Short-term exposure to ozone and levels of exhaled nitric oxide

Genetic susceptibility to airway inflammation and exposure to short-term outdoor air pollution

BACKGROUND

Air pollution is a large environmental health hazard whose exposure and health effects are unequally distributed among individuals. This is, at least in part, due to gene-environment interactions, but few studies exist. Thus, the current study aimed to explore genetic susceptibility to airway inflammation from short-term air pollution exposure through mechanisms of gene-environment interaction involving the SFTPA, GST and NOS genes.

METHODS

Five thousand seven hundred two adults were included. The outcome measure was fraction of exhaled nitric oxide (FeNO), at 50 and 270 ml/s. Exposures were ozone (O₃), particulate matter < 10 µm (PM₁₀), and nitrogen dioxide (NO₂) 3, 24, or 120-h prior to FeNO measurement. In the SFTPA, GST and NOS genes, 24 single nucleotide polymorphisms (SNPs) were analyzed for interaction effects. The data were analyzed using quantile regression in both single-and multipollutant models.

RESULTS

Significant interactions between SNPs and air pollution were found for six SNPs (p < 0.05): rs4253527 (SFTPA1) with O₃ and NO_x, rs2266637 (GSTT1) with NO₂, rs4795051 (NOS2) with PM₁₀, NO₂ and NO_x, rs4796017 (NOS2) with PM₁₀, rs2248814 (NOS2) with PM₁₀ and rs7830 (NOS3) with NO₂. The marginal effects on FeNO for three of these SNPs were significant (per increase of 10 µg/m³):rs4253527 (SFTPA1) with O₃ (β: 0.155, 95%CI: 0.013-0.297), rs4795051 (NOS2) with PM₁₀ (β: 0.073, 95%CI: 0.00-0.147 (single pollutant), β: 0.081, 95%CI: 0.004-0.159 (multipollutant)) and NO₂ (β: -0.084, 95%CI: -0.147; -0.020 (3 h), β: -0.188, 95%CI: -0.359; -0.018 (120 h)) and rs4796017 (NOS2) with PM₁₀ (β: 0.396, 95%CI: 0.003-0.790).

CONCLUSIONS

Increased inflammatory response from air pollution exposure was observed among subjects with polymorphisms in SFTPA1, GSTT1, and NOS genes, where O₃ interacted with SFTPA1 and PM10 and NO₂/NO_x with the GSTT1 and NOS genes. This provides a basis for the further exploration of biological mechanisms as well as the identification of individuals susceptible to the effects of outdoor air pollution.

Ambient Environmental Ozone and Variation of Fractional Exhaled Nitric Oxide (FeNO) in Hairdressers and Healthcare Workers

Fractional exhaled nitric oxide (FeNO) is a breath-related biomarker of eosinophilic asthma. The aim of this study was to investigate FeNO variations due to environmental or occupational exposures in respiratory healthy subjects. Overall, 14 hairdressers and 15 healthcare workers in Oslo were followed for 5 workdays. We registered the levels of FeNO after commuting and arriving at the workspace and after ≥3 h of work, in addition to symptoms of cold, commuting method, and hair treatments that were performed. Both short- and intermediate-term effects after exposure were evaluated. Environmental assessment of daily average levels of air quality particulate matter 2.5 (PM_2.5), particulate matter 10 (PM₁₀), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and ozone (O₃) indicated a covariation in ozone and FeNO in which a 35-50% decrease in ozone was followed by a near 20% decrease in FeNO with a 24-h latency. Pedestrians had significantly increased FeNO readings. Symptoms of cold were associated with a significant increase in FeNO readings. We did not find any FeNO increase of statistical significance after occupational chemical exposure to hair treatments. The findings may be of clinical, environmental and occupational importance.

