Promotion of myofibroblast differentiation through repeated treatment of fibroblasts to low concentrations of PM2.5.

Exposure to particulate matter ≤ 2.5 µm (PM2.5) is a risk factor for many lung diseases. Although the toxicologic effects of PM2.5 on airway epithelium are well-described, the effects of PM2.5 on fibroblasts in the lung are less studied. Here, we sought to examine the effects of PM2.5 on the differentiation of fibroblasts into myofibroblasts. Although a single treatment of fibroblasts did not result in a change in collagen or the myofibroblast marker α-SMA, exposing fibroblasts to sequential treatments with PM2.5 at low concentrations caused a robust increase in these proteins. Treatment of fibroblasts with IMD0354, an inhibitor to nuclear factor κB, but not with an antagonist to aryl hydrocarbon receptor, abolished the ability of PM2.5 to induce myofibroblast differentiation. These data demonstrate that potential impact of PM2.5 to fibroblast activation and fibrosis and support the importance of utilizing low concentrations and varying exposure protocols to toxicologic studies.

Atmospheric Dry and Wet Deposition of Total Phosphorus to the Great Lakes.

Quantifying atmospheric loadings of total phosphorus (TP) to freshwater environments is essential to improve understanding of its fate and transport, and to mitigate the effects of excessive levels in freshwater ecosystems. To date, atmospheric deposition of TP in the U.S. is poorly characterized due to the lack of long-term deposition observations. Here, we integrate several historical datasets to develop an estimate of dry and wet deposition to the Great Lakes region. For dry deposition, we use TP concentrations in fine particulate matter (PM2.5) samples from fourteen land-based IMPROVE sites (2013-2020) upwind of the Great Lakes to provide new fine particle phosphorus dry deposition estimates. For wet deposition, we use TP concentrations in wet-only precipitation samples collected at eleven land-based sites (2001-2009) in the Great Lakes region. For both wet and dry deposition, a seasonal cycle is evident with higher concentrations in warmer and wetter months when compared to colder months. Additionally, there is an increasing gradient from north to south in wet deposition, likely driven by both higher precipitation and increased emissions near southern sites. Despite different sampling time periods, these updated observations can provide further constraints on the TP loadings to each of the five Great Lakes. We estimate annual deposition of TP to Lakes Superior, Michigan, Huron, Erie and Ontario at 526, 702, 495, 212, and 185 MTA per year, which is lower than prior estimates for Lakes Superior, Erie and Ontario, comparable for Lake Huron, and about two times greater for Lake Michigan. When considering only the contribution of fine particulate PM to the dry deposition, wet deposition dominated over dry at all lakes except for Lake Huron. However, prior global estimates suggest greater contributions from larger particles (PM10 and PM100), yet observations to validate these estimates over the Great Lakes are not available. Our findings indicate that dry deposition of a range of particle sizes are needed to constrain the total atmospheric deposition of TP over the Great Lakes.

Monitoring SARS-CoV-2 in air and on surfaces and estimating infection risk in buildings and buses on a university campus.

