Urban Outdoor Air Research Articles

Characteristics of indoor and outdoor Polycyclic Aromatic Hydrocarbons (PAHs) pollution in TSP in rural Northeast China: A case study of heating and non-heating periods.

Approximately 91% of the world's population lives in an air-polluted environment, and environmental pollution has become a widespread concern. Urban indoor and outdoor air pollution has been fully researched and effective control measures have been proposed. However, the issue of air pollution in rural areas has not been explored in depth. Compared to urban air pollution, the rural air pollution problem is more complex and urgent. Due to climatic factors and economic conditions in rural Northeast China, most households use solid fuels such as biomass straw and coal as domestic energy during the heating period, which will cause serious pollution problems of Total Suspended Particulate (TSP) and Polycyclic Aromatic Hydrocarbons (PAHs). To investigate the pollution characteristics of PAHs in indoor and outdoor TSP in rural Northeast China during the heating and non-heating periods, a medium-sized particulate matter collector 1108A was used to collect TSP for 7days, and GC-MS was used to detect PAHs. The results showed that indoor TSP and PAHs pollution levels were the highest during the heating period. PAHs source analysis by Diagnostic Ratio (DR) and Principal Component Analysis (PCA) indicated that the main sources were biomass and coal combustion, vehicle emissions, and domestic waste incineration. According to the results of carcinogenic risk model calculations, there is a potential carcinogenic risk to the population in the Northeast rural living area. This study reflects the pollution characteristics and sources of indoor and outdoor TSP and PAHs in rural Northeast China during heating and non-heating periods, and provides a reference for further prevention and control of air pollution in rural areas, which is conducive to improving the living environment and improving human health.

Combined effects of Thermal-PM2.5 indicators on subjective evaluation of campus environment

This paper selects six typical spaces of a university campus in Xi'an to study the comprehensive effect of heat and PM2.5 in open spaces. Subjects are required to complete a subjective perception questionnaire in a thermal-PM2.5 interactive environment combined with on-site actual measurement. The results are shown in three aspects: (1) PM2.5 has a significant effect on thermal sensation and thermal comfort in the afternoon. PM2.5 concentration of 0–20 and 20–40 μg/m³ aggravates heat sensation of the crowd in summer and reduces subjective thermal comfort. (2) At constant physiological equivalent temperature (PET), air quality comfort decreases with increase in PM2.5 concentration. Generally, PM2.5 is 20–27, 20–23, and 20–24 μg/m³ in the morning, afternoon, and evening, respectively. People are more sensitive to the air quality with the increase of PET as the quality of comfort gradually improved. (3) Further, when PM2.5 concentration decreased from 20 to 40 to 0–20 μg/m³ at night, the mean value of overall comfort vote (OCV) increased by 0.46. Therefore, this paper can provide experimental support for establishing a human thermal comfort research system under the interaction of multiple environments, and can also provide a strategic basis for improving the urban outdoor thermal environment and air quality.

Personal Exposure to Fine Particles (PM2.5) in Northwest Africa: Case of the Urban City of Bamako in Mali.

Personal exposure to particulate matter (PM) from anthropogenic activities is a major concern in African countries, including Mali. However, knowledge of particulates is scant. This study was undertaken to characterize personal exposure to PM2.5 microns or less in diameter (PM2.5) in the city of Bamako in Mali. The exposure to PM2.5, through daily activities was observed from September 2020 to February 2021. Participants wore palm-sized optical PM2.5 sensors on their chest during their daily activities. The exposure levels in four different groups of residents were investigated in relation to their daily activities. The variation in PM2.5 concentration was measured during different activities in different microenvironments, and the main sources of exposure were identified. The highest average 10 min concentrations were observed at home and in bedrooms, while the participants were using specific products typically used in Africa, Asia, and South America that included insecticides (IST; 999 µg/m3) and incense (ICS; 145 µg/m3), followed by traffic (216 µg/m3) and cooking (150 µg/m3). The lowest average 10 min concentrations were also observed in the same microenvironment lacking IST or ICS (≤14 µg/m3). With no use of specific products, office workers and students were the least exposed, and drivers and cooks were the most exposed. The concentrations are up to 7.5 and 3 times higher than the World Health Organization’s yearly and daily recommended exposure levels, respectively, indicating the need to promptly elaborate and apply effective mitigation strategies to improve air quality and protect public health. This study highlights the importance of indoor air pollution sources related to culture and confirms previous studies on urban outdoor air pollution sources, especially in developing countries. The findings could be applied to cities other than Bamako, as similar practices and lifestyles are common in different cultures.

