Assessing the impact of air pollution on childhood asthma morbidity: how, when, and what to do

Comparative analysis of ambient, in-home, and personal exposures reveals associations between breathing zone pollutant levels and asthma exacerbations in high-risk children

BACKGROUND

Air pollution is associated with poor asthma outcomes in children. However, most studies focus on ambient or indoor monitor pollution levels. Few studies evaluate breathing zone exposures, which may be more consequential for asthma outcomes.

METHODS

We measured personal exposures to NO2, O3, PM10 and PM10 constituents, including black carbon (BC), brown carbon (BrC), environmental tobacco smoke (ETS), endotoxins, and 𝛽-glucan, in a cohort of children with exacerbation-prone asthma for 72 h using wearable monitors. Personal exposures were compared to concentrations from in-home monitors in the child's bedroom and ambient EPA air quality monitoring using correlation analyses. Personal exposures were tested for association with lung function and compared between participants with and without well-controlled asthma and signs of exacerbation in the prior 60 days using censored regression with robust standard errors.

RESULTS

81 children completed 219 monitoring sessions. Personal NO2, O3, and PM10 exposures ranged from < 2 to 99.1 parts per billion (ppb), < 1.5 to 23.3 ppb, and < 1 to 141.9 𝜇g/m3, respectively. Personal endotoxin ranged from 0.04 to 101.3 EU/m3, 𝛽-glucan from 18.5 to 1,162 pg/m3, BC from < 0.3 to 46.9 𝜇g/m3, BrC from < 0.3 to 6.1 𝜇g/m3, and ETS from < 0.3 to 56.6 𝜇g/m3. Correlations between personal and ambient PM10, NO2, and O3 concentrations were poor, whereas personal PM10 and NO2 correlated with in-home concentrations. In-home monitoring less frequently detected BrC (Personal:79% > lower limit of detection, Home:36.8%) and ETS (Personal:83.7%, Home:4.1%) than personal exposures, and detected BC in participants without personal exposure (Personal: 26.5%, Home: 96%). Personal exposures were not significantly associated with lung function or daily asthma control. Children requiring corticosteroid treatment for asthma exacerbation within 60 days of exposure monitoring had 1.98, 2.21 and 2.04 times higher personal exposures to BrC (p < 0.001; 95% CI: 1.43-2.37), ETS (p = 0.007; 95% CI: 1.25-3.91), and endotoxin (p = 0.012; 95% CI: 1.14-3.68), respectively.

CONCLUSIONS

Although in-home monitoring was correlated with personal exposure to PM10 and NO2, in-home detection of ETS and BrC was not associated with personal exposures. Personal PM10 exposures in general, as well as BrC, ETS, and endotoxin levels were associated with recent childhood asthma exacerbations.

CLINICAL TRIAL NUMBER

Not applicable.

Effect of the COVID-19 Lockdown on Pediatric Bronchial Asthma Patients in Saudi Arabia: A Comparative Study

BACKGROUND

The lockdowns imposed during the COVID-19 pandemic and social distancing measures may have decreased traffic and air pollution, which may contribute to reducing asthma exacerbation. However, there is not enough information about the relationship between asthma and COVID-19 lockdown, especially in children. Therefore, the aim of this study is to identify the effects of the COVID-19 lockdown on pediatric patients with moderate to severe bronchial asthma.

METHODS

This is a retrospective cross-sectional analytical study of pediatric patients with moderate to severe asthma who came to King Abdullah Specialist Children's Hospital (KASCH) in Riyadh, Saudi Arabia. The study was conducted for a period of 14 months from March 2019 to May 2020, using the charts of children aged 3 to 14 years. We investigated changes in the severity of asthma using indirect parameters including hospital visits, ER visits, and changes in medications used before and during the COVID-19 lockdown.

RESULTS

A total of 343 asthmatic patients aged mean±SD of 8±3 years were included in the study. More than half 233 (68%) of them were male. The number of patients admitted to the hospital in 2019 was 46 patients (85%), while in 2020, it was only 17 patients (32%). In 2020, the usage of oral steroids has been decreased from 96 (28%) to 50 (15%). The number of people using the leukotriene inhibitor reduced from 171 in 2019 to 162 in 2020. The ER mean visit was 1.6±1.3 in 2019; however, ER visits in 2020 were 0.6 ±0.7 showing a considerable reduction in the ER visits (p < 0.001).

CONCLUSION

The COVID-19 lockdown had a positive impact on asthma patients, with our study showing a significant reduction in ER visits, hospitalizations, and the use of oral steroids between March-May 2019 and 2020, suggesting lower asthma severity. However, a holistic approach is needed post-pandemic to improve asthma management, including increased awareness, better healthcare access, and reduction of environmental triggers to promote better control and overall well-being.

How Can Outdoor Air Pollutants Adversely Affect the Women's Fertility? Systematic Review

In the current century, air pollution is known as one of the most critical environmental problems and it is important to find the relations of air pollution and human health. Various air pollutants, such as volatile organic compounds (VOCs), can negatively affect women's fertility. An exhaustive electronic search was done from 2013 until July 2023 in PUBMED and The Cochrane Central Register of Controlled Trials. The following keywords were combined using Boolean hints in the databases queried: air pollution AND (fertility OR miscarriage OR embryo quality OR embryo development OR pregnancy OR implantation OR live birth). The randomized controlled trials, case-control and cohort studies analyzing the impact of air pollutants on fertility were included in the review. In this systematic review, a significant relation was found between the increase in air pollution and the reduction of fertility health, live birth rates, embryo quality, fertility, implantation rates, and miscarriage in exposed women. These results suggest low fertility health rates are associated with traffic-related air pollution. This review has concluded four components (particulate matter, nitrogen dioxide, sulfur, and carbon monoxide) of traffic pollution that can impair women's fertility. Air pollution harms women's fertility. These effects affect gamete's quality at the genetic and epigenetic level. These effects also alter fetal development. Studies have also reported an effect on fetal growth with increased miscarriages. Since air pollution is everywhere and has many sources, it seems necessary to increase the awareness of people and government officials, especially in hygiene and health, to limit air pollutants as much as possible.

