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Diesel, children and respiratory disease
BMJ Paediatrics Open
Abstract and Figures
Air pollution generated in urban areas is a global public health burden since half of the world’s population live in either cities, megacities or periurban areas. Its direct effects include initiating and exacerbating disease, with indirect effects on health mediated via climate change putting the basic needs of water, air and food at risk.
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... Long commute times have been linked to inadequate sleep and other potential negative outcomes among students, which could exacerbate or create issues of disability for student populations (Voulgaris et al. 2019;Cordes et al. 2022). 3 Additionally, bad air quality is shown to have negative effects on the health of children and youth, as well as later in life (Liu and Grigg 2018). Increased exposure to air pollutants can cause respiratory disabilities, and increased exposure in bus cabins can particularly impact children with respiratory disabilities such as asthma, which is found in 4.5 million children in the United States (CDC NCEH 2023). ...
... ESBs serve as one of many proposed remedies to address the damage caused by pollution, as evidence finds that children are particularly susceptible to the negative health impacts of diesel exhaust (Liu and Grigg 2018). Truly equitable deployment strategies should ensure investment in districts most harmed by emissions, while distributing innovative resources responsibly without repeating environmentally unjust practices and rolling out plans that include diverse disability considerations. ...
The following working paper is informed by a range of perspectives from disability, transportation, and environmental justice advocates to electric school bus operators, manufacturers, and stakeholders. Focusing on the rights and justice of people with disabilities, this paper explores how the electrification of school buses affects students and adults with disabilities and shares their suggestions for ensuring fairness and accessibility during the transition.
... SO 2 is more associated with industrial activity and power station emissions. 38 We noted an improvement in air pollution levels between birth and time of spirometry, with the majority of pollution levels being below European Union legal limits and WHO guidelines. 38 However, even within these recommended limits, we have noted air pollution continues to have a detrimental association with FVC. ...
... 38 We noted an improvement in air pollution levels between birth and time of spirometry, with the majority of pollution levels being below European Union legal limits and WHO guidelines. 38 However, even within these recommended limits, we have noted air pollution continues to have a detrimental association with FVC. This highlights the Table 3 Continued paucity of evidence on what constitutes a 'safe' level of air pollution exposure. ...
Rationale
Increased outdoor air pollution worsens lung function in children. However, these associations are less well studied in preterm-born individuals.
Objectives
We assessed associations between ambient air pollutants and spirometry measures in preterm-born children.
Methods
The Respiratory Health Outcomes in Neonates study recruited preterm-born children aged 7–12 years who were born at ≤34 week's gestation. We associated four ambient air pollutants (particulate matter with aerodynamic diameter ≤2.5 µm (PM 2.5 ), PM 10 , nitrogen dioxide (NO 2 ) and sulfur dioxide) at time of birth and spirometry assessment and averaged exposure between these two time points with spirometry measures, using linear regression analyses. Gestational age was banded into 23–28, 29–31 and 32–34 week's. Regression models estimated spirometry values against pollutant levels at birth and at the time of spirometry.
Measurements and main results
From 565 preterm-born children, 542 (96%) had satisfactory data. After adjustments for early and current life factors, significant detrimental associations were noted between PM 10 at birth and per cent predicted forced vital capacity (%FVC) for the 23–28 and 29–31 week's gestation groups and between current PM 2.5 and NO 2 exposure and %FVC for the 23–28 week's gestation group. No associations with spirometry were noted for the averaged pollution exposure between birth and spirometry. Predictive models showed 5.9% and 7.4% differences in %FVC between the highest and lowest current pollution exposures for PM 2.5 and NO 2, respectively, in the 23–28 week group.
Conclusions
Birth and current exposures to road-traffic-associated pollutants detrimentally affected %FVC in preterm-born school-aged children, who already have compromised lung function.
... d. Espinoza and Vemireddy 2018;Liu and Grigg 2018;Vieira et al. 2012. e. Austin et al. 2019. ...
This comprehensive study and guide offer school districts and others an overview of the electric school bus market and a catalog that presents electric school bus models available today with detailed vehicle specifications.
... Children are particularly susceptible to the harms of diesel exhaust, including reduced lung function, greater likelihood of asthma, and reduced cognitive function, among other adverse impacts (Liu and Grigg 2018). Specifically, buses manufactured before 2010-and, in particular, before 2000-produce significantly more exhaust, which infiltrates the cabin and exposes children to diesel exhaust pollution during their rides to and from school (Beatty and Shimshack 2011). ...