BACKGROUND: Evidence is needed on the presence of SARS-CoV-2 in various types of environmental samples and on the estimated transmission risks in non-healthcare settings on campus. OBJECTIVES: The objective of this research was to collect data on SARS-CoV-2 viral load and to examine potential infection risks of people exposed to the virus in publicly accessible non-healthcare environments on a university campus. METHODS: Air and surface samples were collected using wetted wall cyclone bioaerosol samplers and swab kits, respectively, in a longitudinal environmental surveillance program from August 2020 until April 2021 on the University of Michigan Ann Arbor campus. Quantitative rRT-PCR with primers and probes targeting gene N1 were used for SARS-CoV-2 RNA quantification. The RNA concentrations were used to estimate the probability of infection by quantitative microbial risk assessment modeling and Monte-Carlo simulation. RESULTS: In total, 256 air samples and 517 surface samples were collected during the study period, among which positive rates were 1.6% and 1.4%, respectively. Point-biserial correlation showed that the total case number on campus was significantly higher in weeks with positive environmental samples than in non-positive weeks (p = 0.001). The estimated probability of infection was about 1 per 100 exposures to SARS-CoV-2-laden aerosols through inhalation and as high as 1 per 100,000 exposures from contacting contaminated surfaces in simulated scenarios. SIGNIFICANCE: Viral shedding was demonstrated by the detection of viral RNA in multiple air and surface samples on a university campus. The low overall positivity rate indicated that the risk of exposure to SARS-CoV-2 at monitored locations was low. Risk modeling results suggest that inhalation is the predominant route of exposure compared to surface contact, which emphasizes the importance of protecting individuals from airborne transmission of SARS-CoV-2 and potentially other respiratory infectious diseases. IMPACT: Given the reoccurring epidemics caused by highly infectious respiratory viruses in recent years, our manuscript reinforces the importance of monitoring environmental transmission by the simultaneous sampling and integration of multiple environmental surveillance matrices for modeling and risk assessment.

Independent and Joint Contributions of Fine Particulate Matter Exposure and Population Vulnerability to Mortality in the Detroit Metropolitan Area.

Fine particulate matter is associated with adverse health outcomes. Exposure to fine particulate matter may disproportionately affect urban communities with larger numbers of vulnerable residents. We used multilevel logistic regression models to estimate the joint effects of fine particulate matter (PM2.5) and population vulnerabilities on cardiopulmonary mortality (CPM). We estimated the health benefits of reductions in PM2.5 across census tracts in the Detroit metropolitan area with varying levels of population vulnerability, using cluster-specific odds ratios scaled to reflect PM2.5-attributable cardiopulmonary risk. PM2.5 and population vulnerability were independently associated with odds of CPM. Odds of CPM and the number of deaths attributable to PM2.5 were greatest in census tracts with both high PM2.5 exposures and population vulnerability. Reducing PM2.5 in census tracts with high PM2.5 would lead to an estimated 18% annual reduction in PM2.5-attributable CPM. Between 78⁻79% of those reductions in CPM would occur within census tracts with high population vulnerabilities. These health benefits of reductions in PM2.5 occurred at levels below current U.S. reference concentrations. Focusing efforts to reduce PM2.5 in the Detroit metropolitan area in census tracts with currently high levels would also lead to greater benefits for residents of census tracts with high population vulnerabilities.

Effects of Airborne Particulate Matter on Respiratory Health in a Community near a Cement Factory in Chilanga, Zambia: Results from a Panel Study.

We conducted a panel study to investigate seasonal variations in concentrations of airborne PM2.5 and PM10 and the effects on respiratory health in a community near a cement factory; in Chilanga; Zambia. A panel of 63 and 55 participants aged 21 to 59 years from a community located at the edge of the factory within 1 km and a control community located 18 km from the factory respectively; were followed up for three climatic seasons July 2015 to February 2016. Symptom diary questionnaires were completed and lung function measurements taken daily for 14 days in each of the three climatic seasons. Simultaneously, PM2.5 and PM10 concentrations in ambient air were monitored at a fixed site for each community. Mean seasonal concentrations of PM2.5 and PM10 ranged from 2.39-24.93 µg/m3 and 7.03-68.28 µg/m³ respectively in the exposed compared to the control community 1.69-6.03 µg/m³ and 2.26-8.86 µg/m³. The incident rates of reported respiratory symptoms were higher in the exposed compared to the control community: 46.3 vs. 13.8 for cough; 41.2 vs. 9.6 for phlegm; 49.0 vs.12.5 for nose; and 13.9 vs. 3.9 for wheeze per 100 person-days. There was a lower performance on all lung indices in the exposed community compared to the control; overall the mean FEV1 (forced expiratory volume in one second) and FVC (forced vital capacity) predicted percentage for the exposed was six and four percentage points lower than the control. Restriction of industrial emissions coupled with on-going monitoring and regulatory enforcement are needed to ensure that PM (airborne particulate matter) levels in the ambient air are kept within recommended levels to safeguard the respiratory health of nearby community residents.

