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

Effect of Air Pollutants Particulate Matter PM2.5, PM10, Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), and Ozone (O3) on Fractional Exhaled Nitric Oxide (FeNO)

Objectives

This study aimed to investigate the effect of Environmental Pollutants Particulate Matter PM2.5, PM10, Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), and Ozone (O3) on lung airway inflammation by assessing the Fractional Exhaled Nitric Oxide (FeNO) in students studying in schools located in or away from air-polluted areas.

Methods

This matched case-control cross-sectional study was conducted in the Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia from August 2022 to July 2023. In this study, two schools were selected, one was located near a traffic-polluted area (School #1), and the second was located away from the traffic-polluted area (School #2). A total of 300 students were recruited, 150 (75 male and 75 female) students from the school located in a traffic-polluted area, and 150 students (75 male and 75 female) from the school located away from a traffic-polluted area. Environmental pollutants PM2.5, PM10, CO, NO2, O3, and SO2, were recorded. The Fractional Exhaled Nitric Oxide (FeNO) was measured using a Niox Mino.

Results

The mean concentration of PM2.5, PM10, CO, NO2, O3, and SO2 were 35.00±0.65 significantly higher in a school located in motor vehicle polluted area compared to a school located away from a motor vehicle-polluted area (29.95±0.32) (p=0.001). The mean values for FeNO were significantly higher (18.75±0.90) among students studying in a school located in the motor vehicle-polluted area compared to students studying in a school located away from the motor vehicle-polluted area (11.26±0.56) (p=0.001).

Conclusions

Environmental pollution can cause lung inflammation among students in schools located in traffic-polluted areas.

Associations between fine particulate air pollution with small-airway inflammation: A nationwide analysis in 122 Chinese cities

Alveolar nitric oxide is a non-invasive indicator of small-airway inflammation, a key pathophysiologic mechanism underlying lower respiratory diseases. However, no epidemiological studies have investigated the impact of fine particulate matter (PM2.5) exposure on the concentration of alveolar nitric oxide (CANO). To explore the associations between PM2.5 exposure in multiple periods and CANO, we conducted a nationwide cross-sectional study in 122 Chinese cities between 2019 and 2021. Utilizing a satellite-based model with a spatial resolution of 1 × 1 km, we matched long-term, mid-term, and short-term PM2.5 exposure for 28,399 individuals based on their home addresses. Multivariable linear regression models were applied to estimate the associations between PM2.5 at multiple exposure windows and CANO. Stratified analyses were also performed to identify potentially vulnerable subgroups. We found that per interquartile range (IQR) unit higher in 1-year average, 1-month average, and 7-day average PM2.5 concentration was significantly associated with increments of 17.78% [95% confidence interval (95%CI): 12.54%, 23.26%], 8.76% (95%CI: 7.35%, 10.19%), and 4.00% (95%CI: 2.81%, 5.20%) increment in CANO, respectively. The exposure-response relationship curves consistently increased with the slope becoming statistically significant beyond 20 μg/m3. Males, children, smokers, individuals with respiratory symptoms or using inhaled corticosteroids, and those living in Southern China were more vulnerable to PM2.5 exposure. In conclusion, our study provided novel evidence that PM2.5 exposure in long-term, mid-term, and short-term periods could significantly elevate small-airway inflammation represented by CANO. Our results highlight the significance of CANO measurement as a non-invasive tool for early screening in the management of PM2.5-related inflammatory respiratory diseases.

Perceptions surrounding the possible interaction between physical activity, pollution and asthma in children and adolescents with and without asthma

A cornerstone of asthma management is maintaining physical activity (PA), but this may lead to increased exposure to, and deeper inhalation of, pollutants. Furthermore, children and adolescents may be more susceptible to the deleterious impacts of such exposures. Despite the recent air quality campaigns and media coverage surrounding the dangers of air pollution to respiratory health, few target children and their understanding of such issues.Using semi structured interviews, understanding of PA, air pollution and their interaction was explored with 25 youth aged 7-17 years. Utilising NVIVO 12 software, an atheoretical, inductive thematic analysis was conducted to identify key themes which were subsequently presented as pen profiles with the number of common responses within a theme indicative of its strength.The majority (88%) of youth's indicated traffic-related air pollution and global manufacturing as key sources of air pollution. Whilst all youths were aware of outdoor pollution, only 52% were aware of indoor air pollutants, of which 62% had asthma. Despite some uncertainty, all youths described pollution in a negative fashion, with 52% linking air pollution to undesirable effects on health, specifically respiratory health. PA in a polluted area was thought to be more dangerous than beneficial by 44%, although 24% suggested the benefits of PA would outweigh any detriment from pollution.Youth are aware of, and potentially compensate for, the interaction between air pollution and PA. Strategies are needed to allow youth to make more informed decisions regarding how to promote PA whilst minimising exposure to air pollution.

