Effect of nitrogen dioxide and ozone on the risk of dying in patients with severe asthma

Effect of altered human exposome on the skin and mucosal epithelial barrier integrity

Pollution in the world and exposure of humans and nature to toxic substances is continuously worsening at a rapid pace. In the last 60 years, human and domestic animal health has been challenged by continuous exposure to toxic substances and pollutants because of uncontrolled growth, modernization, and industrialization. More than 350,000 new chemicals have been introduced to our lives, mostly without any reasonable control of their health effects and toxicity. A plethora of studies show exposure to these harmful substances during this period with their implications on the skin and mucosal epithelial barrier and increasing prevalence of allergic and autoimmune diseases in the context of the "epithelial barrier hypothesis". Exposure to these substances causes an epithelial injury with peri-epithelial inflammation, microbial dysbiosis and bacterial translocation to sub-epithelial areas, and immune response to dysbiotic bacteria. Here, we provide scientific evidence on the altered human exposome and its impact on epithelial barriers.

Effect of NO2 exposure on airway inflammation and oxidative stress in asthmatic mice

Nitrogen dioxide (NO₂) is a widespread air pollutant. Epidemiological evidence indicates that NO₂ is associated with an increase of incidence rate and mortality of asthma, but its mechanism is still unclear. In this study, we exposed mice to NO₂ (5 ppm, 4 h per day for 30 days) intermittently to investigate the development and potential toxicological mechanisms of allergic asthma. We randomly assigned 60 male Balb/c mice to four groups: saline control, ovalbumin (OVA) sensitization, NO₂ alone, and OVA+NO₂ groups. The involved mechanisms were found from the perspective of airway inflammation and oxidative stress. The results showed that NO₂ exposure could aggravate lung inflammation in asthmatic mice, and airway remodeling was characterized by significant thickening of the airway wall and infiltration of inflammatory cells. Moreover, NO₂ would aggravate the airway hyperresponsiveness (AHR), which is characterized by significantly elevated inspiratory resistance (Ri) and expiratory resistance (Re), as well as decreased dynamic lung compliance (Cldyn). In addition, NO₂ exposure promoted pro-inflammatory cytokines (IL-6 and TNF-α) and serum immunoglobulin (IgE) production. The imbalance of Th1/Th2 cell differentiation (IL-4 increased, IFN-γ reduced, IL-4/IFN-γ significantly increased) played a key role in the inflammatory response of asthma under NO₂ exposure. In a nutshell, NO₂ exposure could promote allergic airway inflammation and increase asthma susceptibility. The levels of ROS and MDA among asthmatic mice exposed to NO₂ increased significantly, while GSH levels sharply decreased. These findings may provide better toxicological evidence for the mechanisms of allergic asthma risk due to NO₂ exposure.

Associations between short-term exposure to ambient air pollution and lung function in adults

BACKGROUND

Evidence of the acute effects of high-level air pollution on small airway function and systemic inflammation in adults is scarce.

OBJECTIVE

To examined the associations of short-term (i.e., daily) exposure to multiple air pollutants with lung function and inflammatory markers.

METHODS

We assessed short-term (daily) effects of air pollutants, including particulate matter with aerodynamic diameter less than 2.5 μm (PM_2.5) and 10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and carbon monoxide (CO), on lung function and peripheral immune cell counts over various lag times using generalized linear regression models.

RESULTS

A total of 4764 adults were included from the general community-dwelling population in Shanghai, China. Exposure to air pollutants and lung function were negatively correlated. Decline in FEF between 25% and 75% of vital capacity (FEF_25-75%) were found associated with PM_2.5, SO₂, and CO, and decline in forced expiratory volume in 3 s (FEV₃) to forced vital capacity (FVC) ratio were associated with all examined pollutants, indicating obstruction in small airways. Obstructed airflow in large and middle airways as indicated by decline in FEV₁/FVC were also associated with all pollutants. In subgroup analysis, significant negative associations between the five pollutants and SAD parameters were found only in males but not in females. The difference in the associations of SO₂ with FEF_75% between males and females achieved statistical significance. Additionally, all examined pollutants were significantly associated with lower peripheral neutrophil count.

IMPACT STATEMENT

Acute exposure to air pollutants were associated with airflow-limitation. Both small airways and proximal airways were affected. Acute exposure to air pollutants were accompanied with a lower neutrophil count.

Impacts of residential indoor air quality and environmental risk factors on adult asthma-related health outcomes in Chicago, IL

BACKGROUND

Residential environments are known to contribute to asthma.

OBJECTIVE

To examine the joint impacts of exposures to residential indoor and outdoor air pollutants and housing risk factors on adult asthma-related health outcomes.

METHODS

We analyzed >1-year of data from 53 participants from 41 homes in the pre-intervention period of the Breathe Easy Project prior to ventilation and filtration retrofits. Health outcomes included surveys of asthma control, health-related quality of life, stress, and healthcare utilizations. Environmental assessments included quarterly measurements of indoor and outdoor pollutants (e.g., HCHO, CO, CO2, NO2, O3, and PM), home walk-throughs, and surveys of environmental risk factors. Indoor pollutant concentrations were also matched with surveys of time spent at home to estimate indoor pollutant exposures.

RESULTS

Cross-sectional analyses using mixed-effects models indicated that lower annual average asthma control test (ACT) scores were associated (p < 0.05) with higher indoor NO2 (concentration/exposure: β = -2.42/-1.57), indoor temperature (β = -1.03 to -0.94), and mold/dampness (β = -3.09 to -2.41). In longitudinal analysis, lower ACT scores were also associated (p < 0.05) with higher indoor NO2 concentrations (β = -0.29), PM1 (concentration/exposure: β = -0.12/-0.24), PM2.5 (concentration/exposure: β = -0.12/-0.26), and PM10 (concentration/exposure: β = 10.14/-0.28). Emergency department visits were associated with poorer asthma control [incidence rate ratio (IRR) = 0.84; p < 0.001], physical health (IRR = 0.95; p < 0.05), mental health (IRR = 0.95; p < 0.05), higher I/O NO2 ratios (IRR = 1.30; p < 0.05), and higher indoor temperatures (IRR = 1.41; p < 0.05).

SIGNIFICANCE

Findings suggest that residential risk factors, including indoor air pollution (especially NO2 and particulate matter), higher indoor temperature, and mold/dampness, may contribute to poorer asthma control.

IMPACT

This study highlights the importance of residential indoor air quality and environmental risk factors for asthma control, health-related quality of life, and emergency department visits for asthma. Two timescales of mixed models suggest that exposure to indoor NO2 and particulate matter, higher indoor temperature, and mold/dampness was associated with poorer asthma control. Additionally, emergency department visits were associated with poorer asthma control and health-related quality of life, as well as higher I/O NO2 ratios and indoor temperatures. These findings deepen our understanding of the interrelationships between housing, air quality, and health, and have important implications for programs and policy.

Quantifying the multiple environmental, health, and economic benefits from the electrification of the Delhi public transport bus fleet, estimating a district-wise near roadway avoided PM2.5 exposure

This study investigates the co-benefits from the utilization of the battery-electric bus (BEB) fleet in the Delhi public transportation system as a part of the Delhi electric vehicles policy 2020. To this aim, an integrated quantitative assessment framework is developed to estimate the expected environmental, health, and economic co-benefits from replacing the currently existing public bus fleet with the new BEBs in Delhi. First, the model estimates the avoided emissions from deploying the BEB fleet, using a detailed battery energy simulation model, considering the impact of the battery capacity loss on the annual operational time (hours of service) of the BEB. The annual operational time of the BEB is greatly affected by its battery degradation, which results in time lost due to charging the battery. This indicates that the annual passenger-kilometer (PKM) delivered by the BEB is less than the regular bus, under the same traveling condition. Second, considering fine particles (PM_2.5) as the most health-harming pollutant, the model calculates the near roadway avoided PM_2.5 exposure in the selected traffic zones of 11 major districts of Delhi, using a Gaussian dispersion model. Third, the near roadway avoided PM_2.5 exposure is further used in a health impact assessment model, which considers concentration-response functions for several diseases to evaluate the public health benefits from introducing the BEB fleet in Delhi. The research findings indicate that, the utilization of the new BEB fleet leads to a 74.67% reduction in the total pollutant emissions from the existing bus fleet in Delhi. The results of the integrated co-benefits assessment reveal a significant reduction in PM_2.5 emissions (44 t/y), leading to avoidance of mortality (1370 cases) and respiratory diseases related hospital admissions (2808 cases), respectively, and an annual savings of about USD 383 million from the avoided mortality and morbidity cases in Delhi.