Resolution of the M-shape Pattern of the Outdoor Air Temperature Environmental Kuznets Curve (EKC) for Metropolitan Areas in a Country: Using Long-term Monthly Level Data of Taipei City as Empirical Evidence

In Taiwan, the heat island effect is the most significant in Taipei City. Thus this research provides a causal explanation for why urban outdoor air temperature has an M-shape EKC pattern for metropolitan areas in a country. Results show that the growth rate change in CO2 concentration can induce changes to the periods of the La Nino effect and EI Nino effect, causing high fluctuations in rain accumulation. The amount of rain then alters A-type evaporation, and so the evaporation amount is the top factor for the diffusion of a city’s heat. This fluctuation plays as a cooling and heating source for the V region of the M shape in the outdoor air temperature EKC pattern. In our previous studies, the growth rate change in CO2 concentration correlates to the energy structure. Therefore, a heat sinking model has been proposed to explain the accumulation of heat in a city, in which a proportion process for the solar irradiation source from buildings and remodeling engineering from a public housing policy and the private sector can play as a heating source of the two peaks of the M shape and present long-term linear growth in the outdoor air temperature EKC pattern.

ATLAS: Software for analysing the relationship between urban microclimate and urban morphology in a tropical city

This research applied clustering to unsupervised learning of meteorological data and evaluated the impact of urban morphology on temperature in different weather. Air Temperature Learning Algorithms (ATLAS) was developed for the cluster analysis of urban meteorological data and regression analysis of urban morphology and outdoor air temperature. The case study experiment was conducted on the university campus. Based on principal component analysis (PCA) reduced K-means clustering, this study evaluated the characteristics of reference meteorological data, and local solar irradiance and air temperature. Three weather conditions were identified for the given reference meteorological data. Revised selection criteria for clear, hot, and calm weather in tropical climate were proposed. The mean Raintot shall be less than 0.01 mm, with 25th, 50th and 75th quartile to be 0 mm, respectively. The mean Wavg and its quartiles shall be less than 3 m/s. The mean, 50th and 75th quartile of Stot, Smax, and Savg shall be higher than 5000 Wh/m2, 800 W/m2 and 200 W/m2, respectively. The mean, 50th and 75th quartile of Tavg, Tmax and Tmin shall be higher than 29 °C, 32 °C and 26 °C, respectively. The hourly ground level air temperature models were established in different weather. The results indicate the ground level air temperature in rainy and cool weather conditions are more predictable than hot and dry weather conditions. The sky view factor, exterior wall area, and green plot ratio have a greater impact on air temperature in sunny days than rainy days.

Defining local extreme heat thresholds and Indoor Cooling Degree Necessity for vulnerable residential dwellings during the 2020 summer in Ankara – Part I: Air temperature

This study discusses the preliminary assessment of Indoor Cooling Degree Necessity (ICDN) based upon the standard air temperature (Ta) value of 22 °C which is defined to be the standard upper mean temperature limit (Tl) for interior comfort as defined by the WHO. By considering indoor air temperature (TaI), levelled oscillations above Tl are utilised to determine indoor temperature extremes/frequencies at a 10 min temporal resolution during the months of July and August 2020 in Ankara. These recordings were undertaken through the use of an interior in-situ Meteorological Station (MS), simultaneously, an outdoor in-situ MS was also mounted outside the naturally ventilated dwelling with the identical measurement interval period. Moreover, to supplement the encompassing outdoor data collection, two WMO MSs were utilised in the study to account for both encompassing local peri-urban Esenboga (EMS) and Ankara’s urban (AMS) outdoor air temperatures (TaO) at a 1 h temporal resolution.In addition to the ICDN’s identified variation of Tl levels, which frequently remained between +7 °C and +10 °C during periods of accentuated urban outdoor heat stress; their direct/latent cause-and-effect relationship with newly defined local extreme heat thresholds were established. Relative to July and August 2020, a total of 19 Very Hot Days (VHD33), 10 Monthly Tropical Night (MRT20), and 4 Heatwave Events (HWE31) were determined. These thresholds further underlined the growing need to associate indoor and outdoor heat stress during local extreme heat events, particularly in more vulnerable residential contexts; and moreover, in an era of increasing heat stress as result of rapid urbanisation and climate change.

