Characterization of fine particulate matter and associations between particulate chemical constituents and mortality in Seoul, Korea

Background: Numerous studies have linked fine particles [≤ 2.5 µm in aerodynamic diameter (PM_2.5)] and health. Most studies focused on the total mass of the particles, although the chemical composition of the particles varies substantially. Which chemical components of fine particles that are the most harmful is not well understood, and research on the chemical composition of PM_2.5 and the components that are the most harmful is particularly limited in Asia.Objectives: We characterized PM_2.5 chemical composition and estimated the effects of cause-specific mortality of PM_2.5 mass and constituents in Seoul, Korea. We compared the chemical composition of particles to those of the eastern and western United States.Methods: We examined temporal variability of PM_2.5 mass and its composition using hourly data. We applied an overdispersed Poisson generalized linear model, adjusting for time, day of week, temperature, and relative humidity to investigate the association between risk of mortality and PM_2.5 mass and its constituents in Seoul, Korea, for August 2008 through October 2009.Results: PM_2.5 and chemical components exhibited temporal patterns by time of day and season. The chemical characteristics of Seoul’s PM_2.5 were more similar to PM_2.5 found in the western United States than in the eastern United States. Seoul’s PM_2.5 had lower sulfate (SO₄) contributions and higher nitrate (NO₃) contributions than that of the eastern United States, although overall PM_2.5 levels in Seoul were higher than in the United States. An interquartile range (IQR) increase in magnesium (Mg) (0.05 μg/m³) was associated with a 1.4% increase (95% confidence interval: 0.2%, 2.6%) in total mortality on the following day. Several components that were among the largest contributors to PM_2.5 total mass—NO₃, SO₄, and ammonium (NH₄)—were moderately associated with same-day cardiovascular mortality at the p < 0.10 level. Other components with smaller mass contributions [Mg and chlorine (Cl)] exhibited moderate associations with respiratory mortality on the following day (p < 0.10).Conclusions: Our findings link PM_2.5 constituents with mortality and have implications for policy making on sources of PM_2.5 and on the relevance of PM_2.5 health studies from other areas to this region.     

Acute health effects of urban fine and ultrafine particles on children with atopic dermatitis

Although ambient particulate pollutants have been shown to exacerbate existing allergic symptoms of mucous membranes including rhinitis and asthma, the effects on skin such as atopic dermatitis in childhood deserve further study. We investigated the effects of urban particulate pollutants including ultrafine particles on atopic severity in children with atopic dermatitis. We included 41 schoolchildren, 8–12 years old, who had been diagnosed with atopic dermatitis. For 67 consecutive days, all of them measured their symptoms in a diary. To assess exposure, the daily ambient mass concentrations of particulate matter less than 10, 2.5 and 1 μm (PM₁₀, PM_2.5 and PM₁, respectively) and concentrations of submicron particles (0.01–1 μm) were measured at a local school. The mean mass concentrations of PM₁₀, PM_2.5 and PM₁ were 74.0, 57.8 and 50.8 μg/m³, respectively. The mean concentrations were 41,335/cm³ ultrafine particles (UFPs) and 8577/cm³ accumulation mode (0.1–1 μm) particles. Significant associations were found between the concentrations of ultrafine particles and the itchiness symptom in children with atopic dermatitis. An interquartile range (IQR) increase in previous day ultrafine particles concentration (IQR: 28–140/m³) was significantly associated with a 3.1% (95% confidence interval, 0.2–6.1) increase in the itch symptom score for children with atopic dermatitis. The results suggested that the concentration of ambient ultrafine particles may exacerbate skin symptoms in children with atopic dermatitis.     

