High Particulate Matter Exposure Research Articles

Fine particle pollution during megafires contains potentially toxic elements

Wildfires that raged across Australia during the 2019–2020 ‘Black Summer’ produced an enormous quantity of particulate matter (PM) pollution, with plumes that cloaked many urban centres and ecosystems along the eastern seaboard. This has motivated a need to understand the magnitude and nature of PM exposure, so that its impact on both built and natural environments can be more accurately assessed. Here we present the potentially toxic fingerprint of PM captured by building heating, ventilation, and air conditioning filters in Sydney, Australia during the peak of the Wildfires, and from ambient urban emissions one year later (Reference period). Atmospheric PM and meteorological monitoring data were also assessed to determine the magnitude and source of high PM exposure. The wildfires were a major source of PM pollution in Sydney, exceeding the national standards on 19 % of days between November–February. Wildfire particles were finer and more spherical compared to Reference PM, with count median diameters of 892.1 ± 23.1 versus 1484.8 ± 96.7 nm (mean ± standard error). On an equal-mass basis, differences in potentially toxic elements were predominantly due to higher SO42−-S (median 20.4 vs 4.7 mg g−1) and NO3−-N (2.4 vs 1.2 mg g−1) in Wildfire PM, and higher PO43−-P (10.4 vs 1.4 mg g−1) in Reference PM. Concentrations of remaining elements were similar or lower than Reference PM, except for enrichments to F−, Cl−, dissolved Mn, and particulate Mn, Co and Sb. Fractional solubilities of trace elements were similar or lower than Reference PM, except for enhanced Hg (12.1 vs 1.0 %) and greater variability in Cd, Hg and Mn solubility, which displayed upper quartiles exceeding that of Reference PM. These findings contribute to our understanding of human and ecosystem exposures to the toxic components of mixed smoke plumes, especially in regions downwind of the source.

Comparison of short-term effects of particulate matter with different particle sizes on first-ever stroke: A national case-crossover study in China

ObjectivesTo compare the effects of short-term exposure to particulate matter (PM) with different particle sizes on first-ever stroke risk in the middle-aged and elderly Chinese population. MethodsHealth information was collected from the China National Stroke Screening Survey (CNSSS) from March 1, 2013, to April 10, 2015. Ambient exposures to PM1, PM2.5, and PM10 were obtained from ChinaHighAirPollutants (CHAP) Grid data. Case-crossover design was used to estimate the increase of first-ever stroke risk per 10 μg/m3 increase in ambient exposures to different size particles. We used distributed lag linear model (DLM) to estimate the hysteresis effects of particle exposures. In addition, in order to assess the effect modification of long-term exposure, we did a stratified analysis using median exposure as the dividing line. ResultsWe included 1326 first-ever stroke events from 242 communities in the present study. We found that effects on first-ever stroke risk increased with the decrease in particle size. The percent increases of first-ever stroke risk increased by 6.6% (95% CI: 1.4, 12.0), 3.3% (95% CI: 0.5, 6.1), and 0.6% (95% CI: -1.2, 2.6) per 10 g/m3 increases in PM1, PM2.5, and PM10 exposures in lag 0–2 days, respectively. Furthermore, the cumulative effect of PM on first-ever stroke reached its peak at distinct time points under different layers of long-term PM exposure. In areas with low PM exposure, the cumulative effects of the three kinds of particles on stroke reached their peak in lag1 day, while the cumulative effect peaked in lag3 day in areas with high PM exposure. ConclusionsThis study found that smaller particles had a stronger short-term effect on first-ever stroke. We also found that people in areas with long-term exposures to lower levels were more sensitive to short-term exposures. These results have public health significance for stroke prevention and air pollution reduction.

