Source category-specific PM2.5 and urinary levels of Clara cell protein CC16. The ULTRA study

Long non-coding RNAs mediate the association between short-term PM2.5 exposure and circulating biomarkers of systemic inflammation

Although short-term fine particulate matter (PM2.5) exposure is associated with systemic inflammation, the effect of lncRNA on these association remains unknown. This study aims to investigate whether the plasma lncRNA mediate the effect of short-term PM2.5 exposure on systemic inflammation. In this cross-sectional study, plasma Clara cell protein 16 (CC16), interleukin 6 (IL-6), IL-8, tumor necrosis factor-α (TNF-α) and lncRNA expression levels were measured in 161 adults between March and April in 2018 in Shijiazhuang, China. PM2.5 concentrations were estimated 0-3 days prior to the examination date and the moving averages were calculated. Multiple linear regressions were used to evaluate the associations between PM2.5, the four biomarkers and lncRNA expression levels. Mediation analyses were performed to explore the potential roles of lncRNA expression in these associations. The median concentration of PM2.5 ranged from 39.65 to 60.91 mg/m3 across different lag days. The most significant effects on IL-6 and TNF-α per interquartile range increase in PM2.5 were observed at lag 0-3 days, with increases of 0.70 pg/mL (95% CI: 0.33, 1.07) and 0.21 pg/mL (95% CI: 0.06, 0.36), respectively. While the associations between PM2.5 and IL-8 (0.68 pg/mL, 95% CI: 0.34, 1.02) and CC16 (3.86 ng/mL, 95% CI: 1.60, 6.13) were stronger at lag 0 day. Interestingly, a negative association between PM2.5 and the expression of four novel lncRNAs (lnc-ACAD11-1:1, lnc-PRICKLE1-4:1, lnc-GPR39-7:2, and lnc-MTRNR2L12-3:6) were observed at each lag days. Furthermore, these lncRNAs mediated the effects of PM2.5 on the four biomarkers, with proportions of mediation ranged from 2.27% (95% CI: 1.19%, 9.82%) for CC16 to 35.60% (95% CI: 17.16%, 175.45%) for IL-6. Our findings suggested that plasma lncRNA expression mediat the acute effects of PM2.5 exposure on systematic inflammation. These highlight a need to consider circulating lncRNA expression as biomarkers to reduce health risks associated with PM2.5.

Long-term exposure to ambient fine particulate components and leukocyte epigenome-wide DNA Methylation in older men: the Normative Aging Study

BACKGROUND

Epigenome-wide association studies of ambient fine particulate matter (PM2.5) have been reported. However, few have examined PM2.5 components (PMCs) and sources or included repeated measures. The lack of high-resolution exposure measurements is the key limitation. We hypothesized that significant changes in DNA methylation might vary by PMCs and the sources.

METHODS

We predicted the annual average of 14 PMCs using novel high-resolution exposure models across the contiguous U.S., between 2000-2018. The resolution was 50 m × 50 m in the Greater Boston Area. We also identified PM2.5 sources using positive matrix factorization. We repeatedly collected blood samples and measured leukocyte DNAm with the Illumina HumanMethylation450K BeadChip in the Normative Aging Study. We then used median regression with subject-specific intercepts to estimate the associations between long-term (one-year) exposure to PMCs / PM2.5 sources and DNA methylation at individual cytosine-phosphate-guanine CpG sites. Significant probes were identified by the number of independent degrees of freedom approach, using the number of principal components explaining > 95% of the variation of the DNA methylation data. We also performed regional and pathway analyses to identify significant regions and pathways.

RESULTS

We included 669 men with 1,178 visits between 2000-2013. The subjects had a mean age of 75 years. The identified probes, regions, and pathways varied by PMCs and their sources. For example, iron was associated with 6 probes and 6 regions, whereas nitrate was associated with 15 probes and 3 regions. The identified pathways from biomass burning, coal burning, and heavy fuel oil combustion sources were associated with cancer, inflammation, and cardiovascular diseases, whereas there were no pathways associated with all traffic.

CONCLUSIONS

Our findings showed that the effects of PM2.5 on DNAm varied by its PMCs and sources.