The association between short-term exposure to ambient air pollution and fractional exhaled nitric oxide level: A systematic review and meta-analysis of panel studies

Several epidemiological studies have evaluated the fractional exhaled nitric oxide (FeNO) of ambient air pollution but the results were controversial. We therefore conducted a systematic review and meta-analysis to investigate the associations between short-term exposure to air pollutants and FeNO level. We searched PubMed and Web of Science and included a total of 27 articles which focused on associations between ambient air pollutants (PM₁₀, PM_2.5, black carbon (BC), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃)) exposure and the change of FeNO. Random effect model was used to calculate the percent change of FeNO in association with a 10 or 1 μg/m³ increase in air pollutants exposure concentrations. A 10 μg/m³ increase in short-term PM₁₀, PM_2.5, NO₂, and SO₂ exposure was associated with a 3.20% (95% confidence interval (95%CI): 1.11%, 5.29%), 2.25% (95%CI: 1.51%, 2.99%),4.90% (95%CI: 1.98%, 7.81%), and 8.28% (95%CI: 3.61%, 12.59%) change in FeNO, respectively. A 1 μg/m³ increase in short-term exposure to BC was associated with 3.42% (95%CI: 1.34%, 5.50%) change in FeNO. The association between short-term exposure to O₃ and FeNO level was insignificant (P＞0.05). Future studies are warranted to investigate the effect of multiple pollutants, different sources and composition of air pollutants on airway inflammation.

Ambient air pollution is associated with airway inflammation in older women: a nested cross-sectional analysis

BACKGROUND

Air pollution is a risk factor for chronic obstructive pulmonary disease (COPD). Fraction of exhaled nitric oxide (FeNO) could be a useful biomarker for health effects of air pollutants. However, there were limited data from older populations with higher prevalence of COPD and other inflammatory conditions.

METHODS

We obtained data from the German Study on the influence of Air pollution on Lung function, Inflammation and Ageing. Spirometry and FeNO were measured by standard techniques. Air pollutant exposures were estimated following the European Study of Cohorts for Air Pollution Effects protocols, and ozone (O3) measured at the closest ground level monitoring station. Multiple linear regression models were fitted to FeNO with each pollutant separately and adjusted for potential confounders.

RESULTS

In 236 women (mean age 74.6 years), geometric mean FeNO was 15.2ppb. Almost a third (n=71, 30.1%) of the women had some chronic inflammatory respiratory condition. A higher FeNO concentration was associated with exposures to fine particles (PM2.5), PM2.5absorbance and respirable particles (PM10). There were no significant associations with PMcoarse, NO2, NOx, O3 or length of major roads within a 1 km buffer. Restricting the analysis to participants with a chronic inflammatory respiratory condition, with or without impaired lung function produced similar findings. Adjusting for diabetes did not materially alter the findings. There were no significant interactions between individual pollutants and asthma or current smoking.

CONCLUSIONS

This study adds to the evidence to reduce ambient PM2.5 concentrations as low as possible to protect the health of the general population.

Short-term exposure to air pollution: Associations with lung function and inflammatory markers in non-smoking, healthy adults

INTRODUCTION

Air pollution impacts health by increasing mortality and the incidence of acute events in unhealthy individuals. In contrast, the acute effects of pollution in healthy individuals are less obvious. The present study was designed to evaluate the associations between short-term exposure to air pollution on one hand and lung function, and inflammatory markers on the other in middle-aged, non-smoking adults with no respiratory disease, in two urban areas in northern France.

METHODS

A sample of 1506 non-smoking adults (aged from 40 to 65) with no respiratory disease was selected from the participants in the 2011-2013 cross-sectional Enquête Littoral Souffle Air Biologie Environnement (ELISABET) survey in two urban areas in the northern France. We evaluated the associations between (i) mean levels of particulate matter with aerodynamic diameter < 10 μm (PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) exposure on the day and the day before the study examination for each participant, and (ii) spirometry data and levels of inflammatory markers. Coefficients of multiple linear regression models were expressed (except for the forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio) as the percentage change [95% confidence interval] per 10 μg increment in each pollutant.

RESULTS

Levels of PM₁₀, NO₂ and O₃ exposure were below or only close to the World Health Organization's recommended limits in our two study areas. An increment in NO₂ levels was significantly associated with a lower FEV1/FVC ratio (-0.38 [-0.64; -0.12]), a lower forced expiratory flow between 25% and 75% of FVC (FEF25-75%) (-1.70 [-3.15; -0.23]), and a lower forced expiratory flow measured at 75% of FVC (FEF75%) (-3.07 [-4.92; -1.18]). An increment in PM₁₀ levels was associated with lower FEF75% (-1.41 [-2.79; -0.01]) and a non-significant elevation in serum levels of high-sensitivity C-reactive protein (+3.48 [-0.25; 7.36], p = 0.07). Lastly, an increment in O₃ levels was associated with a significantly higher blood eosinophil count (+2.41 [0.10; 4.77]) and a non-significant elevation in fractional exhaled nitric oxide (+2.93 [-0.16; 6.13], p = 0.06).