282 Food Intake REstriction for Health OUtcome Support and Education (FIREHOUSE): a Proof of Concept Randomized Clinical Trial

OBJECTIVES/GOALS: Particulate matter (PM) and metabolic syndrome (MetSyn) increase risk of World Trade Center-Lung Injury (WTC-LI). Mediterranean-type diets have also been found to improve lung function. Fire Department of New York 1st-responders with a high PM exposure at WTC and MetSyn may have improved lung function after a Mediterranean dietary intervention. METHODS/STUDY POPULATION: Food Intake REstriction for Health OUtcome Support and Education (FIREHOUSE) randomized clinical trial (RCT) assessed our hypothesis that a low-calorie Mediterranean (LoCalMed) intervention targeting clinically relevant disease modifiers will improve metabolic risk, subclinical indicators of cardiopulmonary disease, quality of life, and lung function in firefighters with WTC-LI. Primary-outcome targeted a LoCalMed loss of BMI(≥1kg/m2). Secondary-outcomes included lung function, quality of life, and cardiovascular health. Male firefighters with WTC-LI and a BMI>27kg/m2 were randomized to: 1. LoCalMed (n=46); or 2. Usual Care (UC; n=43). Clinicaltrials.gov:NCT03581006. RESULTS/ANTICIPATED RESULTS: LoCalMed’s estimated efficacy on BMI reduction crossed the pre-specified significance boundary on interim analysis compared to UC. In addition, improvements were observed in secondary-outcomes of lung health (FEV1 and FVC), inflammation (WBC), vascular disease (DBP), quality of life (SF-36, health perception) and dietary habits (less cholesterol, carbohydrates, fats, and sweets and increased protein) in the LoCalMed arm. DISCUSSION/SIGNIFICANCE: LoCalMed significantly decreased BMI and alleviated adverse health outcomes in our WTC-exposed first responders. A fully powered RCT is required to determine if this approach is efficacious for the treatment of WTC-associated pulmonary disease, as well as LoCalMed’s generalizability to PM associated disease.

Particulate matter in the workplace: effects of a mental models-based folder combined with a practical assignment

BackgroundWith increasing knowledge on the adverse health effects of certain constituents of PM (particulate matter), such as silica, metals, insoluble ions, and black carbon, PM has been under the attention of work safety experts. Previously, we investigated the perceptions of blue-collar workers in highly exposed areas of work. Subsequently, we developed an instruction folder highlighting the most important aspects of PM risk and mitigation, and tested this folder in a digital experiment. The digital experiment yielded positive results with regards to acquired knowledge about PM, but did not on risk perception or safety behavior.MethodsIn this study, we investigate the effects of the folder when combined with a practical assignment involving a PM exposimeter, showing the amount of particulate matter in microgram per cubic meter in real time on its display for various activities. We tested this at six workplaces of four companies in the roadwork and construction branch.ResultsThe results indicate that the folder itself yields an increased knowledge base in employees about PM, but the effects of the practical assignment are more contentious. Nevertheless, there is an indication that using the assignment may lead to a higher threat appraisal among employees for high exposure activities.ConclusionWe recommend implementing our folder in companies with high PM exposure and focusing further research on appropriate methods of implementation.

Risk communication about particulate matter in the workplace: A digital experiment

Workers do not always showcase adequate knowledge on potential long-term health effects and other properties of particulate matter (PM), which may lead to a decreased tendency to work safely in a high-PM environment. To empower workers to work more safely in environments with high PM exposure, we developed an educational folder tethered to their information needs. In the present study, we test two versions of our folder in a digital panel experiment with 227 participants who regularly worked in environments where they are potentially highly exposed to PM. We tested one version with and one without visualizations of the exposure and health effects, as it is currently unclear whether such visualizations can improve risk understanding. We compared them with an existing folder about PM and with a control condition involving a text unrelated to the subject. The outcome variables included people’s opinions about the quality of the material; learning effects by means of knowledge questions; and perception- and behavior-related effects about PM and mitigation methods. The results revealed a significant and relevant difference on improvement of knowledge scores between our folder with extra visualizations and the control condition. No significant difference between the conditions with regards to perception and behavior effects were found.