MXene-Derived Metal-Organic Framework@MXene Heterostructures toward Electrochemical NO Sensing

The electrochemical sensing of nitric oxide (NO) molecules by metal-organic framework (MOF) catalysts has been impeded, to a large extent, owing to their poor electrical conductivity and weak NO adsorption. In this work, incomplete in situ conversion of V₂ CT_x (T = terminal atoms) MXene to MOF is adopted, forming MOF@MXene heterostructures, which outperform MXene and MOF monocomponents toward electrochemical NO sensing. Density functional theory (DFT) calculation results indicate metal-like electronic characters for the heterostructure benefiting from the dominating contribution of the V 3d orbitals of the metallic MXene. Moreover, plane-averaged charge density difference shows substantial charge redistribution occurs at the heterointerfaces, producing a built-in field, which facilitates charge transfer. Besides, molecular mechanics-based simulated annealing calculation reveals greatly enhanced adsorption energies of NO molecules on the heterointerfaces than that on separate MOFs and MXenes. Hence, the facilitated charge transfer and preferential NO adsorption are responsible for the dramatically promoted performance toward NO sensing. The prudent design of MOF@MXene heterostructure may spur advanced electrocatalysts for electrochemical sensing.

Effect of fungal indoor air pollutant 1-octen-3-ol on levels of reactive oxygen species and nitric oxide as well as dehydrogenases activities in drosophila melanogaster males

Fungal pollution of indoor environments contributes to several allergic symptoms and represents a public health problem. It is well-established that 1-octen-3-ol, also known as mushroom alcohol, is a fungal volatile organic compound (VOC) commonly found in damp indoor spaces and responsible for the typical musty odor. Previously it was reported that exposure to 1-octen-3-ol induced inflammations and disrupted mitochondrial morphology and bioenergetic rate in Drosophila melanogaster. The aim of this study was to examine the influence of 1-octen-3-ol on dehydrogenase activity, apoptotic biomarkers, levels of nitric oxide (NO) and reactive oxygen species (ROS), as well as antioxidant enzymes activities. D. melanogaster flies were exposed to an atmosphere containing 1-octen-3-ol (2.5 or ∞l/L) for 24 hr. Data demonstrated that 1-octen-3-ol decreased dehydrogenases activity and NO levels but increased ROS levels accompanied by stimulation of glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities without altering caspase 3/7 activation. These findings indicate that adverse mitochondrial activity effects following exposure of D. melanogaster to 1-octen-3-ol, a fungal VOC, may be attributed to oxidant stress. The underlying mechanisms involved in adverse consequences of indoor fungal exposure appear to be related to necrotic but not apoptotic mechanisms. The adverse consequences were sex-dependent with males displaying higher sensitivity to 1-octen-3-ol. Based upon on the fact that the fly genome shares nearly 75% of disease-related genes to human exposure to this fungus may explain the adverse human responses to mold especially for males.

Singlet Oxygen and Mobile Hydroxyl Radicals Co-operating on Gas-Solid Catalytic Reaction Interfaces for Deeply Oxidizing NOx

Learning from the important role of porphyrin-based chromophores in natural photosynthesis, a bionic photocatalytic system based on tetrakis (4-carboxyphenyl) porphyrin-coupled TiO₂ was designed for photo-induced treating low-concentration NO_x indoor gas (550 parts per billion), achieving a high NO removal rate of 91% and a long stability under visible-light (λ ≥ 420 nm) irradiation. Besides the great contribution of the conventional ^•O₂^- reactive species, a synergic effect between a singlet oxygen (¹O₂) and mobile hydroxyl radicals (^•OH_f) was first illustrated for removing NO_x indoor gas (¹O₂ + 2NO → 2NO₂, NO₂ + ^•OH_f → HNO₃), inhibiting the production of the byproducts of NO₂. This work is helpful for understanding the surface mechanism of photocatalytic NO_x oxidation and provides a new perspective for the development of highly efficient air purification systems.

Amorphous Boron Carbide on Titanium Dioxide Nanobelt Arrays for High-Efficiency Electrocatalytic NO Reduction to NH3

Electrocatalytic NO reduction is regarded as an attractive strategy to degrade the NO contaminant into useful NH₃ , but the lack of efficient and stable electrocatalysts to facilitate such multiple proton-coupled electron-transfer processes impedes its applications. Here, we report on developing amorphous B_2.6 C supported on a TiO₂ nanoarray on a Ti plate (a-B_2.6 C@TiO₂ /Ti) as an NH₃ -producing nanocatalyst with appreciable activity and durability toward the NO electroreduction. It shows a yield of 3678.6 μg h^-1  cm^-2 and a FE of 87.6 %, superior to TiO₂ /Ti (563.5 μg h^-1  cm^-2 , 42.6 %) and a-B_2.6 C/Ti (2499.2 μg h^-1  cm^-2 , 85.6 %). An a-B_2.6 C@TiO₂ /Ti-based Zn-NO battery achieves a power density of 1.7 mW cm^-2 with an NH₃ yield of 1125 μg h^-1  cm^-2 . An in-depth understanding of catalytic mechanisms is gained by theoretical calculations.