World Resources Institute and Equitable Cities investigate how the fuel type and age of school bus fleets may be affecting U.S. communities disproportionately exposed to air pollution. Researchers explore how a focus on equity has brought zero-emission electric school buses to the school districts most harmed by the oldest, most polluting diesel school buses.
... In the UK, the majority of underfives, young adults and poorer households live in areas with the highest concentrations of trafficrelated air pollution (TRAP) (4), resulting in a disproportionate health burden falling on some of the most disadvantaged and vulnerable members of society (5) and disproportionate numbers of poor and vulnerable people being affected (6). Children are particularly sensitive to the harmful effects of air pollution (7) and concern has increased over recent years that long-term exposures can cause developmental delays with long-term consequences on children's health across the life course (8). ...
Traffic-related air pollution (TRAP) poses significant health risks particularly for children, with adverse effects that may impact health in later life. Low emission zones are a public health policy designed to reduce TRAP in urban areas.
The CHILL (Children's Health in London and Luton) Study will evaluate the impact of London's Ultra Low Emission Zone (ULEZ) on children's health, using a prospective two-arm parallel longitudinal cohort design. CHILL will examine associations between air pollution metrics and lung function growth, plus secondary outcomes. Here we describe the characteristics of the CHILL cohort at baseline, prior to the introduction of the ULEZ.
We recruited 3414 children aged 6-9 years attending 84 schools (London, intervention site: 1664 children, 44 schools; Luton, comparator site: 1750 children, 40 schools). Baseline health assessments were conducted in 2018-2019 (before the introduction of the ULEZ in London). 97.0% of recruited children were assessed (London 96.5%, Luton 97.4%), with the primary outcome measure of post-bronchodilator forced expiratory volume in one second being successfully measured in 76.7% (London 76.9%, Luton 76.5%). 92.1% returned a completed parental questionnaire (London 89.3%, Luton 94.7%), including data for analysis of the secondary outcomes. Demographic characteristics and outcomes were similar across the two sites.
We established well-matched cohorts of school children, in our intervention (London) and comparator (Luton) sites. Data on primary and secondary outcomes have been successfully collected, which, combined with detailed air quality metrics, provides a robust platform for evaluating the impact of London's ULEZ on children's health and development.
... These authors emphasized once more how widespread allergies are in school environments with huge populations of students and staff. According to a research by Liu and Grigg (2018), children's exposure to diesel exhaust from school buses and other vehicles aggravates asthma and allergies. These issues can inevitably affect student performance, comfort, and attendance, as well as negatively affect teachers' and students' work. ...
The aim of this study was to assess the environmental pollutants present in the cobwebs found in selected lecture rooms; Mathematics lecture room (MTH), Chemistry lecture room (CHM), Biology lecture room (BIO) and Environmental Science lecture room (EMT) in the Faculty of Science, Federal University Dutse. Bacterial pollutants coupled with Arsenic (As) Lead (Pb) in the sampled cobwebs were isolated and identified using standard procedures. One-way Analysis of variance was used to determine the variation in the concentrations of Pb and As in the sampled cobwebs. Staphylococcus aureus (28.1%), Bacillus sp. (37.5%), Streptococcus sp. (18.8%), and Streptobacillus sp. (15.6%) were detected in all the cobwebs samples. MTH 4 had the highest Pb concentration (1.2800 mg/kg) while CHM 3 had the lowest (0.470 mg/kg) Pb concentration. CHM 3 and BIO 3 had very low concentrations of Pb, which were significantly different from each other (p˂0.05). This study has revealed that spider cobwebs can be an effective bio-indicator in determining indoor air quality.
... Many studies have revealed associations between respiratory diseases and air pollution. The prognoses of such diseases are poor, and their treatment and management are costly [3]. The sources of air pollution vary from local cigarette and coal smoke and industrial dust to widespread emissions from engines and industrial sources. ...