Combustion-Related Organic Species in Temporally Resolved Urban Airborne Particulate Matter.

Accurate characterization of the chemical composition of particulate matter (PM) is essential for improved understanding of source attribution and resultant health impacts. To explore this we conducted ambient monitoring of a suite of 15 combustion-related organic species in temporally resolved PM 2.5 samples during an ongoing animal exposure study in a near source environment in Detroit, MI. All of the 15 species detected were above the method detection limit in 8 hour samples. This study focused on two molecular classes: Polycyclic Aromatic Hydrocarbons (PAHs) and Hopanes measured in samples. Of the 12 PAHs studied, benzo[b]fluoranthene (169 pg m-3), benzo[g,h,i]perylene (124 pg m-3), and benzo[e]pyrene (118, pg m-3) exhibited the three highest mean concentrations while 17α(H),21ß(H)-Hopane (189 pg m-3) and 17α(H),21ß(H)-30-Norhopane (145 pg m-3) had the highest mean concentrations of the 3 Hopanes analyzed in samples. Ratios of individual compound concentrations to total compound concentrations (∑ 15 compounds) showed the greatest daily variation for 17α(H),21ß(H)-Hopane (11-28%) and 17α(H),21ß(H)-30-Norhopane (8-20%). Diagnostic PAH concentration ratios ([IP]/[IP + BP] (range 0.30 - 0.45), [BaP]/[BaP+BeP] (range 0.26 - 0.44), [BaP]/[BP] (range 0.41 - 0.82), [Bb]/[Bk] (range 2.07 - 2.66), in samples reflected impacts froma mixture of combustion sources consistent with greater prevalence of petroleum combustion source emissions (gasoline, diesel, kerosene, and crude oil) compared to coal or wood combustion emissions impacts at this urban site. Results from this study demonstrate that short duration sampling for organic speciation provides temporally relevant exposure information.

Acute increase in blood pressure during inhalation of coarse particulate matter air pollution from an urban location.

Particulate matter (PM) air pollution is a leading global risk factor for cardiovascular mortality. Although exposure to fine PM <2.5 µm raises arterial blood pressure (BP), few studies have evaluated the impact of coarse PM which differs in size (2.5-10 µm), sources, and chemistry. Twenty-nine healthy adults (30.4 ± 8.2 years) underwent a randomized double-blind crossover study involving 2-hour exposures to concentrated ambient coarse PM (164.2 ± 80.4 µg/m(3)) at an urban location (Dearborn, Michigan) versus filtered air. Cardiovascular outcomes were measured during, immediately, and 2 hours after exposures. Both systolic (1.9 mm Hg; 95% confidence interval: 0.96, 2.8; P < .001) and diastolic (1.9 mm Hg; 95% confidence interval: 1.1, 2.7; P < .001) BP levels were higher throughout coarse PM compared with filtered air exposures by mixed-model analyses. Heart rate variability, endothelial function, and arterial compliance were not significantly affected. Brief exposure to coarse PM in an urban environment raises arterial BP. These findings add mechanistic support to the contention that coarse PM may be capable of promoting cardiovascular events.

Oil sands development and its impact on atmospheric wet deposition of air pollutants to the Athabasca Oil Sands Region, Alberta, Canada.

Characterization of air pollutant deposition resulting from Athabasca oil sands development is necessary to assess risk to humans and the environment. To investigate this we collected event-based wet deposition during a pilot study in 2010-2012 at the AMS 6 site 30 km from the nearest upgrading facility in Fort McMurray, AB, Canada. Sulfate, nitrate and ammonium deposition was (kg/ha) 1.96, 1.60 and 1.03, respectively. Trace element pollutant deposition ranged from 2 × 10(-5) - 0.79 and exhibited the trend Hg < Se < As < Cd < Pb < Cu < Zn < S. Crustal element deposition ranged from 1.4 × 10(-4) - 0.46 and had the trend: La < Ce < Sr < Mn < Al < Fe < Mg. S, Se and Hg demonstrated highest median enrichment factors (130-2020) suggesting emissions from oil sands development, urban activities and forest fires were deposited. High deposition of the elements Sr, Mn, Fe and Mg which are tracers for soil and crustal dust implies land-clearing, mining and hauling emissions greatly impacted surrounding human settlements and ecosystems.