Energy poverty influences urban outdoor air pollution levels during COVID-19 lockdown in south-central Chile

The effect of COVID-19 lockdowns on ambient air pollution levels in urban south-central Chile, where outdoor air pollution primarily originates indoors from wood burning for heating, may differ from trends in cities where transportation and industrial emission sources dominate. This quasi-experimental study compared hourly fine (PM2.5) and coarse (PM10) particulate matter measurements from six air monitors (three beta attenuation monitors; three low-cost sensors) in commercial and low/middle-income residential areas of Temuco, Chile between 2019 and 2020. The potential impact of varying annual meterological conditions on air quality was also assessed. During COVID-19 lockdown, average monthly ambient PM2.5 concentrations in a commercial and middle-income residential neighborhood of Temuco were up to 50% higher (from 12 to 18 μg/m3) and 59% higher (from 22 to 35 μg/m3) than 2019 levels, respectively. Conversely, PM2.5 levels decreased by up to 52% (from 43 to 21 μg/m3) in low-income areas. The fine fraction of PM10 in April 2020 was 48% higher than in April 2017–2019 (from 50% to 74%) in a commercial area. These changes did not appear to result from meterological differences between years. During COVID-19 lockdown, higher outdoor PM2.5 pollution from wood heating existed in more affluent areas of Temuco, while PM2.5 concentrations declined among poorer households refraining from wood heating. To reduce air pollution and energy poverty in south-central Chile, affordability of clean heating fuels (e.g. electricity) should be a policy priority.

COVID-19 Highlights an Environmental Injustice: Influence of Energy Insecurity on Urban Outdoor Air Pollution during Community Lockdown in South-Central Chile

BACKGROUND AND AIM: In south-central Chile, outdoor air pollution primarily originates as household air pollution from wood burning for heating. The effect of COVID-19 lockdowns on ambient air pollution levels in urban south-central Chile, may therefore be different from trends observed in cities where transportation/industrial emission sources dominate. This study investigates the impact of COVID-19 lockdown on outdoor fine (PM2.5) and coarse (PM10) particulate matter concentrations in Temuco, Chile. METHODS: Hourly PM2.5 and PM10 measurements from six air monitoring stations (three reference-grade beta attenuation monitors and three low-cost sensors) in commercial and low- and middle-income residential areas of Temuco were compared during winter months (March-September) in 2019 and 2020 (spanning COVID-19 lockdown). RESULTS:Average monthly PM2.5 concentrations in low-income residential areas of Temuco during winter 2019 ranged from (36-53 µg/m3), approximately twice as high as concentrations in commercial areas (12-29 µg/m3). During COVID-19 lockdown, average monthly ambient PM2.5 concentrations in a commercial and middle-income residential area of Temuco were up to 50% higher (12 µg/m3 to 18 µg/m3) and 59% higher (22 µg/m3 to 35 µg/m3) than 2019 levels, respectively. Conversely, PM2.5 levels decreased by up to 52% (43 µg/m3 to 21 µg/m3) in three low-income neighborhoods. The night-time mass percent of PM10 that was PM2.5 in April 2020 increased by 48% above April 2017-2019 proportions (50% to 74%) in a commercial area. CONCLUSIONS:Wood burning was responsible for a significantly higher proportion of ambient PM2.5 pollution in commercial areas and a middle-income neighborhood of Temuco during COVID-19 lockdown, compared to winter months in 2019. Energy insecure households likely refrained from wood heating during lockdown, leading to PM2.5 concentration declines in low-income neighborhoods. To reduce ambient air pollution and energy insecurity resulting from reliance on wood for heating in south-central Chile, affordability of clean heating fuels (e.g. electricity, liquefied petroleum gas) should be a policy priority. KEYWORDS: COVID-19, residential heating, household air pollution, particulate matter, energy insecurity, PM2.5

Outdoor air pollution in India is not only an urban problem

Urban outdoor air pollution in the developing world, mostly due to particulate matter with diameters smaller than 2.5 µm (PM2.5), has been highlighted in recent years. It leads to millions of premature deaths. Outdoor air pollution has also been viewed mostly as an urban problem. We use satellite-derived demarcations to parse India's population into urban and nonurban regions, which agrees with the census data. We also use the satellite-derived surface PM2.5 levels to calculate the health impacts in the urban and nonurban regions. We show that outdoor air pollution is just as severe in nonurban regions as in the urban regions of India, with implications to monitoring, regulations, health, and policy.