Artificial Intelligence-Based Smart Solution to Reduce Respiratory Problems Caused by Air Pollution

Globally, air pollution is a significant concern for human health. Artificial sources of particulate matter (fine dust particles suspended in the air), especially PM2.5, are the significant constituents in indoor air pollution and prominently leads to many lung-related illnesses. Research suggests that around 90% of people spend ~22 hours inside every day, either at a home, office, factory, or restaurant. Plants act as a natural detoxifying agent by taking particulate matter (PM) waste from the atmosphere. Our hypothesis tested whether placing specific plants indoors can reduce levels of PM inside by using principles of biomedical engineering and machine-learning approaches. Our data showed that plants improved the overall quality of the air in the room. Levels of PM2.5 were decreased dramatically in the rooms compared to the average levels measured outside the house. As higher PM exposure in humans is associated with many diseases, our research suggests that plant-based interventions coupled with a sensor and cloud-based application using artificial intelligence may be useful in the long run to reduce indoor air pollution.

Oxidative stress-induced inflammation in susceptible airways by anthropogenic aerosol.

Ambient air pollution is one of the leading five health risks worldwide. One of the most harmful air pollutants is particulate matter (PM), which has different physical characteristics (particle size and number, surface area and morphology) and a highly complex and variable chemical composition. Our goal was first to comparatively assess the effects of exposure to PM regarding cytotoxicity, release of pro-inflammatory mediators and gene expression in human bronchial epithelia (HBE) reflecting normal and compromised health status. Second, we aimed at evaluating the impact of various PM components from anthropogenic and biogenic sources on the cellular responses. Air-liquid interface (ALI) cultures of fully differentiated HBE derived from normal and cystic fibrosis (CF) donor lungs were exposed at the apical cell surface to water-soluble PM filter extracts for 4 h. The particle dose deposited on cells was 0.9–2.5 and 8.8–25.4 μg per cm2 of cell culture area for low and high PM doses, respectively. Both normal and CF HBE show a clear dose-response relationship with increasing cytotoxicity at higher PM concentrations. The concurrently enhanced release of pro-inflammatory mediators at higher PM exposure levels links cytotoxicity to inflammatory processes. Further, the PM exposure deregulates genes involved in oxidative stress and inflammatory pathways leading to an imbalance of the antioxidant system. Moreover, we identify compromised defense against PM in CF epithelia promoting exacerbation and aggravation of disease. We also demonstrate that the adverse health outcome induced by PM exposure in normal and particularly in susceptible bronchial epithelia is magnified by anthropogenic PM components. Thus, including health-relevant PM components in regulatory guidelines will result in substantial human health benefits and improve protection of the vulnerable population.

Blood-derived extracellular vesicles isolated from healthy donors exposed to air pollution modulate in vitro endothelial cells behavior

The release of Extracellular Vesicles (EVs) into the bloodstream is positively associated with Particulate Matter (PM) exposure, which is involved in endothelial dysfunction and related to increased risk of cardiovascular disease. Obesity modifies the effects of PM exposure on heart rate variability and markers of inflammation, oxidative stress, and acute phase response. We isolated and characterized plasmatic EVs from six healthy donors and confirmed a positive association with PM exposure. We stratified for Body Mass Index (BMI) and observed an increased release of CD61+ (platelets) and CD105+ (endothelium) derived-EVs after high PM level exposure in Normal Weight subjects (NW) and no significant variations in Overweight subjects (OW). We then investigated the ability to activate endothelial primary cells by plasmatic EVs after both high and low PM exposure. NW-high-PM EVs showed an increased endothelial activation, measured as CD105+/CD62e+ (activated endothelium) EVs ratio. On the contrary, cells treated with OW-high-PM EVs showed reduced endothelial activation. These results suggest the ability of NW plasmatic EVs to communicate to endothelial cells and promote the crosstalk between activated endothelium and peripheral cells. However, this capacity was lost in OW subjects. Our findings contribute to elucidate the role of EVs in endothelial activation after PM exposure.