Construction of organic-inorganic "chelate" adsorption sites on metal oxide semiconductor for room temperature NO2 sensing

Metal oxide semiconductors (MOS) have been extensively studied for gas sensing due to their excellent chemical stability and adjustable electronic properties. However, there is still a lack of ingenious design strategies to achieve customizable gas detection in complex environments. Herein, a novel and scalable strategy of constructing organic-inorganic "chelate" adsorption sites is proposed to promote the affinity of MOS sensing materials to target molecules. Specifically, 3-aminopropyltriethoxysilane (APTES)-functionalized reduced graphene oxide (rGO) was decorated on In₂O₃ tubes (AG/In_x), and its NO₂ sensing performance was studied. As a result, the optimal AG/In_x shows boosted room-temperature NO₂ response, and its response to 1 ppm NO₂ is 4.8 times that of In₂O₃. More attractively, the optimal AG/In_x exhibits good selectivity, as well as outstanding detection ability (R_g/R_a = 1.6) for low concentration NO₂ (20 ppb). Experimental results suggest that APTES-rGO not only acts as the electron acceptor to accelerate charge transfer, but also enhances NO₂ adsorption. Further theoretical calculations reveal that NO₂ is simultaneously adsorbed at rGO and APTES via a flexible "chelate" mechanism. The multidentate adsorption configuration remarkably strengthens the NO₂-host interaction, which is conducive to improving sensing performance. This work may inspire the material design of a new generation high-performance gas sensors.

Melatonin antagonizes ozone-exacerbated asthma by inhibiting the TRPV1 channel and stabilizing the Nrf2 pathway

Over the past few years, ozone has been identified as a potential risk factor for exacerbating asthma. However, few attempts have been made to prevent the progression of ozone-exacerbated asthma. This study investigated the attenuating effects of melatonin on ozone-aggravated allergic asthma, and explored the changes to the transient receptor potential vanilloid 1 (TRPV1)-nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway associated with melatonin treatment. The levels of TRPV1 and calcitonin gene-related peptides (CGRP) in lung tissue were detected by immunohistochemistry, western blot, and enzyme-linked immunosorbent assay (ELISA). The Nrf2 signaling involved proteins and mRNA were evaluated by western blot and RT-qPCR. The change of Immunoglobulin E (IgE) and T helper (Th) 2 and Th17 cytokines in serum and bronchoalveolar lavage fluid (BALF) was determined by ELISA. Recruitment of inflammatory cells in BALF, histopathological changes, and airway hyperresponsiveness (AHR) were also determined in lung tissues. Our results indicated that melatonin treatment significantly reduced oxidative stress, as indicated by levels of glutathione (GSH), malonaldehyde (MDA), and 8-hydroxy-2-deoxyguanosine (8-OH-dG). Moreover, ozone-exacerbated asthma symptoms, such as inflammatory cell infiltration, levels of serum immunoglobulin, Th2 and Th17 cytokines in BALF, obvious changes in lung histology, and AHR, were all ameliorated by melatonin treatment. Interestingly, melatonin not only markedly decreased the protein levels of TRPV1 and CGRP, but also enhanced the expression of Nrf2, quinone oxidoreductase-1 (NQO-1), and heme oxygenase-1 (HO-1). Taken together, our results demonstrate that melatonin administration could antagonize ozone-exacerbated asthma by inhibiting the TRPV1 channel and stabilizing the Nrf2 pathway.

Secondary and Tertiary Prevention: Medical Rehabilitation

Allergies are a major public health burden, and targeted measures are required in terms of prevention and treatment. The most common allergic conditions encompass atopic dermatitis (AD), food allergy (FA), allergic asthma (AA), and allergic rhino-conjunctivitis (AR). Primary prevention aims at preventing the onset of allergic disease, before the disease process begins. Secondary prevention aims at preventing progression and exacerbation of allergic disease whereas tertiary prevention aims at reducing disease burden in patients with established disease, by allergen immunotherapy (AIT) or medical rehabilitation. Rehabilitation programs are used for treatment of AA and AD and usually consist of extensive patient assessment, optimization of treatment management, patient education, and behavioral interventions, ideally involving a multidisciplinary treatment team and sometimes provided in a specific climate, usually alpine or maritime. Similarly, prevention of occupational skin diseases requires interdisciplinary approaches on the level of secondary and tertiary preventive intervention; if this is provided, then prevention programs have proven highly (cost-) effective. Unfortunately, the recently published Minimal Standards of Prevention of these dermatoses, underlining especially the importance of meticulous allergological diagnosis and subsequent multidisciplinary patient education, are so far being adhered to only in very few European countries.

Nitrogen dioxide increases the risk of mortality in idiopathic pulmonary fibrosis

Ambient air pollution is associated with the prognosis of idiopathic pulmonary fibrosis (IPF) patients. We aimed to identify the impacts of individual exposure to particulate matter with a 50% cut-off aerodynamic diameter of 10 μm (PM₁₀) and nitrogen dioxide (NO₂) on IPF patients' mortality.1114 patients (mean age 65.7 years; male 80.5%) diagnosed with IPF between 1995 and 2016 were included in this study. Individual-level long-term concentrations of PM₁₀ and NO₂ at residential addresses of patients were estimated using a national-scale exposure prediction model. The effect of PM₁₀ and NO₂ on mortality was estimated using a Cox proportional hazards model adjusted for individual- and area-level covariates.The median follow-up period was 3.8 years and 69.5% of the patients died or underwent lung transplantation. When adjusted for individual- and area-level covariates, a 10 ppb increase in NO₂ concentration was associated with a 17% increase in mortality (hazard ratio (HR) 1.172, 95% CI 1.030-1.344; p=0.016). When IPF patients were stratified by age (≥65 versus <65 years) or by sex, NO₂ was a significant prognostic factor for mortality in the elderly (HR 1.331, 95% CI 1.010-1.598; p=0.010). When stratified by age and sex jointly, NO₂ showed the stronger association with mortality in elderly males (HR 1.305, 95% CI 1.072-1.598; p=0.008) than in other groups. PM₁₀ was not associated with IPF mortality in all patients and in subgroups stratified by age or sex.Our findings suggest that increased exposure to NO₂ can increase the risk of mortality in patients with IPF, specifically in elderly males.

Comparative Numerical Study of PM2.5 in Exit-and-Entrance Areas Associated with Transboundary Transport over China, Japan, and Korea

We report the results of year-long PM2.5 (particulate matter less than 2.5 µm in diameter) simulations over Northeast Asia for the base year of 2013 under the framework of the Long-range Transboundary Air Pollutants in Northeast Asia (LTP) project. LTP is a tripartite project launched by China, Japan, and Korea for cooperative monitoring and modeling of the long-range transport (LRT) of air pollutants. In the modeling aspect in the LTP project, each country’s modeling group employs its own original air quality model and options. The three regional air quality models employed by the modeling groups are WRF-CAMx, NHM-RAQM2, and WRF-CMAQ. PM2.5 concentrations were simulated in remote exit-and-entrance areas associated with the LRT process over China, Japan, and Korea. The results showed apparent bias that remains unexplored due to a series of uncertainties from emission estimates and inherent model limitations. The simulated PM10 levels at seven remote exit-and-entrance sites were underestimated with the normalized mean bias of 0.4 ± 0.2. Among the four chemical components of PM2.5 (SO42−, NO3−, organic carbon (OC), and elemental carbon (EC)), the largest inter-model variability was in OC, with the second largest discrepancy in NO3−. Our simulation results also indicated that under considerable SO42− levels, favorable environments for ammonium nitrate formation were found in exit-and-entrance areas between China and Korea, and gas-aerosol partitioning for semi-volatile species of ammonium nitrate could be fully achieved prior to arrival at the entrance areas. Other chemical characteristics, including NO3−/SO42− and OC/EC ratios, are discussed to diagnose the LRT characteristics of PM2.5 in exit-and-entrance areas associated with transboundary transport over China, Japan, and Korea.