High-efficiency NO electroreduction to NH3 over honeycomb carbon nanofiber at ambient conditions

Electrocatalytic NO reduction is a promising technology for ambient NO removal with simultaneous production of highly value-added NH₃. Herein, we report that honeycomb carbon nanofiber coated on carbon paper acts as an efficient metal-free catalyst for ambient electroreduction of NO to NH₃. In 0.2 M Na₂SO₄ solution, such catalyst achieves an NH₃ yield of 22.35 μmol h^-1 cm^-2 with a high Faradaic efficiency of up to 88.33%. Impressively, it also shows excellent stability for 10-h continuous electrolysis. Theoretical calculations reveal that the most active center of functional groups is -OH group for NO reduction with a low energy barrier (ΔG of 0.29 eV) for the potential-determining step (*NO + H → *HNO).

Efficient nitric oxide electroreduction toward ambient ammonia synthesis catalyzed by a CoP nanoarray

The ever-increasing anthropic NO emission from fossil fuel combustion has resulted in a series of severe environmental issues. Ambient electrocatalytic NO reduction has emerged as a promising route for sustainable...

High-Performance Electrochemical NO Reduction into NH3 by MoS2 Nanosheet

Electrochemical reduction of NO not only offers an attractive alternative to the Haber-Bosch process for ambient NH₃ production but mitigates the human-caused unbalance of nitrogen cycle. Herein, we report that MoS₂ nanosheet on graphite felt (MoS₂ /GF) acts as an efficient and robust 3D electrocatalyst for NO-to-NH₃ conversion. In acidic electrolyte, such MoS₂ /GF attains a maximal Faradaic efficiency of 76.6 % and a large NH₃ yield of up to 99.6 μmol cm^-2  h^-1 . Using MoS₂ nanosheet-loaded carbon paper as the cathode, a proof-of-concept device of Zn-NO battery was assembled to deliver a discharge power density of 1.04 mW cm^-2 and an NH₃ yield of 411.8 μg h^-1  mg_cat. ^-1 . Calculations reveal that the positively charged Mo-edge sites facilitate NO adsorption/activation via an acceptance-donation mechanism and disfavor the binding of protons and the coupling of N-N bond.

Personal Exposure to Black Carbon at School and Levels of Fractional Exhaled Nitric Oxide in New York City

BACKGROUND

Schools are often located near traffic sources, leading to high levels of exposure to traffic-related air pollutants, including black carbon (BC). Thus, the school environment could play in a significant role in the adverse respiratory health of children.

OBJECTIVES

Our objective was to determine associations between personal BC levels at school and airway inflammation [i.e., fractional exhaled nitric oxide (FeNO)] in school-age children. We hypothesized that higher school BC (SBC) would be associated with higher FeNO.

METHODS

Children 9-14 years of age in New York City (NYC) (n=114) wore BC monitors for two 24-h periods over a 6-d sampling period, repeated 6 months later. SBC was defined as the average personal BC concentrations measured during NYC school hours (i.e., 0830-1430 hours). FeNO was measured following each 24-h BC monitoring period. Multivariable linear regression in generalized estimating equation models were used to examine associations between SBC and FeNO. Results are presented as percentage difference (PD) in FeNO.

RESULTS

Personal BC at school was associated with higher FeNO (PD=7.47% higher FeNO per 1-μg/m3 BC (95% CI: 1.31, 13.9), p=0.02]. Compared with BC exposure during school, a smaller PD in FeNO was observed in association with BC exposure while commuting to and from school [PD=6.82% (95% CI: 0.70, 13.3), p=0.03]. Personal BC in non-school environments and residential BC were not associated with FeNO (p>0.05). A significant association between personal BC at school and FeNO was observed among children with seroatopy who did not have asthma [PD=21.5% (95% CI: 4.81, 40.9), p=0.01].

DISCUSSION

Schools may be important sources of BC exposure that contribute to airway inflammation in school-age children. Our results provide rationale for interventions that target improved air quality in urban schools and classrooms. https://doi.org/10.1289/EHP8985.