Associations between Particulate Matter Air Pollution, Presence and Progression of Subclinical Coronary and Carotid Atherosclerosis: A Systematic Review

Abstract Background and aims Long-term exposure to particulate matter (PM) air pollution has been linked with increased cardiovascular events and mortality, however, studies had shown inconsistent associations between PM exposure and subclinical atherosclerosis. Methods We performed an updated systematic literature review to identify studies evaluating the associations between PM and subclinical atherosclerosis, measured using presence/progression of coronary artery calcium (CAC) or carotid intima-media thickness (CIMT) in adult populations. Quality was assessed using the Newcastle-Ottawa scale. Results Eighteen studies were included: 5 cohorts and 13 cross-sectional. Amongst 7 studies that evaluated the associations between PM and prevalence of CAC, 4 reported significantly higher odds of detectable CAC>0 or CAC>400 with increased PM exposure. Nine studies evaluated the association between exposure to at least one of the particulates and CIMT; of these, 6 reported significant independent associations. Two studies evaluated PM2.5 and CAC progression, with 1 reporting a greater progression of CAC with increased exposure to PM, while 3 out of 4 studies evaluating CIMT progression showed no significant difference in CIMT progression with a higher PM2.5 exposure. Additionally, 3 studies found significant associations between proximity to major roadways and measures of subclinical atherosclerosis. Among null studies, most displayed non-significant trends towards higher atherosclerosis burden with higher PM exposure. Conclusions Overall, available observational studies support a positive association between PM exposure and subclinical atherosclerosis. Further longitudinal studies are needed to better establish this relationship and assess the efficacy of previously identified interventions on mitigation of clinical cardiovascular disease.

Associations between particulate matter air pollution, presence and progression of subclinical coronary and carotid atherosclerosis: A systematic review

Background and aimsLong-term exposure to particulate matter (PM) air pollution has been linked with increased cardiovascular events and mortality, however, studies had shown inconsistent associations between PM exposure and subclinical atherosclerosis. MethodsWe performed an updated systematic literature review to identify studies evaluating the associations between PM and subclinical atherosclerosis, measured using presence/progression of coronary artery calcium (CAC) or carotid intima-media thickness (CIMT) in adult populations. Quality was assessed using the Newcastle-Ottawa scale. ResultsEighteen studies were included: 5 cohorts and 13 cross-sectional. Amongst 7 studies that evaluated the associations between PM and prevalence of CAC, 4 reported significantly higher odds of detectable CAC>0 or CAC>400 with increased PM exposure. Nine studies evaluated the association between exposure to at least one of the particulates and CIMT; of these, 6 reported significant independent associations. Two studies evaluated PM2.5 and CAC progression, with 1 reporting a greater progression of CAC with increased exposure to PM, while 3 out of 4 studies evaluating CIMT progression showed no significant difference in CIMT progression with a higher PM2.5 exposure. Additionally, 3 studies found significant associations between proximity to major roadways and measures of subclinical atherosclerosis. Among null studies, most displayed non-significant trends towards higher atherosclerosis burden with higher PM exposure. ConclusionsOverall, available observational studies support a positive association between PM exposure and subclinical atherosclerosis. Further longitudinal studies are needed to better establish this relationship and assess the efficacy of previously identified interventions on mitigation of clinical cardiovascular disease.