Influence of collection region and site type on the composition of paved road dust

Exposures to particulate matter (PM) re-suspended by traffic from paved roads are ubiquitous, but little is known about the variability in composition of paved road dust (PRD). This knowledge gap hinders estimates of exposure to PM components near roadways. Respirable fractions of PRD collected from multiple U.S. regions and site types were analyzed to explore chemical composition and variability. Fifty samples were collected from streets, traffic arterials, street canyons, freeways, and industrial sites in six urban regions in the southwestern, Southern California, northeastern, and southeastern U.S. regions and five rural sites. Samples were sieved, aerosolized, and size-classified into fine (PM_2.5) and coarse (PM_10-2.5) fractions. Analyses included metals and other elements, organic and elemental carbon, inorganic ions, endotoxin and glucan. Crustal elements, organic carbon, and reactive metals comprised the PRD mass with smaller fractions of elemental carbon and inorganic ions. Proportions of many inorganic components were strongly correlated between particle sizes, but fine and coarse organic carbon poorly correlated. Composition varied both among and within regions and site types, with evidence that chemical signatures varied more systematically by region than by site type. Local sources strongly influenced some samples. Samples from large urban areas had greater contents of reactive metals, but these comprised less than 0.2 % of the mass. Near-feedlot samples had high levels of endotoxin. The results provide insight into the variability of PRD composition, differences between re-suspended PRD and regional airborne PM, and improved source signatures for estimates of exposure to different PM components near roadways.     

Induction of IL-6 and inhibition of IL-8 secretion in the human airway cell line Calu-3 by urban particulate matter collected with a modified method of PM sampling

Exposure to particulate matter (PM) induces inflammatory cytokines. In the present study, we evaluated the secretion of IL-6 and IL-8 by an airway cell line exposed to PM with a mean aerodynamic size equal to or less than 10 or 2.5 μm (PM₁₀ and PM_2.5, respectively) collected in Mexico City, using a modified high-volume sampling method avoiding the use of solvents or introducing membrane components into the samples. PM was collected on cellulose-nitrate (CN) membranes modified for collection on high-volume samplers. Composition of the particles was evaluated by particle-induced X-ray emission (PIXE) and scanning electron microscopy. The particles (10-160 μg/cm²) were tested on Calu-3 cells. Control cultures were exposed to LPS (10 ng/mL to 100 μg/mL) or silica (10-160 μg/cm²). IL-6 and IL-8 secretions were evaluated by ELISA. An average of 10 mg of PM was recovered form each cellulose-nitrate filter. No evidence of contamination from the filter was found. Cells exposed to PM₁₀ presented an increase in the secretion of IL-6 (up to 400%), while IL-8 decreased (from 40% to levels below the detection limit). A similar but weaker effect was observed with PM_2.5. In conclusion, our modified sampling method provides a large amount of urban PM free of membrane contamination. The urban particles induce a decrease in IL-8 secretion that contrasts with the LPS and silica effects. These results suggest that the regulation of IL-8 expression is different for urban particles (complex mixture containing combustion-related particles, soil and biologic components) than for biogenic compounds or pure mineral particles.     

Determinants of the Proinflammatory Action of Ambient Particulate Matter in Immortalized Murine Macrophages

Background

Proximity to traffic-related pollution has been associated with poor respiratory health in adults and children.

Objectives

We wished to test the hypothesis that particulate matter (PM) from high-traffic sites would display an enhanced capacity to elicit inflammation.

Methods

We examined the inflammatory potential of coarse [2.5–10 μm in aerodynamic diameter (PM_2.5–10)] and fine [0.1–2.5 μm in aerodynamic diameter (PM_0.1–2.5)] PM collected from nine sites throughout Europe with contrasting traffic contributions. We incubated murine monocytic-macrophagic RAW264.7 cells with PM samples from these sites (20 or 60 μg/cm²) and quantified their capacity to stimulate the release of arachidonic acid (AA) or the production of interleukin-6 and tumor necrosis factor-α (TNFα) as measures of their inflammatory potential. Responses were then related to PM composition: metals, hydrocarbons, anions/cations, and endotoxin content.

Results

Inflammatory responses to ambient PM varied markedly on an equal mass basis, with PM_2.5–10 displaying the largest signals and contrasts among sites. Notably, we found no evidence of enhanced inflammatory potential at high-traffic sites and observed some of the largest responses at sites distant from traffic. Correlation analyses indicated that much of the sample-to-sample contrast in the proinflammatory response was related to the content of endotoxin and transition metals (especially iron and copper) in PM_2.5–10. Use of the metal chelator diethylene triamine pentaacetic acid inhibited AA release, whereas recombinant endotoxin-neutralizing protein partially inhibited TNFα production, demonstrating that different PM components triggered inflammatory responses through separate pathways.

