Impact of London's low emission zone on air quality and children's respiratory health: a sequential annual cross-sectional study

Redox and inflammatory mechanisms linking air pollution particulate matter with cardiometabolic derangements

Air pollution is the largest environmental risk factor for disease and premature death. Among the different components that are present in polluted air, fine particulate matter below 2.5 μm in diameter (PM2.5) has been identified as the main hazardous constituent. PM2.5 mainly arises from fossil fuel combustion during power generation, industrial processes, and transportation. Exposure to PM2.5 correlates with enhanced mortality risk from cardiovascular diseases (CVD), such as myocardial infarction and stroke. Over the last decade, it has been increasingly suggested that PM2.5 affects CVD already at the stage of risk factor development. Among the multiple biological mechanisms that have been described, the interplay between oxidative stress and inflammation has been consistently highlighted as one of the main drivers of pulmonary, systemic, and cardiovascular effects of PM2.5 exposure. In this context, PM2.5 uptake by tissue-resident immune cells in the lung promotes oxidative and inflammatory mediators release that alter tissue homeostasis at remote locations. This pathway is central for PM2.5 pathogenesis and might account for the accelerated development of risk factors for CVD, including obesity and diabetes. However, transmission and end-organ mechanisms that explain PM2.5-induced impaired function in metabolic active organs are not completely understood. In this review, the main features of PM2.5 physicochemical characteristics related to PM2.5 ability to induce oxidative stress and inflammation will be presented. Hallmark and recent epidemiological and interventional studies will be summarized and discussed in the context of current air quality guidelines and legislation, knowledge gaps, and inequities. Lastly, mechanistic studies at the intersection between redox metabolism, inflammation, and function will be discussed, with focus on heart and adipose tissue alterations. By offering an integrated analysis of PM2.5-induced effects on cardiometabolic derangements, this review aims to contribute to a better understanding of the pathogenesis and potential interventions of air pollution-related CVD.

Investigating the impact of London's ultra low emission zone on children's health: children's health in London and Luton (CHILL) protocol for a prospective parallel cohort study

BACKGROUND

Air pollution harms health across the life course. Children are at particular risk of adverse effects during development, which may impact on health in later life. Interventions that improve air quality are urgently needed both to improve public health now, and prevent longer-term increased vulnerability to chronic disease. Low Emission Zones are a public health policy intervention aimed at reducing traffic-derived contributions to urban air pollution, but evidence that they deliver health benefits is lacking. We describe a natural experiment study (CHILL: Children's Health in London and Luton) to evaluate the impacts of the introduction of London's Ultra Low Emission Zone (ULEZ) on children's health.

METHODS

CHILL is a prospective two-arm parallel longitudinal cohort study recruiting children at age 6-9 years from primary schools in Central London (the focus of the first phase of the ULEZ) and Luton (a comparator site), with the primary outcome being the impact of changes in annual air pollutant exposures (nitrogen oxides [NOx], nitrogen dioxide [NO2], particulate matter with a diameter of less than 2.5micrograms [PM2.5], and less than 10 micrograms [PM10]) across the two sites on lung function growth, measured as post-bronchodilator forced expiratory volume in one second (FEV1) over five years. Secondary outcomes include physical activity, cognitive development, mental health, quality of life, health inequalities, and a range of respiratory and health economic data.

DISCUSSION

CHILL's prospective parallel cohort design will enable robust conclusions to be drawn on the effectiveness of the ULEZ at improving air quality and delivering improvements in children's respiratory health. With increasing proportions of the world's population now living in large urban areas exceeding World Health Organisation air pollution limit guidelines, our study findings will have important implications for the design and implementation of Low Emission and Clean Air Zones in the UK, and worldwide.

CLINICALTRIALS

GOV: NCT04695093 (05/01/2021).

"In small places, close to home": Urban environmental impacts on child rights across four global cities

Urban environments influence child behaviours, exposures and experiences and may affect health, development, achievement and realization of fundamental human rights. We examined the status of eleven UN Convention on the Rights of the Child articles, in a multi-case study across four global cities. Within all study cities, children experienced unequal exposure to urban environmental risks and amenities. Many violations of child rights are related to car-based transportation systems and further challenged by pressures on urban systems from rapid population increases in the context of climate change. A child rights framework provides principles for a collective, multi-sectoral re-imagination of urban environments that support the human rights of all citizens.

Air pollution and COPD: GOLD 2023 committee report

Exposure to air pollution is a major contributor to the pathogenesis of COPD worldwide. Indeed, most recent estimates suggest that 50% of the total attributable risk of COPD may be related to air pollution. In response, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) Scientific Committee performed a comprehensive review on this topic, qualitatively synthesised the evidence to date and proffered recommendations to mitigate the risk. The review found that both gaseous and particulate components of air pollution are likely contributors to COPD. There are no absolutely safe levels of ambient air pollution and the relationship between air pollution levels and respiratory events is supra-linear. Wildfires and extreme weather events such as heat waves, which are becoming more common owing to climate change, are major threats to COPD patients and acutely increase their risk of morbidity and mortality. Exposure to air pollution also impairs lung growth in children and as such may lead to developmental COPD. GOLD recommends strong public health policies around the world to reduce ambient air pollution and for implementation of public warning systems and advisories, including where possible the use of personalised apps, to alert patients when ambient air pollution levels exceed acceptable minimal thresholds. When household particulate content exceeds acceptable thresholds, patients should consider using air cleaners and filters where feasible. Air pollution is a major health threat to patients living with COPD and actions are urgently required to reduce the morbidity and mortality related to poor air quality around the world.

A natural experiment to assess how urban interventions in lower socioeconomic areas influence health behaviors: the UrbASanté study

BACKGROUND

Mechanisms underlying the associations between changes in the urban environment and changes in health-related outcomes are complex and their study requires specific approaches. We describe the protocol of the interdisciplinary UrbASanté study, which aims to explore how urban interventions can modify environmental exposures (built, social, and food environments; air quality; noise), health-related behaviors, and self-reported health using a natural experiment approach.