Noninvasive integrative approach applied to children in the context of recent air pollution exposure demonstrates association between fractional exhaled nitric oxide (FeNO) and urinary CC16

Exposure to the air pollutant particulate matter (PM) is associated with increased risks of respiratory diseases and enhancement of airway inflammation in children. In the context of large scale air pollution studies, it can be challenging to measure fractional exhaled nitric oxide (FeNO) as indicator of lung inflammation. Urinary CC16 (U-CC16) is a potential biomarker of increased lung permeability and toxicity, increasing following short-term PM_2.5 exposure. The single nucleotide polymorphism (SNP) CC16 G38A (rs3741240) affects CC16 levels and respiratory health. Our study aimed at assessing the use of U-CC16 (incl. CC16 G38A from saliva) as potential alternative for FeNO by investigating their mutual correlation in children exposed to PM. Samples from a small-scale study conducted in 42 children from urban (n = 19) and rural (n = 23) schools examined at two time points, were analysed. When considering recent (lag1) low level exposure to PM_2.5 as air pollution measurement, we found that U-CC16 was positively associated with FeNO (β = 0.23; 95% CI [-0.01; 0.47]; p = 0.06) in an adjusted analysis using a linear mixed effects model. Further, we observed a positive association between PM_2.5 and FeNO (β = 0.56; 95% CI [0.02; 1.09]; p = 0.04) and higher FeNO in urban school children as compared to rural school children (β = 0.72; 95% CI [0.12; 1.31]; p = 0.02). Although more investigations are needed, our results suggest that inflammatory responses evidenced by increased FeNO are accompanied by potential increased lung epithelium permeability and injury, evidenced by increased U-CC16. In future large scale studies, where FeNO measurement is less feasible, the integrated analysis of U-CC16 and CC16 G38A, using noninvasive samples, might be a suitable alternative to assess the impact of air pollution exposure on the respiratory health of children, which is critical for policy development at population level.

Urinary CC16, a potential indicator of lung integrity and inflammation, increases in children after short-term exposure to PM2.5/PM10 and is driven by the CC16 38GG genotype

Particular matter (PM) exposure is a big hazard for public health, especially for children. Serum CC16 is a well-known biomarker of respiratory health. Urinary CC16 (U-CC16) can be a noninvasive alternative, albeit requiring adequate adjustment for renal handling. Moreover, the SNP CC16 G38A influences CC16 levels. This study aimed to monitor the effect of short-term PM exposure on CC16 levels, measured noninvasively in schoolchildren, using an integrative approach. We used a selection of urine and buccal DNA samples from 86 children stored in an existing biobank. Using a multiple reaction monitoring method, we measured U-CC16, as well as RBP4 (retinol binding protein 4) and β2M (beta-2-microglobulin), required for adjustment. Buccal DNA samples were used for CC16 G38A genotyping. Linear mixed-effects models were used to find relevant associations between U-CC16 and previously obtained data from recent daily PM ≤ 2.5 or 10 μm exposure (PM_2.5, PM₁₀) modeled at the child's residence. Our study showed that exposure to low PM at the child's residence (median levels 18.9 μg/m³ (PM_2.5) and 23.6 μg/m³ (PM₁₀)) one day before sampling had an effect on the covariates-adjusted U-CC16 levels. This effect was dependent on the CC16 G38A genotype, due to its strong interaction with the association between PM levels and covariates-adjusted U-CC16 (P = 0.024 (PM_2.5); P = 0.061 (PM₁₀)). Only children carrying the 38GG genotype showed an increase of covariates-adjusted U-CC16, measured 24h after exposure, with increasing PM_2.5 and PM₁₀ (β = 0.332; 95% CI: 0.110 to 0.554 and β = 0.372; 95% CI: 0.101 to 0.643, respectively). To the best of our knowledge, this is the first study using an integrative approach to investigate short-term PM exposure of children, using urine to detect early signs of pulmonary damage, and taking into account important determinants such as the genetic background and adequate adjustment of the measured biomarker in urine.

Particle Safety Assessment in Additive Manufacturing: From Exposure Risks to Advanced Toxicology Testing