Interactive effects of allergens and air pollution on respiratory health: A systematic review

BACKGROUND

Studies have demonstrated an adverse role of outdoor allergens on respiratory symptoms. It is unknown whether this effect is independent or synergistic of outdoor air pollutants.

METHODS

We systematically reviewed all epidemiological studies that examined interaction effects between counts of outdoor airborne allergens (pollen, fungal spores) and air pollutants, on any respiratory health outcome in children and adults. We searched the MEDLINE, EMBASE and Scopus databases. Each study was summarized qualitatively and assessed for quality and risk of bias (International Prospective Register for Systematic Reviews, registration number CRD42020162571).

RESULTS

Thirty-five studies were identified (15 timeseries, eight case-crossovers, 11 panels and one cohort study), of which 12 reported a significant statistical interaction between an allergen and air pollutant. Eight interactions were related to asthma outcomes, including one on lung function measures and wheeze, three to medical consultations for pollinosis and one to allergic symptoms (nasal, ocular or bronchial). There was no consensus as to which allergen or air pollutant is more likely to interact. No study investigated whether interactions are stronger in atopic individuals.

CONCLUSION

Despite strong evidence from small experimental studies in humans, only a third of studies identified significant allergen-pollutant interactions using common epidemiological study designs. Exposure misclassification, failure to examine subgroups at risk, inadequate statistical power or absence of population-level effects are possible explanations.

Oxidative damage of proline residues by nitrate radicals (NO3˙): a kinetic and product study

Tertiary amides, such as in N-acylated proline or N-methyl glycine residues, react rapidly with nitrate radicals (NO₃˙) with absolute rate coefficients in the range of 4-7 × 10⁸ M^-1 s^-1 in acetonitrile. The major pathway proceeds through oxidative electron transfer (ET) at nitrogen, whereas hydrogen abstraction is only a minor contributor under these conditions. However, steric hindrance at the amide, for example by alkyl side chains at the α-carbon, lowers the rate coefficient by up to 75%, indicating that NO₃˙-induced oxidation of amide bonds proceeds through initial formation of a charge transfer complex. Furthermore, the rate of oxidative damage of proline and N-methyl glycine is significantly influenced by its position in a peptide. Thus, neighbouring peptide bonds, particularly in the N-direction, reduce the electron density at the tertiary amide, which slows down the rate of ET by up to one order of magnitude. The results from these model studies suggest that the susceptibility of proline residues in peptides to radical-induced oxidative damage should be considerably reduced, compared with the single amino acid.

Nitrogen-Dioxide Remains a Valid Air Quality Indicator

In epidemiological studies, both spatial and temporal variations in nitrogen dioxide (NO₂) are a robust predictor of health risks. Compared to particulate matter, the experimental evidence for harmful effects at typical ambient concentrations is less extensive and not as clear for NO₂. In the wake of the “Diesel emission scandal—Dieselgate”, the scientific basis of current limit values for ambient NO₂ concentrations was attacked by industry lobbyists. It was argued that associations between NO₂ levels and medical endpoints were not causal, as NO₂ in older studies served as a proxy for aggressive particulate matter from incineration processes. With the introduction of particle filters in diesel cars, NO₂ would have lost its meaning as a health indicator. Austria has a high percentage of diesel-powered cars (56%). If, indeed, associations between NO₂ concentrations and health risks in previous studies were only due to older engines without a particle filter, we should expect a reduction in effect estimates over time as an increasing number of diesel cars on the roads were outfitted with particle filters. In previous time series studies from Vienna over shorter time intervals, we have demonstrated distributed lag effects over days up to two weeks and previous day effects of NO₂ on total mortality. In a simplified model, we now assess the effect estimates for moving 5-year periods from the beginning of NO₂ monitoring in Vienna (1987) until the year 2018 of same and previous day NO₂ on total daily mortality. Contrary to industry claims of a spurious, no longer valid indicator function of NO₂, effect estimates remained fairly stable, indicating an increase in total mortality of previous day NO₂ by 0.52% (95% CI: 0.35–0.7%) per 10 µg/m³ change in NO₂ concentration.

Short-Term Exposure to Ambient Air Pollution and Asthma Mortality

Rationale: Short-term exposure to air pollution has been associated with asthma exacerbation and increased healthcare use caused by asthma, but its effect on asthma mortality remains largely unknown. Objectives: To quantitatively assess the association between short-term exposure to air pollution and asthma mortality. Methods: We investigated 4,454 individuals who lived in Hubei province, China, and died from asthma between 2013 and 2018. A case-crossover design and conditional logistic regression models were applied for data analyses. Exposures to particulate matter ≤2.5 μm in aerodynamic diameter (PM_2.5), particulate matter ≤10 μm in aerodynamic diameter (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃) were estimated by inverse distance weighted averages of all monitoring stations within 50 km from each case's home address. Measurements and Main Results: Each interquartile range (IQR) increase of PM_2.5 (lag 3; IQR, 47.1 μg/m³), NO₂ (lag 03; IQR, 26.3 μg/m³), and O₃ (lag 3; IQR, 52.9 μg/m³) were positively associated with asthma mortality, with odds ratios of 1.07 (95% confidence interval, 1.01-1.12), 1.11 (95% confidence interval, 1.01-1.22), and 1.09 (95% confidence interval, 1.01-1.18), respectively. There was no evidence of departure from linearity for these associations. Further adjustment for other pollutants did not change the associations materially. We did not observe significant associations between PM₁₀, SO₂, and CO exposures and asthma mortality. Overall, the estimates remained consistent in various sensitivity analyses. Conclusions: Our results provide new evidence that short-term exposures to PM_2.5, NO₂, and O₃ may increase asthma mortality risk. Further studies are needed to confirm our findings in other populations.

The hospitalization attributable burden of acute exacerbations of chronic obstructive pulmonary disease due to ambient air pollution in Shijiazhuang, China

Few studies have investigated the acute exacerbations of chronic obstructive pulmonary disease (AECOPD)-associated attributable burden under exposure to high levels of air pollution among Asians. Data on hospitalization for AECOPD, air pollution and meteorological factors from 1 January 2013 to 31 December 2016 were collected in Shijiazhuang, China. We used a Poisson generalized linear regression model combined with a distributed lag nonlinear model (DLNM) to evaluate the relative cumulative risk for a lag of 0-7 days and examined the potential effect modifications by age and sex via stratification analyses, controlling for long-term trends, seasonal patterns, meteorological factors, and other possible confounders. Then, we computed hospitalization percentages attributable to air pollutants. The AECOPD-associated relative cumulative risks for PM_2.5, PM₁₀, NO₂, SO₂, and CO for a lag of 0-7 days were significantly positively correlated with hospitalization. The associations were stronger in females and retired patients. The NO₂ Cum RR of AECOPD admission was the greatest. A 10μg/m³ increase in daily NO₂ concentration was associated with 6.7% and 5.7% increases in COPD hospitalizations in the retired and female groups, respectively. The results showed that 13%, 9.4%, 1.7%, 9.7%, and 8.8% of AECOPD hospitalizations were attributable to exposure to PM_2.5, PM₁₀, SO₂, NO₂, and CO, respectively. If the air pollutant concentration was reduced to the 24-h average grade II levels of NAAQS of China, the AECOPD attributable percentage for PM_2.5 and PM₁₀ would decrease by 80%. The air pollutants PM_2.5, PM₁₀, SO₂, NO₂, and CO were significantly relevant to AECOPD-associated hospitalization. The associations differed by individual characteristics. The retired and female populations were highly vulnerable.