Hierarchical Bayesian estimation of covariate effects on airway and alveolar nitric oxide

Exhaled breath biomarkers are an important emerging field. The fractional concentration of exhaled nitric oxide (FeNO) is a marker of airway inflammation with clinical and epidemiological applications (e.g., air pollution health effects studies). Systems of differential equations describe FeNO—measured non-invasively at the mouth—as a function of exhalation flow rate and parameters representing airway and alveolar sources of NO in the airway. Traditionally, NO parameters have been estimated separately for each study participant (Stage I) and then related to covariates (Stage II). Statistical properties of these two-step approaches have not been investigated. In simulation studies, we evaluated finite sample properties of existing two-step methods as well as a novel Unified Hierarchical Bayesian (U-HB) model. The U-HB is a one-step estimation method developed with the goal of properly propagating uncertainty as well as increasing power and reducing type I error for estimating associations of covariates with NO parameters. We demonstrated the U-HB method in an analysis of data from the southern California Children’s Health Study relating traffic-related air pollution exposure to airway and alveolar airway inflammation.

The contribution of cooking appliances and residential traffic proximity to aerosol personal exposure

PURPOSE

Indoor and outdoor factors affect personal exposure to air pollutants. Type of cooking appliance (i.e. gas, electricity), and residential location related to traffic are such factors. This research aims to investigate the effect of cooking with gas and electric appliances, as an indoor source of aerosols, and residential traffic as outdoor sources, on personal exposures to particulate matter with an aerodynamic diameter lower than 2.5 μm (PM_2.5), black carbon (BC), and ultrafine particles (UFP).

METHODS

Forty subjects were sampled for four consecutive days measuring personal exposures to three aerosol pollutants, namely PM_2.5, BC, and UFP, which were measured using personal sensors. Subjects were equally distributed into four categories according to the use of gas or electric stoves for cooking, and to residential traffic (i.e. houses located near or away from busy roads).

RESULTS/CONCLUSION

Cooking was identified as an indoor activity affecting exposure to aerosols, with mean concentrations during cooking ranging 24.7-50.0 μg/m³ (PM_2.5), 1.8-4.9 μg/m³ (BC), and 1.4 × 10⁴-4.1 × 10⁴ particles/cm³ (UFP). This study also suggest that traffic is a dominant source of exposure to BC, since people living near busy roads are exposed to higher BC concentrations than those living further away from traffic. In contrast, the contribution of indoor sources to personal exposure to PM_2.5 and UFP seems to be greater than from outdoor traffic sources. This is probably related to a combination of the type of building construction and a varying range of activities conducted indoors. It is recommended to ensure a good ventilation during cooking to minimize exposure to cooking aerosols.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-020-00604-7.

Exposure to traffic-related air pollution and changes in exhaled nitric oxide and DNA methylation in arginase and nitric oxide synthase in children with asthma

BACKGROUND

Traffic-related air pollution (TRAP) has been associated with increased risk of airway inflammation in children with asthma. While epigenetic changes could potentially modulate TRAP-induced inflammatory responses, few studies have assessed the temporal pattern of exposure to TRAP, epigenetic changes and inflammation in children with asthma. Our goal was to test the time-lag patterns of personal exposure to TRAP, airway inflammation (measured as fractional exhaled nitric oxide, FeNO), and DNA methylation in the promoter regions of genes involved in nitric oxide synthesis among children with asthma.

METHODS

We measured personal exposure to black carbon (BC) and FeNO for up to 30 days in a panel of children with asthma. We collected 90 buccal cell samples for DNA methylation analysis from 18 children (5 per child). Methylation in promoter regions of nitric oxide synthase (NOS1, NOS2A, NOS3) and arginase (ARG1, ARG2) was assessed by bisulfite pyrosequencing. Linear-mixed effect models were used to test the associations of BC at different lag periods, percent DNA methylation at each site and FeNO level.

RESULTS

Exposure to BC was positively associated with FeNO, and negatively associated with DNA methylation in NOS3. We found strongest association between FeNO and BC at lag 0-6 h while strongest associations between methylation at positions 1 and 2 in NOS3 and BC were at lag 13-24 h and lag 0-24 h, respectively. The strengths of associations were attenuated at longer lag periods. No significant associations between exposure to TRAP and methylation levels in other NOS and ARG isoforms were observed.

CONCLUSIONS

Exposure to TRAP was associated with higher levels of FeNO and lower levels of DNA methylation in the promoter regions of the NOS3 gene, indicating that DNA methylation of the NOS3 gene could be an important epigenetic mechanism in physiological responses to TRAP in children with asthma.