The Effect of Particulate Matter Exposure on the Inflammatory Airway Response of Street Runners and Sedentary People

Physical exercise promotes many health benefits. However, its effects are not well known in a polluted environment. Thus, this study aimed to compare upper airway inflammatory responses between street runners and sedentary individuals. Twenty-eight volunteers were recruited: runners (n = 14) and sedentary individuals (n = 14), who lived and worked in the same metropolitan area of São Paulo, Brazil. Particulate matter (PM) levels were monitored ten weeks before winter (low PM levels) and ten weeks after the beginning of winter (high PM levels) [PM10 (p < 0.0001) and PM2.5 (p < 0.0001)]. The cytokines (TNF-α, IL-6, IL-10, and IL-17A) levels in the nasal lavage and fractional exhaled nitric oxide (FeNO) were taken at the beginning of the winter (baseline) and ten weeks afterwards (after ten weeks of high PM exposure). IL-6 concentration increased in both runners (p = 0.037) and sedentary individuals (p = 0.027) after high PM exposure compared to the baseline. IL-10 concentration increased in sedentary individuals (p = 0.037) while IL-17A levels were increased in runners (p = 0.001) after high PM exposure compared to the baseline. FeNO levels decreased in runners (p = 0.025) after high PM exposure compared to the baseline. Outdoor endurance training acts as an inducer of a differentiated immune response in the upper airways of runners compared to individuals with a sedentary lifestyle from the same community after elevated PM exposure.

Association between air pollution exposure and diabetic retinopathy among diabetics

BackgroundExposure to air pollution has been linked to adverse effects on vascular diseases. However, the effects of air pollution exposure on diabetic retinopathy (DR), a vascular disease, have not been studied. ObjectiveTo determine the association of ambient air pollution exposure with DR risk. MethodsPatients newly diagnosed as having diabetes mellitus (DM) during 2003–2012 from Longitudinal Health Insurance Database 2005), a subset of National Health Insurance Research Database, were included as the study cohort. Newly diagnosed DR patients one year or later after DM diagnosis were identified as cases. Kriging was used to interpolate yearly concentrations of air pollutants at township levels and linked with every individual's residence in each year; average concentrations during the follow-up period were then calculated as personal exposure. Conditional logistic regressions with adjustments for age at DM diagnosis and comorbidities were applied. ResultsOf newly diagnosed DM cases during 2003–2012, 579 were newly diagnosed as having DR over a mean follow-up period of 5.6 years. The Odds ratio (95% confidence interval) of DR occurrence for every 10-μg/m3 increase in particulate matter with ≤2.5 and 2.5–10-μm diameter was 1.29 (1.11–1.50) and 1.37 (1.17–1.61), respectively. ConclusionIn patients with DM, the higher particulate matter exposure, the higher is the DR risk.

Personal level exposure and hazard potential of particulate matter during haze and non-haze periods in Singapore.

Severe haze episodes originating from biomass burning are common in Southeast Asia. However, there is a paucity of data on the personal exposure and characteristics of Particulate Matter (PM) present in ambient air during haze and non-haze periods. Aims of this study were to monitor 24h ambulatory exposure to PM among school children in Singapore; characterize haze and non-haze PM for their physicochemical properties, cytotoxicity and inflammatory potential, using bronchial epithelial cell culture model (BEAS-2B). Forty-six children had ambulatory PM exposure monitored using portable Aethalometer and their hourly activity recorded. The mean (±SE) PM exposure on a typical school day was 3343 (±174.4) ng/m3/min. Higher PM exposure was observed during haze periods and during commuting to and from the school. Characterization of PM collected showed a drastic increase in the proportion of ultrafine particle (UFP) in haze PM. These PM fraction showed higher level of sulphur, potassium and trace metals in comparison to those collected during non-haze periods. Dose dependent increases in abiotic reactive oxygen species generation, activation of NF-κB and cytotoxicity were observed for both haze and non-haze PM. Generally, haze PM induced significantly higher release of IL-6, IL-8 and TNFα by BEAS-2B cells in comparison to non-haze PM. In summary, this study provides experimental evidence for higher PM exposure during haze period which has the potential to elicit oxidative stress and pro-inflammatory cytokine release from airway epithelial cells.