METHODS

The study is based on a natural experiment design using a before/after protocol with a control group to assess changes in environmental exposures, health-risk behaviors, and self-reported health outcomes of a resident adult population before and after the implementation of a time series of urban interventions in four contiguous neighborhoods in Paris (France). The changes in environmental exposures, health-related behaviors, and self-reported health outcomes of a resident adult population will be concurrently monitored in both intervention and control areas. We will develop a mixed-method framework combining substantial fieldwork with quantitative and qualitative analytical approaches. This study will make use of (i) data relating to exposures and health-related outcomes among all participants and in subsamples and (ii) interviews with residents regarding their perceptions of their neighborhoods and with key stakeholders regarding the urban change processing, and (iii) existing geodatabases and field observations to characterize the built, social, and food environments. The data collected will be analyzed with a focus on interrelationships between environmental exposures and health-related outcomes using appropriate approaches (e.g., interrupted time series, difference-in-differences method).

DISCUSSION

Relying on a natural experiment approach, the research will provide new insights regarding issues such as close collaboration with urban/local stakeholders, recruitment and follow-up of participants, identification of control and intervention areas, timing of the planned urban interventions, and comparison of subjective and objective measurements. Through the collaborative work of a consortium ensuring complementarity between researchers from different disciplines and stakeholders, the UrbASanté study will provide evidence-based guidance for designing future urban planning and public health policies.

TRIAL REGISTRATION

This research was registered at the ClinicalTrial.gov (NCT05743257).

Incorporating Health Cobenefits into Province-Driven Climate Policy: A Case of Banning New Internal Combustion Engine Vehicle Sales in China

Incorporating health cobenefits from coabated air pollution into carbon mitigation policy making is particularly important for developing countries to boost policy efficiency. For sectors that highly depend on electrification for decarbonization, it remains unclear how the increased electricity demand and consequent health impacts from sectoral mitigation policy in one province would change the scale and the regional and sectoral distributions of the overall health impacts in the whole country. This study chooses the banning of new sales of internal combustion engine vehicles in the private vehicle sector in China as a case. The results show that, without carbon neutrality and air pollution control goals in electricity generation, 53% of CO2 reduction and 65% of health benefits from the private vehicle sector would be offset by increased electricity demand. The regional distributions of CO2 reduction and health benefits due to a province-driven ban policy are greatly uneven, as the top five provinces take up over one-third of the total impact in China. Health benefits per ton of carbon reduction (H/C) may vary by up to 8 times across provinces. Finally, the provinces in southeast China and the Sichuan Basin, with their stably high H/C values, are suggested to enact the province-driven ban policy first.

Study Protocol. Evaluating the life-course health impact of a city-wide system approach to improve air quality in Bradford, UK: A quasi-experimental study with implementation and process evaluation

BACKGROUND

Air quality is a major public health threat linked to poor birth outcomes, respiratory and cardiovascular disease, and premature mortality. Deprived groups and children are disproportionately affected. Bradford will implement a Clean Air Zone (CAZ) as part of the Bradford Clean Air Plan (B-CAP) in 2022 to reduce pollution, providing a natural experiment. The aim of the current study is to evaluate the impact of the B-CAP on health outcomes and air quality, inequalities and explore value for money. An embedded process and implementation evaluation will also explore barriers and facilitators to implementation, impact on attitudes and behaviours, and any adverse consequences.

METHODS

The study is split into 4 work packages (WP). WP1A: 20 interviews with decision makers, 20 interviews with key stakeholders; 10 public focus groups and documentary analysis of key reports will assess implementation barriers, acceptability and adverse or unanticipated consequences at 1 year post-implementation (defined as point at which charging CAZ goes 'live'). WP1B: A population survey (n = 2000) will assess travel behaviour and attitudes at baseline and change at 1 year post-implementation). WP2: Routine air quality measurements will be supplemented with data from mobile pollution sensors in 12 schools collected by N = 240 pupil citizen scientists (4 within, 4 bordering and 4 distal to CAZ boundary). Pupils will carry sensors over four monitoring periods over a 12 month period (two pre, and two post-implementation). We will explore whether reductions in pollution vary by CAZ proximity. WP3A: We will conduct a quasi-experimental interrupted time series analysis using a longitudinal routine health dataset of > 530,000 Bradford residents comparing trends (3 years prior vs 3 years post) in respiratory health (assessed via emergency/GP attendances. WP3B: We will use the richly-characterised Born in Bradford cohort (13,500 children) to explore health inequalities in respiratory health using detailed socio-economic data. WP4: will entail a multi-sectoral health economic evaluation to determine value for money of the B-CAP.

DISCUSSION

This will be first comprehensive quasi-experimental evaluation of a city-wide policy intervention to improve air quality. The findings will be of value for other areas implementing this type of approach.

TRIAL REGISTRATION

ISRCTN67530835 https://doi.org/10.1186/ISRCTN67530835.

Shifting towards healthier transport: carrots or sticks? Systematic review and meta-analysis of population-level interventions

BACKGROUND

Promoting active travel can be beneficial for both health and the environment. However, evidence about the most effective strategies is inconsistent. We aimed to compare the effectiveness of interventions with positive (ie, carrot), negative (ie, stick), or a combination of strategies on changing population-level travel behaviour. We also aimed to identify which intervention functions, or mechanisms of how interventions seek to alter behaviour (eg, by addressing safety or accessibility), affect transport outcomes.

METHODS

For this systematic review and meta-analysis, we searched eight online databases for studies published before March 28, 2022: Web of Science, MEDLINE, Scopus, Applied Social Sciences Index and Abstracts, Global Health, PsycINFO, CINAHL, and Transport Research International Documentation. We did not restrict searches by language or publication date. We included controlled before-and-after studies of population-level interventions and travel behaviours (ie, driving, public transport, walking, and cycling) from adults in the general population. We categorised interventions according to their function. Depending on whether gains or losses due to intervention function could occur, we classified interventions as carrot (eg, new bike-share programmes), stick (eg, congestion charging), or combined carrot-and-stick interventions (eg, pedestrianising areas by use of reallocated parking space). We used harvest plots to summarise the findings and guide narrative synthesis. Where possible, we converted outcomes into standardised mean differences and did random-effects meta-analyses.