Prevalence and determinants of mucous membrane irritations in a community near a cement factory in Zambia: a cross sectional study.

Exposure to cement dust has been associated with deleterious health effects in humans. This study investigated whether residing near a cement factory increases the risk of irritations to the mucous membranes of the eyes and respiratory system. A cross sectional study was conducted in Freedom Compound, a community bordering a cement factory in Chilanga, Zambia and a control community, Bauleni, located 18 km from the cement plant. A modified American Thoracic Society questionnaire was administered to 225 and 198 respondents aged 15-59 years from Freedom and Bauleni, respectively, to capture symptoms of the irritations. Respondents from Freedom Compound, were more likely to experience the irritations; adjusted ORs 2.50 (95% CI: 1.65, 3.79), 4.36 (95% CI (2.96, 6.55)) and 1.94 (95% CI (1.19, 3.18)) for eye, nose and sinus membrane irritations respectively. Cohort panel studies to determine associations of cement emissions to mucous membrane irritations and respiratory symptoms, coupled with field characterization of the exposure are needed to assess whether the excess prevalence of symptoms of mucous membrane irritations observed in Freedom compound are due to emissions from the cement factory.

The use of Pb, Sr, and Hg isotopes in Great Lakes precipitation as a tool for pollution source attribution.

The anthropogenic emission and subsequent deposition of heavy metals including mercury (Hg) and lead (Pb) present human health and environmental concerns. Although it is known that local and regional sources of these metals contribute to deposition in the Great Lakes region, it is difficult to trace emissions from point sources to impacted sites. Recent studies suggest that metal isotope ratios may be useful for distinguishing between and tracing source emissions. We measured Pb, strontium (Sr), and Hg isotope ratios in daily precipitation samples that were collected at seven sites across the Great Lakes region between 2003 and 2007. Lead isotope ratios ((207)Pb/(206)Pb=0.8062 to 0.8554) suggest that Pb deposition was influenced by coal combustion and processing of Mississippi Valley-Type Pb ore deposits. Regional differences in Sr isotope ratios ((87)Sr/(86)Sr=0.70859 to 0.71155) are likely related to coal fly ash and soil dust. Mercury isotope ratios (δ(202)Hg=-1.13 to 0.13‰) also varied among the sites, likely due to regional differences in coal isotopic composition, and fractionation occurring within industrial facilities and in the atmosphere. These data represent the first combined characterization of Pb, Sr, and Hg isotope ratios in precipitation collected across the Great Lakes region. We demonstrate the utility of multiple metal isotope ratios in parallel with traditional trace element multivariate statistical modeling to enable more complete pollution source attribution.

The characteristics of coarse particulate matter air pollution associated with alterations in blood pressure and heart rate during controlled exposures.

Although fine particulate matter (PM) air pollution <2.5 µm in aerodynamic diameter (PM2.5) is a leading cause of global morbidity and mortality, the potential health effects of coarse PM (2.5-10 µm in aerodynamic diameter; PM10-2.5) remain less clearly understood. We aimed to elucidate the components within coarse PM most likely responsible for mediating these hemodynamic alterations. Thirty-two healthy adults (25.9 ± 6.6 years) were exposed to concentrated ambient coarse PM (CAP) (76.2 ± 51.5 µg/m(3)) and filtered air (FA) for 2 h in a rural location in a randomized double-blind crossover study. The particle constituents (24 individual elements, organic and elemental carbon) were analyzed from filter samples and associated with the blood pressure (BP) and heart rate (HR) changes occurring throughout CAP and FA exposures in mixed model analyses. Total coarse PM mass along with most of the measured elements were positively associated with similar degrees of elevations in both systolic BP and HR. Conversely, total PM mass was unrelated, whereas only two elements (Cu and Mo) were positively associated with and Zn was inversely related to diastolic BP changes during exposures. Inhalation of coarse PM from a rural location rapidly elevates systolic BP and HR in a concentration-responsive manner, whereas the particulate composition does not appear to be an important determinant of these responses. Conversely, exposure to certain PM elements may be necessary to trigger a concomitant increase in diastolic BP. These findings suggest that particulate mass may be an adequate metric of exposure to predict some, but not all, hemodynamic alterations induced by coarse PM mass.