Air pollutants are associated with exacerbations of asthma, chronic bronchitis, and airway inflammation. Diesel exhaust particles (DEPs) can induce and worsen lung diseases. However, there are insufficient data to guide polymerase chain reaction (PCR) array proteomics studies regarding the impacts of DEPs on respiratory diseases. This study was performed to identify genes and proteins expressed in normal human bronchial epithelial (NHBE) cells. MicroRNAs (miRNAs) and proteins expressed in NHBE cells exposed to DEPs at 1 μg/cm2 for 8 h and 24 h were identified using PCR array analysis and 2D PAGE/LC-MS/MS, respectively. YWHAZ gene expression was estimated using PCR, immunoblotting, and immunohistochemical analyses. Genes discovered through an overlap analysis were validated in DEP-exposed mice. Proteomics approaches showed that exposing NHBE cells to DEPs led to changes in 32 protein spots. A transcriptomics PCR array analysis showed that 6 of 84 miRNAs were downregulated in the DEP exposure groups compared to controls. The mRNA and protein expression levels of YWHAZ, β-catenin, vimentin, and TGF-β were increased in DEP-treated NHBE cells and DEP-exposed mice. Lung fibrosis was increased in mice exposed to DEPs. Our combined PCR array–omics analysis demonstrated that DEPs can induce airway inflammation and lead to lung fibrosis through changes in the expression levels of YWHAZ, β-catenin, vimentin, and TGF-β. These findings suggest that dual approaches can help to identify biomarkers and therapeutic targets involved in pollutant-related respiratory diseases.
Air pollution poses a significant threat to public health, contributing to respiratory and cardiovascular diseases, especially among vulnerable populations such as children and the elderly. Key pollutants, including particulate matter, nitrogen oxides, sulfur dioxide, and volatile organic compounds, largely stem from industrial activities, transportation, agriculture, and urbanization. Understanding these pollutants’ formation, dispersion, and health impacts is crucial for developing effective mitigation strategies. This paper explores the processes underlying air pollution, the health consequences of exposure, and the latest innovations in pollution mitigation technologies. Strategies such as advanced air filtration systems, low-emission transportation technologies, and green energy solutions offer promising avenues to improve air quality. Furthermore, effective environmental health management requires comprehensive policies integrating urban planning, regulatory frameworks, and public engagement. Collaboration among governments, industries, and communities is essential to address the global burden of air pollution. With urbanization and industrialization continuing to challenge air quality, adopting sustainable environmental management practices and innovative technologies is critical to safeguarding public health. Ongoing research and a collective commitment to air quality improvement will reduce pollution-related health impacts and foster a healthier environment for future generations.
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).
Background:
Asthma is the most common chronic disease in children and has been linked to high levels of ambient air pollution and certain hazardous air pollutants (HAPs). Outdoor pollutants such as benzene, released by car emissions, and organic chemicals found in diesel exhaust, as well as particles and irritant gases, including nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3), contribute to an increased prevalence of respiratory diseases such as asthma.
Objectives:
The objectives of this study were to: 1) conduct a screening survey to identify high risk for asthma among school-age children in Hidalgo County, and, 2) study the potential health impact of school-related exposure to HAPs pertaining to asthma risk.
Methods:
We carried out a quantitative cross-sectional study combining a school-based asthma screening survey across 198 schools in Hidalgo County, Texas, with information on school neighborhood environments, including census tract-level information on hazardous air pollutants (HAPs) and socioeconomic status (SES) in the respective school neighborhoods. HAPs levels were assessed based on the EPA 2011 National-Scale Air Toxics Assessment (NATA) while SES information was assessed using data from the 2010-2014 American Community Survey.
Results:
2930 students completed the asthma screening survey and results showed an overall asthma prevalence of 9.4%, slightly higher than the national and state prevalence. Participants in the 14-18 years old age group showed a much higher asthma prevalence of 16.7%. When assessing school-neighborhood characteristics, our results revealed no significant differences in asthma prevalence across census tracts with different SES levels. For HAPs, in the single-pollutant model, chlorine levels showed a significant linear trend for prevalence of asthma (p=0.03) while hydrochloric acid had a marginally significant linear trend (p=0.08). The association with chlorine remained significant in the multi-pollutant model.
Conclusions:
Asthma prevalence among school-age children in Hidalgo County, Texas, is 9.4%, which is slightly higher than the state rate, especially among young adults, ages 14-18 years who had an asthma rate of 16.7%. Results support an association between exposures to school-neighborhood HAPs and risk for pediatric asthma, especially as related to chlorine. No significant effects of school-level SES on asthma risk were observed.