FINDINGS

From 38 916 records screened, 102 reports describing 121 interventions met the inclusion criteria. 79 interventions were carrots, 22 were carrot-and-sticks, and 20 were sticks. Results for carrot interventions were less consistent than for stick or combined interventions. Findings from the meta-analysis (64 reports describing 67 interventions) agreed with those in the narrative synthesis; although effects were statistically non-significant, for driving outcomes, interventions with stick strategies (standardised mean difference [SMD] -0·17, 95% CI -0·36 to 0·02) and combined carrot-and-stick strategies (-0·13, -0·47 to 0·20) had point estimates of greater magnitude than those for interventions with carrot strategies (-0·10, -0·23 to 0·03). Likewise, for active travel outcomes, combined carrot-and-stick strategies had a higher point estimate (0·33, -0·01 to 0·68) compared with carrot interventions (0·08, -0·05 to 0·21). Functions thought to change behaviour using financial means were effective at decreasing driving behaviour, whereas those improving access, safety, and space were effective for increasing active travel outcomes.

INTERPRETATION

This Article found that, although transport interventions with only positive strategies are more commonly evaluated, interventions that combine both positive and negative strategies might be more effective at encouraging alternatives to driving at the population level. Further research is needed for interventions involving a stick strategy, which remain less widely implemented or well studied than those with only carrot strategies.

FUNDING

Medical Research Council, Cambridge Trust.

Towards healthy school neighbourhoods: A baseline analysis in Greater London

Creating healthy environments around schools is important to promote healthy childhood development and is a critical component of public health. In this paper we present a tool to characterize exposure to multiple urban environment features within 400 m (5-10 min walking distance) of schools in Greater London. We modelled joint exposure to air pollution (NO₂ and PM_2.5), access to public greenspace, food environment, and road safety for 2,929 schools, employing a Bayesian non-parametric approach based on the Dirichlet Process Mixture modelling. We identified 12 latent clusters of schools with similar exposure profiles and observed some spatial clustering patterns. Socioeconomic and ethnicity disparities were manifested with respect to exposure profiles. Specifically, three clusters (containing 645 schools) showed the highest joint exposure to air pollution, poor food environment, and unsafe roads and were characterized with high deprivation. The neighbourhood of the most deprived cluster of schools had a median of 2.5 ha greenspace, 29.0 µg/m³ of NO₂, 19.3 µg/m³ of PM_2.5, 20 fast food retailers, and five child pedestrian crashes over a three-year period. The neighbourhood of the least deprived cluster of schools had a median of 21.8 ha greenspace, 15.6 µg/m³ of NO₂, 15.1 µg/m³ of PM_2.5, 2 fast food retailers, and one child pedestrian crash over a three-year period. To have a school-level understanding of exposure levels, we then benchmarked schools based on the probability of exceeding the median exposure to various features of interest. Our study accounts for multiple exposures, enabling us to highlight spatial distribution of exposure profile clusters, and to identify predominant exposure to urban environment features for each cluster of schools. Our findings can help relevant stakeholders, such as schools and public health authorities, to compare schools based on their exposure levels, prioritize interventions, and design local policies that target the schools most in need.

A longitudinal analysis of PM2.5 exposure and multimorbidity clusters and accumulation among adults aged 45-85 in China

While previous studies have emphasised the role of individual factors in understanding multimorbidity disparities, few have investigated contextual factors such as air pollution (AP). We first use cross-sectional latent class analysis (LCA) to assess the associations between PM2.5 exposure and multimorbidity disease clusters, and then estimate the associations between PM2.5 exposure and the development of multimorbidity longitudinally using growth curve modelling (GCM) among adults aged 45-85 in China. The results of LCA modelling suggest four latent classes representing three multimorbidity patterns (respiratory, musculoskeletal, cardio-metabolic) and one healthy pattern. The analysis shows that a 1 μg/m3 increase in cumulative exposure to PM2.5 is associated with a higher likelihood of belonging to respiratory, musculoskeletal or cardio-metabolic clusters: 2.4% (95% CI: 1.02, 1.03), 1.5% (95% CI: 1.01, 1.02) and 3.3% (95% CI: 1.03, 1.04), respectively. The GCM models show that there is a u-shaped association between PM2.5 exposure and multimorbidity, indicating that both lower and higher PM2.5 exposure is associated with increased multimorbidity levels. Higher multimorbidity in areas of low AP is explained by clustering of musculoskeletal diseases, whereas higher AP is associated with cardio-metabolic disease clusters. The study shows how multimorbidity clusters vary contextually and that PM2.5 exposure is more detrimental to health among older adults.

Short-term effects of air pollutants on hospital admissions for acute bronchitis in children: a multi-city time-series study in Southwest China

BACKGROUND

Few studies have investigated the effects of air pollutants on children with acute bronchitis. This study aimed to explore the acute effects of four air pollutants [fine particulate matter (PM_2.5), inhalable particulate matter (PM₁₀), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂)] on the daily number of children admitted to the hospital for acute bronchitis in Sichuan Province, China.

METHODS

The 49,975 records of hospitalized children with acute bronchitis from medical institutions in nine cities/prefectures, Sichuan Province, China, as well as the simultaneous meteorological data and air pollution data from 183 monitoring sites, were collected from 1 January 2017 to 31 December 2018. A generalized additive model was adopted to analyze the exposure-response and lag effects of hospitalizations of children with acute bronchitis to air pollutants. Stratified analyses were conducted based on sex, age, and season.