Effects of particulate matter and antioxidant dietary intake on blood pressure.

OBJECTIVES: We assessed 2 pathways through which dietary antioxidants may counter adverse effects of exposure to particulate matter less than 2.5 micrometers in diameter (PM2.5) on blood pressure (BP): main (compensatory) and modifying (protective) models. METHODS: We used 2002 to 2003 data from the Detroit Healthy Environments Partnership community survey conducted with a multiethnic sample of adults (n = 347) in low- to moderate-income, predominantly Hispanic and non-Hispanic Black neighborhoods in Detroit, Michigan. We used generalized estimating equations to test the effects of ambient exposure to PM2.5 and dietary antioxidant intake on BP, with adjustment for multiple confounders. RESULTS: Dietary antioxidant intake was inversely associated with systolic BP (b = -0.5; P < .05) and pulse pressure (b = -0.6; P < .05) in neighborhoods closest to major sources of air pollutants. Adverse effects of PM2.5 remained significant after accounting for antioxidant intakes. Exploratory analyses suggested potential modifying effects of antioxidant intake on associations between ambient PM2.5 exposure and BP. CONCLUSIONS: Interventions to improve access to antioxidant-rich foods in polluted urban areas may be protective of cardiovascular health. However, efforts to reduce PM2.5 exposure remain critical for cardiovascular health promotion.

Fine particulate matter air pollution and blood pressure: the modifying role of psychosocial stress.

BACKGROUND: Consensus is growing on the need to investigate the joint effects of psychosocial stress and environmental hazards on health. Some evidence suggests that psychosocial stress may be an important modifier of the association between air pollution respiratory outcomes, but few have examined cardiovascular outcomes. OBJECTIVES: We examined the modifying effect of psychosocial stress on the association between fine particulate matter air pollution (PM2.5) and blood pressure (BP). METHODS: Our data came from the Detroit Healthy Environments Partnership (HEP) 2002-2003 survey. Of 919 participants, BP was collected at two time points in a subset of 347. Building on previous work reporting associations between PM2.5 and BP in this sample, we regressed systolic (SBP) and diastolic (DBP) BP and pulse pressure (PP), in separate linear models, on the interaction among psychosocial stress, PM2.5, and HEP neighborhood (Southwest, Eastside, Northwest). RESULTS: The association between PM2.5 and SBP was stronger for those who reported high levels of stress, but this interaction was significant only in the Southwest Detroit neighborhood. Southwest Detroit residents who reported low stress showed 2.94 mmHg (95% CI: -0.85, 6.72) increase in SBP for each 10 µg/m(3) increase in 2-day prior PM2.5 exposure. Those who reported high stress showed 9.05 mmHg (95% CI: 3.29, 14.81) increase in SBP for each 10 µg/m(3) increase in PM2.5 exposure. CONCLUSIONS: These results suggest that psychosocial stress may increase vulnerability to the hypertensive effects of PM2.5. This work contributes to an understanding of the ways in which the social and physical environments may jointly contribute to poor health and to health disparities.

PM2.5-induced cardiovascular dysregulation in rats is associated with elemental carbon and temperature-resolved carbon subfractions.