Our aim is to estimate associations between acute increases in particulate matter with diameter of 2.5 µm or less (PM2.5) concentrations and risk of infant bronchiolitis and otitis media among Massachusetts births born 2001 through 2008.Our case-crossover study included 20,017 infant bronchiolitis and 42,336 otitis media clinical encounter visits. PM2.5 was modeled using satellite, remote sensing, meteorological and land use data. We applied conditional logistic regression to estimate odds ratios (ORs) and confidence intervals (CIs) per 10-µg/m3 increase in PM2.5. We assessed effect modification to determine the most susceptible subgroups. Infant bronchiolitis risk was elevated for PM2.5 exposure 1 day (OR = 1.07, 95% CI = 1.03–1.11) and 4 days (OR = 1.04, 95% CI = 0.99–1.08) prior to clinical encounter, but not 7 days. Non-significant associations with otitis media varied depending on lag. Preterm infants were at substantially increased risk of bronchiolitis 1 day prior to clinical encounter (OR = 1.17, 95% CI = 1.08–1.28) and otitis media 4 and 7 days prior to clinical encounter (OR = 1.09, 95% CI = 1.02–1.16 and OR = 1.08, 95% CI = 1.02–1.15, respectively). In conclusion, preterm infants are most susceptible to infant bronchiolitis and otitis media associated with acute PM2.5 exposures.
Background:
São Paulo city, Brazil, faces challenges caused by rapid urbanization. We illustrate how future travel patterns could lead to different health consequences in the city.
Methods:
We evaluated the health impacts of different travel pattern scenarios for the São Paulo adult population by comparing the travel patterns of São Paulo in 2012 with counterfactual scenarios in which the city adopted travel patterns of i) those living in the city's expanded centre; ii) London (2012); iii) a highly motorized São Paulo (SP California); and iv) a visionary São Paulo (SP 2040), with high levels of walking and cycling and low levels of car and motorcycle use. For each scenario we estimated changes in exposure to air pollution, road injury risk, and physical activity. Health outcomes were estimated using disability adjusted life years (DALYs) and premature deaths averted. Sensitivity analyses were performed to identify the main sources of uncertainty.
Results:
We found considerable health gains in the SP 2040 scenario (total 63.6k DALYs avoided), with 4.7% of premature deaths from ischemic heart disease avoided from increases in physical activity alone. Conversely, we found substantial health losses in the scenario favouring private transport (SP California, total increase of 54.9k DALYs), with an increase in road traffic deaths and injuries among pedestrians and motorized vehicles. Parameters related to air pollution had the largest impact on uncertainty.
Conclusions:
Shifting travel patterns towards more sustainable transport can provide major health benefits in São Paulo. Reducing the uncertainties in the findings should be a priority for empirical and modelling research on the health impacts of such shifts.
São Paulo city, Brazil, faces challenges caused by rapid urbanization. We illustrate how future travel patterns could lead to different health consequences in the city. We evaluated the health impacts of different travel pattern scenarios for the São Paulo adult population by comparing the travel patterns of São Paulo in 2012 with counterfactual scenarios in which the city adopted travel patterns of i) those living in the city's expanded centre; ii) London (2012); iii) a highly motorized São Paulo (SP California); and iv) a visionary São Paulo (SP 2040), with high levels of walking and cycling and low levels of car and motorcycle use. For each scenario we estimated changes in exposure to air pollution, road injury risk, and physical activity. Health outcomes were estimated using disability adjusted life years (DALYs) and premature deaths averted. Sensitivity analyses were performed to identify the main sources of uncertainty. We found considerable health gains in the SP 2040 scenario (total 63.6k DALYs avoided), with 4.7% of premature deaths from ischemic heart disease avoided from increases in physical activity alone. Conversely, we found substantial health losses in the scenario favouring private transport (SP California, total increase of 54.9k DALYs), with an increase in road traffic deaths and injuries among pedestrians and motorized vehicles. Parameters related to air pollution had the largest impact on uncertainty. Shifting travel patterns towards more sustainable transport can provide major health benefits in São Paulo. Reducing the uncertainties in the findings should be a priority for empirical and modelling research on the health impacts of such shifts.