Additive manufacturing (AM) or industrial three-dimensional (3D) printing drives a new spectrum of design and production possibilities; pushing the boundaries both in the application by production of sophisticated products as well as the development of next-generation materials. AM technologies apply a diversity of feedstocks, including plastic, metallic, and ceramic particle powders with distinct size, shape, and surface chemistry. In addition, powders are often reused, which may change the particles’ physicochemical properties and by that alter their toxic potential. The AM production technology commonly relies on a laser or electron beam to selectively melt or sinter particle powders. Large energy input on feedstock powders generates several byproducts, including varying amounts of virgin microparticles, nanoparticles, spatter, and volatile chemicals that are emitted in the working environment; throughout the production and processing phases. The micro and nanoscale size may enable particles to interact with and to cross biological barriers, which could, in turn, give rise to unexpected adverse outcomes, including inflammation, oxidative stress, activation of signaling pathways, genotoxicity, and carcinogenicity. Another important aspect of AM-associated risks is emission/leakage of mono- and oligomers due to polymer breakdown and high temperature transformation of chemicals from polymeric particles, both during production, use, and in vivo, including in target cells. These chemicals are potential inducers of direct toxicity, genotoxicity, and endocrine disruption. Nevertheless, understanding whether AM particle powders and their byproducts may exert adverse effects in humans is largely lacking and urges comprehensive safety assessment across the entire AM lifecycle—spanning from virgin and reused to airborne particles. Therefore, this review will detail: 1) brief overview of the AM feedstock powders, impact of reuse on particle physicochemical properties, main exposure pathways and protective measures in AM industry, 2) role of particle biological identity and key toxicological endpoints in the particle safety assessment, and 3) next-generation toxicology approaches in nanosafety for safety assessment in AM. Altogether, the proposed testing approach will enable a deeper understanding of existing and emerging particle and chemical safety challenges and provide a strategy for the development of cutting-edge methodologies for hazard identification and risk assessment in the AM industry.

Biomarkers for the adverse effects on respiratory system health associated with atmospheric particulate matter exposure

Large amounts of epidemiological evidence have confirmed the atmospheric particulate matter (PM_2.5) exposure was positively correlated with the morbidity and mortality of respiratory diseases. Nevertheless, its pathogenesis remains incompletely understood, probably resulting from the activation of oxidative stress, inflammation, altered genetic and epigenetic modifications in the lung upon PM_2.5 exposure. Currently, biomarker investigations have been widely used in epidemiological and toxicological studies, which may help in understanding the biologic mechanisms underlying PM_2.5-elicited adverse health outcomes. Here, the emerging biomarkers to indicate PM_2.5-respiratory system interactions were summarized, primarily related to oxidative stress (ROS, MDA, GSH, etc.), inflammation (Interleukins, FE_NO, CC16, etc.), DNA damage (8-OHdG, γH2AX, OGG1) and also epigenetic modulation (DNA methylation, histone modification, microRNAs). The identified biomarkers shed light on PM_2.5-elicited inflammation, fibrogenesis and carcinogenesis, thus may favor more precise interventions in public health. It is worth noting that some inconsistent findings may possibly relate to the inter-study differentials in the airborne PM_2.5 sample, exposure mode and targeted subjects, as well as methodological issues. Further research, particularly by -omics technique to identify novel, specific biomarkers, is warranted to illuminate the causal relationship between PM_2.5 pollution and deleterious lung outcomes.

Exposure to traffic-related particle matter and effects on lung function and potential interactions in a cross-sectional analysis of a cohort study in west Sweden

OBJECTIVES

To investigate the long-term effects of source-specific particle matter (PM) on lung function, effects of Surfactant Protein A (SP-A) and glutathione S-transferase (GST) genes GSTP1 and GSTT1 gene variants and effect modification by single-nucleotide polymorphism (SNP) genotype.

DESIGN

Cohort study with address-based annual PM exposure assigned from annual estimates of size (PM₁₀, PM_2.5 and PM_BC) and source-specific (traffic, industry, marine traffic and wood burning) dispersion modelling.

SETTING

Gothenburg, Sweden.

PARTICIPANTS

The ADult-Onset asthma and NItric oXide Study had 6685 participants recruited from the general population, of which 5216 (78%) were included in the current study with information on all variables of interest. Mean age at the time of enrolment was 51.4 years (range 24-76) and 2427 (46.5%) were men.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁). Secondary outcome measures were effects and gene-environment interactions of SP-A and GSTT1 and GSTP1 genotypes.

RESULTS

Exposure to traffic-related PM₁₀ and PM_2.5 was associated with decreases in percent-predicted (% predicted) FEV₁ by -0.48% (95% CI -0.89% to -0.07%) and -0.47% (95% CI -0.88% to -0.07%) per IQR 3.05 and 2.47 µg/m³, respectively, and with decreases in % predicted FVC by -0.46% (95% CI -0.83% to -0.08%) and -0.47% (95% CI -0.83% to -0.10%). Total and traffic-related PM_BC was strongly associated with both FEV₁ and FVC by -0.53 (95% CI -0.94 to -0.13%) and -0.43% (95% CI -0.77 to -0.09%) per IQR, respectively, for FVC, and similarly for FEV₁. Minor allele carrier status for two GSTP1 SNPs and the GSTT1 null genotype were associated with decreases in % predicted lung function. Three SP-A SNPs showed effect modification with exposure to PM_2.5 from industry and marine traffic.