ERS/EAACI statement on severe exacerbations in asthma in adults: facts, priorities and key research questions

Despite the use of effective medications to control asthma, severe exacerbations in asthma are still a major health risk and require urgent action on the part of the patient and physician to prevent serious outcomes such as hospitalisation or death. Moreover, severe exacerbations are associated with substantial healthcare costs and psychological burden, including anxiety and fear for patients and their families. The European Academy of Allergy and Clinical Immunology (EAACI) and the European Respiratory Society (ERS) set up a task force to search for a clear definition of severe exacerbations, and to also define research questions and priorities. The statement includes comments from patients who were members of the task force.

Economic value of regulating ecosystem services: a comprehensive at the global level review

This study is the first meta-regression analysis of the economic value of regulating ecosystem services at the global level. Most of the regulating ecosystem services have not been properly estimated in terms of economic value and are also ignored in the everyday decision-making process. This study has reviewed 100 publications and included 275 economic value estimates. This study includes explanatory variables in the meta-analysis to account for these influences on the estimated economic value of regulating ecosystem services. This study has estimated the economic value of regulating ecosystem services at US$29.085 trillion for 2015. This study also has found that the values of climate and water regulations are the highest contributors to the total value of regulating ecosystem services. This study indicates that the results of meta-analysis might be helpful to decision-making with respect to three aspects: first, planning and management of urban green cover for sustainable cities; second, integration of the economic value of all the regulating ecosystem services; third, budget allocation for conservation and improvement of regulating ecosystem services for the present and future generations.

Air Health Trend Indicator: Association between Short-Term Exposure to Ground Ozone and Circulatory Hospitalizations in Canada for 17 Years, 1996⁻2012

The Air Health Trend Indicator is designed to estimate the public health risk related to short-term exposure to air pollution and to detect trends in the annual health risks. Daily ozone, circulatory hospitalizations and weather data for 24 cities (about 54% of Canadians) for 17 years (1996⁻2012) were used. This study examined three circulatory causes: ischemic heart disease (IHD, 40% of cases), other heart disease (OHD, 31%) and cerebrovascular disease (CEV, 14%). A Bayesian hierarchical model using a 7-year estimator was employed to find trends in the annual national associations by season, lag of effect, sex and age group (≤65 vs. >65). Warm season 1-day lagged ozone returned higher national risk per 10 ppb: 0.4% (95% credible interval, -0.3⁻1.1%) for IHD, 0.4% (-0.2⁻1.0%) for OHD, and 0.2% (-0.8⁻1.2%) for CEV. Overall mixed trends in annual associations were observed for IHD and CEV, but a decreasing trend for OHD. While little age effect was identified, some sex-specific difference was detected, with males seemingly more vulnerable to ozone for CEV, although this finding needs further investigation. The study findings could reduce a knowledge gap by identifying trends in risk over time as well as sub-populations susceptible to ozone by age and sex.

Accuracy and practicality of a portable ozone monitor for personal exposure estimates

Accurate measurements of personal exposure to atmospheric pollutants such as ozone are important for understanding health risks. We tested a new personal ozone monitor (POM; 2B Technologies) for accuracy, precision, and ease of use. The POM's measurements were compared to simultaneous ozone measurements from a 2B Model 205 monitor and a ThermoScientific 49i monitor, and multiple POMs were placed side-by-side to check precision. Tests were undertaken in a controlled environmental facility, outdoors, and in a private residence. Additionally, ten volunteers wore a POM for five days and answered a questionnaire about its ease of use. The POM measured ozone accurately compared to the 49i ozone monitor, with average relative differences of less than 8%. In the controlled environment tests, the POM's ozone measurements did not change in the presence of additional atmospheric constituents with similar absorption lines to ozone, though there may have been a small decrease in precision and accuracy. Precision between POMs varied by environment (r² = 0.98 outdoors; r² = 0.3 to 0.9 in controlled lab conditions). Volunteers reported that the POM was reasonably comfortable to wear, although all reported that they felt that it was too noisy. Overall, the POM is a viable option for personal ozone monitoring.

Air Pollution and Public Health: A PRISMA-Compliant Systematic Review

(1) Background: Particulate matter increases the risk of respiratory, allergic and oncological diseases in both exposed workers and the general population due to its toxic compounds (e.g., PAHs, gases, heavy metals, microorganisms). The aim of this review is to show the results obtained by our department regarding air pollution’s contributions to health damage in both occupationally and non-occupationally exposed people. (2) Methods: This review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, searching articles on PubMed, using eligibility criteria, extracting data independently from reports to reduce bias and considering the accuracy of the statistical analyses. (3) Results: Of fifteen papers, only three respected the abovementioned criteria. A total of 453 cases (174 occupationally exposed and 279 non-occupationally exposed individuals) were included in the review. Qualitative analysis showed that among workers, occupational exposure to air pollution increased the risk of allergic and pulmonary diseases, whereas environmental exposure to PM increased heavy metal intake, the last of which was characterized by well-known carcinogenic effects. 4) Conclusion: The use of personal protective equipment, a meticulous health surveillance program and specific environmental protection policies are needed to protect public health from damages due to air pollution.

Effect of outdoor air pollution on asthma exacerbations in children and adults: Systematic review and multilevel meta-analysis

Background

Several observational studies have suggested that outdoor air pollution may induce or aggravate asthma. However, epidemiological results are inconclusive due to the presence of numerous moderators which influence this association. The goal of this study was to assess the relationship between outdoor air pollutants and moderate or severe asthma exacerbations in children and adults through a systematic review and multilevel meta-analysis.

Material and methods

We searched studies published in English on PubMed, Scopus, and Google Scholar between January 2000 and October 2016. Studies following a case-crossover design with records of emergency departments and/or hospital admissions as a surrogate of moderate or severe asthma exacerbations were selected. A multilevel meta-analysis was employed, taking into account the potential clustering effects within studies examining more than one lag. Odds ratios (ORs) and 95% confidence intervals were estimated. A subgroup analysis in children aged 0 to 18 years and a sensitivity analysis based on the quality of the included studies as defined in the Newcastle-Ottawa Scale were performed. Publication bias was evaluated through visual inspection of funnel plots and by a complementary search of grey literature. (Prospero Registration number CRD42015032323).

Results

Database searches retrieved 208 records, and finally 22 studies were selected for quantitative analysis. All pollutants except SO₂ and PM₁₀ showed a significant association with asthma exacerbations (NO₂: 1.024; 95% CI: 1.005,1.043, SO₂: 1.039; 95% CI: 0.988,1.094), PM₁₀: 1.024; 95% CI: 0.995,1.053, PM_2.5: 1.028; 95% CI: 1.009,1.047, CO: 1.045; 95% CI: 1.005,1.086, O₃: 1.032; 95% CI: 1.005,1.060. In children, the association was significant for NO₂, SO₂ and PM_2.5.

Conclusion

This meta-analysis provides evidence of the association between selected air pollutants and asthma exacerbations for different lags.

Evaluation of Chronic Obstructive Pulmonary Disease (COPD) attributed to atmospheric O3, NO2, and SO2 using Air Q Model (2011-2012 year)

Chronic obstructive pulmonary disease (COPD) is an important disease worldwide characterized by chronically poor airflow. The economic burden of COPD on any society can be enormous if not managed. We applied the approach proposed by the World Health Organization (WHO) using the AirQ2.2.3 software developed by the WHO European Center for Environment and Health on air pollutants in Tabriz (Iran) (2011-2012 year). A 1h average of concentrations of ozone (O3), daily average concentrations of nitrogen dioxide (NO2) and sulfur dioxide (SO2) were used to assess human exposure and health effect in terms of attributable proportion of the health outcome and annual number of excess cases of Hospital Admissions for COPD (HA COPD). The results of this study showed that 2% (95% CI: 0.8-3.1%) of HA COPD were attributed to O3 concentrations over 10 μg/m(3). In addition, 0.7 % (95% CI: 0.1-1.8%) and 0.5% (95% CI: 0-1%) of HA COPD were attributed to NO2 and SO2 concentrations over 10 μg/m(3) respectively. In this study, we have shown that O3, NO2 and SO2 have a significant impact on COPD hospitalization. Given these results the policy decisions are needed in order to reduce the chronic pulmonary diseases caused by air pollution and furthermore better quantification studies are recommended.