Conclusions

We found no evidence that PM collected from sites in close proximity to traffic sources displayed enhanced proinflammatory activity in RAW264.7 cells.     

Acute respiratory effects of particles: mass or number?

OBJECTIVES—To determine whether associations might be found, in patients with chronic airflow obstruction, between symptoms, peak flow rate (PEF), and particle mass and numbers, and to assess which measure was most closely associated with changes in health. Epidemiological studies have shown associations between particulate air pollution and cardiovascular and respiratory disease, and it has been proposed that these may be mediated by particles of nm size (ultrafine).
METHODS—Relations were investigated between symptom scores, PEF, and bronchodilator use in 44 patients aged 50 years with chronic obstructive pulmonary disease, and daily measurements of both mass of ambient particles of aerodynamic diameter less than 10 µm (PM₁₀) and numbers of ultrafine particles (<100 nm), allowing for meteorological variables. Symptom scores, bronchodilator use, and PEF were recorded daily for 3 months. Counts of ultrafine particles were made by the TSI model 3934 scanning mobility particle sizer (SMPS) and PM₁₀ measurements by the tapered element oscillating microbalance (TEOM).
RESULTS—Ultrafine particle counts indoors and outdoors were significantly correlated, those indoors being about half of those outdoors. No associations were found between actual PEF and PM₁₀ or ultrafine particles. However, there was a 19% increase in the rate of 10% decrements in daytime PEF with increases in PM₁₀ from 10 to 20 µg/m³ which was of borderline significance (p=0.05). A change in PM₁₀ from 10 to 20 µg/m³ was significantly associated with a 14% increase in the rate of high scores of shortness of breath (p=0.003). A similar change in PM₁₀ as a moving average of the same day and 2 previous days was associated with a 31% increase in the rate of high scores for cough (p=0.02). Cough symptoms were also associated with lower temperatures (p=0.02). Higher use of medicines was also associated with higher PM₁₀, but the increases were very small in clinical terms.
CONCLUSIONS—Evidence was not found to support the hypothesis that the component of particulate pollution responsible for effects on respiratory symptoms or function resides in the fraction below 100 nm diameter. The consistent associations between symptoms and PM₁₀ suggest that a contribution of the coarser fraction should not be dismissed. Further studies will be needed before the conclusions of this specific project may be generalised.


Keywords: air pollution; ultrafine particles; chronic obstructive lung disease     

Associations between short-term exposure to particulate matter and ultrafine particles and myocardial infarction in Augsburg,Germany

BackgroundShort-term exposure to increased particulate matter (PM) concentration has been reported to trigger myocardial infarction (MI). However, the association with ultrafine particles remains unclear.ObjectivesWe aimed to assess the effects of short-term air pollution and especially ultrafine particles on registry-based MI events and coronary deaths in the area of Augsburg, Germany.MethodsBetween 1995 and 2009, the MONICA/KORA myocardial infarction registry recorded 15,417 cases of MI and coronary deaths. Concentrations of PM < 10 μm (PM₁₀), PM < 2.5 μm (PM_2.5), particle number concentration (PNC) as indicator for ultrafine particles, and meteorological parameters were measured in the study region. Quasi-Poisson regression adjusting for time trend, temperature, season, and weekday was used to estimate immediate, delayed and cumulative effects of air pollutants on the occurrence of MI. The daily numbers of total MI, nonfatal and fatal events as well as incident and recurrent events were analysed.ResultsWe observed a 1.3% risk increase (95%-confidence interval: [−0.9%; 3.6%]) for all events and a 4.4% [−0.4%; 9.4%] risk increase for recurrent events per 24.3 μg/m³ increase in same day PM₁₀ concentrations. Nonfatal events indicated a risk increase of 3.1% [−0.1%; 6.5%] with previous day PM₁₀. No association was seen for PM_2.5 which was only available from 1999 on. PNC showed a risk increase of 6.0% [0.6%; 11.7%] for recurrent events per 5529 particles/cm³ increase in 5-day average PNC.ConclusionsOur results suggested an association between short-term PM₁₀ concentration and numbers of MI, especially for nonfatal and recurrent events. For ultrafine particles, risk increases were notably high for recurrent events. Thus, persons who already suffered a MI seemed to be more susceptible to air pollution.     