RESULTS

The single-pollutant model showed that a 10 µg/m³ increase at lag07 of PM_2.5, PM₁₀, SO₂, and NO₂ corresponded to an increase of 1.23% [95% confidence interval (CI) 0.21-2.26%], 1.33% (95% CI 0.62-2.05%), 23.52% (95% CI 11.52-36.81%), and 12.47% (95% CI 8.46-16.64%) in daily hospitalizations for children with acute bronchitis, respectively. Children aged 0-2 were more prone to PM_2.5 (P < 0.05). Interestingly, the effects were stronger in the warm season than in transition seasons and the cool season for PM_2.5 and PM₁₀ (P < 0.05).

CONCLUSION

The higher daily average concentrations of four pollutants in Sichuan Province can result in an increased number of children hospitalized for acute bronchitis.

The Exposure of Workers at a Busy Road Node to PM2.5: Occupational Risk Characterisation and Mitigation Measures

The link between air pollution and health burden in urban areas has been well researched. This has led to a plethora of effective policy-induced monitoring and interventions in the global south. However, the implication of pollutant species like PM_2.5 in low middle income countries (LMIC) still remains a concern. By adopting a positivist philosophy and deductive reasoning, this research addresses the question, to what extent can we deliver effective interventions to improve air quality at a building structure located at a busy road node in a LMIC? This study assessed the temporal variability of pollutants around the university environment to provide a novel comparative evaluation of occupational shift patterns and the use of facemasks as risk control interventions. The findings indicate that the concentration of PM_2.5, which can be as high as 300% compared to the WHO reference, was exacerbated by episodic events. With a notable decay period of approximately one-week, adequate protection and/or avoidance of hotspots are required for at-risk individuals within a busy road node. The use of masks with 80% efficiency provides sufficient mitigation against exposure risks to elevated PM_2.5 concentrations without occupational shift, and 50% efficiency with at least ‘2 h ON, 2 h OFF’ occupational shift scenario.

Exposure and dose assessment of school children to air pollutants in a tropical coastal-urban area

This study estimates exposure and inhaled dose to air pollutants of children residing in a tropical coastal-urban area in Southeast Brazil. For that, twenty-one children filled their time-activities diaries and wore the passive samplers to monitor NO₂. The personal exposure was also estimated using data provided by the combination of WRF-Urban/GEOS-Chem/CMAQ models, and the nearby monitoring station. Indoor/outdoor ratios were used to consider the amount of time spent indoors by children in homes and schools. The model's performance was assessed by comparing the modelled data with concentrations measured by urban monitoring stations. A sensitivity analyses was also performed to evaluate the impact of the model's height on the air pollutant concentrations. The results showed that the mean children's personal exposure to NO₂ predicted by the model (22.3 μg/m³) was nearly twice to those measured by the passive samplers (12.3 μg/m³). In contrast, the nearest urban monitoring station did not represent the personal exposure to NO₂ (9.3 μg/m³), suggesting a bias in the quantification of previous epidemiological studies. The building effect parameterisation (BEP) together with the lowering of the model height enhanced the air pollutant concentrations and the exposure of children to air pollutants. With the use of the CMAQ model, exposure to O₃, PM₁₀, PM_2.5, and PM₁ was also estimated and revealed that the daily children's personal exposure was 13.4, 38.9, 32.9, and 9.6 μg/m³, respectively. Meanwhile, the potential inhalation daily dose was 570-667 μg for PM_2.5, 684-789 μg for PM₁₀, and 163-194 μg for PM₁, showing to be favourable to cause adverse health effects. The exposure of children to air pollutants estimated by the numerical model in this work was comparable to other studies found in the literature, showing one of the advantages of using the modelling approach since some air pollutants are poorly spatially represented and/or are not routinely monitored by environmental agencies in many regions.

School neighbourhood and compliance with WHO-recommended annual NO2 guideline: A case study of Greater London

Despite several national and local policies towards cleaner air in England, many schools in London breach the WHO-recommended concentrations of air pollutants such as NO₂ and PM_2.5. This is while, previous studies highlight significant adverse health effects of air pollutants on children's health. In this paper we adopted a Bayesian spatial hierarchical model to investigate factors that affect the odds of schools exceeding the WHO-recommended concentration of NO₂ (i.e., 40 μg/m³ annual mean) in Greater London (UK). We considered a host of variables including schools' characteristics as well as their neighbourhoods' attributes from household, socioeconomic, transport-related, land use, built and natural environment characteristics perspectives. The results indicated that transport-related factors including the number of traffic lights and bus stops in the immediate vicinity of schools, and borough-level bus fuel consumption are determinant factors that increase the likelihood of non-compliance with the WHO guideline. In contrast, distance from roads, river transport, and underground stations, vehicle speed (an indicator of traffic congestion), the proportion of borough-level green space, and the area of green space at schools reduce the likelihood of exceeding the WHO recommended concentration of NO₂. We repeated our analysis under a hypothetical scenario in which the recommended concentration of NO₂ is 35 μg/m³ - instead of 40 μg/m³. Our results underscore the importance of adopting clean fuel technologies on buses, installing green barriers, and reducing motorised traffic around schools in reducing exposure to NO₂ concentrations in proximity to schools. Also, our findings highlight the presence of environmental inequalities in the Greater London area. This study would be useful for local authority decision making with the aim of improving air quality for school-aged children in urban settings.

Methods for Evaluating Environmental Health Impacts at Different Stages of the Policy Process in Cities

PURPOSE OF REVIEW

Evaluating the environmental health impacts of urban policies is critical for developing and implementing policies that lead to more healthy and equitable cities. This article aims to (1) identify research questions commonly used when evaluating the health impacts of urban policies at different stages of the policy process, (2) describe commonly used methods, and (3) discuss challenges, opportunities, and future directions.