Home and school pollutant exposure, respiratory outcomes, and influence of historical redlining

BACKGROUND

The discriminatory and racist policy of historical redlining in the United States during the 1930s played a role in perpetuating contemporary environmental health disparities.

OBJECTIVE

Our objectives were to determine associations between home and school pollutant exposure (fine particulate matter [PM2.5], NO2) and respiratory outcomes (Composite Asthma Severity Index, lung function) among school-aged children with asthma and examine whether associations differed between children who resided and/or attended school in historically redlined compared to non-redlined neighborhoods.

METHODS

Children ages 6 to 17 with moderate-to-severe asthma (N = 240) from 9 US cities were included. Combined home and school exposure to PM2.5 and NO2 was calculated based on geospatially assessed monthly averaged outdoor pollutant concentrations. Repeated measures of Composite Asthma Severity Index and lung function were collected.

RESULTS

Overall, 37.5% of children resided and/or attended schools in historically redlined neighborhoods. Children in historically redlined neighborhoods had greater exposure to NO2 (median: 15.4 vs 12.1 parts per billion) and closer distance to a highway (median: 0.86 vs 1.23 km), compared to those in non-redlined neighborhoods (P < .01). Overall, PM2.5 was not associated with asthma severity or lung function. However, among children in redlined neighborhoods, higher PM2.5 was associated with worse asthma severity (P < .005). No association was observed between pollutants and lung function or asthma severity among children in non-redlined neighborhoods (P > .005).

CONCLUSIONS

Our findings highlight the significance of historical redlining and current environmental health disparities among school-aged children with asthma, specifically, the environmental injustice of PM2.5 exposure and its associations with respiratory health.

Predictors of Pediatric Asthma Management: Identifying Actionable Results With Geographic Determinants

BACKGROUND

Pediatric asthma remains one of the most prominent chronic health conditions among US youth. Geographic determinants such as air pollutants have been identified as playing a role in asthma development and exacerbation. The purpose of this study was to determine geospatial predictors of pediatric asthma exacerbation events and to prioritize housing remediation resources.

METHODS

Electronic medical records were abstracted from a health plan in Southern California. The inclusion criteria that created a sample of 51 557 members were those aged 21 years and younger, who had at least 1 asthma-related encounter between January 2019 and December 2021. Diagnoses, age, number of clinic and emergency department visits, and home addresses were included. The air quality index from the closest monitoring station during the study period, residential distance from a primary roadway, and residential distance from manufacturing sites were included in the spatial analysis.

RESULTS

The average number of asthma-related clinic visits was 2 across the sample. Individuals with more asthma-related clinic visits residing in public housing were more likely to live within 4 km of industrial manufacturing locations (P < .001), reside closer to a major roadway (P < .001), and experience a higher number of poor air quality days (P < .001). Modeling results show these factors were also significantly predictive of an increase of asthma-related health care encounters.

CONCLUSIONS

The findings of this study were consistent with previous studies linking asthma and poor air quality and further highlighted some of the additive and potentially exponential challenges that public housing, major roadways, and manufacturing sites provide communities in their proximity. This research can guide environmental interventions, including the frequency of public housing inspections, community outreach, and the development of communication strategies, to reduce asthma-related experiences across neighborhoods.

Joint associations of air pollutants during pregnancy, infancy, and childhood with childhood persistent asthma: Nationwide database study in Japan

The joint effect of air pollutants at relatively low levels requires further investigation. Here, a database study was performed to evaluate the effects of exposure to mixtures of air pollutants during pregnancy, infancy, and childhood on childhood persistent asthma. We used the Japan Medical Data Center database, which provides access to family linkages and healthcare provider addresses, and included child-mother dyads in which the child was born between January 2010 and January 2017. The exposure of interest was ground-level air pollutants, and the primary outcome was childhood persistent asthma at 45 years of age, as defined based on outpatient and inpatient asthma disease codes and/or asthma medication dispensing claims. The weighted quantile sum (WQS) regression was used to evaluate the effects of air pollutant mixtures on 52,526 child-mother dyads from 1149 of 1907 municipalities (60.3 %) in Japan. The WQS regression models showed that with every 10th percentile increase in the WQS index, ground-level air pollutants during pregnancy, infancy, and childhood increased the risk of childhood persistent asthma by an odds ratio of 1.04 (95 % CI: 1.02-1.05; p<0.001), 1.02 (95 % CI: 1.01-1.03; p<0.001), and 1.03 (95 % CI: 1.01-1.04; p<0.001), respectively. Moreover, particulate matter with an aerodynamic diameter ≤ 2.5 µm was assigned the highest weight across all three exposure periods. Relatively high weights were assigned to suspended particulate matter and photochemical oxidants during pregnancy, carbon monoxide during infancy, and photochemical oxidants during childhood. Our study showed that a mixture of low-level air pollutants has a detrimental association with childhood persistent asthma.

The Health-Related and Learning Performance Effects of Air Pollution and Other Urban-Related Environmental Factors on School-Age Children and Adolescents-A Scoping Review of Systematic Reviews

PURPOSE OF REVIEW

This scoping review aims to assess the impact of air pollution, traffic noise, heat, and green and blue space exposures on the physical and cognitive development of school-age children and adolescents. While existing evidence indicates adverse effects of transport-related exposures on their health, a comprehensive scoping review is necessary to consolidate findings on various urban environmental exposures' effects on children's development.