CONCLUSIONS

PM exposure, specifically traffic related, was associated with FVC and FEV₁ reductions and not modified by genotype. Genetic effect modification was suggested for industry and marine traffic PM_2.5.

Ophiopogonin D attenuates PM2.5-induced inflammation via suppressing the AMPK/NF-κB pathway in mouse pulmonary epithelial cells

Exposure to fine particulate matter, such as particulate matter of ≤2.5 µm in diameter (PM2.5), causes pulmonary inflammation and injury to other organs. It has been reported that Ophiopogonin D (OP-D) has anti-inflammatory activity. The aim of the present study was to investigate this anti-inflammatory activity of OP-D on PM2.5-induced acute airway inflammation and its underlying mechanisms. The viability of PM2.5-treated mouse lung epithelial (MLE-12) cells with or without OP-D treatment was determined using a Cell Counting Kit-8 assay. The corresponding levels of IL-1β, IL-6, IL-8 and TNF-α were examined via ELISA. Subcellular localization of NF-κBp65 was detected using immunofluorescence staining. The expression levels of AMP-activated protein kinase (AMPK), phosphorylated (p)-AMPK, NF-κBp65 and p-NF-κBp65 were analyzed using western blotting. The selective AMPK inhibitor Compound C (CC) was utilized to investigate the involvement of AMPK in the protection against PM2.5-induced cell inflammation by OP-D treatment. The results demonstrated that OP-D significantly ameliorated the PM2.5-stimulated release of proinflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-8) and inhibited the translocation of NF-κBp65 from the cytoplasm to the nucleus in MLE-12 cells. Moreover, OP-D significantly prevented the PM2.5-triggered phosphorylation of NF-κBp65 and upregulated AMPK activity. The anti-inflammatory activity of OP-D could also be attenuated by the AMPK-specific inhibitor CC. The present results suggested that the anti-inflammatory activity of OP-D was mediated via AMPK activation and NF-κB signaling pathway downregulation, which ameliorated the expression of proinflammatory cytokines. Therefore, OP-D could be a candidate drug to treat PM2.5-induced airway inflammation.

CC16 Levels into Adult Life Are Associated with Nitrogen Dioxide Exposure at Birth

Rationale: Lung function and growth are adversely associated with nitrogen dioxide (NO2) exposure. Lower levels of circulating club cell secretory protein (CC16) in childhood are also associated with subsequent decreased lung function. NO2 exposure may induce epithelial damage in lungs and alter club cell proliferation and morphology.Objectives: To determine if increased ambient NO2 levels at participants' home addresses in early life were associated with decreased levels of CC16 from age 6 to 32 years.Methods: Participants were enrolled at birth in the Tucson Children's Respiratory Study and had circulating CC16 measured at least once between age 6 and 32. Linear mixed models were used to determine the association between estimated ambient NO2 exposure at participants' home address at birth or age 6 with CC16 levels from age 6 to 32.Measurements and Main Results: NO2 exposures at birth or age 6 were available for 777 children with one or more CC16 measurement. We found a negative association between NO2 exposure and CC16 levels, with a 4.7% (95% confidence interval, -8.6 to -0.7) decrease in CC16 levels from age 6 to 32 per interquartile range increase in NO2 exposure (6.0 ppb) at the participants' birth address. We observed modification by race (p interaction = 0.04), with stronger associations among participants with at least one black parent (-29.6% [95% confidence interval, -42.9% to -13.2%] per interquartile range). NO2 at participant's age 6 address was not significantly associated with CC16 levels (-1.9%; 95% confidence interval, -6.3 to 2.6).Conclusions: Higher exposure to NO2 at birth is associated with persistently low levels of CC16 from 6 to 32 years.

Recent Approaches to Estimate Associations Between Source-Specific Air Pollution and Health

PURPOSE OF REVIEW

Estimating health effects associated with source-specific exposure is important for better understanding how pollution impacts health and for developing policies to better protect public health. Although epidemiologic studies of sources can be informative, these studies are challenging to conduct because source-specific exposures (e.g., particulate matter from vehicles) often are not directly observed and must be estimated. We reviewed recent studies that estimated associations between pollution sources and health to identify methodological developments designed to address important challenges.