Building energy modeling at neighborhood scale

The urban climate and outdoor air quality of cities that have a positive thermal balance depending on the thermal consumptions of buildings cause an increase of the urban heat island and global warming effects. The aim of this work has been to develop an energy balance using the energy consumption data of the district heating network. The here presented engineering energy model is at a neighborhood scale, and the energy-use results have been obtained from a heat balance of residential buildings, by means of a quasi-steady state method, on a monthly basis. The modeling approach also considers the characteristics of the urban context that may have a significant effect on its energy performance. The model includes a number of urban variables, such as solar exposition and thermal radiation lost to the sky of the built environment. This methodology was applied to thirty-three 1 km × 1 km meshes in the city of Turin, using the monthly energy consumption data of three consecutive heating seasons. The results showed that the model is accurate for old built areas; the average error is 10% for buildings constructed before 1970, while the error reaches 20% for newer buildings. The importance and originality of this study are related to the fact that the energy balance is applied at neighborhood scale and urban parameters are introduced with the support of a GIS tool. The resulting engineering models can be applied as a decision support tool for citizens, public administrations, and policy makers to evaluate the distribution of energy consumptions and the relative GHG emissions to promote a more sustainable urban environment. Future researches will be carried out with the aim of introducing other urban variables into the model, such as the canyon effect and the presence of vegetation.

Dependence between urban morphology and outdoor air temperature: A tropical campus study using random forests algorithm

The study proposes a nonparametric approach that uses machine learning to predict outdoor temperatures based on field measurements at the National University of Singapore (NUS) Kent Ridge campus from February 2019 to July 2019. Six urban morphology variables (e.g. BDG, PAVE, WALL, HBDG, SVF, GnPR) were extracted from geographical information system (GIS) maps, three dimensional (3D) model and field surveys. This study compares the predictive power between ordinary least squares linear regression (LR) and machine learning (e.g. random forest (RF)). By using RF as a regression model, the air temperature has a greater RMSE reduction than LR, ranging from 10 % to 33 %. The relationship between outdoor air temperature and urban morphology variables based on non-parametric regression is presented. On average, lower SVF space can reduce the heat on campus. As the WALL increases, the temperature rises, but the changes in day and night are different. Greenery reduces daytime temperature due to the shading of solar radiation, although the shading from trees blocks the release of long-wave radiation from artificial materials at night. The observation indicates nighttime temperature can be reduced by planting low height greenery while keeping SVF unchanged.

Systèmes urbains et pollution de l’air extérieur : application du concept de résilience

La pollution de l’air extérieur est considérée comme un risque diffus auquel les villes doivent s’adapter pour éviter des impacts sanitaires et économiques de plus en plus importants. Le concept de résilience, jusqu’alors essentiellement appliqué aux chocs en milieu urbain, peut apporter un regard nouveau mais aucun cadre conceptuel n’existe pour la pollution de l’air. Le but de cet article est de proposer une première réflexion sur l’applicabilité du concept de résilience à la problématique de la pollution de l’air extérieur pour les villes, que nous considérons ici comme des systèmes urbains. Les résiliences adaptatives et inhérentes sont considérées pour, respectivement, observer des mécanismes de résilience des villes et caractériser les propriétés qu’une ville doit posséder pour être résiliente à la pollution de l’air. L’application des propriétés des systèmes socio-écologiques résilients à notre problématique permet d’apporter un premier cadre de réflexion et d’identifier plusieurs exemples de leviers d’actions pour améliorer la résilience des villes à la pollution de l’air extérieur, selon les différentes dimensions de la résilience (technique, organisationnelle, politique, sociale et économique).