C-reactive protein (CRP) and long-term air pollution with a focus on ultrafine particles

Background

Long-term exposure to ambient air pollution contributes to the global burden of disease by particularly affecting cardiovascular (CV) causes of death. We investigated the association between particle number concentration (PNC), a marker for ultrafine particles, and other air pollutants and high sensitivity C-reactive protein (hs-CRP) as a potential link between air pollution and CV disease.

Associations of Mortality with Long-Term Exposures to Fine and Ultrafine Particles,Species and Sources: Results from the California Teachers Study Cohort

Background

Although several cohort studies report associations between chronic exposure to fine particles (PM_2.5) and mortality, few have studied the effects of chronic exposure to ultrafine (UF) particles. In addition, few studies have estimated the effects of the constituents of either PM_2.5 or UF particles.

Methods

We used a statewide cohort of > 100,000 women from the California Teachers Study who were followed from 2001 through 2007. Exposure data at the residential level were provided by a chemical transport model that computed pollutant concentrations from > 900 sources in California. Besides particle mass, monthly concentrations of 11 species and 8 sources or primary particles were generated at 4-km grids. We used a Cox proportional hazards model to estimate the association between the pollutants and all-cause, cardiovascular, ischemic heart disease (IHD), and respiratory mortality.

Results

We observed statistically significant (p < 0.05) associations of IHD with PM_2.5 mass, nitrate, elemental carbon (EC), copper (Cu), and secondary organics and the sources gas- and diesel-fueled vehicles, meat cooking, and high-sulfur fuel combustion. The hazard ratio estimate of 1.19 (95% CI: 1.08, 1.31) for IHD in association with a 10-μg/m³ increase in PM_2.5 is consistent with findings from the American Cancer Society cohort. We also observed significant positive associations between IHD and several UF components including EC, Cu, metals, and mobile sources.

Conclusions

Using an emissions-based model with a 4-km spatial scale, we observed significant positive associations between IHD mortality and both fine and ultrafine particle species and sources. Our results suggest that the exposure model effectively measured local exposures and facilitated the examination of the relative toxicity of particle species.

Citation

Ostro B, Hu J, Goldberg D, Reynolds P, Hertz A, Bernstein L, Kleeman MJ. 2015. Associations of mortality with long-term exposures to fine and ultrafine particles, species and sources: results from the California Teachers Study cohort. Environ Health Perspect 123:549–556; http://dx.doi.org/10.1289/ehp.1408565     

Using a pattern recognition approach to link inorganic chemical fingerprints of ambient PM2.5–0.1 with in vitro biological effects

Atmospheric fine particulates act as prime vehicles for the transport of toxic chemicals into the human respiratory system on a daily basis and adverse human health effects do exist. By examining toxicological differences and chemical composition of ambient fine particles using a novel experimental design and chemometric approach, the present work examines the hypothesis: that it is not clear whether there are significant differences in public health risk from exposure to fine particles in a rural location compared to those in urban locations. In the present study, an investigation into the inorganic chemical characteristics and biological effects of PM_2.5–0.1 on human lung epithelial cell line A549 has been performed. Biological responses were evaluated by in vitro tests using equivalent masses of PM_2.5–0.1 samples, collected during different seasons at urban and rural locations in Cork, Ireland. The relationship between the biological responses and the chemical composition of the samples were investigated using Principal Component Analysis followed by Partial Least Squares regression analysis. The PM_2.5–0.1 samples collected at three contrasting sites in Cork demonstrated the ability to generate reactive oxygen species upon exposure irrespective of season. However, the magnitude of generation was somewhat higher for samples collected in the urban sites, compared to those generated by rural samples. Similarly, metals such as Cu and Mn were found to be present in larger quantities in the urban-based composite samples compared to those for their rural counterparts. The induction of interleukin 6 determined in this study followed a very similar seasonal trend to the measured concentrations of potassium ions in the PM_2.5–0.1 samples to which the A549 cells were exposed. The current study provides further support that identifying important chemical components and their sources, with subsequent targeted emission controls, which will likely prove to be a more cost-effective strategy for mitigating toxicity and protecting human health, than current approaches which depend on uncharacterized total particle mass, especially when sophisticated pattern recognition techniques are employed to assess limited airborne datasets.     