Acute nitrogen dioxide (NO2) exposure enhances airway inflammation via modulating Th1/Th2 differentiation and activating JAK-STAT pathway

Nitrogen dioxide (NO2) is an air pollutant associated with poor respiratory health, asthma exacerbation, and an increased likelihood of inhalational allergies. However, the underlying mechanisms are not clear. In the present study, the airway inflammatory response was first assessed in rats exposed to 5mg/m(3) NO2 for seven days. The results showed that NO2 exposure caused the pulmonary pathological alteration, and significantly stimulated MUC5AC expression. Following this, obviously up-regulated changes of pro-inflammatory cytokines (IL-1β, IL-6, and ICAM-1) were observed. Also, NO2 inhalation induced the imbalance in the ratio of Th1/Th2 differentiation (IL-4, IFN-γ, GATA-3 and T-bet) and the activation of following JAK-STAT pathway (JAK1, JAK3 and STAT6). The findings clarify an important mechanism for NO2 inhalation being injurious to the lung and augmenting the degree of allergic airway inflammation.

Health impact assessment of air pollution in Valladolid, Spain

OBJECTIVE

To estimate the attributable and targeted avoidable deaths (ADs; TADs) of outdoor air pollution by ambient particulate matter (PM10), PM2.5 and O3 according to specific WHO methodology.

DESIGN

Health impact assessment.

SETTING

City of Valladolid, Spain (around 300 000 residents).

DATA SOURCES

Demographics; mortality; pollutant concentrations collected 1999-2008.

MAIN OUTCOME MEASURES

Attributable fractions; ADs and TADs per year for 1999-2008.

RESULTS

Higher TADs estimates (shown here) were obtained when assuming as 'target' concentrations WHO Air Quality Guidelines instead of Directive 2008/50/EC. ADs are considered relative to pollutant background levels. All-cause mortality associated to PM10 (all ages): 52 ADs (95% CI 39 to 64); 31 TADs (95% CI 24 to 39).All-cause mortality associated to PM10 (<5 years): 0 ADs (95% CI 0 to 1); 0 TADs (95% CI 0 to 1). All-cause mortality associated to PM2.5 (>30 years): 326 ADs (95% CI 217 to 422); 231 TADs (95% CI 153 to 301). Cardiopulmonary and lung cancer mortality associated to PM2.5 (>30 years): Cardiopulmonary: 186 ADs (95% CI 74 to 280); 94 TADs (95% CI 36 to 148). Lung cancer : 51 ADs (95% CI 21 to 73); 27 TADs (95% CI 10 to 41).All-cause, respiratory and cardiovascular mortality associated to O3 (all ages): All-cause: 52ADs (95% CI 25 to 77) ; 31 TADs (95% CI 15 to 45). Respiratory: 5ADs (95% CI -2 to 13) ; 3 TADs (95% CI -1 to 8). Cardiovascular: 30 ADs (95% CI 8 to 51) ; 17 TADs (95% CI 5 to 30). Negative estimates which should be read as zero were obtained when pollutant concentrations were below counterfactuals or assumed risk coefficients were below one.

CONCLUSIONS

Our estimates suggest a not negligible negative impact on mortality of outdoor air pollution. The implementation of WHO methodology provides critical information to distinguish an improvement range in air pollution control.

Inflammasome Activity in Non-Microbial Lung Inflammation

The understanding of interleukin-1 (IL-1) family cytokines in inflammatory disease has rapidly developed, due in part to the discovery and characterization of inflammasomes, which are multi-subunit intracellular protein scaffolds principally enabling recognition of a myriad of cellular stimuli, leading to the activation of caspase-1 and the processing of IL-1β and IL-18. Studies continue to elucidate the role of inflammasomes in immune responses induced by both microbes and environmental factors. This review focuses on the current understanding of inflammasome activity in the lung, with particular focus on the non-microbial instigators of inflammasome activation, including inhaled antigens, oxidants, cigarette smoke, diesel exhaust particles, mineral fibers, and engineered nanomaterials, as well as exposure to trauma and pre-existing inflammatory conditions such as metabolic syndrome. Inflammasome activity in these sterile inflammatory states contribute to diseases including asthma, chronic obstructive disease, acute lung injury, ventilator-induced lung injury, pulmonary fibrosis, and lung cancer.

Who is more affected by ozone pollution? A systematic review and meta-analysis

Ozone is associated with adverse health; however, less is known about vulnerable/sensitive populations, which we refer to as sensitive populations. We systematically reviewed epidemiologic evidence (1988-2013) regarding sensitivity to mortality or hospital admission from short-term ozone exposure. We performed meta-analysis for overall associations by age and sex; assessed publication bias; and qualitatively assessed sensitivity to socioeconomic indicators, race/ethnicity, and air conditioning. The search identified 2,091 unique papers, with 167 meeting inclusion criteria (73 on mortality and 96 on hospitalizations and emergency department visits, including 2 examining both mortality and hospitalizations). The strongest evidence for ozone sensitivity was for age. Per 10-parts per billion increase in daily 8-hour ozone concentration, mortality risk for younger persons, at 0.60% (95% confidence interval (CI): 0.40, 0.80), was statistically lower than that for older persons, at 1.27% (95% CI: 0.76, 1.78). Findings adjusted for publication bias were similar. Limited/suggestive evidence was found for higher associations among women; mortality risks were 0.39% (95% CI: -0.22, 1.00) higher than those for men. We identified strong evidence for higher associations with unemployment or lower occupational status and weak evidence of sensitivity for racial/ethnic minorities and persons with low education, in poverty, or without central air conditioning. Findings show that some populations, especially the elderly, are particularly sensitive to short-term ozone exposure.

Long-term dynamics of death rates of emphysema, asthma, and pneumonia and improving air quality

BACKGROUND

The respiratory tract is a major target of exposure to air pollutants, and respiratory diseases are associated with both short- and long-term exposures. We hypothesized that improved air quality in North Carolina was associated with reduced rates of death from respiratory diseases in local populations.

MATERIALS AND METHODS

We analyzed the trends of emphysema, asthma, and pneumonia mortality and changes of the levels of ozone, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matters (PM2.5 and PM10) using monthly data measurements from air-monitoring stations in North Carolina in 1993-2010. The log-linear model was used to evaluate associations between air-pollutant levels and age-adjusted death rates (per 100,000 of population) calculated for 5-year age-groups and for standard 2000 North Carolina population. The studied associations were adjusted by age group-specific smoking prevalence and seasonal fluctuations of disease-specific respiratory deaths.

RESULTS

Decline in emphysema deaths was associated with decreasing levels of SO2 and CO in the air, decline in asthma deaths-with lower SO2, CO, and PM10 levels, and decline in pneumonia deaths-with lower levels of SO2. Sensitivity analyses were performed to study potential effects of the change from International Classification of Diseases (ICD)-9 to ICD-10 codes, the effects of air pollutants on mortality during summer and winter, the impact of approach when only the underlying causes of deaths were used, and when mortality and air-quality data were analyzed on the county level. In each case, the results of sensitivity analyses demonstrated stability. The importance of analysis of pneumonia as an underlying cause of death was also highlighted.

CONCLUSION

Significant associations were observed between decreasing death rates of emphysema, asthma, and pneumonia and decreases in levels of ambient air pollutants in North Carolina.

PM10 and gaseous pollutants trends from air quality monitoring networks in Bari province: principal component analysis and absolute principal component scores on a two years and half data set

Background

The chemical composition of aerosols and particle size distributions are the most significant factors affecting air quality. In particular, the exposure to finer particles can cause short and long-term effects on human health. In the present paper PM₁₀ (particulate matter with aerodynamic diameter lower than 10 μm), CO, NO_x (NO and NO₂), Benzene and Toluene trends monitored in six monitoring stations of Bari province are shown. The data set used was composed by bi-hourly means for all parameters (12 bi-hourly means per day for each parameter) and it’s referred to the period of time from January 2005 and May 2007. The main aim of the paper is to provide a clear illustration of how large data sets from monitoring stations can give information about the number and nature of the pollutant sources, and mainly to assess the contribution of the traffic source to PM₁₀ concentration level by using multivariate statistical techniques such as Principal Component Analysis (PCA) and Absolute Principal Component Scores (APCS).