BACKGROUND: We tested the hypothesis that cardiovascular responses to PM2.5 exposure will be enhanced in hypertensive rats and linked to specific carbonaceous pollutants in an urban industrial setting. METHODS: Spontaneously hypertensive rats were exposed by inhalation to concentrated PM2.5 in an industrial area of Dearborn, Michigan, for four consecutive summer days. Blood pressure (BP), heart rate (HR) and HR variability (HRV) metrics (SDNN, RMSSD) were assessed by radiotelemetry and compared to 1 h- and 8 h-averaged fluctuations in PM2.5 composition, with a focus on elemental and organic carbon (EC and OC, respectively), and temperature-resolved subfractions (EC1-EC5, PC (pyrolized carbon), and OC1-OC4), as well as other major and minor PM components. RESULTS: Mean HR and BP were increased, while HRV was decreased over 4 days of exposure. Using 1 h averages, EC (1 µg/m3 increase) was associated with increased HR of 11-32 bpm (4-11% increase), 1.2-1.5 ms (22-27%) decreases in SDNN, 3-14 mmHg (1.5-8%) increases in systolic BP, and 5-12 mmHg (4-9%) increases in diastolic BP. By comparison, associations with OC were negligible. Using 8 h averages, EC subfractions were linked with increased heart rate (EC1: 13 bpm; EC2, EC3, PC: <5 bpm) and SDNN (EC1> > EC2 > EC3, EC4, PC), but with decreased RMSSD (EC2, EC5 > EC3, EC4). Minimal effects were associated with OC and OC1. Associations between carbon subfractions and BP were negligible. Associations with non-carbonaceous components and trace elements were generally non-significant or of negligible effect size. CONCLUSIONS: These findings are the first to describe associations between acute cardiovascular responses and thermally resolved carbon subfractions. We report that cardiovascular responses to PM2.5 carbonaceous materials appear to be driven by EC and its EC1 fraction.

Hemodynamic, autonomic, and vascular effects of exposure to coarse particulate matter air pollution from a rural location.

BACKGROUND: Fine particulate matter (PM) air pollution is associated with numerous adverse health effects, including increased blood pressure (BP) and vascular dysfunction. Coarse PM substantially contributes to global air pollution, yet differs in characteristics from fine particles and is currently not regulated. However, the cardiovascular (CV) impacts of coarse PM exposure remain largely unknown. OBJECTIVES: Our goal was to elucidate whether coarse PM, like fine PM, is itself capable of eliciting adverse CV responses. METHODS: We performed a randomized double-blind crossover study in which 32 healthy adults (25.9 ± 6.6 years of age) were exposed to concentrated ambient coarse particles (CAP; 76.2 ± 51.5 µg/m(3)) in a rural location and filtered air (FA) for 2 hr. We measured CV outcomes during, immediately after, and 2 hr postexposures. RESULTS: Both systolic (mean difference = 0.32 mmHg; 95% CI: 0.05, 0.58; p = 0.021) and diastolic BP (0.27 mmHg; 95% CI: 0.003, 0.53; p = 0.05) linearly increased per 10 min of exposure during the inhalation of coarse CAP when compared with changes during FA exposure. Heart rate was on average higher (4.1 bpm; 95% CI: 3.06, 5.12; p < 0.0001) and the ratio of low-to-high frequency heart rate variability increased (0.24; 95% CI: 0.07, 0.41; p = 0.007) during coarse particle versus FA exposure. Other outcomes (brachial flow-mediated dilatation, microvascular reactive hyperemia index, aortic hemodynamics, pulse wave velocity) were not differentially altered by the exposures. CONCLUSIONS: Inhalation of coarse PM from a rural location is associated with a rapid elevation in BP and heart rate during exposure, likely due to the triggering of autonomic imbalance. These findings add mechanistic evidence supporting the biological plausibility that coarse particles could contribute to the triggering of acute CV events.

No effect of acute exposure to coarse particulate matter air pollution in a rural location on high-density lipoprotein function.