Effects of short-term exposure to particulate matter air pollution on cognitive performance

This paper assesses the effect of short-term exposure to particulate matter (PM) air pollution on human cognitive performance via a double cross over experimental design. Two distinct experiments were performed, both of which exposed subjects to low and high concentrations of PM. Firstly, subjects completed a series of cognitive tests after being exposed to low ambient indoor PM concentrations and elevated PM concentrations generated via candle burning, which is a well-known source of PM. Secondly, a different cohort underwent cognitive tests after being exposed to low ambient indoor PM concentrations and elevated ambient outdoor PM concentrations via commuting on or next to roads. Three tests were used to assess cognitive performance: Mini-Mental State Examination (MMSE), the Stroop Color and Word test, and Ruff 2 & 7 test. The results from the MMSE test showed a statistically robust decline in cognitive function after exposure to both the candle burning and outdoor commuting compared to ambient indoor conditions. The similarity in the results between the two experiments suggests that PM exposure is the cause of the short-term cognitive decline observed in both. The outdoor commuting experiment also showed a statistically significant short-term cognitive decline in automatic detection speed from the Ruff 2 and 7 selective attention test. The other cognitive tests, for both the candle and commuting experiments, showed no statistically significant difference between the high and low PM exposure conditions. The findings from this study are potentially far reaching; they suggest that elevated PM pollution levels significantly affect short term cognition. This implies average human cognitive ability will vary from city to city and country to country as a function of PM air pollution exposure.

Effects of short- and long-term exposures to particulate matter on inflammatory marker levels in the general population.

The effect of particulate matter (PM) on health increases with exposure duration but the change from short to longer term is not well studied. We examined the exposure to PM smaller 10μm (PM10) from short to longer duration and their associations with levels of inflammatory markers in the population-based CoLaus cohort in Lausanne, Switzerland. Baseline and follow-up CoLaus data were used to study the associations between PM10 exposure and inflammatory markers, including the high-sensitivity C-reactive protein (CRP), as well as interleukin 1-beta (IL-1β), interleukin 6 (IL-6), and tumor-necrosis-factor alpha (TNF-α) using mixed models. Exposure was determined for each participant's home address from hourly air quality simulations at a 5-m resolution. Short-term exposure intervals were 1day, 1week, and 1month prior to the hospital visit (blood withdrawal); long-term exposure intervals were 3 and 6months prior to the visit. In most time windows, IL-6, IL-1β, and TNF-α were positively associated with PM10. No significant associations were identified for CRP. Adjusted associations with long-term exposures were stronger and more significant than those for short-term exposures. In stratified models, gender, age, smoking status, and hypertension only led to small modifications in effect estimates, though a few of the estimates for IL-6 and TNF-α became non-significant. In this general adult cohort exposed to relatively low average PM10 levels, clear associations with markers of systemic inflammation were observed. Longer duration of elevated exposure was associated with an exacerbated inflammatory response. This may partially explain the elevated disease risk observed with chronic PM10 exposure. It also suggests that reducing prolonged episodes of high PM exposure may be a strategy to reduce inflammatory risk.