CONCLUSION

A short-term exposure to air pollution was associated with a subclinical decrement in distal lung function and increment in inflammatory markers in healthy inhabitants of two urban areas in France. If these exploratory results are confirmed, this could suggest that even moderate levels of air pollution could have an impact on respiratory health on the general population, and not solely on susceptible individuals.

Exposure to Household Air Pollution from Biomass Cookstoves and Levels of Fractional Exhaled Nitric Oxide (FeNO) among Honduran Women

Household air pollution is estimated to be responsible for nearly three million premature deaths annually. Measuring fractional exhaled nitric oxide (FeNO) may improve the limited understanding of the association of household air pollution and airway inflammation. We evaluated the cross-sectional association of FeNO with exposure to household air pollution (24-h average kitchen and personal fine particulate matter and black carbon; stove type) among 139 women in rural Honduras using traditional stoves or cleaner-burning Justa stoves. We additionally evaluated interaction by age. Results were generally consistent with a null association; we did not observe a consistent pattern for interaction by age. Evidence from ambient and household air pollution regarding FeNO is inconsistent, and may be attributable to differing study populations, exposures, and FeNO measurement procedures (e.g., the flow rate used to measure FeNO).

Personal Ozone Exposure and Respiratory Inflammatory Response: The Role of DNA Methylation in the Arginase-Nitric Oxide Synthase Pathway

Little is known regarding the molecular mechanisms behind respiratory inflammatory response induced by ozone. We performed a longitudinal panel study with four repeated measurements among 43 young adults in Shanghai, China from May to October in 2016. We collected buccal samples and measured the fractional exhaled nitric oxide (FeNO) after 3-day personal ozone monitoring. In buccal samples, we measured concentrations of inducible nitric oxide synthase (iNOS) and arginase (ARG), and DNA methylation of NOS2A and ARG2. We used linear mixed-effect models to analyze the effects of ozone on FeNO, two enzymes and their DNA methylation. A 10 ppb increase in ozone (lag 0-8 h) was significantly associated with a 3.89% increase in FeNO, a 36.33% increase in iNOS, and a decrease of 0.36 in the average methylation (%5mC) of NOS2A. Ozone was associated with decreased ARG and elevated ARG2 methylation, but the associations were not significant. These effects were more pronounced among allergic subjects than healthy subjects. The effects were much stronger when using personal exposure monitoring than fixed-site measurements. Our study demonstrated that personal short-term exposure to ozone may result in acute respiratory inflammation, which may be mainly modulated by NOS2A hypomethylation in the arginase-nitric oxide synthase pathway.

Coarse Fraction Particle Matter and Exhaled Nitric Oxide in Non-Asthmatic Children

Coarse particle matter, PM_coarse, is associated with increased respiratory morbidity and mortality. The aim of this study was to investigate the association between short-term changes in PM_coarse and sub-clininal airway inflammation in children. Healthy children aged 11 years from two northern Swedish elementary schools underwent fraction of exhaled nitrogen oxide (FENO) measurements to determine levels of airway inflammation twice weekly during the study period from 11 April–6 June 2011. Daily exposure to PM_coarse, PM_2.5, NO₂, NOx, NO and O₃ and birch pollen was estimated. Multiple linear regression was used. Personal covariates were included as fixed effects and subjects were included as a random effect. In total, 95 children participated in the study, and in all 493 FENO measurements were made. The mean level of PM_coarse was 16.1 μg/m³ (range 4.1–42.3), and that of O₃ was 75.0 μg/m³ (range: 51.3–106.3). That of NO₂ was 17.0 μg/m³ (range: 4.7–31.3), NOx was 82.1 μg/m³ (range: 13.3–165.3), and NO was 65 μg/m³ (range: 8.7–138.4) during the study period. In multi-pollutant models an interquartile range increase in 24 h PM_coarse was associated with increases in FENO by between 6.9 ppb (95% confidence interval 0.0–14) and 7.3 ppb (95% confidence interval 0.4–14.9). PM_coarse was associated with an increase in FENO, indicating sub-clinical airway inflammation in healthy children.