The study of TSP and PM10 concentration and their heavy metal content in central area of Tehran, Iran

Atmospheric particulate matter may exert serious health hazards because of its chemical characteristics. The main objective of this study is to assess the concentrations of total suspended particles (TSP), particulate matter (PM) with an aerodynamic diameter ≤10 μm (PM₁₀), and air-transmitted particulate trace metals in Tehran University (a central location in Tehran, capital of Iran) ambient air, for the period of 5 months viz. February–June 2007. Furthermore, the present work examines the daily levels of fine particles in comparison with the proposed limiting values from the U.S. Environmental Protection Agency (65 μg m⁻³ for PM₁₀). The sampling for TSP and PM₁₀ was performed using a high-volume sampler. The TSP and PM₁₀ levels were determined by gravimetry and the metals by flame atomic absorption spectrometry. Arithmetic means of 151 ± 44 μg m⁻³ and 90 ± 38 μg m⁻³ were determined for TSP and PM₁₀, respectively. Comparing with EPA primary and secondary air quality standards, only PM₁₀ concentrations in 3 days were higher than the standard values. Heavy metal content of both TSP and PM₁₀, such as chromium (Cr), cadmium (Cd), and lead (Pb), were also analyzed separately during the same period using atomic absorption spectrometry. The average concentrations of heavy metal in TSP were Pb: 183.63 ± 147.81 ng m⁻³; Cr: 13.72 ± 2.40 ng m⁻³; and Cd: 6.80 ± 1.97 ng m⁻³ and for PM₁₀ were: 150.36 ± 157.01 ng m⁻³; Cr: 9.12 ± 2.14 ng m⁻³ and Cd: 6.87 ± 2.22 ng m⁻³.

Elemental composition and source characterization of airborne PM10 at residences with relative proximities to metal-industrial complex

Objectives: Exposure estimates based solely on proximity to air pollution sources are not robust and require confirmation. Consequently, the present study was designed to scientifically evaluate the atmospheric particulate pollution in residences relative to their proximity to a Korean major metal-industrial complex (MIC). Methods: This purpose was achieved by concurrently measuring the concentrations and elemental composition of particulate matter with aerodynamic diameters equal to or less than 10 μm (PM₁₀) and characterizing the PM₁₀ source types in industrial ambient air from MIC and residential ambient air with relative proximities to MIC. Trace metals were analyzed using an inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The elemental composition data were employed to calculate enrichment factors and statistically analyzed using a principal component analysis (PCA) to characterize the PM₁₀ source types. The source contributions were quantitatively analyzed using an absolute PCA (APCA). Results: The most enriched elements for which a significant anthropogenic origin can be suggested were Cd, Cu, Pb, Sb, Tl, and Zn. For PCA, four or five factors with eigenvalues greater than unity were obtained for each sampling site, and those having high loadings with the same variables represented similar source types. The APCA result yielded significant regression coefficients, explaining 74–85% of the variability in the PM₁₀, which depends on the sampling site. The industrial mean values exceeded the Korean year/70 μg/m³ standard for PM₁₀, whereas the residential mean values did not. However, the maximum residential values did exceed or were close to the Korean PM₁₀ year standard. For individual elements, the ambient concentrations ranged widely from values in the order of a few ng/m³ to thousands of ng/m³. The residential mean mass concentrations in the PM₁₀ measured in the present study were higher than or similar to those reported in earlier studies. Conclusions: The present study confirmed that residents in neighborhoods near the MIC are exposed to elevated particulate and metal levels compared to residents living further away from such a source, thereby supporting that proximity to air pollution sources can be employed to indicate environmental exposure.     