RECENT FINDINGS

There is consistent evidence on how air pollution negatively affects children's cognitive and respiratory health and learning performance, increasing their susceptibility to diseases in their adult life. Scientific evidence on heat and traffic noise, while less researched, indicates that they negatively affect children's health. On the contrary, green space exposure seems to benefit or mitigate these adverse effects, suggesting a potential strategy to promote children's cognitive and physical development in urban settings. This review underscores the substantial impact of urban exposures on the physical and mental development of children and adolescents. It highlights adverse health effects that can extend into adulthood, affecting academic opportunities and well-being beyond health. While acknowledging the necessity for more research on the mechanisms of air pollution effects and associations with heat and noise exposure, the review advocates prioritizing policy changes and urban planning interventions. This includes minimizing air pollution and traffic noise while enhancing urban vegetation, particularly in school environments, to ensure the healthy development of children and promote lifelong health.

A Comprehensive Look at the Development of Asthma in Children

Asthma, a prevalent chronic respiratory condition affecting millions of children globally, presents a significant health challenge. This review critically examines the developmental pathways of asthma in children, focusing on genetic, environmental, and early-life determinants. Specifically, we explore the impact of prenatal and postnatal factors such as maternal smoking, nutrition, respiratory infections, and allergen exposure on asthma development. Our analysis highlights the intricate interplay of these influences and their contribution to childhood asthma. Moreover, we emphasize targeted strategies and interventions to mitigate its burden, including genetic counseling for at-risk families, environmental modifications to reduce triggers, and early-life immunomodulation. By delving into these preventive measures and interventions, our review aims to provide actionable insights for healthcare professionals in developing tailored strategies to address the complexities of childhood asthma. In summary, this article offers a detailed examination of asthma development in children, aiming to enhance understanding and inform efforts to reduce its burden through targeted interventions.

Association of TLR4 gene rs4986790 and rs4986791 polymorphisms with asthma susceptibility: meta-analysis and trial sequential analysis

BACKGROUND

The current understanding of the correlation between TLR4 gene (toll-like receptor 4) rs4986790 and rs4986791 polymorphisms and asthma susceptibility is inconclusive, with studies and populations yielding conflicting results.

OBJECTIVES

Evaluate this relationship using meta-analysis and trial sequential analysis (TSA).

PATIENTS AND METHODS

Databases were systematically queried for relevant articles from the establishment of the database to 19 June 2023 adhering to predefined inclusion and exclusion criteria. Two authors independently conducted screening, data extraction, and quality evaluation. Meta-analysis and TSA were carried out using RevMan 5.4, StataMP 17.0, and TSA 0.9.5.10 Beta, with α=0.05. Subgroup analyses were conducted based on racial demographics. A sensitivity analysis was conducted employing a one-by-one exclusion method. Publication bias was assessed using the Begg and Egger tests.

MAIN OUTCOME MEASURES

Association of asthma susceptibility with TLR4 gene rs4986790 and rs4986791 polymorphisms.

SAMPLE SIZE

23 articles included 22 studies on the rs4986790 polymorphism and 11 studies on the rs4986791 polymorphism on the TLR4 gene.

RESULTS

Out of 692 studies screened, 23 met the inclusion criteria. While the overall meta-analysis showed no significant association between the TLR4 rs4986790 polymorphism and asthma susceptibility, subgroup analysis revealed a significant link in the Caucasian population. A significant association was noted in the meta-analysis, particularly among Asian populations, on the rs4986791 polymorphism. The sensitivity analysis indicated that the meta-analysis results were relatively stable. Publication bias analysis revealed minimal influence from publication bias. However, TSA was underscored by the necessity for additional original studies to further validate specific outcomes.

CONCLUSIONS

Our study underscores the ethnicity-specific impact on the relationship between TLR4 polymorphisms and asthma susceptibility. While the overall findings for rs4986790 were not significant, the association with the Caucasian population merits further investigation. Furthermore, rs4986791 demonstrated a significant correlation with asthma susceptibility, specifically among Asian populations.

LIMITATIONS

Our study predominantly examined the rs4986790 and rs4986791 polymorphisms, overlooking the potential influence of other genetic variants within TLR4.

Impact of climate change on paediatric respiratory health: pollutants and aeroallergens

Paediatric populations are particularly vulnerable to respiratory diseases caused and exacerbated by aeroallergens, pollutants and infectious agents. Worsening climate change is expected to increase the prevalence of pollutants and aeroallergens while amplifying disease severity and causing disproportionate effects in under-resourced areas. The purpose of this narrative review is to summarise the role of anthropogenic climate change in the literature examining the future impact of aeroallergens, pollutants and infectious agents on paediatric respiratory diseases with a focus on equitable disease mitigation. The aeroallergens selected for discussion include pollen, dust mites and mould as these are prevalent triggers of paediatric asthma worldwide. Human rhinovirus and respiratory syncytial virus are key viruses interacting with climate change and pollution and are primary causal agents of viral respiratory disease. Within this review, we present the propensity for aeroallergens, climate change and pollution to synergistically exacerbate paediatric respiratory disease and outline measures that can ameliorate the expected increase in morbidity and severity of disease through a health equity lens. We support shifting from fossil fuels to renewable energy worldwide, across sectors, as a primary means of reducing increases in morbidity.

Respiratory Health Effects of Air Pollutants

Air pollution is a risk factor for asthma and respiratory infection. Avoidance of air pollution is the best approach to mitigating the impacts of pollution. Personal preventive strategies are possible, but policy interventions are the most effective ways to prevent pollution and its effect on asthma and respiratory infection.

Breathing zone pollutant levels are associated with asthma exacerbations in high-risk children

Background

Indoor and outdoor air pollution levels are associated with poor asthma outcomes in children. However, few studies have evaluated whether breathing zone pollutant levels associate with asthma outcomes.