Facile synthesis of the Z-scheme graphite-like carbon nitride/silver/silver phosphate nanocomposite for photocatalytic oxidative removal of nitric oxides under visible light

In this study, a novel ternary Z-scheme Graphite-like Carbon Nitride (g-C₃N₄)/Silver (Ag)/Silver Phosphate (Ag₃PO₄) photocatalyst was designed and prepared using a two-step method (sodium chloride (NaCl) template-assisted strategy plus selective deposition). Its photocatalysts performance against removing 400 ppm of Nitric Oxides (NOx) was then investigated. We found 50 wt% g-C₃N₄/Ag/Ag₃PO₄(AP-CN 2:1) catalyst removes up to 74% of NO in 90 min under the illumination of visible light (>420 nm), which is respectively 3.5 and 1.8 times higher than using g-C₃N₄ or Ag₃PO₄, alone. This improved performance was attributed to the formation of Z-scheme g-C₃N₄/Ag/Ag₃PO₄ heterojunction, driven by the built-in electric field across the g-C₃N₄/Ag/Ag₃PO₄ interface. These separated the electron-hole but enhanced the original strong oxidation and reduction performance of related components. The superior performance is also attributed to the improved surface area, enhanced hydrophilicity (H₂O₂) and better visible-light-harvesting capability of the composite compound. More importantly, the AP-CN 2:1 sample maintained a NO removal rate of more than 73% even after four rounds of recycling. The photocatalytic oxidation removal mechanism was evaluated using the radical-capture experiments, electron spin resonance (ESR) and ion-exchange high-performance liquid chromatography (HPLC) analysis. The findings of this work offer a simple but effective design of a highly reactive and practical ternary Z-scheme heterojunction photocatalysts for the removal of toxic NO.

Impact of low-level fine particulate matter and ozone exposure on absences in K-12 students and economic consequences

High air pollution levels are associated with school absences. However, low level pollution impacts on individual school absences are under-studied. Understanding the variability of pollution at individual schools within an urban region could improve school recess decisions, better identify local pollution sources, and improve local economic impact assessments by providing granular information relevant to specific schools. We modelled PM_2.5 and ozone concentrations at 36 schools from July 2015 to June 2018 using data from a dense, research grade regulatory sensor network. We determined exposures and daily absences at each school. We used a generalized estimating equations model to retrospectively estimate rate ratios for association between outdoor pollutant concentrations and school absences. We estimated lost school revenue, productivity, and family economic burden. PM_2.5 and ozone concentrations and absence rates vary across the School District. Pollution exposure was associated with a rate ratio as high as 1.02 absences per μg m^-3 and 1.01 per ppb increase for PM_2.5 and ozone, respectively. Significantly, even PM_2.5 and ozone exposure below the air quality index breakpoints for good air quality (<12.1 μg m^-3 and <55 ppb, respectively) was associated with positive rate ratios of absences: 1.04 per μg m^-3 and 1.01 per ppb increase, respectively. Granular local measurements enabled demonstration of air pollution impacts that varied between schools and were undetectable with averaged pollution levels. Reducing pollution by 50% would save $426000 per year districtwide. Pollution reduction benefits would be greatest in schools located in socioeconomically disadvantaged areas. Heterogeneity in exposure, disproportionately affecting socioeconomically disadvantaged schools, points to the need for fine resolution exposure estimation. The economic cost of absences associated with air pollution is substantial even excluding indirect costs such as hospital visits and medication. These findings may help elucidate the differential burden on individual schools and inform local decisions about recess and regulatory considerations for localized pollution sources.

The association between ambient NO2 and PM2.5 with the respiratory health of school children residing in informal settlements: A prospective cohort study

BACKGROUND

No previous epidemiological study has investigated the combined association of long-term ambient nitrogen dioxide (NO₂) and particulate matter of diameter size-2.5 (PM_2.5) exposure with asthma outcomes among schoolchildren in Africa.

OBJECTIVES

This study investigated the independent and co-pollutant association of long-term exposures to ambient air pollutants on asthma-associated outcomes in a cohort of schoolchildren in the Western Cape Province of South Africa.

METHODS

A total of 590 grade-4 schoolchildren residing in four informal settlements were studied. Spirometry and fractional exhaled nitric-oxide (FeNO) measurements were conducted, including a standardized questionnaire administered to caregivers at baseline and 12-months follow-up. Annual NO₂ and PM_2.5 levels were estimated for each child's home using land-use regression modelling. Single- and two-pollutant models were constructed to assess the independent and co-pollutant association of both air pollutants (NO₂ and PM_2.5) on new cases of asthma-associated outcomes adjusting-for host characteristics, indoor exposures and study area.

RESULTS

The annual average concentration of PM_2.5 and NO₂ were 10.01μg/m³ and 16.62μg/m³ respectively, across the four study areas, and were below the local Standards of 20μg/m³ and 40μg/m³, for both pollutants, respectively. In the two-pollutant-adjusted models, an interquartile range (IQR) increase of 14.2μg/m³ in NO₂ was associated with an increased risk of new onset of ocular-nasal symptoms (adjusted odds ratio-aOR: 1.63, 95% CI: 1.01-2.60), wheezing (aOR: 3.57, 95% CI: 1.18-10.92), more than two or more asthma symptom score (aOR: 1.71, 95% CI: 1.02-2.86), and airway inflammation defined as FeNO > 35 ppb (aOR: 3.10, 95% CI: 1.10-8.71), independent of PM_2.5 exposures.