Results

Comparing the night and day mean concentrations (per day) for each parameter it has been pointed out that there is a different night and day behavior for some parameters such as CO, Benzene and Toluene than PM₁₀. This suggests that CO, Benzene and Toluene concentrations are mainly connected with transport systems, whereas PM₁₀ is mostly influenced by different factors.

The statistical techniques identified three recurrent sources, associated with vehicular traffic and particulate transport, covering over 90% of variance. The contemporaneous analysis of gas and PM₁₀ has allowed underlining the differences between the sources of these pollutants.

Conclusions

The analysis of the pollutant trends from large data set and the application of multivariate statistical techniques such as PCA and APCS can give useful information about air quality and pollutant’s sources. These knowledge can provide useful advices to environmental policies in order to reach the WHO recommended levels.

The endogenous Th17 response in NO2-promoted allergic airway disease is dispensable for airway hyperresponsiveness and distinct from Th17 adoptive transfer

Severe, glucocorticoid-resistant asthma comprises 5-7% of patients with asthma. IL-17 is a biomarker of severe asthma, and the adoptive transfer of Th17 cells in mice is sufficient to induce glucocorticoid-resistant allergic airway disease. Nitrogen dioxide (NO2) is an environmental toxin that correlates with asthma severity, exacerbation, and risk of adverse outcomes. Mice that are allergically sensitized to the antigen ovalbumin by exposure to NO2 exhibit a mixed Th2/Th17 adaptive immune response and eosinophil and neutrophil recruitment to the airway following antigen challenge, a phenotype reminiscent of severe clinical asthma. Because IL-1 receptor (IL-1R) signaling is critical in the generation of the Th17 response in vivo, we hypothesized that the IL-1R/Th17 axis contributes to pulmonary inflammation and airway hyperresponsiveness (AHR) in NO2-promoted allergic airway disease and manifests in glucocorticoid-resistant cytokine production. IL-17A neutralization at the time of antigen challenge or genetic deficiency in IL-1R resulted in decreased neutrophil recruitment to the airway following antigen challenge but did not protect against the development of AHR. Instead, IL-1R-/- mice developed exacerbated AHR compared to WT mice. Lung cells from NO2-allergically inflamed mice that were treated in vitro with dexamethasone (Dex) during antigen restimulation exhibited reduced Th17 cytokine production, whereas Th17 cytokine production by lung cells from recipient mice of in vitro Th17-polarized OTII T-cells was resistant to Dex. These results demonstrate that the IL-1R/Th17 axis does not contribute to AHR development in NO2-promoted allergic airway disease, that Th17 adoptive transfer does not necessarily reflect an endogenously-generated Th17 response, and that functions of Th17 responses are contingent on the experimental conditions in which they are generated.

Interleukin-1 receptor and caspase-1 are required for the Th17 response in nitrogen dioxide-promoted allergic airway disease

Nitrogen dioxide (NO2) is an environmental pollutant and endogenously generated oxidant associated with the development, severity, and exacerbation of asthma. NO2 exposure is capable of allergically sensitizing mice to the innocuous inhaled antigen ovalbumin (OVA), promoting neutrophil and eosinophil recruitment, and a mixed Th2/Th17 response upon antigen challenge that is reminiscent of severe asthma. However, the identity of IL-17A-producing cells and the mechanisms governing their ontogeny in NO2-promoted allergic airway disease remain unstudied. We measured the kinetics of lung inflammation after antigen challenge in NO2-promoted allergic airway disease, including inflammatory cells in bronchoalveolar lavage and antigen-specific IL-17A production from the lung. We determined that IL-17A(+) cells were predominately CD4(+)T cell receptor (TCR)β(+) Th17 cells, and that a functional IL-1 receptor was required for Th17, but not Th2, cytokine production after in vitro antigen restimulation of lung cells. The absence of natural killer T cells, γδ T cells, or the inflammasome scaffold nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain (Nlrp)3 did not affect the development of NO2-promoted allergic inflammation or IL-17A production. Similarly, neutrophil depletion or the neutralization of IL-1α during sensitization exerted no effect on these parameters. However, the absence of caspase-1 significantly reduced IL-17A production from lung cells without affecting Th2 cytokines or lung inflammation. Finally, the intranasal administration of IL-1β and the inhalation of antigen promoted allergic sensitization that was reflected by neutrophilic airway inflammation and IL-17A production from CD4(+)TCRβ(+) Th17 cells subsequent to antigen challenge. These data implicate a role for caspase-1 and IL-1β in the IL-1 receptor-dependent Th17 response manifest in NO2-promoted allergic airway disease.

Air pollution and asthma control in the Epidemiological study on the Genetics and Environment of Asthma

BACKGROUND

The associations between exposure to air pollution and asthma control are not well known. The objective of this study was to assess the association between long-term exposure to NO(2), O(3) and PM(10) and asthma control in the follow-up of the Epidemiological study on the Genetics and Environment of Asthma (EGEA2) (2003-2007).

METHODS

Modelled outdoor NO(2), O(3) and PM(10) estimates were linked to each residential address using the 4 km grid air pollutant surface developed by the French Institute of Environment in 2004. Asthma control was assessed in 481 subjects with current asthma using a multidimensional approach following the 2006-2009 Global Initiative for Asthma guidelines. Multinomial and ordinal logistic regressions were conducted adjusted for sex, age, body mass index, education, smoking and use of inhaled corticosteroids. The association between air pollution and the three domains of asthma control (symptoms, exacerbations and lung function) was assessed. ORs are reported per IQR.

RESULTS

Median concentrations (in micrograms per cubic metre) were 32 (IQR 25-38) for NO(2) (n=465), 46 (41-52) for O(3) and 21 (18-21) for PM(10) (n=481). In total, 44%, 29% and 27% had controlled, partly controlled and uncontrolled asthma, respectively. The ordinal ORs for O(3) and PM(10) with asthma control were 1.69 (95% CI 1.22 to 2.34) and 1.35 (95% CI 1.13 to 1.64), respectively. When including both pollutants in the same model, both associations persisted. Associations were not modified by sex, smoking status, use of inhaled corticosteroids, atopy, season of examination or body mass index. Both pollutants were associated with each of the three main domains of control.

CONCLUSIONS

The results suggest that long-term exposure to PM(10) and O(3) is associated with uncontrolled asthma in adults, defined by symptoms, exacerbations and lung function.

Current treatment of severe asthma

Severe asthma is considered a heterogeneous disease in which a variety of clinical, physiological and inflammatory markers determine disease severity. Pivotal studies in the last 5 years have led to substantial progress in many areas, ranging from a more accurate definition of truly severe, refractory asthma, to classification of the disease into distinct clinical phenotypes, and introduction of new therapies. This review focuses on three common clinical phenotypes of severe asthma in adults (early onset severe allergic asthma, late onset non-atopic eosinophilic asthma, late onset non-eosinophilic asthma with obesity), and provides an overview of recent developments regarding treatment options that are best suited for each of these phenotypes.

GSTM1 modulation of IL-8 expression in human bronchial epithelial cells exposed to ozone

Exposure to the major air pollutant ozone can aggravate asthma and other lung diseases. Our recent study in human volunteers has shown that the glutathione S-transferase Mu 1 (GSTM1)-null genotype is associated with increased airway neutrophilic inflammation induced by inhaled ozone. The aim of this study was to examine the effect of GSTM1 modulation on interleukin 8 (IL-8) production in ozone-exposed human bronchial epithelial cells (BEAS-2B) and the underlying mechanisms. Exposure of BEAS-2B cells to 0.4 ppm ozone for 4 h significantly increased IL-8 release, with a modest reduction in intracellular reduced glutathione (GSH). Ozone exposure induced reactive oxygen species (ROS) production and NF-κB activation. Pharmacological inhibition of NF-κB activation or mutation of the IL-8 promoter at the κB-binding site significantly blocked ozone-induced IL-8 production or IL-8 transcriptional activity, respectively. Knockdown of GSTM1 in BEAS-2B cells enhanced ozone-induced NF-κB activation and IL-8 production. Consistently, an ozone-induced overt increase in IL-8 production was detected in GSTM1-null primary human bronchial epithelial cells. In addition, supplementation with reduced GSH inhibited ozone-induced ROS production, NF-κB activation, and IL-8 production. Taken together, GSTM1 deficiency enhances ozone-induced IL-8 production, which is mediated by generated ROS and subsequent NF-κB activation in human bronchial epithelial cells.