Objective

Determine breathing zone exposure levels of NO 2 , O 3 , total PM 10 and PM 10 constituents among children with exacerbation-prone asthma, and examine correspondence with in-home and community measurements and associations with outcomes.

Methods

We assessed children's personal breathing zone exposures using wearable monitors. Personal exposures were compared to in-home and community measurements and tested for association with lung function, asthma control, and asthma exacerbations.

Results

81 children completed 219 monitoring sessions. Correlations between personal and community levels of PM 10 , NO 2 , and O 3 were poor, whereas personal PM 10 and NO 2 levels correlated with in-home measurements. However, in-home monitoring underdetected brown carbon (Personal:79%, Home:36.8%) and ETS (Personal:83.7%, Home:4.1%) personal exposures, and detected black carbon in participants without these personal exposures (Personal: 26.5%, Home: 96%). Personal exposures were not associated with lung function or asthma control. Children experiencing an asthma exacerbation within 60 days of personal exposure monitoring had 1.98, 2.21 and 2.04 times higher brown carbon (p<0.001), ETS (p=0.007), and endotoxin (p=0.012), respectively. These outcomes were not associated with community or in-home exposure levels.

Conclusions

Monitoring pollutant levels in the breathing zone is essential to understand how exposures influence asthma outcomes, as agreement between personal and in-home monitors is limited. Inhaled exposure to PM 10 constituents modifies asthma exacerbation risk, suggesting efforts to limit these exposures among high-risk children may decrease their asthma burden.

CLINICAL IMPLICATIONS

In-home and community monitoring of environmental pollutants may underestimate personal exposures. Levels of inhaled exposure to PM 10 constituents appear to strongly influence asthma exacerbation risk. Therefore, efforts should be made to mitigate these exposures.

CAPSULE SUMMARY

Leveraging wearable, breathing-zone monitors, we show exposures to inhaled pollutants are poorly proxied by in-home and community monitors, among children with exacerbation-prone asthma. Inhaled exposure to multiple PM 10 constituents is associated with asthma exacerbation risk.

Air Pollution and Diet: Potential Interacting Exposures in Asthma

PURPOSE OF REVIEW

To provide a review of emerging literature describing the impact of diet on the respiratory response to air pollution in asthma.

RECENT FINDINGS

Asthma phenotyping (observable characteristics) and endotyping (mechanistic pathways) have increased the specificity of diagnostic and treatment pathways and opened the doors to the identification of subphenotypes with enhanced susceptibility to exposures and interventions. Mechanisms underlying the airway immune response to air pollution are still being defined but include oxidative stress, inflammation, and activation of adaptive and innate immune responses, with genetic susceptibility highlighted. Of these, neutrophil recruitment and activation appear prominent; however, understanding neutrophil function in response to pollutant exposures is a research gap. Diet may play a role in asthma pathogenesis and morbidity; therefore, diet modification is a potential target opportunity to protect against pollutant-induced lung injury. In particular, in vivo and in vitro data suggest the potential for diet to modify the inflammatory response in the airways, including impacts on neutrophil recruitment and function. Murine models provide compelling results in regard to the potential for dietary components (including fiber, antioxidants, and omega-3 fatty acids) to buffer against the inflammatory response to air pollution in the lung. Precision lifestyle approaches to asthma management and respiratory protection in the context of air pollution exposures may evolve to include diet, pending the results of further epidemiologic and causal investigation and with neutrophil recruitment and activation as a candidate mechanism.

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.

Persistent Asthma at School Age: Associated Factors in Preschool Children with Asthma

Most patients with childhood asthma present their first symptoms at preschool age. Identifying modifiable risks and protective factors at an early age may help develop asthma prevention and control strategies. This study aimed to identify factors at preschool age that are associated with persistent asthma at school age. This retrospective observational study included preschool children with asthma from 2015 to 2020 at a university hospital in Southern Thailand. In total, 189 eligible participants (70.9% boys; median age, 7.6 [6.7, 8.5] years) were included. Wheeze characteristics included early transient wheeze, persistent wheeze, and late-onset wheeze that accounted for 55%, 27.5%, and 19.5% of the patients, respectively. Approximately 20% of the participants had persistent asthma. Breastfeeding was a protective factor (odds ratio [OR] 0.4 [0.2, 0.9], p = 0.04). The modifiable risk factors were siblings living in the same household (OR 2.6 [1.1, 6.2], p = 0.02) and residence in an industrial area (OR 3.8 [1.4, 10.5], p = 0.009). Additionally, presence of allergic rhinitis was associated with an increased risk of persistent asthma at school age (OR 3.6 [1.6, 8.2], p = 0.002). Early therapeutic interventions targeting modifiable factors provide a window of opportunity to prevent persistent asthma at school age.

A 28-day, 2-year study reveals that adolescents are more fatigued and distressed on days with greater NO2 and CO air pollution

This 2-year, 28-day study examined whether adolescents felt greater fatigue and emotional distress the same day and the day after air quality was worse. We linked objective daily air quality measurements to daily self-reports from 422 Mexican-American adolescents in Los Angeles County, California from 2009 to 2011 (50% girls, M_Age = 15 years). A robust, within-subject analysis of 9696 observations revealed that adolescents with ongoing physical complaints reported greater fatigue and emotional distress on days that the air contained higher levels of nitrogen dioxide (NO₂) and carbon monoxide (CO). Regardless of physical complaints, adolescents on average also reported greater fatigue the day after NO₂ levels were higher. The same-day and next-day associations between air pollution and distress were mediated via daily increases in fatigue. Results were robust when controlling for day of the week, and daily temperature and humidity. Sulfur dioxide (SO₂), ozone (O₃), PM_2.5 and PM₁₀ were not related to daily fatigue or distress.

The association between air pollution and childhood asthma: United States, 2010-2015

OBJECTIVE

The current population-based study examines the association between county-level ambient air pollution and childhood asthma.