CONCLUSION

This study provided evidence that ambient NO₂ levels below local standards and international guidelines, independent of PM_2.5 exposure, increases new cases of asthma-associated outcomes after 12-months.

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.

Repeatability and variation of the flow independent nitric oxide parameters

INTRODUCTION

Fractional exhaled nitric oxide (F_ENO) is a non-invasive marker of airway inflammation. Measuring F_ENO at several flow rates enables the calculation of flow independent NO-parameters (alveolar NO concentration (C_ANO), bronchial flux of NO (J_awNO), bronchial mucosal NO concentration (C_awNO) and bronchial wall NO diffusion capacity (D_awNO)) that are capable of partitioning the source and release mechanism of NO from the lower respiratory tract. However, the current literature on repeatability and normal variation of the NO-parameters is deficient, and this information is needed to develop the method towards clinical use.

METHODS

We calculated NO-parameters in 28 healthy subjects using two different mathematical methods and used three different study protocols to investigate: (i) repeatability of two consecutive measurements of NO-parameters, (ii) within-day variation of the NO-parameters over one working day and (iii) day-to-day variation of the NO-parameters between consecutive days during course of a working week.

RESULTS

J_awNO was the most repeatable among the NO-parameters, whereas D_awNO and C_awNO were notably least repeatable. C_ANO was higher during the second consecutive measurement (1.22 versus 1.57 ppb, p = 0.017). Both investigated mathematical methods yielded equally repeatable results. J_awNO was slightly higher in the afternoon compared to morning (716 versus 881 pl/s, p = 0.01), but other parameters showed no diurnal variation. Upper 95% limit for the day-to-day difference in the parameters in healthy subjects was about 1.2 ppb in C_ANO, 400 pl/s in J_awNO, 92 ppb in C_awNO and 16 pl/s/ppb in D_awNO.

CONCLUSIONS

This is the first study assessing short-time repeatability of the NO-parameters. Repeatability of the NO-parameters was good and day-to-day variation in NO-parameters was quite low. We recommend scheduling F_ENO-measurements at the same time of day, if possible, and in clinical use variation in NO-parameters above the normal limits found in this study suggest changes in the disease's activity.

Annual, seasonal, and morning rush hour Land Use Regression models for black carbon in a school catchment area of Milan, Italy

INTRODUCTION

The European Environment Agency has identified Northern Italy as one of the most polluted areas in Europe. Among air contaminants, black carbon (BC) has been identified as a sensitive marker of traffic related air pollution. This study aims to investigate the spatial distribution of BC in the catchment area of an elementary school of Milan, the biggest city in Northern Italy, using Land Use Regression (LUR) models and focusing especially on Morning Rush Hour (MRH).

METHODS

Two recruitment campaigns were performed asking schoolchildren's parents and residents of the study area to host a monitoring site in their own dwellings. Finally, 34 monitoring sites and 1 reference site were sampled. BC was measured in two seasonal campaigns using eight micro-aethalometers. Six seasonal and annual LUR models were developed, 3 focused on MRH.

RESULTS

Overall, median BC was 3247 and 1309 ng/m³ in the cold and warm season, respectively. In both seasons, there was a significant spatial variation between the monitoring sites. MRH values were higher than the daily values with median concentrations of 4227 and 2331 ng/m³, respectively. Developed LUR models showed that BC variability is well explained only by traffic variables; R² ranged from 0.52 to 0.79 and from 0.65 to 0.81, for seasonal/annual and MRH LUR models respectively.

DISCUSSION

LUR models based on traffic variables explain most of the measured BC distribution variability for both warm and cold season. MRH represents a critical moment for BC during all the year, with an increase of 1000 ng/m³ respective to the daily median value and differences in magnitude according to location. Our results highlight that the mobility issue is one of the most important challenges to reduce air pollution in the city of Milan and this is of particular concern for elementary schoolchildren that commute to school during MRH.

Flow-independent nitric oxide parameters in asthma: a systematic review and meta-analysis

INTRODUCTION

Fractional exhaled nitric oxide (F_ENO) has been proposed as a non-invasive marker of inflammation in the lungs. Measuring F_ENO at several flow rates enables the calculation of flow independent NO-parameters that describe the NO-exchange dynamics of the lungs more precisely. The purpose of this study was to compare the NO-parameters between asthmatics and healthy subjects in a systematic review and meta-analysis.

METHODS

A systematic search was performed in Ovid Medline, Web of Science, Scopus and Cochrane Library databases. All studies with asthmatic and healthy control groups with at least one NO-parameter calculated were included.