RECENT FINDINGS

In the diagnosis and design stages of the policy process, research questions aim to characterize environmental problems affecting human health and to estimate the potential impacts of new policies. Simulation methods using existing exposure-response information to estimate health impacts predominate at these stages of the policy process. In subsequent stages, e.g., during implementation, research questions aim to understand the actual policy impacts. Simulation methods or observational methods, which rely on experimental data gathered in the study area to assess the effectiveness of the policy, can be applied at these stages. Increasingly, novel techniques fuse both simulation and observational methods to enhance the robustness of impact evaluations assessing implemented policies. The policy process consists of interdependent stages, from inception to end, but most reviewed studies focus on single stages, neglecting the continuity of the policy life cycle. Studies assessing the health impacts of policies using a multi-stage approach are lacking. Most studies investigate intended impacts of policies; focusing also on unintended impacts may provide a more comprehensive evaluation of policies.

Childhood asthma- pathogenesis and phenotypes

In the pathogenesis of asthma in children there is a pivotal role for a type 2 inflammatory response to early life exposures or events. Interactions between infections, atopy, genetic susceptibility, and environmental exposures (such as farmyard environment, air pollution, tobacco smoke exposure) influence the development of wheezing illness and the risk for progression to asthma. The immune system, lung function and the microbiome in gut and airways develop in parallel and dysbiosis of the microbiome may be a critical factor in asthma development. Increased infant weight gain and preterm birth are other risk factors for development of asthma and reduced lung function. The complex interplay between these factors explains the heterogeneity of asthma in children. Subgroups of patients can be identified as phenotypes based on clinical parameters, or endotypes, based on a specific pathophysiological mechanism. Paediatric asthma phenotypes and endotypes may ultimately help to improve diagnosis of asthma, prediction of asthma development and treatment of individual children, based on clinical, temporal, developmental or inflammatory characteristics. Unbiased, data-driven clustering, using a multidimensional or systems biology approach may be needed to better define phenotypes. The present knowledge on inflammatory phenotypes of childhood asthma has now been successfully applied in the treatment with biologicals of children with severe therapy resistant asthma, and it is to be expected that more personalized treatment options may become available.

"I am an air quality scientist"- Using citizen science to characterise school children's exposure to air pollution

Children are particularly vulnerable to the harmful effects of air pollution. To tackle this issue and implement effective strategies to reduce child exposure, it is important to understand how children are exposed to this risk. This study followed a citizen science approach to air pollution monitoring, aiming to characterise school children's exposure to air pollution and to analyse how a citizen science approach to data collection could contribute to and enhance the research process. 258 children across five London primary schools attended air pollution education sessions and measured air pollution for a week using backpacks with built-in air quality sensors. Children received a summary of the results, advice and information on how to reduce exposure to air pollution. Data on the impact of the approach on the school community were collected using surveys and focus groups with children and their parents and interviews with the teachers involved. The unique data set obtained permitted us to map different routes and modes of transport used by the children and quantify different exposure levels. We identified that, on average, children were exposed to higher levels of air pollution when travelling to and from school, particularly during the morning journey where air pollution levels were on average 52% higher than exposures at school. Children who walked to and from school through busy main roads were exposed to 33% higher levels of air pollution than those who travelled through back streets. The findings from this study showed that using a citizen science approach to data collection, where children are actively involved in the research process, not only facilitated the gathering of a large data set by encouraging participation and stimulating adherence with the study protocol, but also increased children's awareness of air pollution, encouraging them to adopt positive behaviour changes to reduce their exposure.

Mental health consequences of urban air pollution: prospective population-based longitudinal survey

PURPOSE

The World Health Organisation (WHO) recently ranked air pollution as the major environmental cause of premature death. However, the significant potential health and societal costs of poor mental health in relation to air quality are not represented in the WHO report due to limited evidence. We aimed to test the hypothesis that long-term exposure to air pollution is associated with poor mental health.

METHODS

A prospective longitudinal population-based mental health survey was conducted of 1698 adults living in 1075 households in South East London, from 2008 to 2013. High-resolution quarterly average air pollution concentrations of nitrogen dioxide (NO2) and oxides (NOx), ozone (O3), particulate matter with an aerodynamic diameter < 10 μm (PM10) and < 2.5 μm (PM2.5) were linked to the home addresses of the study participants. Associations with mental health were analysed with the use of multilevel generalised linear models, after adjusting for large number of confounders, including the individuals' socioeconomic position and exposure to road-traffic noise.

RESULTS

We found robust evidence for interquartile range increases in PM2.5, NOx and NO2 to be associated with 18-39% increased odds of common mental disorders, 19-30% increased odds of poor physical symptoms and 33% of psychotic experiences only for PM10. These longitudinal associations were more pronounced in the subset of non-movers for NO2 and NOx.

CONCLUSIONS

The findings suggest that traffic-related air pollution is adversely affecting mental health. Whilst causation cannot be proved, this work suggests substantial morbidity from mental disorders could be avoided with improved air quality.

Allergic rhinitis aggravated by air pollutants in Latin America: A systematic review

The aim of this systematic review (SR) was to evaluate the most frequent pollutants and their effect on allergic rhinitis in Latin American countries. Observational studies up to December 2020 and comparing different indoor and outdoor pollutants that had allergic rhinitis (AR) as an outcome were included in the systematic review. Random-effect meta-analyses were conducted for the presence of allergic rhinitis. Estimates were presented as pooled odds ratios (ORs) and their respective 95% confidence intervals (CIs). Twenty-two publications comprised this review according to the inclusion and exclusion criteria and 12 had data that could be analyzed statistically. The most frequent pollutant was PM10, followed by NO2 /O3 and PM2.5 in studies conducted in Argentina, Brazil, Bolivia, Chile, Colombia, Costa Rica, and Peru. The OR of an exposed subject experiencing allergic rhinitis was 1.43 (95% CI 1.026; 1.980). The OR of children and adolescents experiencing of allergic rhinitis was 1.359 (95% CI 1.051; 1.759). Asymmetry and great variability in the effect estimated from the selected studies were observed. The publication bias was quantified by Kendall's correlation and Egger's test resulted in 0.152 (p-value = 0.493). Egger's test provided an intercept equal to 2.511 and a p-value = 0.398. The I2 statistic was 89.3% and reinforces the hypothesis of heterogeneity. This first systematic review conducted in Latin America confirmed the chance of a person exposed to pollutants and experiencing allergic rhinitis is 43% greater than that of a non-exposed person, reinforcing the importance of policies to reduce pollutant exposure and the use of protection systems for workforces exposed to occupational pollutants in work environments.