METHODS

Data from the nationally representative 2010-2015 National Health Interview Survey were linked to nationwide fine particulate matter (PM2.5) air pollution data at the county-level from the National Environmental Public Health Tracking Network which utilizes air quality monitoring stations and modeled PM2.5 measurements (Downscaler model data) and adjusted by county-level socioeconomic characteristics data from the 2010-2015 American Community Survey. Multilevel modeling techniques were used to assess the association between PM2.5 annual concentrations (quartiles < 8.11, 8.11-9.50, 9.51-10.59, ≥ 10.60 µg/m3) and current childhood asthma along with two asthma outcomes (episode in the past year, emergency room (ER) visit due to asthma).

RESULTS

From 2010 to 2015, there were significant declines in PM2.5 concentrations and asthma outcomes. In unadjusted models, children living in areas with higher PM2.5 concentrations were more likely to have current asthma, ≥1 asthma episode in the past year, and ≥1 ER visit due to asthma compared with children living in areas with the lowest quartile (< 8.11 µg/m3). After adjusting for characteristics at the county, geographic, and child and family-level, significant associations remained for asthma episode, and ER visit among children living in areas with PM2.5 annual concentrations between 9.51 and 10.59 µg/m3 (3rd quartile) compared with children living in areas with the lowest quartile.

CONCLUSIONS

This study adds to the limited literature by incorporating nationally representative county-, child-, and family-level data to provide a multi-level analysis of the associations between air pollution and childhood asthma in the U.S.

Health and Clinical Impacts of Air Pollution and Linkages with Climate Change

Air Pollution Impacts and Climate Change LinksAs part of the NEJM Group series on climate change, Keswani and colleagues review the linkages between climate change and air pollution and suggest strategies that clinicians may use to mitigate the adverse health impacts of air pollution.

Estimating the Impact of Air Pollution on Healthcare-Seeking Behaviour by Applying a Difference-in-Differences Method to Syndromic Surveillance Data

Syndromic surveillance data were used to estimate the direct impact of air pollution on healthcare-seeking behaviour, between 1 April 2012 and 31 December 2017. A difference-in-differences approach was used to control for spatial and temporal variations that were not due to air pollution and a meta-analysis was conducted to combine estimates from different pollution periods. Significant increases were found in general practitioner (GP) out-of-hours consultations, including a 98% increase (2–386, 95% confidence interval) in acute bronchitis and a 16% (3–30) increase in National Health Service (NHS) 111 calls for eye problems. However, the numbers involved are small; for instance, roughly one extra acute bronchitis consultation in a local authority on a day when air quality is poor. These results provide additional information for healthcare planners on the impacts of localised poor air quality. However, further work is required to identify the separate impact of different pollutants.

Association between Land Use Mix and Respiratory Symptoms and Asthma in Children from the Generation XXI Birth Cohort

Land use mix (LUM) in the neighbourhoods has been associated with healthier lifestyles. However, less is known about the association between LUM and health outcomes, namely during childhood. The objective of this study was to evaluate the association between different LUM indexes for Porto Metropolitan Area and asthma and respiratory symptoms in children. A cross-sectional analysis was performed involving 6260 children enrolled in Generation XXI. Land use around the child's residence was assessed with the Portuguese official map of land cover using a GIS. Generalized linear mixed-effects models were fitted to estimate the association between LUM and respiratory symptoms and asthma at 7 years of age. Adjusted associations were quantified using odds ratio (OR) and 95% confidence interval (95% CI). After adjustment, LUM was associated with a lower odds of wheezing in the last 12 months [OR (95% CI) = 0.37 (0.15; 0.93) using Shannon's Evenness Index within 500 m; and OR = 0.93 (0.89; 0.98) using the number of different land use types within 250 m]. Living in neighbourhoods with high LUM has a protective effect on current wheezing symptoms. Our results highlight the association between LUM and respiratory symptoms among children, suggesting that public health considerations should be incorporated in land use decision-making.

Long-Term Trends of Asthma Mortality in China from 2000 to 2019: A Joinpoint Regression and Age-Period-Cohort Analysis

Background: Trends of asthma mortality vary widely all over the world, while the trends in China over the past 15 years are unknown. The aim of this study was to assess the trends of asthma mortality in China. Methods: Asthma deaths and demographic characteristics were collected from National Death Cause Datasets of Disease Surveillance System between 2004 and 2019. The data were analyzed with joinpoint regression analysis and age-period-cohort (APC) analysis for the mortality rate due to asthma in China. Results: Asthma mortality declined from 2.4 (95% confidence interval (CI): 2.3–2.5) per 100,000 in 2004 to 1.6 (95% CI: 1.5–1.7) per 100,000 in 2019. Age-adjusted asthma mortality rates decreased for men and women in urban and rural areas from 2004 through 2019. The decreasing trend of the mortality rate has slowed down substantially during 2007 and 2009. After that, the decreasing trend has stabilized. The asthma mortality rates generally have a positive relationship with the age of the population when controlling for period and cohort. The period trend decreased and then increased when controlling for age and cohort. Conclusions: We should pay more attention to asthma management plans or treatment for aging people who are facing higher risk of asthma death.

Randomized trial of a portable HEPA air cleaner intervention to reduce asthma morbidity among Latino children in an agricultural community

BACKGROUND

Data on pediatric asthma morbidity and effective environmental interventions in U.S. agricultural settings are few. We evaluated the effectiveness of HEPA air cleaners on asthma morbidity among a cohort of rural Latino children.