Objective:
In recent years, air pollutant concentrations in Japan have decreased slightly; however, there are growing concerns about the influences of transnational air pollution on respiratory illness. We aimed to clarify the short-term association between the ambient air pollution and respiratory symptoms among children without asthma, children with asthma not using long-term medications (CA-nonLTM), and those using them (CA-LTM).
Methods:
A total of 138 children attending 2 primary schools and 71 children with asthma regularly visiting cooperating medical institutions were recruited. Study participants measured peak expiratory flow (PEF) twice a day and recorded coughing, nasal symptoms, and medication use in a diary. Predicted associations between daily air pollutant concentrations and respiratory symptoms, and PEF were evaluated using case-crossover and generalized estimate equation models.
Results:
Changes in %maxPEF per 10 ppb oxidant (Ox) increase in children without asthma, CA-nonLTM, and CA-LTM were -0.26% (95% CI: -0.49, -0.03), -0.51% (95% CI: -0.89, -0.12), and -0.20% (95% CI: -0.42, 0.01), respectively. The odds ratios for coughing per 10 ppb Ox increase in the Lag0 model were 1.34 (95% CI: 1.11, 1.60), 1.52 (95% CI: 1.12, 2.07), and 1.06 (95% CI: 0.93, 1.20), respectively. These suggested that the Ox concentration has graded effects on %maxPEF and coughing, in the following descending order, CA-nonLTM, children without asthma, and CA-LTM. The Ox concentration was also positively associated with nasal symptoms in children without asthma and CA-LTM.
Conclusion:
Our results suggest that using long-term medications to manage asthma may play an important role in preventing exacerbation of respiratory symptoms due to air pollution.
The aim of this paper was to review studies analyzing the associations between air pollution and neurodevelopment in children as well as the effect on adult population. Effect of prenatal exposure to polycyclic aromatic hydrocarbons (PAHs, benzo[a]pyrene, B[a]P) were already studied on cohorts from New York, Poland, China, and Spain. All results indicate changes of child behavior and neurodevelopment at the age of 3-9 years, decrease of IQ, increase of Attention Deficit Hyperactivity Disorder (ADHD), decrease of brain-derived neurotrophic factor (BDNF), reduction of left hemisphere white matter. Effect of traffic-related air pollution (TRAP) to neurobehavioral development in children, measured as PM2.5 (particulate matter <2.5 µm), PM10, elemental carbon (EC), black smoke (BC), NO2, NOx, were studied in USA, Spain, Italy, and South Korea. Increased concentrations of TRAP were associated with the increase of ADHD, autism, affected cognitive development; PM2.5 decreased the expression of BDNF in placenta. Increased concentrations of PM2.5 affected adults cognition (episodic memory), increased major depressive disorders. Increased concentrations of NO2 were associated with dementia, NOx with Parkinson's disease. Increased concentrations of PAHs, PM2.5 and NO2 in polluted air significantly affect central nervous system in children and adults and represent a significant risk factor for human health.
Objective:
This study examined the role of exposure to traffic-related air pollution (TRAP) on susceptibility to asthma in children with past episodes of bronchiolitis.
Methods:
The baseline data included 2,627 school children aged 6-14 years who had participated in the longitudinal follow-up survey of the Children's Health and Environmental Research of Korea. Lifetime wheezing, past episodes of bronchiolitis, and doctor-diagnosed asthma were evaluated using an International Study of Asthma and Allergies in Childhood questionnaire. We used generalized linear regression with binomial distribution to calculate the relative risk (RR) between TRAP, assessed by proximity to a main road and the total length of roads, and asthma.
Results:
Compared with the subjects who had less than 100 m of road length within 200-m radius from their home, those with more than 500 m of road length had significantly increased odds for infantile bronchiolitis (adjusted OR [aOR]: 1.57, 95% confidence interval [CI]: 1.01-2.42). Positive exposure-response relationships were found between residential proximity to the main road and asthma (aOR: 1.79, 95% CI: 1.05-3.06; <75 m vs. >700 m from a main road, P for the trend = 0.02). Closer residential proximity to the main road (<75 m) and bronchiolitis combined increased the risks of newly diagnosed asthma (adjusted RR: 3.62, 95% CI: 1.07-12.26) compared with those without bronchiolitis and living ≥ 75 m away from the main road.
Conclusions:
TRAP appeared to be associated with an increased asthma among children with bronchiolitis, indicating the importance of modifying effects of bronchiolitis in asthma pathogenesis.