Traffic-related air pollution and alveolar nitric oxide in southern California children

Mechanisms for the adverse respiratory effects of traffic-related air pollution (TRAP) have yet to be established. We evaluated the acute effects of TRAP exposure on proximal and distal airway inflammation by relating indoor nitric oxide (NO), a marker of TRAP exposure in the indoor microenvironment, to airway and alveolar sources of exhaled nitric oxide (FeNO).FeNO was collected online at four flow rates in 1635 schoolchildren (aged 12-15 years) in southern California (USA) breathing NO-free air. Indoor NO was sampled hourly and linearly interpolated to the time of the FeNO test. Estimated parameters quantifying airway wall diffusivity (DawNO) and flux (J'awNO) and alveolar concentration (CANO) sources of FeNO were related to exposure using linear regression to adjust for potential confounders.We found that TRAP exposure indoors was associated with elevated alveolar NO. A 10 ppb higher indoor NO concentration at the time of the FeNO test was associated with 0.10 ppb higher average CANO (95% CI 0.04-0.16) (equivalent to a 7.1% increase from the mean), 4.0% higher J'awNO (95% CI -2.8-11.3) and 0.2% lower DawNO (95% CI -4.8-4.6).These findings are consistent with an airway response to TRAP exposure that was most marked in the distal airways.

Application environmental epidemiology to vehicular air pollution and health effects research

Vehicular pollution is one of the major contributors to the air pollution in urban areas and perhaps and accounts for the major share of anthropogenic green-house gases such as carbon dioxide, carbon monoxide, nitrogen oxides. Knowledge of human health risks related to environmental exposure to vehicular pollution is a current concern. Analyze the range health effects are attributed varied constituents of vehicular air pollution examine evidence for a causal association to specific health effect. In many instances scenario involves exposure to very low doses of putative agents for extended periods, sometimes the period could mean over a lifetime of an individual and yet may result in small increase in health risk that may be imperceptible. Secondary data analysis and literature review. In environmental exposures, traditional epidemiological approaches evaluating mortality and morbidity indicators display many limiting factors such as nonspecificity of biological effects latency time between exposure and magnitude of the effect. Long latency period between exposure and resultant disease, principally for carcinogenic effects and limitation of epidemiological studies for detecting small risk increments. The present paper discusses the methodological challenges in studying vehicular epidemiology and highlights issues that affect the validity of epidemiological studies in vehicular pollution.

Acute effects of summer air pollution on pulmonary function and airway inflammation in healthy young women

Background

Exposure to air pollution has been reported to be associated with asthma exacerbation. However, little is known about the effects of air pollutant exposure in healthy people. A panel study was conducted to evaluate the acute effects of air pollutants on pulmonary function and airway inflammation in healthy subjects.

Methods

Exhaled breath condensate (EBC) pH, fractional concentration of exhaled nitric oxide (FeNO), and pulmonary function were measured in 21 healthy young women repeatedly for two weeks in the summer in Tokyo, Japan. The concentrations of air pollutants were obtained from the monitoring stations in the neighborhoods where the subjects lived. Statistical analyses were performed using generalized estimating equations.

Results

EBC pH decreased significantly with a 10-ppb increase in the 4-day average ozone (O₃) concentration and a 10-µg/m³ increase in the 4-day average suspended particulate matter (SPM) concentration (−0.07 [95% confidence interval {CI} −0.11 to −0.03] and −0.08 [95% CI −0.12 to −0.03], respectively). Subjects with a history of rhinitis showed marked decreases in EBC pH associated with increases in O₃ and SPM. The changes in forced expiratory volume in 1 second (FEV₁) were also significantly associated with a 10-µg/m³ increase in the 3-day average concentration of SPM (−0.09 L [95% CI −0.17 to −0.01]). FeNO increased significantly in relation to the increase in O₃ and SPM among only subjects with a history of asthma.

Conclusions

Over the course of the study, EBC became significantly acidic with increases in O₃ and SPM concentrations. Furthermore, higher SPM concentrations were associated with decreased FEV₁. Subjects with a history of rhinitis or asthma are considered to be more susceptible to air pollutants.