Stimulation of IL-8 release from epithelial cells by gas cooker PM(10): a pilot study

OBJECTIVE—To measure the effect of matter collected by a method that has a 50% efficiency for particles with an aerodynamic diameter of 10 µm (PM₁₀), generated by gas and electric cooking, on A549 epithelial cells with and without nitrogen dioxide (NO₂).
METHOD—Multiple indoor PM₁₀ samples were collected on Teflon filters during the use of gas or electric cookers. Interleukin-8 (IL-8) concentrations were measured with a sandwich enzyme linked immunosorbent assay (ELISA) system.
RESULTS—Treatment of A549 cells with PM₁₀ generated from gas cooking resulted in increased concentrations of IL-8 compared with untreated cells; particles from the electric cooker had no effect. NO₂ did not alter the concentration of IL-8.
CONCLUSION—PM₁₀ generated by gas cooking has the potential to cause proinflammatory effects in lung cells. This may have implications for susceptible people.


Keywords: indoor air pollution; PM₁₀; interleukin-8     

The effect of outdoor air and indoor human activity on mass concentrations of PM(10), PM(2.5), and PM(1) in a classroom

The 12-h mass concentration of PM₁₀, PM_2.5, and PM₁ was measured in a lecturing room by means of three co-located Harvard impactors. The filters were changed at 8 AM and at 8 PM to cover the periods of presence and absence of students. Concentrations were assessed by gravimetry. Ambient PM₁₀ data were available for corresponding 12-h intervals from the nearest state air-quality-monitoring network station. The data were pooled into four periods according to the presence and absence of students—Monday-Thursday day (workday daytime), Monday-Thursday night (workday night), Friday-Sunday day (weekend daytime), and Friday-Sunday night (weekend night). Average indoor workday daytime concentrations were 42.3, 21.9 and 13.7 μg m⁻³, workday night were 20.9, 19.1 and 15.2 μg m⁻³, weekend daytime were 21.9, 18.1 and 11.4 μg m⁻³, and weekend night were 24.5, 21.3, and 15.6 μg m⁻³ for PM₁₀, PM_2.5, and PM₁, respectively. The highest 12-h mean, median, and maximum (42.3, 43.0, and 76.2 μg m⁻³, respectively) indoor concentrations were recorded on workdays during the daytime for PM₁₀. The statistically significant (r=0.68,P<0.0009) correlation between the number of students per hour per day and the indoor coarse fraction calculated as PM_10−2.5 during daytime on workdays indicates that the presence of people is an important source of coarse particles indoor. On workdays, the daytime PM₁₀ indoor/outdoor ratio was positively associated (r=0.93) with an increasing indoor coarse fraction (PM_10-2.5), also indicating that an important portion of indoor PM₁₀ had its source inside the classroom. With the exception of the calculated coarse fraction (PM_10-2.5), all of the measured indoor particulate matter fractions were significantly highly correlated with outdoor PM₁₀ and negatively correlated with wind velocity, showing that outdoor levels of particles influence their indoor concentrations.     

Association of Heart Rate Variability of the Elderly with Personal Exposure to PM<Subscript>1</Subscript>, PM<Subscript>1–2.5</Subscript>, and PM<Subscript>2.5–10</Subscript>

Environmental epidemiologic studies have shown that elderly people are susceptible to particulate air pollution. The decreases in heart rate variability are important indices of health effect caused by particulate matter. The objective of this study was to investigate the effects of submicron particle (PM₁), PM_1–2.5, and coarse particle (PM_2.5–10) on heart rate variability parameters in the elderly. Results of our study indicated that short-term and medium-term PM exposures were associated with the reduction of heart rate variability in the elderly, with stronger effects found for coarse particles in comparison with particles of other size ranges.     

Symptoms and Medication Use in Children with Asthma and Traffic-Related Sources of Fine Particle Pollution

Background

Exposure to ambient fine particles [particulate matter ≤ 2.5 μm diameter (PM_2.5)] is a potential factor in the exacerbation of asthma. National air quality particle standards consider total mass, not composition or sources, and may not protect against health impacts related to specific components.

Objective

We examined associations between daily exposure to fine particle components and sources, and symptoms and medication use in children with asthma.

Methods

Children with asthma (n = 149) 4–12 years of age were enrolled in a year-long study. We analyzed particle samples for trace elements (X-ray fluorescence) and elemental carbon (light reflectance). Using factor analysis/source apportionment, we identified particle sources (e.g., motor vehicle emissions) and quantified daily contributions. Symptoms and medication use were recorded on study diaries. Repeated measures logistic regression models examined associations between health outcomes and particle exposures as elemental concentrations and source contributions.