High-altitude treatment: a therapeutic option for patients with severe, refractory asthma?

High-altitude treatment has been applied for more than a century in the treatment of pulmonary diseases including asthma. Many uncontrolled and controlled studies have shown its beneficial effects in children and adolescents with house dust mite allergic asthma. A recent study also showed an improvement in markers of airway inflammation in adult patients with severe intrinsic asthma, suggesting that factors other than HDM avoidance may contribute to the beneficial influence of the high-altitude climate therapy on asthma. The dry mountain climate not only has decreased levels of mite allergens but also decreased levels of pollens, fungal spores and air pollution, as well as high exposure to UV light with immunomodulatory and anti-inflammatory effects. Treatments targeting environmental control have never been investigated systematically in severe asthma, which is surprising, as environmental factors have been recognized as important contributors to asthma severity for many years and more evidence has been accumulating ever since. Preliminary evidence shows the beneficial effects of high-altitude treatment in patients with severe refractory asthma on symptoms, lung function and oral corticosteroid requirement, irrespective of atopic status. In this narrative review, we will discuss why high-altitude treatment might be a promising therapeutic option for patients who suffer from this disabling disease.

Case-crossover analysis of air pollution health effects: a systematic review of methodology and application

BACKGROUND

Case-crossover is one of the most used designs for analyzing the health-related effects of air pollution. Nevertheless, no one has reviewed its application and methodology in this context.

OBJECTIVE

We conducted a systematic review of case-crossover (CCO) designs used to study the relationship between air pollution and morbidity and mortality, from the standpoint of methodology and application.

DATA SOURCES AND EXTRACTION

A search was made of the MEDLINE and EMBASE databases.Reports were classified as methodologic or applied. From the latter, the following information was extracted: author, study location, year, type of population (general or patients), dependent variable(s), independent variable(s), type of CCO design, and whether effect modification was analyzed for variables at the individual level.

DATA SYNTHESIS

The review covered 105 reports that fulfilled the inclusion criteria. Of these, 24 addressed methodological aspects, and the remainder involved the design's application. In the methodological reports, the designs that yielded the best results in simulation were symmetric bidirectional CCO and time-stratified CCO. Furthermore, we observed an increase across time in the use of certain CCO designs, mainly symmetric bidirectional and time-stratified CCO. The dependent variables most frequently analyzed were those relating to hospital morbidity; the pollutants most often studied were those linked to particulate matter. Among the CCO-application reports, 13.6% studied effect modification for variables at the individual level.

CONCLUSIONS

The use of CCO designs has undergone considerable growth; the most widely used designs were those that yielded better results in simulation studies: symmetric bidirectional and time-stratified CCO. However, the advantages of CCO as a method of analysis of variables at the individual level are put to little use.

Environmental and occupational allergies

Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma.

Activity pattern and personal exposure to nitrogen dioxide in indoor and outdoor microenvironments

People are exposed to air pollution from a range of indoor and outdoor sources. Concentrations of nitrogen dioxide (NO(2)), which is hazardous to health, can be significant in both types of environments. This paper reports on the measurement and analysis of indoor and outdoor NO(2) concentrations and their comparison with measured personal exposure in various microenvironments during winter and summer seasons. Furthermore, the relationship between NO(2) personal exposure in various microenvironments and including activities patterns were also studied. Personal, indoor microenvironments and outdoor measurements of NO(2) levels were conducted using Palmes tubes for 60 subjects. The results showed significant differences in indoor and outdoor NO(2) concentrations in winter but not for summer. In winter, indoor NO(2) concentrations were found to be strongly correlated with personal exposure levels. NO(2) concentration in houses using a gas cooker was higher in all rooms than those with an electric cooker during the winter campaign, whereas there was no significant difference noticed in summer. The average NO(2) levels in kitchens with a gas cooker were twice as high as those with an electric cooker, with no significant difference in the summer period. A time-weighted average personal exposure was calculated and compared with measured personal exposures in various indoor microenvironments (e.g. front doors, bedroom, living room and kitchen); including non-smokers, passive smokers and smoker. The estimated results were closely correlated, but showed some underestimation of the measured personal exposures to NO(2) concentrations. Interestingly, for our particular study higher NO(2) personal exposure levels were found during summer (14.0+/-1.5) than winter (9.5+/-2.4).

Association of ambient ozone exposure with airway inflammation and allergy in adults with asthma

RATIONALE

Previous studies have demonstrated associations of high ozone levels with increased epidemiologic as well as lung function measures of asthma activity.

OBJECTIVES

In an observational study during the summer months, we hypothesized that higher ambient ozone levels are associated with more frequent symptoms, higher airway and systemic inflammation, as well as worse lung function in asthmatics as compared with non-asthmatic individuals.

METHODS

Thirty-eight asthmatics and thirteen healthy control subjects residing in metropolitan Atlanta were enrolled during peak ozone season. Medical histories, quality-of-life questionnaires, spirometry, serum immunoglobulin (IgE), peripheral eosinophil counts, and exhaled nitric oxide (NO) were obtained during study visits. Personal ozone exposures over the 2 days before presentation were estimated based on location and activity surveys.

MAIN RESULTS

Upper airway symptoms were more frequent in asthmatics. Higher levels of ozone were associated with worse airflow obstruction, lower quality of life scores, greater eosinophilia, and higher exhaled NO levels in asthmatics. Finally, both asthmatics and non-asthmatics with allergies showed associations between air quality and airway inflammation.

CONCLUSIONS

In adults with asthma but not controls studied during peak ozone season, increasing ozone exposure predicted lower lung function and increased biomarkers of respiratory and systemic inflammation. These associations were enhanced in atopic participants, both with and without asthma. Importantly, the study findings were noted while atmospheric ozone levels were predominantly within the current and revised national air quality standards.

Case-crossover analysis of air pollution and cardiorespiratory hospitalizations: using routinely collected health and environmental data for tracking: science and data

BACKGROUND

From the early 1900s until its closure in February 1998, a Steel coke oven in Pittsburgh, Pennsylvania, was a key source of air pollution. A case-crossover study was performed to assess the associations between daily air pollution and cardiorespiratory (International Classification of Disease Ninth Revision [ICD-9]: 390-519) hospitalizations before and after plant closure and to evaluate how closure influenced these associations.

METHODS

Air pollution data, climatic data, and cardiorespiratory hospitalizations among residents ages 65 years and older were obtained for the period of 1996 through 2000 for the study area. Data were analyzed using a case-crossover design and conditional logistical regression. Two distinct referent-sampling approaches were compared.

RESULTS

Significant associations were observed between the fourth quartile in PM10 and cardiorespiratory hospitalizations (odds ratio [OR]: 1.12; 95% CI: 1.02-1.23) and cardiovascular hospitalizations only (ICD-9: 390-459) (OR: 1.13; 95% CI: 1.01-1.26) before the plant closure. After closure of the plant, PM10 was not significantly associated with cardiorespiratory or cardiovascular disease hospitalizations. Moreover, the referent sampling approaches did not greatly alter the estimations in the case-crossover analysis.

CONCLUSIONS

Existing secondary data are an economical source to assess the impact of point source pollution on the environmental landscape. The findings suggest that closure of the steel coke plant was associated with a reduction risk of the cardiovascular hospitalizations.