Objective
As the results from epidemiological studies about the impact of outdoor air pollution on asthma in children are heterogeneous, our objective was to investigate the association between asthma exacerbation in children and exposure to air pollutants.
Methods
A database of 1 264 585 paediatric visits during the 2010–2015 period to the emergency rooms from 20 emergency departments (EDs) of ‘Assistance Publique Hôpitaux de Paris (APHP)’, the largest hospital group in Europe, was used. A total of 47 107 visits were classified as asthma exacerbations. Concentration of air pollutants (nitrogen dioxide, ozone, fine particulate matter (PM) with an aerodynamic diameter smaller than 10 µm (PM10) and 2.5 µm (PM2.5)), as well as meteorological data, evolution of respiratory syncytial virus infection and pollen exposition, were collected on an hourly or daily basis for the same period using institutional databases. To assess the association between air pollution and asthma, mixed-effects quasi-Poisson regression modelling was performed.
Results
The only compound independently associated with ED visits for asthma was PM2.5 (P<10⁻⁴). The association between asthma exacerbation and PM2.5 was not linear, and a sigmoid function described the relationshipsatisfactorily. PM2.5 concentration, which gives half the maximum effect, was estimated at 13.5 µg/m³.
Conclusions
We found an association between daily asthma exacerbation in paediatric visits to the ED and fine particulate air pollutants.
In the last few years, ship emissions have attracted growing attention in the scientific community. The main reason is the constant increase of marine emissions over the last twenty years due to the intensification of port traffic. Thus, this study aimed to evaluate ship emissions (PM10, PM2.5, NOx, SO2, CO, CO2, N2O CH4, NMVOC, and HC) through the activity-based methodology in four of the main ports of Portugal (Leixões, Setúbal, Sines and Viana do Castelo) during 2013 and 2014. The analysis was performed according to ship types (bulk carrier, container, general cargo, passenger, Ro-Ro cargo, tanker and others) and operational modes (manoeuvring, hotelling and during cruising). Results indicated that tankers were the largest emitters in two of the four analysed ports. Regarding cruising emissions, container ships were the largest emitters. . CO2, NOx and SO2 estimated emissions represented more than 95% of the cruising and in-port emissions. Results were also compared with the total national emissions reported by the Portuguese Environment Agency, and if the in-port emissions estimated in the present study would have been taken into account to these totals, emissions of NOx and SO2 would increase 15% and 24% in 2013 and 16% and 28% in 2014. Summing up ships seem to be an important source of air pollution, mainly regarding NOx and SO2.
Introduction:
Recently, we showed that exposure to traffic-related air pollutants (TRAPs) at school was negatively associated with cognitive development, specifically working memory and inattentiveness, in primary schoolchildren during a course of 12 months. The persistence of such associations over longer periods remains as an open question.
Objective:
To study the longitudinal association between TRAPs at school and cognitive development over a period of 3.5 years.
Methods:
Indoor and outdoor levels of TRAPs (elemental carbon (EC), dioxide nitrogen (NO2), particulate matter (PM2.5) from traffic sources and ultrafine particles (UFP)) were measured at 39 schools across Barcelona during 2012/2013. Working memory, as a measure of cognitive development, was evaluated 4 times in 2012/2013 assessment and was re-evaluated one more time in 2015 using computerized n-back test (3-back d' as main outcome). Linear mixed effects models were used to test the association between TRAPs and 3-back d', adding child and school as random effects to account for the multilevel nature of the data, and school air pollutants levels (one at a time) as predictor.
Results:
We found detrimental associations between all TRAPs and annual change in 3-back d' (working memory) (i.e. slower development of working memory in children attending schools with higher levels of air pollution). The associations (per one interquartile range increase in exposure) were strongest for outdoor NO2 (Coefficient (Coef) = - 4.22, 95% confidence interval (CI), - 6.22, - 2.22) and indoor UFP (Coef = - 4.12, 95%CI, - 5.68, - 1.83). These reductions were equivalent to - 20% (95%CI, - 30.1, - 10.7) and - 19.9% (95%CI, - 31.5, - 8.4) change in annual working memory development associated with one interquartile range increase in outdoor NO2 and indoor UFP, respectively.
Conclusion:
Our findings suggest the persistence of the negative association between TRAPs exposure at school and cognitive trajectory measured by n-back test over a period of 3.5 years.