Results

More than half of mean PM_2.5 was attributed to traffic-related sources motor vehicles (42%) and road dust (12%). Increased likelihood of symptoms and inhaler use was largest for 3-day averaged exposures to traffic-related sources or their elemental constituents and ranged from a 10% increased likelihood of wheeze for each 5-μg/m³ increase in particles from motor vehicles to a 28% increased likelihood of shortness of breath for increases in road dust. Neither the other sources identified nor PM_2.5 alone was associated with increased health outcome risks.

Conclusions

Linking respiratory health effects to specific particle pollution composition or sources is critical to efforts to protect public health. We associated increased risk of symptoms and inhaler use in children with asthma with exposure to traffic-related fine particles.     

The London Underground: dust and hazards to health

Aims: To assess hazards associated with exposure to dust in the London Underground railway and to provide an informed opinion on the risks to workers and the travelling public of exposure to tunnel dust.

Methods: Concentrations of dust, as mass (PM_2.5) and particle number, were measured at different underground stations and in train cabs; its size and composition were analysed; likely maximal exposures of staff and passengers were estimated; and in vitro toxicological testing of sample dusts in comparison with other dusts was performed.

Results: Concentrations on station platforms were 270–480 µg/m³ PM_2.5 and 14 000–29 000 particles/cm³. Cab concentrations over a shift averaged 130–200 µg/m³ and 17 000–23 000 particles/cm³. The dust comprised by mass approximately 67% iron oxide, 1–2% quartz, and traces of other metals, the residue being volatile matter. The finest particles are drawn underground from the surface while the coarser dust is generated by interaction of brakes, wheels, and rails. Taking account of durations of exposure, drivers and station staff would have maximum exposures of about 200 µg/m³ over eight hours; the occupational exposure standard for welding fume, as iron oxide, is 5 mg/m³ over an eight hour shift. Toxicology showed the dust to have cytotoxic and inflammatory potential at high doses, consistent with its composition largely of iron oxide.

Discussion: It is unjustifiable to compare PM_2.5 exposure underground with that on the surface, since the adverse effects of iron oxide and combustion generated particles differ. Concentrations of ultrafine particles are lower and of coarser (PM_2.5) particles higher underground than on the surface. The concentrations underground are well below allowable workplace concentrations for iron oxide and unlikely to represent a significant cumulative risk to the health of workers or commuters.

     

Association of Biomarkers of Systemic Inflammation with Organic Components and Source Tracers in Quasi-Ultrafine Particles

Background

Evidence is needed regarding the air pollutant components and their sources responsible for associations between particle mass concentrations and human cardiovascular outcomes. We previously found associations between circulating biomarkers of inflammation and mass concentrations of quasi-ultrafine particles ≤ 0.25 μm in aerodynamic diameter (PM_0.25) in a panel cohort study of 60 elderly subjects with coronary artery disease living in the Los Angeles Basin.

Objectives

We reassessed biomarker associations with PM_0.25 using new particle composition data.

Methods

Weekly biomarkers of inflammation were plasma interleukin-6 (IL-6) and soluble tumor necrosis factor-α receptor II (sTNF-RII) (n = 578). Exposures included indoor and outdoor community organic PM_0.25 constituents [polycyclic aromatic hydrocarbons (PAHs), hopanes, n-alkanes, organic acids, water-soluble organic carbon, and transition metals]. We analyzed the relation between biomarkers and exposures with mixed-effects models adjusted for potential confounders.

Results

Indoor and outdoor PAHs (low-, medium-, and high-molecular-weight PAHs), followed by hopanes (vehicle emissions tracer), were positively associated with biomarkers, but other organic components and transition metals were not. sTNF-RII increased by 135 pg/mL [95% confidence interval (CI), 45–225 pg/mL], and IL-6 increased by 0.27 pg/mL (95% CI, 0.10–0.44 pg/mL) per interquartile range increase of 0.56 ng/m³ outdoor total PAHs. Two-pollutant models of PM_0.25 with PAHs showed that nominal associations of IL-6 and sTNF-RII with PM_0.25 mass were completely confounded by PAHs. Vehicular emission sources estimated from chemical mass balance models were strongly correlated with PAHs (R = 0.71).

