnings of recovery following acute diesel exhaust particle (DEP) exposure. Background Traffic-associated air pollution harms neurologic health and may exacerbate pathologies such as stroke and dementia. Epidemiologic studies demonstrate that reductions in pollution exposure may slow cognitive decline and decrease dementia risk. The underlying mechanisms of neurologic recovery after pollution exposure are not defined. Design/Methods Eight-week male and female C57BL/6 mice were exposed to five hours of filtered air (FA) or aerosolized DEP. One cohort (n= 32) of FA and DEP mice were promptly sacrificed while the other cohort (n= 32) recovered in home cages for two weeks prior to euthanasia. Immunofluorescence was performed on corpus callosum samples to evaluate the presence of markers of oxidative stress (4-HNE and 8-OHdG), complement …

This study investigates the long-term trends of ambient ultrafine particles (UFPs) and associated airborne pollutants in the Los Angeles Basin from 2007 to 2022, focusing on the indirect effects of regulations on UFP levels. The particle number concentration (PNC) of UFPs was compiled from previous studies in the area, and associated co-pollutant data, including nitrogen oxides (NOx), carbon monoxide (CO), elemental carbon (EC), organic carbon (OC), and ozone (O3), were obtained from the chemical speciation network (CSN) database. Over the study period, a general decrease was noted in the PNC of UFPs, NOx, EC, and OC, except for CO, the concentration trends of which did not exhibit a consistent pattern. UFPs, NOx, EC, and OC were positively correlated, while O3 had a negative correlation, especially with NOx. Our analysis discerned two distinct sub-periods in pollutant trends: 2007–2015 and 2016 …

The published article contained an error in the western blot image in Figure 4A. The C5 and C5o strips were duplicate images of the same blot. Due to lack of clear and adequate labeling of the original images, we are not able to determine with confidence which protein each of the strips and condition each lane in this figure and the original blots represent. Therefore, we have removed the western blot analysis (Figure 4A and the accompanying graphs Figure 4B–E) from the article. In addition, the description of the western blot was removed from the “Methods” section and the Figure 4 caption. In the “Methods” section, in the “Study Design” subsection, the fifth sentence of the third paragraph was changed from “However, multiple markers of white matter injury [KB, dMBP, T2 weighted magnetic resonance imaging (MRI)], inflammation (Iba-1, GFAP, C5, C5o, CD88, TLR4), and oxidative stress (8-OHdG, nitrate, nitrite …

METHODS:Our air pollution model used eight weeks of standardized Diesel Exhaust Particles (DEP) from National Institute of Science and Technology (DEP NIST2975). We performed bilateral carotid stenosis (BCAS) surgery to induce CCH using Wild Type (WT) and TLR4 flx/flx (CX3CR1CreER+/-)(TLR4-KD) in 2-month-old male mice. WT and TLR4-KD mice were randomized into eight groups as follows: WT-filtered air (FA), WT-DEP, WT-FA-BCAS, WT-DEP-BCAS, TLR4-KD-FA, TLR4-KD-DEP, TLR4-KD-FA-BCAS, and TLR4-KD-DEP-BCAS. Neurotoxicity was quantified with immunohistochemistry of degraded myelin basic protein (dMBP), ionized calcium-binding adaptor molecule-1 (Iba-1), and complement (C5a).RESULTS:DEP exposure resulted in increased white matter injury in corpus callosum (dMBP), worsened by the presence of CCH (p= 0.004) and significantly attenuated by TLR4-KD (p= 0.005). DEP …

In this study, we developed two online monitors for total organic carbon (TOC) and water-soluble organic carbon (WSOC) measurements in fine (dp < 2.5 μm) and coarse (2.5 μm < dp < 10 μm) particulate matter (PM), respectively. Their performance has been evaluated in laboratory and field tests to demonstrate the feasibility of using these monitors to measure near real-time concentrations, with consideration of their potential for being employed in long-term measurements. The fine PM collection setup was equipped with a versatile aerosol concentration enrichment system (VACES) connected to an aerosol-into-liquid-sampler (AILS), whereas two virtual impactors (VIs) in tandem with a modified BioSampler were used to collect coarse PM. These particle collection setups were in tandem with a Sievers M9 TOC analyzer to read TOC and WSOC concentrations in aqueous samples hourly. The average hourly TOC …

BACKGROUND Air pollution particulate matter exposure and chronic cerebral hypoperfusion (CCH) contribute to white matter toxicity through shared mechanisms of neuroinflammation, oxidative stress, and myelin breakdown. Prior studies showed that exposure of mice to joint particulate matter and CCH caused supra-additive injury to corpus callosum white matter. This study examines the role of TLR4 (toll-like receptor 4) signaling in mediating neurotoxicity and myelin damage observed in joint particulate matter and CCH exposures. METHODS Experiments utilized a novel murine model of inducible monocyte/microglia-specific TLR4 knockout (i-mTLR4-ko). Bilateral carotid artery stenosis (BCAS) was induced surgically to model CCH. TLR4-intact (control) and i-mTLR4-ko mice were exposed to 8 weeks of either aerosolized diesel exhaust particulate (DEP) or filtered air (FA) in 8 experimental groups: (1) control …