RECENT FINDINGS

Notable advances in epidemiologic studies of sources include approaches for (1) propagating uncertainty in source estimation into health effect estimates, (2) assessing regional and seasonal variability in emissions sources and source-specific health effects, and (3) addressing potential confounding in estimated health effects. Novel methodological approaches to address challenges in studies of pollution sources, particularly evaluation of source-specific health effects, are important for determining how source-specific exposure impacts health.

Personal exposure to fine particulate matter, lung function and serum club cell secretory protein (Clara)

BACKGROUND

The underlying mechanisms about the association between ambient fine particulate matter (PM_2.5) and lung function were unclear. Few epidemiological studies have evaluated the potential mediating effects of serum club cell secretory protein (Clara) (CC16), a biomarker of pulmonary epithelium integrity.

OBJECTIVES

To evaluate the short-term effect of personal PM_2.5 exposure on lung function and to explore the potential mediating role of CC16 in this effect.

METHODS

We enrolled 36 healthy, nonsmoking college students for a panel study in Shanghai, China from December 17, 2014 to July 11, 2015. We measured personal and real-time exposure to PM_2.5 for 72 h preceding each of four rounds of health examinations, including lung function test and serum CC16 measurement. We used linear mixed-effect models to examine the effects of PM_2.5 on lung function and CC16 over various lag times. Furthermore, we analyzed the mediating effect of CC16 in the association between PM_2.5 and lung function.

RESULTS

Average PM_2.5 exposure ranged from 36 to 52 μg/m3 across different lag periods. PM_2.5 exposure was negatively associated with lung function and positively associated with serum CC16 concentration. The effect of PM_2.5 on CC16 occurred earlier than that on lung function. For instance, an interquartile range (IQR) increase in 0-2 h average exposure to PM_2.5 was significantly associated with a 4.84% increase in serum CC16; and an IQR increase in 3-6 h average exposure to PM_2.5 was significantly associated with a 1.08% decrease in 1-sec forced expiratory volume. These effects lasted up to 24 h after exposure. Increased serum CC16 contributed 3.9%-36.3% of the association between PM_2.5 and impaired lung function.

CONCLUSIONS

Acute exposure to PM_2.5 might induce an immediate decrease in lung function by virtue of the loss of pulmonary epithelium integrity.

Polycyclic aromatic hydrocarbons are associated with increased risk of chronic obstructive pulmonary disease during haze events in China

Although exposure to particulate matter with a diameter of <2.5μm (PM_2.5) is associated with chronic obstructive pulmonary disease (COPD), the major components of PM_2.5 in COPD pathogenesis are controversial. Here we employed the human lung epithelial cell line BEAS-2B to elucidate the association between COPD and the organic and water-soluble components of PM_2.5. We found that the PM_2.5 organic extract was a potential major risk factor for pulmonary epithelial barrier dysfunction through the depletion of proteins from the zonula occludens. This extract induced severe oxidative stress that increased DNA damage and the production of proinflammatory cytokines by BEAS-2B cells as well as decreased α1-antitrypsin expression, suggesting a mechanism that increases the risk of COPD. These effects were mainly mediated by polycyclic aromatic hydrocarbons (PAHs) through the aryl hydrocarbon receptor pathway. PAHs with high benzo(a)pyrene (BaP)-equivalent concentrations, but not major PAH components, have an increased risk of causing COPD, suggesting that BaP-equivalent concentrations represent a PM_2.5-induced COPD risk metric, which may contribute to provide a rationale for the remediation of air pollution.

The health effects of ambient PM2.5 and potential mechanisms

The impacts of ambient PM2.5 on public health have become great concerns worldwide, especially in the developing countries. Epidemiological and toxicological studies have shown that PM2.5 does not only induce cardiopulmonary disorders and/or impairments, but also contributes to a variety of other adverse health effects, such as driving the initiation and progression of diabetes mellitus and eliciting adverse birth outcomes. Of note, recent findings have demonstrated that PM2.5 may still pose a hazard to public health even at very low levels (far below national standards) of exposure. The proposed underlying mechanisms whereby PM2.5 causes adverse effects to public health include inducing intracellular oxidative stress, mutagenicity/genotoxicity and inflammatory responses. The present review aims to provide an brief overview of new insights into the molecular mechanisms linking ambient PM2.5 exposure and health effects, which were explored with new technologies in recent years.