Air pollution and lung function in children

In this narrative review, we summarize the literature and provide updates on recent studies of air pollution exposures and child lung function and lung function growth. We include exposures to outdoor air pollutants that are monitored and regulated through air quality standards, and air pollutants that are not routinely monitored or directly regulated, including wildfires, indoor biomass and coal burning, gas and wood stove use, and volatile organic compounds. Included is a more systematic review of the recent literature on long-term air pollution and child lung function because this is an indicator of future adult respiratory health and exposure assessment tools have improved dramatically in recent years. We present "summary observations" and "knowledge gaps." We end by discussing what is known about what can be done at the individual/household, local/regional, and national levels to overcome structural impediments, reduce air pollution exposures, and improve child lung function. We found a large literature on adverse air pollution effects on children's lung function level and growth; however, many questions remain. Important areas needing further research include whether early-life effects are fixed or reversible; and what are windows of increased susceptibility, long-term effects of repeated wildfire events, and effects of air quality interventions.

A review of strategies for mitigating roadside air pollution in urban street canyons

Urban street canyons formed by high-rise buildings restrict the dispersion of vehicle emissions, which pose severe health risks to the public by aggravating roadside air quality. However, this issue is often overlooked in city planning. This paper reviews the mechanisms controlling vehicle emission dispersion in urban street canyons and the strategies for managing roadside air pollution. Studies have shown that air pollution hotspots are not all attributed to heavy traffic and proper urban design can mitigate air pollution. The key factors include traffic conditions, canyon geometry, weather conditions and chemical reactions. Two categories of mitigation strategies are identified, namely traffic interventions and city planning. Popular traffic interventions for street canyons include low emission zones and congestion charges which can moderately improve roadside air quality. In comparison, city planning in terms of building geometry can significantly promote pollutant dispersion in street canyons. General design guidelines, such as lower canyon aspect ratio, alignment between streets and prevailing winds, non-uniform building heights and ground-level building porosity, may be encompassed in new development. Concurrently, in-street barriers are widely applicable to rectify the poor roadside air quality in existing street canyons. They are broadly classified into porous (e.g. trees and hedges) and solid (e.g. kerbside parked cars, noise fences and viaducts) barriers that utilize their aerodynamic advantages to ease roadside air pollution. Post-evaluations are needed to review these strategies by real-world field experiments and more detailed modelling in the practical perspective.

Real-World Contribution of Electrification and Replacement Scenarios to the Fleet Emissions in West Midland Boroughs, UK

This study reports the likely real-world effects of fleet replacement with electric vehicles (EVs) and higher efficiency EURO 6 vehicles on the exhaustive emissions of NOx, PM, and CO2 in the seven boroughs of the West Midlands (WM) region, UK. National fleet composition data, local EURO distributions, and traffic compositions were used to project vehicle fleet compositions for different roads in each borough. A large dataset of real-world emission factors including over 90,000 remote-sensing measurements, obtained from remote sensing campaigns in five UK cities, was used to parameterize the emission profiles of the studied scenarios. Results show that adoption of the fleet electrification approach would have the highest emission reduction potential on urban roads in WM boroughs. It would result in maximum reductions ranging from 35.0 to 37.9%, 44.3 to 48.3%, and 46.9 to 50.3% for NOx, PM, and CO2, respectively. In comparison, the EURO 6 replacement fleet scenario would lead to reductions ranging from 10.0 to 10.4%, 4.0 to 4.2%, and 6.0 to 6.4% for NOx, PM, and CO2, respectively. The studied mitigation scenarios have higher efficacies on motorways compared to rural and urban roads because of the differences in traffic fleet composition. The findings presented will help policymakers choose climate and air quality mitigation strategies.

Air pollution and indoor settings

Indoor environments contribute significantly to total human exposure to air pollutants, as people spend most of their time indoors. Household air pollution (HAP) resulting from cooking with polluting ("dirty") fuels, which include coal, kerosene, and biomass (wood, charcoal, crop residues, and animal manure) is a global environmental health problem. Indoor pollutants are gases, particulates, toxins, and microorganisms among others, that can have an impact especially on the health of children and adults through a combination of different mechanisms on oxidative stress and gene activation, epigenetic, cellular, and immunological systems. Air pollution is a major risk factor and contributor to morbidity and mortality from major chronic diseases. Children are significantly affected by the impact of the environment due to biological immaturity, prenatal and postnatal lung development. Poor air quality has been related to an increased prevalence of clinical manifestations of allergic asthma and rhinitis. Health professionals should increase their role in managing the exposure of children and adults to air pollution with better methods of care, prevention, and collective action. Interventions to reduce household pollutants may promote health and can be achieved with education, community, and health professional involvement.

Air Pollution and Asthma: Critical Targets for Effective Action

Evidence to advocate for cleaner air for people with asthma is not in short supply. We know that air pollution is associated with the development and worsening of the condition and that mitigating interventions can improve respiratory outcomes. We have clear targets, particularly traffic emissions, especially in urban areas, and plenty of potentially effective actions. Road traffic must be reduced, and what remains should be cleaner and greener. Urban green spaces, safe cycle networks and wider pavements will promote active travel and leisure time exercise. Healthcare professionals must ensure people are aware of their air quality, its impact on asthma and the appropriate behaviour to safeguard health. What remains are realistic policies and effective measures, based on the correct scientific evidence, to be taken forth with political courage and investment so that air pollution no longer contributes to the development or worsening of respiratory ill health.