METHODS

Seventy-five children with poorly controlled asthma and living in non-smoking homes were randomly assigned to asthma education alone or along with HEPA air cleaners placed in their sleeping area and home living room. The Asthma Control Test (ACT) score, asthma symptoms in prior 2 weeks, unplanned clinical utilization, creatinine-adjusted urinary leukotriene E4 (uLTE4 [ng/mg]), and additional secondary outcomes were evaluated at baseline, six, and 12 months. Group differences were assessed using multivariable-adjusted generalized estimating equations. Incident rate ratios of ever experiencing the metrics of poorer asthma health during follow-up (suboptimal asthma management) were estimated using Poisson regression models in secondary analysis.

RESULTS

Mean child age was 9.2 and 8.6 years in intervention and control groups, respectively, and two-thirds of participants were male. Primary analysis of repeated measures of ACT score did not differ between groups (HEPA group mean change compared to controls 10% [95% CI: - 12-39%]). A suggestion of greater decrease in uLTE4 (ng/mg creatinine) was observed (- 10% [95% CI: - 20 -1%]). Secondary analysis showed children with HEPAs were less likely to have an ACT score meeting a clinically defined cutoff for poorly controlled asthma using repeated measures (IRR: 0.45 [95% CI: 0.21-0.97]). In Poisson models, intervention participants had reduced risk of ever meeting this cutoff (IRR: 0.43 [95% CI: 0.21-0.89]), ever having symptoms in the past 2 weeks (IRR: 0.71 [95% CI: 0.52-0.98]), and lower risk of any unplanned clinical utilization (IRR: 0.35 [95% CI: 0.13-0.94]) compared to control participants.

DISCUSSION

The HAPI study showed generally improved outcomes among children in the HEPA air cleaner group. However, primary analyses did not meet statistical significance and many outcomes were subjective (self-report) in this unblinded study, so findings must be interpreted cautiously. HEPA air cleaners may provide additional benefit for child asthma health where traditional asthmagens (traffic, tobacco smoke) are not prominent factors, but larger studies with more statistical power and blinded designs are needed.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04919915 . Date of retrospective registration: May 19, 2021.

Air Pollution and Adolescent Development: Evidence from a 3-Year Longitudinal Study in China

This study aimed to investigate the impact of air pollution on the development of adolescents and the mediating role of students’ emotional disorders. Participants came from a longitudinal sample group of adolescents (n = 1301) in Southern China from the years 2016 to 2018. They were assessed for the Positive Youth Development and emotional disorders, and air pollution was measured by the Air Quality Index. The results show that students’ higher degree of exposure to air pollution was negatively associated with their positive development. Three out of four emotional disorders (i.e., anxiety, neuroticism, and withdrawal) mediate this association. The results suggest that the physical environment can have a paramount influence on the emotional status and overall development of adolescents, calling for intervention programs by policymakers.

Associations of Exposure to Nitrogen Oxides with Prevalent Asthma and Other Atopic Diseases in Israel

Childhood exposure to nitrogen oxides (NOx) is considered a risk factor for the onset of asthma. However, associations of this exposure with other atopic diseases and factors that modify this association are less clear. We aimed to study associations between exposure to NOx and the prevalence of atopic diseases in Israeli adolescents using a cross-sectional design. The study population comprised all Israeli-born adolescents whose medical status was evaluated for mandatory military recruitment during 1967–2017 (n = 2,523,745), of whom 5.9% had prevalent asthma. We based the exposure assessments on a land-use regression model and estimated associations using multivariable logistic regression models. Across all periods, mean exposure to NOx from birth to adolescence was associated with prevalent asthma at the examination in a dose-response manner, with an odds ratio for the upper quintile of 1.61 (95% CI: 1.56–1.67), in comparison to the lowest quintile. Associations were stronger in males and in lower socioeconomic strata. We found the strongest associations for asthma with comorbid rhinitis, with an almost twofold increase in the odds of upper versus lower quintile of exposure (odds ratio = 1.96, 95% CI: 1.82–2.11). Rhino-conjunctivitis and allergic atopic dermatitis suggested a possible threshold level with NOx. Capsule Summary: Research indicates that half of the global population will suffer from an allergic condition at some point in life. Childhood exposure to nitrogen oxides is a risk factor for the onset of asthma. The association between exposure and allergic diseases other than asthma is unclear. We demonstrate a strong, dose-response relationship between exposure and a group of allergic outcomes, using data comprising 2.5 million subjects over 50 years. The large health benefits from clean air should motivate governments to prioritize mitigation measures.

Air Pollution and Emergency Department Visits for Disease of the Genitourinary System

The aim of this study is to determine associations between ambient air pollution and the number of emergency department (ED) visits for diseases of the genitourinary tract in Toronto, Canada. We used the National Ambulatory Care Reporting System (NACRS) database to obtain the related ED visits and developed statistical models using daily data on ED visits, temperature, relative humidity, and outdoor air pollution concentration levels. The NACRS database contains data on hospital-based and community-based ambulatory care. The environmental data were retrieved from the National Air Pollution Surveillance (NAPS) program. The NAPS is the main source of ambient air quality data in Canada. We considered 2 air quality health indexes and 6 air pollutants: daily means of fine particulate matter PM_2.5, O₃, CO, NO₂, SO₂, and also maximum 8-hour average ozone. For every air pollutant, we fit 270 models (15 lags × 18 strata). We found that same-day air pollution concentrations have the highest number of statistically significantly positive associations with ED visits for genitourinary health outcomes. A total of 133 positive associations were identified over the 14 days lag. In subgroup (strata) analysis, females older than 60 years of age were found to have the most positive associations. In particular, nitrogen dioxide was found to be highly associated with ED visits for females over 60; an increase in NO₂ was associated with an increased relative risk (RR) of ED visits when lagged over 0, 1, and 2 days (RR = 1.040 [95% confidence interval: 1.028, 1.052], 1.020 [1.009, 1.032], and 1.025 [1.013, 1.036], respectively). The values of risks are reported for a 1 interquartile range increase in concentration (8.8 ppb). Our results suggest that urban ambient air pollution affect the number of ED visits due to genitourinary system conditions.