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OBJECTIVES/SPECIFIC AIMS: Obstructive lung disease following particulate matter (PM) exposure is a major health concern. Coexisting metabolic syndrome (MetSyn) often occurs. Receptor for advanced glycation end products (RAGE) is highly expressed in the lung, is a strong predictor of FEV1, and is a key mediator of MetSyn. To determine if the loss of RAGE protects from the persistence of effects of particulate associated lung injury in a murine model. METHODS/STUDY POPULATION: Wild type (WT) and RAGE knockout (RKO) mice were exposed to 100 μg of PM (WTC-Aggregate, PM53) or PBS control by oropharyngeal aspiration. Lung function, methacholine challenge, and bronchoalveolar lavage (BAL) were quantified 28 days after PM exposure using flexiVent (Scireq Montreal, QC). BAL was obtained and cell differentials, cytokines and transcription factors were assayed. Bio-volume to airspace ratio and mean chord length were measured (Image J and Adobe Photoshop). RESULTS/ANTICIPATED RESULTS: WT mice were hyper-reactive to methacholine compared with their PBS controls 28 days after a single exposure to PM. They recovered from increased neutrophilia, loss of FEV, decreased compliance, and increased resistance, which were previously observed 24-hours after exposure. RKO were not hyper-reactive when compared with their own PBS controls. Lung histology shows persistence of loss of alveolar space in WT mice exposed to PM after 28 days. Area fraction was significantly higher in PM exposed WT mice after 28 days which was not significant after 24 hours. Mean chord length was significantly shorter for PM exposed at both time points for WT mice. The relative expression of phosphorylated to total CREB and ERK1/2 proteins was lower in RKO PM exposed mice compared with WT PM while STAT3 expression was lower in WT PM compared with WT PBS. PM induced a lower fold change of total proteins from the PBS controls in RKO for CREB, p38, ERK1/2, STAT3, and STAT5. JNK and p70S6k total proteins expressed a decreased fold change in WT PM exposed mice compared with WT PBS controls. DISCUSSION/SIGNIFICANCE OF IMPACT: A single dose of PM can produce persistent airway hyper-reactivity after 28 days of exposure. This PM induced injury is alleviated in the absence of RAGE, similar to what was seen at 24 hours. Inhibiting RAGE may be key to limiting the persistent inflammatory effects of high intensity PM exposure.

Particulate Matter and Respiratory Symptoms among Adults Living in Windhoek, Namibia: A Cross Sectional Descriptive Study.

This study aimed to estimate the prevalence of respiratory symptoms and to assess respiratory health risks associated with Particulate Matter (PM) exposure among the residents of Windhoek, Namibia. Objectives: To measure particulate pollution concentration in Windhoek through monitoring of particulate matter concentration and to identify any associations between particulate pollution, individual location, and respiratory health among the Windhoek resident’s. Methods: an adapted standardized self-administered questionnaire was used to collect respiratory health related data as well as previous exposure, while PM monitoring was done using the ASTM (American Standard Test Method) D1739 reference method. Results: A high prevalence was observed for cough (43%), breathlessness (25%), and asthma (11.2%). PM was found to be a significant risk factor for episodes of coughing and phlegm, while high PM exposure category had an increased odds ratio (OR) for episodes of phlegm and cough (OR: 2.5, 95% CI (95% confidence intervals): 0.8–8.0). No association was observed between location and respiratory health outcomes. Conclusions: The study found high levels of PM concentration across all Windhoek suburbs which were above the German, American, and Environmental Protection Agency (EPA). Enactment of legislation relating to the control and monitoring of PM related emissions at the point of generation is required at both a country and city level.

Deposition of aerosol particles from a subway microenvironment in the human respiratory tract

Conventional subway systems are characterized by high particulate matter (PM) concentrations. To relate PM exposure to adverse health effects it is important to determine the dose of the inhaled particles in the human respiratory tract (HRT). Therefore, the total and regional doses of particles for a healthy adult male using the dosimetry model ExDoM in the subway system were estimated. The overall dose was determined using the average exposure PM2.5 concentrations obtained from an extensive campaign in the Barcelona subway system, including measurements on the platforms and inside the trains. Despite the lower PM2.5 concentrations inside the trains with respect to those on station platforms, the highest dose was observed inside the trains due to longer exposure time, evidencing the importance of the exposure period in the estimation of the particle dose. Overall, during a subway commuting travel, roughly 80% of the inhaled mass of subway PM2.5 was deposited in the HRT. The highest amount of the inhaled particles was deposited in the extrathoracic region (68%), whereas the deposition was much smaller in the tracheobronchial tree (4%) and alveolar–interstitial region (10%). Individual's daily exposure to PM2.5 and dose were estimated, considering a typical time-activity pattern of an adult male who lives in Barcelona and commutes by subway. While a subject typically spends approx. 3% of the day in the subway system, this microenvironment may account for up to 47% of the total PM2.5 daily dose. These results might be similarly high for other commuting modes due to the reported high PM exposure levels. The dose is mainly dependent on the particle size and exposure concentrations.