Air Pollution and Asthma: Mechanisms of Harm and Considerations for Clinical Interventions

There is global concern regarding the harmful impact of polluted air on the respiratory health of patients with asthma. Multiple epidemiologic studies have shown ongoing associations between high levels of air pollution and poor early life lung growth, development of allergic sensitization, development of asthma, airway inflammation, acutely impaired lung function, respiratory tract infections, and asthma exacerbations. However, studies have often yielded inconsistent findings, and not all studies have found significant associations; this may be related to both variations in statistical, measurement, and modeling methodologies between studies as well as differences in the concentrations and composition of air pollution globally. Overall, this variation in findings suggests we still do not fully understand the effects of ambient pollution on the lungs and on the evolution and exacerbation of airway diseases. There is clearly a need to augment epidemiologic studies with experimental studies to clarify the underlying mechanistic basis for the adverse responses reported and to identify the key gaseous and particle-related components within the complex air pollution mixture driving these outcomes. Some progress toward these aims has been made. This article reviews studies providing an improved understanding of causal pathways linking air pollution to asthma development and exacerbation. The article also considers potential strategies to reduce asthma morbidity and mortality through regulation and behavioral/pharmacologic interventions, including a consideration of pollutant avoidance strategies and antioxidant and/or vitamin D supplementation.

Focus on asthma 2: air pollution and its effects on children and young people

This article is the second in a series on asthma. The first article identified that the UK is experiencing an 'epidemic' of childhood asthma and one of the major culprits is air pollution. This article examines the main causes of air pollution and how they affect the lung health of children from before birth and onwards. It considers the contribution of indoor and outdoor air pollution, how these have changed over time and the unequal effect they may have on vulnerable populations. The nurse's role is discussed, not only in terms of clinical care, but also as adviser to families and schools on what actions to take to limit their exposure and reduce their own emissions of pollutants.

Prenatal, Early-Life, and Childhood Exposure to Air Pollution and Lung Function: The ALSPAC Cohort

Rationale: Exposure to air pollution during intrauterine development and through childhood may have lasting effects on respiratory health.Objectives: To investigate lung function at ages 8 and 15 years in relation to air pollution exposures during pregnancy, infancy, and childhood in a UK population-based birth cohort.Methods: Individual exposures to source-specific particulate matter ≤10 μm in aerodynamic diameter (PM₁₀) during each trimester, 0-6 months, 7-12 months (1990-1993), and up to age 15 years (1991-2008) were examined in relation to FEV₁% predicted and FVC% predicted at ages 8 (n = 5,276) and 15 (n = 3,446) years using linear regression models adjusted for potential confounders. A profile regression model was used to identify sensitive time periods.Measurements and Main Results: We did not find clear evidence of a sensitive exposure period for PM₁₀ from road traffic. At age 8 years, 1 μg/m³ higher exposure during the first trimester was associated with lower FEV₁% predicted (-0.826; 95% confidence interval [CI], -1.357 to -0.296) and FVC% predicted (-0.817; 95% CI, -1.357 to -0.276), but similar associations were seen for exposures for other trimesters, 0-6 months, 7-12 months, and 0-7 years. Associations were stronger among boys, as well as children whose mother had a lower education level or smoked during pregnancy. For PM₁₀ from all sources, the third trimester was associated with lower FVC% predicted (-1.312; 95% CI, -2.100 to -0.525). At age 15 years, no adverse associations with lung function were seen.Conclusions: Exposure to road-traffic PM₁₀ during pregnancy may result in small but significant reductions in lung function at age 8 years.

Air pollution and its effects on the immune system

A well-functioning immune system is vital for a healthy body. Inadequate and excessive immune responses underlie diverse pathologies such as serious infections, metastatic malignancies and auto-immune conditions. Therefore, understanding the effects of ambient pollutants on the immune system is vital to understanding how pollution causes disease, and how that pathology could be abrogated. The immune system itself consists of multiple types of immune cell that act together to generate (or fail to generate) immune responses and in this article we review evidence of how air pollutants can affect different immune cell types such as particle-clearing macrophages, inflammatory neutrophils, dendritic cells that orchestrate adaptive immune responses and lymphocytes that enact those responses. Common themes that emerge are of the capacity of air pollutants to stimulate pro-inflammatory immune responses across multiple classes of immune cell. Air pollution can enhance T helper lymphocyte type 2 (Th2) and T helper lymphocyte type 17 (Th17) adaptive immune responses, as seen in allergy and asthma, and dysregulate anti-viral immune responses. The clinical effects of air pollution, in particular the known association between elevated ambient pollution and exacerbations of asthma and chronic obstructive pulmonary disease (COPD), are consistent with these identified immunological mechanisms. Further to this, as inhaled air pollution deposits primarily on the respiratory mucosa this review focuses on mechanisms of respiratory disease. However, as discussed in the article, air pollution also affects the wider immune system for example in the neonate and gastrointestinal tract. Whilst the many identified actions of air pollution on the immune system are notably diverse, immunological research does suggest potential strategies to ameliorate such effects, for example with vitamin D supplementation. An in-depth understanding of the immunological effects of ambient pollutants should hopefully yield new ideas on how to reduce the adverse health effects of air pollution.

Associations between ambient air pollution and daily incidence of pediatric hand, foot and mouth disease in Ningbo, 2014-2016: a distributed lag nonlinear model

Hand, foot and mouth disease (HFMD) has high prevalence around the world, with serious consequences for children. Due to the long survival period of HFMD virus in ambient air, air pollutants may play a critical role in HFMD epidemics. We collected data on daily cases of HFMD among children aged 0–14 years in Ningbo City between 2014 and 2016. Distributed lag nonlinear models were used to assess the effects of particulate matter (PM_2.5), sulphur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃) on the daily incidence of HFMD among children, with analyses stratified by gender and age. Compared with moderate levels of air pollution, high SO₂ levels had a relative risk (RR) of 2.32 (95% CI 1.42–3.79) and high NO₂ levels had a RR of 2.01 (95% CI 1.22–3.31). The RR of O₃ was 2.12 (95% CI 1.47–3.05) and that of PM_2.5 was 0.77 (95% CI 0.64–0.92) at moderate levels of air pollution. Specifically, high levels of SO₂ and NO₂ had RRs of 2.39 (95% CI 1.44–3.96) and 2.02 (95% CI 1.21–3.39), respectively, among 0–4-year-old children, while high O₃ had an RR of 2.31 (95% CI 1.09–4.89) among 5–14-year-old children. Our findings suggest significant associations of high SO₂ and NO₂ levels and moderate O₃ levels in HFMD epidemics, and also indicate that air pollution causes lagged effects on HFMD epidemics. Our study provides practical and useful data for targeted prevention and control of HMFD based on environmental evidence.