CONTEXT: High-density lipoprotein (HDL) particles perform numerous vascular-protective functions. Animal studies demonstrate that exposure to fine or ultrafine particulate matter (PM) can promote HDL dysfunction. However, the impact of PM on humans remains unknown. OBJECTIVE: We aimed to determine the effect of exposure to coarse concentrated ambient particles (CAP) on several metrics of HDL function in healthy humans. METHODS: Thirty-two adults (25.9 ± 6.6 years) were exposed to coarse CAP [76.2 ± 51.5 µg·m(-3)] in a rural location and filtered air (FA) for 2 h in a randomized double-blind crossover study. Venous blood collected 2- and 20-h post-exposures was measured for HDL-mediated efflux of [(3)H]-cholesterol from cells and 20-h exposures for HDL anti-oxidant capacity by a fluorescent assay and paraoxonase activity. The changes [median (first, third quartiles)] between exposures among 29 subjects with available results were compared by matched Wilcoxon tests. RESULTS: HDL-mediated cholesterol efflux capacity did not differ between exposures at either time point [16.60% (15.17, 19.19) 2-h post-CAP versus 17.56% (13.43, 20.98) post-FA, p = 0.768 and 14.90% (12.47, 19.15) 20-h post-CAP versus 17.75% (13.22, 23.95) post-FA, p = 0.216]. HOI [0.26 (0.24, 0.35) versus 0.28 (0.25, 0.40), p = 0.198] and paraoxonase activity [0.54 (0.39, 0.82) versus 0.60 µmol·min(-1 )ml plasma(-1) (0.40, 0.85), p = 0.137] did not differ 20-h post-CAP versus FA, respectively. CONCLUSIONS: Brief inhalation of coarse PM from a rural location did not acutely impair several facets of HDL functionality. Whether coarse PM derived from urban sites, fine particles or longer term PM exposures can promote HDL dysfunction warrant future investigations.

Cardiovascular depression in rats exposed to inhaled particulate matter and ozone: effects of diet-induced metabolic syndrome.

BACKGROUND: High ambient levels of ozone (O3) and fine particulate matter (PM2.5) are associated with cardiovascular morbidity and mortality, especially in people with preexisting cardiopulmonary diseases. Enhanced susceptibility to the toxicity of air pollutants may include individuals with metabolic syndrome (MetS). OBJECTIVE: We tested the hypothesis that cardiovascular responses to O3 and PM2.5 will be enhanced in rats with diet-induced MetS. METHODS: Male Sprague-Dawley rats were fed a high-fructose diet (HFrD) to induce MetS and then exposed to O3, concentrated ambient PM2.5, or the combination of O3 plus PM2.5 for 9 days. Data related to heart rate (HR), HR variability (HRV), and blood pressure (BP) were collected. RESULTS: Consistent with MetS, HFrD rats were hypertensive and insulin resistant, and had elevated fasting levels of blood glucose and triglycerides. Decreases in HR and BP, which were found in all exposure groups, were greater and more persistent in HFrD rats compared with those fed a normal diet (ND). Coexposure to O3 plus PM2.5 induced acute drops in HR and BP in all rats, but only ND rats adapted after 2 days. HFrD rats had little exposure-related changes in HRV, whereas ND rats had increased HRV during O3 exposure, modest decreases with PM2.5, and dramatic decreases during O3 plus PM2.5 coexposures. CONCLUSIONS: Cardiovascular depression in O3- and PM2.5-exposed rats was enhanced and prolonged in rats with HFrD-induced MetS. These results in rodents suggest that people with MetS may be prone to similar exaggerated BP and HR responses to inhaled air pollutants.

Spatial patterns in wet and dry deposition of atmospheric mercury and trace elements in central Illinois, USA.