Framingham risk score modifies the effect of PM10 on heart rate variability

Health conditions may greatly modify the association between particulate matter (PM) and heart rate variability (HRV), but whether the modification of PM effect by coronary artery disease (CAD) risk status depends on the PM levels remains unknown. We investigated the associations between personal exposures to PM with aerodynamic diameter of ≤10μm (PM10) and ≤2.5μm (PM2.5) and concurrent HRV, and whether the effect of PM on HRV was modified by Framingham risk score (FRS) in healthy subjects with different PM exposure levels. Personal exposures to PM10 and PM2.5 were measured for 24h in 152 volunteers of community residents who were free of cardiovascular disease in two cities (Zhuhai and Wuhan) that differ in air quality. Simultaneously, 24h HRV indices were obtained from 3-channel Holter monitor. FRS was calculated based on age, sex, lipid profiles, blood pressure, diabetes, and smoking status. Linear regression models were constructed after adjusting for potential confounders. We found significant decrease in total power (TP) and low power (LF) with increased PM10 concentrations (P for trend<0.05) in the high PM levels city (Wuhan) and total population, but not in the low PM levels city (Zhuhai). We also observed significant modification of FRS on PM10 effect in Wuhan. Interestingly, elevated PM10 was associated in a greater decreased HRV in the low FRS subgroup, but not in the high FRS subgroup. However, we did not find any significant main effects of PM2.5 or PM2.5–FRS interactions on HRV in city-specified or city-combined analyses. Overall, the findings indicate that individual coronary risk profiles may modulate the association between particulate air pollution and HRV in high PM exposure levels.

Altered DNA Hydroxymethylation and Methylation and High Particulate Matter Exposure in Beijing, China

Background: DNA methylation has been widely proposed as an epigenetic mediator of the effects of Particulate Matter (PM) exposure on human health. 5-hydroxymethylcytosine (5hmC), generated by oxidation of standard DNA methylation (5-methylcytosine, 5mC), has emerged as a novel epigenomic mark. 5hmC is both an intermediate for de-methylation and an active epigenetic mark that increases gene expression. Oxidant exposures such as PM may increase 5hmC, but effects in humans have not yet been evaluated. Methods: The Beijing Truck Driver Air Pollution Study included 60 office workers (OW) and 60 truck drivers (TD) examined on two workdays. Ambient PM10 was averaged from 27 Beijing monitors. Personal PM2.5 and Elemental Carbon (EC) were measured by portable monitors. We measured blood DNA global 5mC and 5hmC by ELISA. We fitted mixed-effects models adjusted for multiple confounders. Results: Ambient PM10 on the examination days was associated with increased global 5hmC in TD (β=0.012, 95% CI 0.004-0.021), and all participants (β=0.009, 95% CI 0.003- 0.015). Average ambient PM10 on days 4, 7, and 14 before the examinations was positively associated with global 5hmC in OW and all participants (p&lt;0.05). 5hmC was also positively associated with personal PM2.5 in OW (β=0.012, 95% CI 0.001-0.023), TD (β=0.012, 95% CI 0.002-0.022), and all participants (β=0.008, 95% CI 0.001-0.015). In contrast, global 5mC levels were associated among OW with personal EC (β=0.564, 95% CI 0.058-1.070), and marginally with personal PM2.5 (β=0.401, 95% CI 0.004-0.798). Conclusion: 5hmC and 5mC showed different patterns of association with PM measures and time windows. 5hmC may reflect epigenetic information not captured in 5mC.