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

Environmental tobacco smoke exposure, urine CC-16 levels, and asthma outcomes among Chinese children

BACKGROUND

Previous studies have shown the relationship between club cell secretory protein (Clara) (CC-16) and respiratory diseases. However, few studies have explored the associations between urine CC-16 levels and environmental tobacco smoke (ETS) exposure in children. The objective of this study was to evaluate whether ETS exposure is associated with CC-16 when stratified by asthma status.

METHODS

In our study, CC-16 was measured on 537 children aged 9-15 from northeast China in 2011-2012 using the Human Clara Cell Protein ELISA kits. Doctor-diagnosed asthma was defined as having ever been diagnosed with asthma by a physician. The relationship between ETS exposure and urine CC-16 level was assessed using linear regression.

RESULTS

When stratified by asthma status, a negative association between ETS exposure and urine CC-16 was observed after adjusting for the effects of the related covariates, with an adjusted β coefficient [P value] = -0.31 [0.006] in the first 2 years of life and with an adjusted β coefficient [P value] = -0.68 [0.004] in the first 2 years of life and current.

CONCLUSIONS

Our study shows long-term exposure to ETS was associated with urinary CC-16 among children without asthma.

A curated review of recent literature of biomarkers used for assessing air pollution exposures and effects in humans

This is a cross-sectional review of biomarkers used in air pollution research from January 2009 through December 2012. After an initial keyword search in PubMed retrieving 426 articles, a comprehensive abstract review identified 54 articles of experimental design that used biomarkers of exposure or effect in human studies in the area of air pollution research during this specified time period. A thorough bibliographic search of the included articles retrieved an additional 65 articles meeting the inclusion criteria. This review presents these 119 studies and the 234 biomarkers employed in these air pollution research investigations. Data presented are 70 biomarkers of exposure with 54% relating to polycyclic aromatic hydrocarbons, 36% volatile organic carbons, and 10% classified as other. Of the 164 biomarkers of effect, 91 and 130 were used in investigating effects of short-term and chronic exposure, respectively. Results of biomarkers used in short-term exposure describe different lag times and pollutant components such as primary and secondary pollutants, and particle number associated with corresponding physiological mechanisms including airway inflammation, neuroinflammation, ocular, metabolic, early endothelial dysfunction, coagulation, atherosclerosis, autonomic nervous system, oxidative stress, and DNA damage. The review presents three different exposure scenarios of chronic, occupational, and extreme exposure scenarios (indoor cooking) with associated biomarker findings presented in three broad categories of (1) immune profile, (2) oxidative stress, and (3) DNA damage. This review offers a representation of the scope of data being explored by air pollution researchers through the use of biomarkers and has deliberately been restricted to this particular subject rather than an extensive or in-depth review. This article provides a contextualization of air pollution studies conducted with biomarkers in human subjects in given areas while also integrating this complex body of information to offer a useful review for investigators in this field of study.

Effects on airways of short-term exposure to two kinds of wood smoke in a chamber study of healthy humans

INTRODUCTION

Air pollution causes respiratory symptoms and pulmonary disease. Airway inflammation may be involved in the mechanism also for cardiovascular disease. Wood smoke is a significant contributor to air pollution, with complex and varying composition. We examined airway effects of two kinds of wood smoke in a chamber study.

MATERIALS AND METHODS

Thirteen subjects were exposed to filtered air and to wood smoke from the start-up phase and the burn-out phase of the wood-burning cycle. Levels of PM(2.5) were 295 µg/m(3) and 146 µg/m(3), number concentrations 140 000/cm(3) and 100 000/cm(3). Biomarkers in blood, breath and urine were measured before and on several occasions after exposure. Effects of wood smoke exposure were assessed adjusting for results with filtered air.

RESULTS

After exposure to wood smoke from the start-up, but not the burn-out session, Clara cell protein 16 (CC16) increased in serum after 4 hours, and in urine the next morning. CC16 showed a clear diurnal variation. Fraction of exhaled nitric oxide (FENO) increased after wood smoke exposure from the burn-out phase, but partly due to a decrease after exposure to filtered air. No other airway markers increased.

CONCLUSIONS

The results indicate that relatively low levels of wood smoke exposure induce effects on airways. Effects on airway epithelial permeability was shown for the start-up phase of wood burning, while FENO increased after the burn-out session. CC16 seems to be a sensitive marker of effects of air pollution both in serum and urine, but its function and the significance need to be clarified.