Improving air quality needs to be a policy priority for governments globally

In this Perspective, Aziz Sheikh discusses the importance of research to understand the impact of air pollution on human health, commenting on a study by Yaohua Tian and colleagues that examined associations between ambient air quality and risk of hospitalization for pneumonia in adults in China.

School environment associates with lung function and autonomic nervous system activity in children: a cross-sectional study

Children are in contact with local environments, which may affect respiratory symptoms and allergic sensitization. We aimed to assess the effect of the environment and the walkability surrounding schools on lung function, airway inflammation and autonomic nervous system activity. Data on 701 children from 20 primary schools were analysed. Lung function, airway inflammation and pH from exhaled breath condensate were measured. Pupillometry was performed to evaluate autonomic activity. Land use composition and walkability index were quantified within a 500 m buffer zone around schools. The proportion of effects explained by the school environment was measured by mixed-effect models. We found that green school areas tended to be associated with higher lung volumes (FVC, FEV1 and FEF25–75%) compared with built areas. FVC was significantly lower in-built than in green areas. After adjustment, the school environment explained 23%, 34% and 99.9% of the school effect on FVC, FEV1, and FEF25–75%, respectively. The walkability of school neighbourhoods was negatively associated with both pupil constriction amplitude and redilatation time, explaining −16% to 18% of parasympathetic and 8% to 29% of sympathetic activity. Our findings suggest that the environment surrounding schools has an effect on the lung function of its students. This effect may be partially mediated by the autonomic nervous system.

Digital health for COPD care: the current state of play

Chronic obstructive pulmonary disease (COPD) imposes a huge burden to our healthcare systems and societies. To alleviate the burden, digital health-"the use of digital technologies for health"-has been recognized as a potential solution for improving COPD care at scale. The aim of this review is to provide an overview of digital health interventions in COPD care. We accordingly reviewed recent and emerging evidence on digital transformation approaches for COPD care focusing on (I) self-management, (II) in-hospital care, (III) post-discharge care, (IV) hospital-at-home, (V) ambient environment, and (VI) public health surveillance. The emerging approaches included digital-technology-enabled homecare programs, electronic records, big data analytics, and environment-monitoring applications. The digital health approaches of telemonitoring, telehealth and mHealth support the self-management, post-discharge care, and hospital-at-home strategy, with prospective effects on reducing acute COPD exacerbations and hospitalizations. Electronic records and classification tools have been implemented; and their effectiveness needs to be further evaluated in future studies. Air pollution concentrations in the ambient environment are associated with declined lung functions and increased risks for hospitalization and mortality. In all the digital transformation approaches, clinical evidence on reducing mortality, the ultimate goal of digital health intervention, is often inconsistent or insufficient. Digital health transformation provides great opportunities for clinical innovations and discovery of new intervention strategies. Further research remains needed for achieving reliable improvements in clinical outcomes and cost-benefits in future studies.

Inequalities in Exposure to Nitrogen Dioxide in Parks and Playgrounds in Greater London

Elevated levels of nitrogen dioxide (NO₂) have been associated with adverse health outcomes in children, including reduced lung function and increased rates of asthma. Many parts of London continue to exceed the annual average NO₂ concentration of 40 µg/m³ set by the EU directive. Using high-resolution maps of annual average NO₂ for 2016 from the London Atmospheric Emissions Inventory and detailed maps of open spaces from Britain’s national mapping agency, Ordnance Survey, we estimated average NO₂ concentrations for every open space in Greater London and analysed geospatial patterns comparing Inner verses Outer London and the 32 London Boroughs. Across Greater London, 24% of play spaces, 67% of private parks and 27% of public parks had average levels of NO₂ that exceeded the EU limit for NO₂. Rates of exceedance were higher in Inner London; open spaces in the City of London had the highest average NO₂ values among all the London Boroughs. The closest play space for more than 250,000 children (14% of children) under 16 years old in Greater London had NO₂ concentrations above the recommended levels. Of these children, 66% (~165,000 children) lived in the most deprived areas of London, as measured by the Index of Multiple Deprivations, where average NO₂ concentrations in play spaces were on average 6 µg/m³ higher than for play spaces in the least deprived quintile. More action is needed to reduce NO₂ in open spaces to safe levels through pollution reduction and mitigation efforts, as currently, open spaces in Greater London, including play spaces, parks and gardens, still have dangerously high levels of NO₂, according to the most recent NO₂ map.

Advances in the aetiology, management, and prevention of acute asthma attacks in children

Acute attacks of wheeze or asthma are among the most common reasons for paediatric hospital attendance, and the incidence of severe attacks in the UK is among the highest in Europe. Although most attacks are driven by infection, there are important differences in the underlying pathophysiology of asthma and wheeze between preschool and school-aged children. Allergen sensitisation, airway eosinophilia, and type 2 inflammation predominate in older children, whereas phenotypes in preschool children are variable, often including non-atopic episodes driven by neutrophilic infection. Currently, a universal approach is adopted towards management, but there is a need to make objective assessments of airway function, inflammation, and infection, both during the attack and during stable periods, to identify treatable traits and to target therapy if outcomes are to be improved. An assessment of the risk factors that led to the attack and early, focused follow-up are essential to ensure attacks never occur again.