RESULTS

From 1137 identified studies, 33 were included in the meta-analysis. All NO-parameters (alveolar NO concentration (C_ANO), bronchial flux of NO (J_awNO), bronchial mucosal NO concentration (C_awNO) and bronchial wall NO diffusion capacity (D_awNO)) were found increased in glucocorticoid-treated and glucocorticoid-naïve asthma. J_awNO and C_ANO were most notably increased in both study groups. Elevation of D_awNO and C_awNO seemed less prominent in both asthma groups.

DISCUSSION

We found that all the NO-parameters are elevated in asthma as compared to healthy subjects. However, results were highly heterogenous and the evidence on C_awNO and D_awNO is still quite feeble due to only few studies reporting them. To gain more knowledge on the NO-parameters in asthma, nonlinear methods and standardized study protocols should be used in future studies.

Sources of indoor particulate matter (PM) and outdoor air pollution in China in relation to asthma, wheeze, rhinitis and eczema among pre-school children: Synergistic effects between antibiotics use and PM10 and second hand smoke

We studied indoor sources of indoor particulate matter (PM), outdoor air pollution and antibiotic use in relation to asthma, rhinitis and eczema among pre-school children and investigated synergistic effects between PM and antibiotics use. Children (3-6y) from randomly selected day care centres in seven cities across China were included (n = 39,782). Data on ambient temperature and air pollution were collected from local monitoring stations. Data on indoor PM sources (ETS, burning of incense or mosquito coils and biomass for cooking), antibiotics use and health (doctor diagnosed asthma and rhinitis, lifetime eczema, current wheeze and current rhinitis) were assessed by a parental questionnaire. Associations were calculated by multilevel logistic regression. Asthma diagnosis was associated with outdoor temperature, NO₂ and burning mosquito coils. Rhinitis diagnosis was associated with NO₂, ETS, gas cooking and burning biomass for cooking. Lifetime eczema was associated with temperature, PM_10, NO₂, ETS, biomass cooking and burning mosquito coils. Burning incense was associated with current wheeze and current rhinitis. Children using antibiotics had more asthma, wheeze, rhinitis, and eczema. Excluding children with respiratory infections did not change associations with antibiotics use. Antibiotics use enhanced the effects of ETS and PM₁₀ (a synergistic effect). In conclusion, a warmer climate, outdoor NO₂ and PM_10, ETS, gas cooking and burning biomass, incense and mosquito coils can increase the risk of asthma, wheeze, rhinitis and eczema among pre-school children in China. Antibiotics use is a risk factor for childhood asthma, wheeze, rhinitis and eczema and ETS and outdoor PM₁₀ can enhance the effect.

Is residential ambient air limonene associated with asthma? Findings from the Canadian Health Measures Survey

Asthma is a common chronic disease. Exposure to limonene is commonplace because it may be used in the manufacture of personal care products and household cleaners. We investigated the influence of limonene on asthma in a population-based sample of approximately 3000 Canadians. During the Canada Health Measures Survey, carried out between 2012 and 2013, participants were asked if they wheezed or had a diagnosis of asthma, and underwent spirometry and measurement of the fraction of exhaled nitric oxide (FeNO). These variables were tested for an association with limonene concentrations measured in their household air samples, using linear regression analysis A 100% increase in air limonene concentration was associated with an approximate 17% adjusted relative increase wheezing with an odds ratio of 1.17 (95%CI 1.16, 1.18). The percent change in FeNO for a 100% increase in limonene was twice as large for children, 2.89% (95% CI 1.88, 4.43) compared to adults, 1.44% (95%CI 1.16, 1.79). Among boys, the odds ratio was 1.50 (95%CI 1.48, 1.52) between a 100% increase in limonene and a diagnosis of asthma. This study provides evidence that household exposure to limonene may increase the prevalence of asthma in the general population.

Short-term effects of airport-associated ultrafine particle exposure on lung function and inflammation in adults with asthma

BACKGROUND

Exposure to ultrafine particles (UFP, particles with aerodynamic diameter < 100 nm) is associated with reduced lung function and airway inflammation in individuals with asthma. Recently, elevated UFP number concentrations (PN) from aircraft landing and takeoff activity were identified downwind of the Los Angeles International Airport (LAX) but little is known about the health impacts of airport-related UFP exposure.

METHODS

We conducted a randomized crossover study of 22 non-smoking adults with mild to moderate asthma in Nov-Dec 2014 and May-Jul 2015 to investigate short-term effects of exposure to LAX airport-related UFPs. Participants conducted scripted, mild walking activity on two occasions in public parks inside (exposure) and outside (control) of the high UFP zone. Spirometry, multiple flow exhaled nitric oxide, and circulating inflammatory cytokines were measured before and after exposure. Personal UFP PN and lung deposited surface area (LDSA) and stationary UFP PN, black carbon (BC), particle-bound PAHs (PB-PAH), ozone (O3), carbon dioxide (CO2) and particulate matter (PM2.5) mass were measured. Source apportionment analysis was conducted to distinguish aircraft from roadway traffic related UFP sources. Health models investigated within-subject changes in outcomes as a function of pollutants and source factors.