Effects of nitrogen dioxide on human health: systematic review of experimental and epidemiological studies conducted between 2002 and 2006

In order to assess health effects in humans caused by environmental nitrogen dioxide (NO(2)) a systematic review of studies in humans was conducted. MEDLINE database was searched for epidemiological studies and experiments on adverse effects of NO(2) published between 2002 and 2006. The evidence with regard to NO(2) exposure limits was assessed using the Scottish Intercollegiate Guidelines Network (SIGN) grading system and the modified three star system. Of the 214 articles retrieved 112 fulfilled the inclusion criteria. There was limited evidence that short-term exposure to a 1-h mean value below 200 microg NO(2)/m(3) is associated with adverse health effects provided by only one study on mortality in patients with severe asthma (*2+). The effect remained after adjusting for other air pollutants. There was moderate evidence that short-term exposure below a 24-h mean value of 50 microg NO(2)/m(3) at monitor stations increases hospital admissions and mortality (**2+). Evidence was also moderate when the search was restricted to susceptible populations (children, adolescents, elderly, and asthmatics). There was moderate evidence that long-term exposure to an annual mean below 40 microg NO(2)/m(3) was associated with adverse health effects (respiratory symptoms/diseases, hospital admissions, mortality, and otitis media) provided by generally consistent findings in five well-conducted cohort and case-control studies with some shortcomings in the study quality (**2+). Evidence was also moderate when the search was restricted to studies in susceptible populations (children and adolescents) and for the combination with other air pollutants. The most frequent reasons for decreased study quality were potential misclassification of exposure and selection bias. None of the high-quality observational studies evaluated was informative for the key questions due to the choice of the dose parameter (e.g., 1-week mean) and exposure levels above the limit values. Inclusion of study designs unlisted in the SIGN grading system did not bring additional evidence regarding exposures below the current air quality limit values for NO(2). As several recent studies reported adverse health effects below the current exposure limits for NO(2) particularly among susceptible populations regarding long-term exposure further research is needed. Apart from high-quality epidemiological studies on causality and the interaction of NO(2) with other air pollutants there is a need for double-blinded randomized cross-over studies among susceptible populations for further evaluation of the short-term exposure limits.

[Contribution of case-crossover design to the analysis of short-term health effects of air pollution: reanalysis of air pollution and health data]

BACKGROUND

During the last decades, numerous studies have shown significant links between short-term exposure to air pollution and health. Time series design have been widely used in order to study these associations. In recent years, the case-crossover design has been applied to the analysis of acute effects of environmental exposures, especially air pollution. The aims of this paper are to describe the case-crossover design and to compare this approach with time series design to assess the association between air pollution and health.

METHODS

In the case-crossover approach, a case-control study is conducted whereby each person who had a health event (case period) is matched with himself/herself on a nearby time period where he/she did not have the event (control period). Review of the literature shows that the referent selection strategies can be associated to a bias in the estimation of the health effect of air pollution. In comparison with time series design, the case-crossover design is easier to conduct, and individual factors can be taken into account. Nevertheless, it is not possible to take into account the overdispersion in the health indicator with this approach.

RESULTS AND CONCLUSION

In conclusion, we suggest to use time series analysis with population data and case-crossover design with individual data.

Particulate matter (PM(2.5), PM(10-2.5), and PM(10)) and children's hospital admissions for asthma and respiratory diseases: a bidirectional case-crossover study

Epidemiological studies reported adverse effects of air pollution on the prevalence of respiratory diseases in children. The purpose of this study was to examine the association between air pollution and admissions for asthma and other respiratory diseases among children who were younger than 15 yr of age. The study used data on respiratory hospital admissions and air pollutant concentrations, including thoracic particulate matter (PM(10)), fine (PM(2.5)), and coarse (PM(10-2.5)) particulate matter in Zonguldak, Turkey. A bidirectional case-crossover design was used to calculate odds ratios for the admissions adjusted for daily meteorological parameters. Significant increases were observed for hospital admissions in children for asthma, allergic rhinitis (AR), and upper (UPRD) and lower (LWRD) respiratory diseases. All fraction of PM in children showed significant positive associations with asthma admissions. The highest association noted was 18% rise in asthma admissions correlated with a 10-microg/m(3) increase in PM(10-2.5) on the same day of admissions. The adjusted odds ratios for exposure to PM(2.5) with an increment of 10 microg/m(3) were 1.15 and 1.21 for asthma and allergic rhinitis with asthma, respectively. PM(10) exerted significant effects on hospital admissions for all outcomes, including asthma, AR, UPRD, and LWRD. Our study suggested a greater effect of fine and coarse PM on asthma hospital admissions compared with PM(10) in children.

Investigating asthma deaths among children and young adults: Michigan Asthma Mortality Review

OBJECTIVE

We developed a surveillance system to investigate asthma deaths in children and young adults.

METHODS

A rapid asthma death notification and investigation system for Michigan was developed to identify interventions to prevent future deaths among people aged 2-34 years. Multidisciplinary panels to determine causal factors and recommend preventative actions reviewed information from death certificates, autopsies, next-of-kin interviews, and medical records. An annual report was disseminated to public health workers, health-care providers, insurers, and others.

RESULTS

Eighty-six asthma deaths in Michigan residents, aged 2-34, occurred from 2002-2004. Sixty-one next of kin were interviewed and medical records were obtained for 84 of the deceased. Summaries were prepared on each of the deceased and were reviewed by expert panels, which reached consensus on causal factors and potential preventive action for each death. Each year an annual report, which summarized the causal factors and potential preventive activity, was prepared.

CONCLUSION

This review has informed and catalyzed interventions to improve asthma care and management in Michigan. Factors leading to the review's success and future activities are discussed.

Relation between concentration of air pollution and cause-specific mortality: four-year exposures to nitrogen dioxide and particulate matter pollutants in 470 neighborhoods in Oslo, Norway

This study investigated the concentration-response relation between air pollution (nitrogen dioxide and particulate matter pollutants PM(10) and PM(2.5)) and cause-specific mortality. The population included all inhabitants of Oslo, Norway, aged 51-90 years on January 1, 1992 (n = 143,842) with follow-up of deaths from 1992 to 1998. An air dispersion model (AirQUIS; Norwegian Institute for Air Research (NILU), Oslo, Norway) was used to estimate levels of exposure in 1992-1995 in all 470 administrative neighborhoods. These data were linked to census, education, and death registries. A consistent effect on all causes of death was found for both sexes and age groups by all indicators of air pollution. The effects appeared to increase at nitrogen dioxide levels higher than 40 micro g/m(3) in the youngest age group and with a linear effect in the interval 20-60 micro g/m(3) for the oldest. An effect of all indicators on cardiovascular causes, lung cancer, and chronic obstructive pulmonary disease was also found in both age groups and sexes. The effects were particularly strong for chronic obstructive pulmonary disease, which appeared to have linear effects, whereas cardiovascular causes and lung cancer seemed to have threshold effects. Results show that vulnerable persons with chronic obstructive pulmonary disease and the elderly seem to be susceptible to air pollution at lower levels than the general population.

Relationship between ozone and temperature during the 2003 heat wave in France: consequences for health data analysis

Background

PAPRICA is a research program designed to estimate the impact on the health of patients with chronic respiratory insufficiency of a prevention strategy based on notification of ozone pollution. The first year of this study was conducted during the 2003 heat wave, and high temperatures were therefore considered as a confounding factor in the data analysis. The aim of the present study was to assess the relationship between ozone and temperature in order to propose a methodology to distinguish between the effects of ozone and temperature on the impact of a prevention strategy with regard to ozone pollution.

Methods

Multivariate analyses were used to identify associated climate and ozone pollution profiles. This descriptive method is of great value to highlight the complexity of interactions between these parameters.

Results

Ozone concentration and temperature were strongly correlated, but the health impact of ozone pollution alone will be evaluated by focusing on situations characterized by ozone concentrations above 110 μg/m³/8h (air quality guidelines to protect human health defined by the French legislation) and temperatures lower than 26°C, below the discomfort threshold.

Conclusion

The precise relationship between ambient ozone concentration and temperature identified during the PAPRICA 2003 study period will be used in analysing the PAPRICA health data.