Conclusions

Traffic emission sources of organic chemicals represented by PAHs are associated with increased systemic inflammation and explain associations with quasi-ultrafine particle mass.     

Study of metals in radical-mediated toxicity of particulate matter in indoor environments of Pune,India

The concentration of coarse and fine indoor particulate matter (PM) was measured along with that of metals (Fe, Cu, Zn, Mn, Pb, Cd, Co, Ni, and Cr) collected from rural and urban residential environments of Pune City with the purpose of examining their free radical generation and its related toxicity. The average mass concentration of indoor PM₁₀ and PM_2.5 was ～3.3 and ～4.5 times higher than the threshold limits of the Indian National Ambient Air Quality Standards (NAAQS) at urban and rural sites, respectively. The concentration of metals was found to be higher in the fine fraction of PM collected from the rural site. Metal analysis revealed the dominance of Fe concentrations in both PM₁₀ and PM_2.5 followed by Zn, Ni, and Cu. Electron paramagnetic resonance (EPR) was used to evaluate the presence of free radicals in samples collected from both the sites. EPR spectra for these particles were attributed to both Fe³⁺ (g = 1.99～2.0) and free radicals (g = 2.0023 and g = 2.003) in PM samples. Dithiothreitol (DTT) assay was also performed which supports the presence of higher redox activity in the fine fraction of PM at the rural site. Significant DNA damage was observed by both fractions of PM when tested in the controlled experiment, with averages of 43 and 30.9 % for PM₁₀ and 55.3 and 40.5 % for PM_2.5 at the rural and urban sites, respectively. This study articulates a significant amount of evidence to understand the importance of size and composition (especially metals) of indoor PM in the toxicological mechanism.     

Effects of short-term exposure to fine and ultrafine particles from indoor sources on arterial stiffness – A randomized sham-controlled exposure study

ObjectivesParticulate air pollution is linked to adverse cardiovascular effects, including arterial stiffness. The aim of the study was to investigate the effect of short-term exposure to indoor fine and ultrafine particles on augmentation index (AIx), augmentation pressure (AP), and pulse wave velocity (PWV), early signs of vascular damage.MethodsWe analyzed the association of particle emissions from typical indoor sources (candle burning - CB, toasting bread - TB, and frying sausages - FS) with changes in pulse wave analysis indices in 55 healthy adults in a randomized cross-over controlled exposure study. Particle mass concentration (PMC), size-specific particle number concentration (PNC) and lung-deposited particle surface area concentration (PSC) were measured during the 2 h exposure. AIx and AP were measured before, directly, 2, 4 and 24 h after exposure. PWV was measured directly and 24 h after exposure. We performed multiple mixed linear regression analyses of different particle metrics and AIx, AP and PWV.ResultsThe highest mean PMC was observed during FS reaching a maximum of 210 μg/m³ PM₁₀. The maximal PNC for UFP <100 nm was reached during CB with 2.3 million particles/cm³. PSC was similar across all three exposures (about 3000 μm²/cm³). Strongest associations between different particles metrics and arterial stiffness indices could be observed for UFP from CB and FS and for PMC from TB. The highest mean increase could be observed for the UFP fraction <10 nm, measured during CB, and AIx with an increase of 9.5%-points (95%-CI: 3.1; 15.9). PSC seemed to follow the pattern of PNC. PM₁₀ and PM_2.5 from TB led to clear changes in AIx with biggest increases for PM₁₀ of 5.8%-points (95%-CI: 3.2; 8.4) 2 h after exposure and for PM_2.5 of 8.1%-points (95%-CI: 2.5; 13.7) directly after exposure.ConclusionsOur study indicates effects of indoor exposure to fine and ultrafine particles on systemic arterial stiffness indices that depend on the indoor source as well as on particle metric. Differences in size-specific physical characteristics of source-specific particles might account for these differential effects. We did not observe clear and stable associations of indoor particle exposure and PWV.