Exposure to indoor and outdoor air pollution from solid fuel combustion and respiratory outcomes in children in developed countries: a systematic review and meta-analysis

Epidemiological studies have shown a positive association between exposure to outdoor and indoor solid fuel combustion and adverse health effects. We reviewed the epidemiological evidence from Europe, North America, Australia and New Zealand on the association between outdoor and indoor exposure to solid fuel combustion and respiratory outcomes in children. We performed a systematic review and meta-analysis. Pooled relative risks (RRs) and 95% confidence intervals (CI) were calculated using random-effects models. We identified 74 articles. Due to limited evidence on other exposures and outcomes, we performed meta-analyses on the association between indoor wood burning exposure and respiratory outcomes. The RR for the highest vs the lowest category of indoor wood exposure was 0.90 (95% CI 0.77-1.05) considering asthma as an outcome. The corresponding pooled RRs for lower respiratory infection (LRI) and upper respiratory infection (URI) were 1.11 (95% CI 0.88, 1.41) and 1.11 (95% CI 0.85, 1.44) respectively. No association was found between indoor wood burning exposure and risk of wheeze and cough. Inconsistent and limited results were found considering the relationship between indoor wood burning exposure and other respiratory outcomes (rhinitis and hay fever, influenza) as well as indoor coal burning exposure and respiratory outcomes in children. Results from epidemiological studies that evaluated the relationship between the exposure to outdoor emissions derived from indoor combustion of solid fuels are too limited to allow firm conclusions. We found no association between indoor wood burning exposure and risk of asthma. A slight, but not significant, increased risk of LRI and URI was identified, although the available evidence is limited. Epidemiological studies evaluating the relationship between indoor coal burning exposure and respiratory outcomes, as well as, studies considering exposure to outdoor solid fuels, are too limited to draw any firm conclusions.

The Impact of Air Pollution on Outpatient Visits of Children with Asthma in Xi'an, China

INTRODUCTION

The number of children with asthma has increased significantly in China. In recent years, there has been a steady increase in outpatient visits of children with asthma, attributed to poor air quality and environmental pollution reported regionally and at our institution. This study aimed to assess the association between air pollution and the number of outpatient visits of children with asthma in Xi'an, the largest city in northwest China.

METHODS

We searched the database of the largest children's hospital in Xi'an for related information from 2014 to 2018 and then acquired data on air pollution, including the daily average concentrations of fine particles (PM_2.5), inhalable particles (PM₁₀), nitrogen dioxide (NO₂), and sulfur dioxide (SO₂) of that same time period. Time-series generalized additive models were used to analyze the relationships.

RESULTS

Our results revealed that air pollution was very serious in Xi'an, with elevated average concentrations of PM_2.5, PM₁₀, and NO₂ from 2015 to 2018. The relative risk of outpatient visits due to asthma associated with PM_2.5, PM₁₀, and SO₂ pollution rose significantly and reached 1.11 (1.02-1.21), 1.25 (1.01-1.55), and 1.71 (1.31-2.25), respectively, when there was a 10 ug·m^-3 increase in concentration, during a lag of 21 d.

CONCLUSIONS

A high concentration of particulate matter (PM_2.5 and PM₁₀) was the prominent feature of air pollution in Xi'an. Exposure to air pollutant (PM_2.5, PM₁₀, SO₂) was positively associated with an increased risk of children's outpatient visits for asthma in Xi'an.

The Respiratory Risks of Ambient/Outdoor Air Pollution

Globally, exposure to ambient air pollutants is responsible for premature mortality and is implicated in the development and exacerbation of several acute and chronic lung disease across all ages. In this article, we discuss the source apportionment of ambient pollutants and the respiratory health effects in humans. We specifically discuss the evidence supporting ambient pollution in the development of asthma and chronic obstructive pulmonary disease and acute exacerbations of each condition. Practical advice is given to health care providers in how to promote a healthy environment and advise patients with chronic conditions to avoid unsafe air quality.

Impact of Air Pollution on Asthma Outcomes

Asthma is a chronic respiratory disease characterized by variable airflow obstruction, bronchial hyperresponsiveness, and airway inflammation. Evidence suggests that air pollution has a negative impact on asthma outcomes in both adult and pediatric populations. The aim of this review is to summarize the current knowledge on the effect of various outdoor and indoor pollutants on asthma outcomes, their burden on its management, as well as to highlight the measures that could result in improved asthma outcomes. Traffic-related air pollution, nitrogen dioxide and second-hand smoking (SHS) exposures represent significant risk factors for asthma development in children. Nevertheless, a causal relation between air pollution and development of adult asthma is not clearly established. Exposure to outdoor pollutants can induce asthma symptoms, exacerbations and decreases in lung function. Active tobacco smoking is associated with poorer asthma control, while exposure to SHS increases the risk of asthma exacerbations, respiratory symptoms and healthcare utilization. Other indoor pollutants such as heating sources and molds can also negatively impact the course of asthma. Global measures, that aim to reduce exposure to air pollutants, are highly needed in order to improve the outcomes and management of adult and pediatric asthma in addition to the existing guidelines.

School Nurses and Climate Change

Climate change is a serious threat to human health. Nurses recognize vulnerable populations are disproportionately affected by the consequences from climate change, especially the elderly, pregnant women, and children. Children with asthma and chronic health conditions are at the greatest risk for negative health outcomes and are the most important reason for climate advocacy. This descriptive correlational study seeks to assess the knowledge, attitudes, and behaviors of school nurses related to the health impacts of climate change. School nurses are in a unique position to address the health impacts of climate change and become fierce advocates of climate justice because of population they serve. School-age and adolescent students are particularly vulnerable to the consequences climate change, which include poor air quality, increasing temperatures, and increasing pollen counts. School nurses were invited to participate in the study via email and provided information about the Nurses Climate Change Challenge. It was the goal of the study to assess these domains in school nurses' and later develop continuing education to support the care and advocacy of students. The results suggest more continuing education on climate change and climate conscious care is needed for school nurses. The current challenge is not only to be more prepared to treat a greater number of illnesses induced by climate change, it is also to maintain expertise and adapt to a changing environment. Nurses must address the impact of climate change on a local level by making changes in practice and engaging in research so that they are prepared with the knowledge, and skills to offer expertise in environmental health and the care of school-age populations.