RESULTS

A high two-hour walking period average contrast of ~34,000 particles·cm-3 was achieved with mean (std) PN concentrations of 53,342 (25,529) and 19,557 (11,131) particles·cm-3 and mean (std) particle size of 28.7 (9.5) and 33.2 (11.5) at the exposure and control site, respectively. Principal components analysis differentiated airport UFPs (PN), roadway traffic (BC, PB-PAH), PM mass (PM2.5, PM10), and secondary photochemistry (O3) sources. A standard deviation increase in the 'Airport UFPs' factor was significantly associated with IL-6, a circulating marker of inflammation (single-pollutant model: 0.21, 95% CI = 0.08-0.34; multi-pollutant model: 0.18, 0.04-0.32). The 'Traffic' factor was significantly associated with lower Forced Expiratory Volume in 1 s (FEV1) (single-pollutant model: -1.52, -2.28 to -0.77) and elevated sTNFrII (single-pollutant model: 36.47; 6.03-66.91; multi-pollutant model: 64.38; 6.30-122.46). No consistent associations were observed with exhaled nitric oxide.

CONCLUSIONS

To our knowledge, our study is the first to demonstrate increased acute systemic inflammation following exposure to airport-related UFPs. Health effects associated with roadway traffic exposure were distinct. This study emphasizes the importance of multi-pollutant measurements and modeling techniques to disentangle sources of UFPs contributing to the complex urban air pollution mixture and to evaluate population health risks.

Acute changes in a respiratory inflammation marker in guards following Beijing air pollution controls

The adverse respiratory health effects of PM_2.5 have been studied. However, the epidemiological evidence for the association of specific PM_2.5 sources with health outcomes is still limited. This study investigated the association between PM_2.5 components and sources with a biomarker of acute respiratory inflammation (FeNO) in guards. Personal exposure was estimated by microenvironment samplers and FeNO measurements were carried out before, during and after the Victory Day Military Parade in Beijing. Four sources were determined by factor analysis, including urban pollution, dust, alloy steel abrasion and toxic metals. A mixed-effect model was used to estimate the associations of FeNO with PM_2.5 sources and chemical constituents, controlling for age, BMI, smoke activity, physical activity, waist circumference, temperature and relative humidity. In summary, large concentration decreases in PM_2.5 concentration and PM_2.5 chemical constituents were observed in both roadside and indoor environments during the air control periods, immediately followed by statistically significant decreases in FeNO of roadside guards and patrol guards. Besides, statistically significant increases in FeNO were found to be associated with interquartile range (IQR) increases in some pollutants, with an increase of 1.45ppb (95% CI: 0.69, 2.20), 0.65ppb (95% CI: 0.13, 1.17), 1.48ppb (95% CI: 0.60, 2.35), 0.82ppb (95% CI: 0.44, 1.20), 0.77ppb (95% CI: 0.42, 1.11) in FeNO for mass, sulfate, BC, Ca²⁺ and Sm, respectively. In addition, compared to alloy steel abrasion and toxic metals, urban pollution and dust factors were more associated with acute airway inflammation for highly-exposed populations.

The cumulative effect of air pollutants on the acute exacerbation of COPD in Shanghai, China

BACKGROUND

Epidemiologic studies have shown the effect of air pollutants on acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, little is known regarding the dose-response relationship. This study aimed to investigate the cumulative effect of air pollutants on AECOPD.

METHODS

We collected 101 patients with AECOPD from November 2010 through August 2011 in Shanghai. Multiple logistic regression was used to estimate associations between air pollutants and AECOPD. Poisson regression was then applied to determine the cumulative effect of air pollutants including particulate matter 10 (PM10), PM2.5, nitrogen dioxide (NO₂), sulphur dioxide (SO₂) and ozone (O₃) on AECOPD, of which the seasonal variation was further explored.

RESULTS

The monthly episodes of AECOPD were associated with the concentrations of PM2.5 (r=0.884, p<0.05) and NO₂ (r=0.763, p<0.05). The cutoff value of PM2.5 and NO₂ for predicting AECOPD was 83.0μg/m³ and 53.5μg/m³, respectively. It showed that per 10μg/m³ increment in PM2.5 increased the relative risks (RR) for AECOPD was 1.09 with 3days cumulative effect in cold season, whereas 7days in warm season. The RR for AECOPD for per 10μg/m³ increment in NO₂ was 1.07, with a 5-day cumulative effect without seasonal variation.

CONCLUSIONS

High consecutive levels of PM2.5 and NO₂ increase the risk of developing AECOPD. Cumulative effect of PM2.5 and NO₂ appears before the exacerbation onset. These gradations were more evident in the PM2.5 during different seasons.