An intensive 1-month atmospheric sampling campaign was conducted concurrently at eight monitoring sites in central Illinois, USA, from June 9 to July 3, 2011 to assess spatial patterns in wet and dry deposition of mercury and other trace elements. Summed wet deposition of mercury ranged from 3.1 to 5.4 µg/m(2) across sites for the total study period, while summed dry deposition of reactive mercury (gaseous oxidized mercury plus particulate bound mercury) ranged from 0.7 to 1.6 µg/m(2), with no statistically significant differences found spatially between northern and southern sites. Ratios of summed wet to summed dry mercury deposition across sites ranged from 2.2 to 4.9 indicating that wet deposition of mercury was dominant during the study period. Volume-weighted mean mercury concentrations in precipitation were found to be significantly higher at northern sites, while precipitation depth was significantly higher at southern sites. These results showed that substantial amounts of mercury deposition, especially wet deposition, occurred during the study period relative to typical annual wet deposition levels. Summed wet deposition of anthropogenic trace elements was much higher, compared to summed dry deposition, for sulfur, selenium, and copper, while at some sites summed dry deposition dominated summed wet deposition for lead and zinc. This study highlights that while wet deposition of Hg was dominant during this spring/summer-season study, Hg dry deposition also contributed an important fraction and should be considered for implementation in future Hg deposition monitoring studies.

The effect of acute exposure to coarse particulate matter air pollution in a rural location on circulating endothelial progenitor cells: results from a randomized controlled study.

CONTEXT: Fine particulate matter (PM) air pollution has been associated with alterations in circulating endothelial progenitor cell (EPC) levels, which may be one mechanism whereby exposures promote cardiovascular diseases. However, the impact of coarse PM on EPCs is unknown. OBJECTIVE: We aimed to determine the effect of acute exposure to coarse concentrated ambient particles (CAP) on circulating EPC levels. METHODS: Thirty-two adults (25.9 ± 6.6 years) were exposed to coarse CAP (76.2 ± 51.5 µg m(-3)) in a rural location and filtered air (FA) for 2 h in a randomized double-blind crossover study. Peripheral venous blood was collected 2 and 20 h post-exposures for circulating EPC (n = 21), white blood cell (n = 24) and vascular endothelial growth factor (VEGF) (n = 16-19) levels. The changes between exposures were compared by matched Wilcoxon signed-rank tests. RESULTS: Circulating EPC levels were elevated 2 [108.29 (6.24-249.71) EPC mL(-1); median (25th-75th percentiles), p = 0.052] and 20 h [106.86 (52.91-278.35) EPC mL(-1), p = 0.008] post-CAP exposure compared to the same time points following FA [38.47 (0.00-84.83) and 50.16 (0.00-104.79) EPC mL(-1)]. VEGF and white blood cell (WBC) levels did not differ between exposures. CONCLUSIONS: Brief inhalation of coarse PM from a rural location elicited an increase in EPCs that persisted for at least 20 h. The underlying mechanism responsible may reflect a systemic reaction to an acute "endothelial injury" and/or a circulating EPC response to sympathetic nervous system activation.

Validating satellite-derived land surface temperature with in situ measurements: a public health perspective.

BACKGROUND: Land surface temperature (LST) and percent surface imperviousness (SI), both derived from satellite imagery, have been used to characterize the urban heat island effect, a phenomenon in which urban areas are warmer than non-urban areas. OBJECTIVES: We aimed to assess the correlations between LSTs and SI images with actual temperature readings from a ground-based network of outdoor monitors. METHODS: We evaluated the relationships among a) LST calculated from a 2009 summertime satellite image of the Detroit metropolitan region, Michigan; b) SI from the 2006 National Land Cover Data Set; and c) ground-based temperature measurements monitored during the same time period at 19 residences throughout the Detroit metropolitan region. Associations between these ground-based temperatures and the average LSTs and SI at different radii around the point of the ground-based temperature measurement were evaluated at different time intervals. Spearman correlation coefficients and corresponding p-values were calculated. RESULTS: Satellite-derived LST and SI values were significantly correlated with 24-hr average and August monthly average ground temperatures at all but two of the radii examined (100 m for LST and 0 m for SI). Correlations were also significant for temperatures measured between 0400 and 0500 hours for SI, except at 0 m, but not LST. Statistically significant correlations ranging from 0.49 to 0.91 were observed between LST and SI. CONCLUSIONS: Both SI and LST could be used to better understand spatial variation in heat exposures over longer time frames but are less useful for estimating shorter-term, actual temperature exposures, which can be useful for public health preparedness during extreme heat events.