Asthma epidemiology and risk factors

Asthma is a clinical syndrome that affects all age groups. Asthma prevalence worldwide has seen a rapid increase in the latter part of the last century. Recent data has shown that asthma prevalence has plateaued and even decreased in some areas of the world, despite continuing to increase in other areas of the world. Many risk factors have been associated with asthma and the differences in distributions of these risk factors may explain the differences in prevalence. This article will review recent trends in the prevalence of asthma and recent studies that investigate risk factors of asthma.

Multi-city study on air pollution and hospital outpatient visits for asthma in China

BACKGROUND

The proportion of asthma patients with mild to moderate exacerbations is far greater than the number who experience episodes that are severe enough to require emergency room visits or hospital admission. However the routinely collected data from hospitals is absent in the past.

OBJECTIVE

To evaluate associations between short-term exposures to air pollutants and hospital outpatient visits for asthma in China.

METHODS

We obtained data for 143,057 asthma outpatient visits from the largest hospitals in 17 Chinese cities, between Jan 01 2013 and Dec 31 2015. We used daily concentrations of air pollutants measured by the China National Environmental Monitoring Centre. We used a time-stratified case-crossover design, and fitted conditional logistic regression models to determine the associations.

RESULTS

Particulate matter ≤10μm in diameter (PM10) and nitrogen dioxide (NO2) were associated with increased risks of hospital outpatient visits for asthma on the same day, while the effects were delayed for particulate matter ≤2.5μm in diameter (PM2.5) and sulphur dioxide (SO2). For the cumulative effect model at lag05 days, 10 μg/m3 increase in air pollutants concentrations were correlated with hospital outpatient visits for asthma with odds ratios (ORs) and 95% confidence intervals 1.004 (1.000-1.008) for PM2.5, 1.005 (1.002-1.008) for PM10, 1.030 (1.021-1.040) for NO2, and 1.015 (1.008-1.021) for SO2. Almost one in nine (10.9%; 7.7, 13.9%) hospital outpatient visits for asthma were attributable to NO2.

CONCLUSION

Short-term exposures to PM2.5, PM10, NO2 and SO2 were associated with hospital outpatient visits for asthma in China.

The "envirome" and what the practitioner needs to know about it

OBJECTIVE

This review on the "envirome" focuses on pollution, microbial, and social stressor elements of the environment that may impact development or expression of allergic diseases.

DATA SOURCES

Peer-reviewed publications on the impact of environmental factors indexed in PubMed were the primary data source for this review.

STUDY SELECTIONS

The primary search strategy for this review employed cross-referencing asthma, atopic dermatitis, and immunoglobulin E (IgE) against pollution (ozone, particulate matter, nitrogen oxides, tobacco smoke), microbial exposures (farm exposure, microbiome, infection, antibiotic use) and psychosocial stressors, with emphasis on results in the past 5 years, with inclusion of key seminal articles or comprehensive reviews.

RESULTS

Air pollution is a clear cause of allergic disease exacerbation, with increasing recognition that pollutant exposure increases risk of allergic disease. Microbial exposures and maternal and child stress also modulate development and expression of allergic disease. Early life exposures are especially critical periods during which all of these factors have notable impacts on allergic disease.

CONCLUSION

Nonallergenic environmental factors are important modulators and adjuvants for development of allergic disease, with early life exposures being especially important. Development and validation of interventions directed toward these factors during early life is a significant opportunity for primary prevention of allergic disease.

Is smaller worse? New insights about associations of PM1 and respiratory health in children and adolescents

BACKGROUND AND OBJECTIVES

Little is known about PM₁ effects on respiratory health, relative to larger size fractions (PM_2.5). To address this literature gap, we assessed associations between PM₁ exposure and asthmatic symptoms in Chinese children and adolescents, compared with PM_2.5.

METHODS

A total of 59,754 children, aged 2-17 years, were recruited from 94 kindergartens, elementary and middle schools in the Seven Northeast Cities (SNEC) study, during 2012-2013. We obtained information on asthma and asthma-related symptoms including wheeze, persistent phlegm, and persistent cough using a standardized questionnaire developed by the American Thoracic Society. PM₁ and PM_2.5 concentrations were estimated using a spatial statistical model matched to the children's geocoded home addresses. To examine the associations, mixed models with school/kindergarten as random intercept were used, controlling for covariates.

RESULTS

Odds ratios (ORs) of doctor-diagnosed asthma associated with a 10-μg/m³ increase for PM₁ and PM_2.5 were 1.56 (95% CI: 1.46-1.66) and 1.50 (1.41-1.59), respectively, and similar pattern were observed for other outcomes. Interaction analyses indicated that boys and the individuals with an allergic predisposition may be vulnerable subgroups. For example, among children with allergic predisposition, the ORs for doctor diagnosed asthma per 10 μg/m³ increase in PM₁ was 1.71 (95% CI: 1.60-1.83), which was stronger than in their counterparts (1.46; 1.37-1.56) (p_{for interaction} < 0.05).

CONCLUSIONS

This study indicated that long-term exposure to PM₁ may increase the risk of asthma and asthma-related symptoms, especially among boys and those with allergic predisposition. Furthermore, these positive associations for PM₁ were very similar to those for PM_2.5.