Direct human health risks of increased atmospheric carbon dioxide

Growing evidence suggests that environmentally relevant elevations in CO2 (<5,000 ppm) may pose direct risks for human health. Increasing atmospheric CO2 concentrations could make adverse exposures more frequent and prolonged through increases in indoor air concentrations and increased time spent indoors. We review preliminary evidence concerning the potential health risks of chronic exposure to environmentally relevant elevations in ambient CO2, including inflammation, reductions in higher-level cognitive abilities, bone demineralization, kidney calcification, oxidative stress and endothelial dysfunction. This early evidence indicates potential health risks at CO2 exposures as low as 1,000 ppm—a threshold that is already exceeded in many indoor environments with increased room occupancy and reduced building ventilation rates, and equivalent to some estimates for urban outdoor air concentrations before 2100. Continuous exposure to increased atmospheric CO2 could be an overlooked stressor of the modern and/or future environment. Further research is needed to quantify the major sources of CO2 exposure, to identify mitigation strategies to avoid adverse health effects and protect vulnerable populations, and to fully understand the potential health effects of chronic or intermittent exposure to indoor air with higher CO2 concentrations. A review of studies on exposure to elevated CO2 concentrations in air suggests that health damages, such as inflammation or reductions in cognitive abilities, can occur at levels as low as 1,000 ppm.

Characteristics of patients with endometrial hyperplasia under different air quality index conditions

ObjectiveAir pollution has been widely recognized to pose a threat to health. Urban outdoor air pollution was listed as the 14th biggest risk factor for global deaths in 2004 in the Global Health Risks report published by the World Health Organization in 2009. Many past studies have indicated that exposure to environmental contaminants promotes changes in the internal mechanisms of diseases, including the infection of various systems in the body, hormonal changes, and vascular proliferation. These changes may be related to the severity of endometrial hyperplasia. Therefore, this study used the air quality monitoring data of the Environmental Protection Administration (EPA) to examine the effects of air pollutant concentration on patients with endometrial hyperplasia. Materials and methodsThis population-based nationwide study used data for 2002–2013 from the National Health Insurance Research Database of Taiwan. Patients who developed endometrial hyperplasia before 2002 were excluded. In total, 14,883 patients with endometrial hyperplasia were tracked. The exposure levels and air quality index (AQI) values in this study were based on the taiwan air quality monitoring network data collected by the EPA from 2000 to 2013. The data were further divided into the good air quality group (AQI ≤ 50) and poor air quality group (AQI > 50). The study used linear regression model to estimate the correlation linking air pollutant concentration with endometrial hyperplasia. ResultsThe results indicated that, in comparison to endometrial hyperplasia patients who were exposed to air with good quality, those exposed to air with poor quality had a higher average age (p < 0.001) and higher proportion of living in southern Taiwan (p < 0.001), as well as higher rates of diabetes (p < 0.001), hyperlipidemia (p < 0.001), hypertension, cerebrovascular diseases (p = 0.024), cerebral vascular accidents (p = 0.024), and chronic kidney disease (p < 0.001). ConclusionThe patients with endometrial hyperplasia in poor AQI area had severe comorbidity. Thus, attention must be paid to the improvement of air quality and the implementation of preventive measures against contaminants.

Outdoor Air Pollution and Lung Function in Middle-Aged Adults of the ELISABET Study

The impact of long-term exposure to outdoor air pollution on lung function remains insufficiently studied in adults. Our aim was to study the associations between long-term exposure to outdoor air pollution, including industrial and urban exposures, and lung function in middle-aged adults.The analyses were conducted among 2994 adults (53 years old in average, 47% men) from the Enqu&amp;#234;te Littoral Souffle Air Biologie Environment (ELISABET, 2011-2013), a French cross-sectional survey. Air pollutant levels (NO2, PM10 and SO2) were estimated at the participants&amp;#8217; residential address by ATMO Nord-Pas-de-Calais, in Lille and Dunkirk urban areas. The lung function tests were performed according to the ATS/ERS guidelines, and FEV1 (Forced Expiratory Volume in one second), FVC (Forced Vital Capacity), FEV1/FVC ratio and FEF25-75 (Forced Expiratory Flow between 25 and 75% of the FVC) were used. Linear regression models adjusted for age, sex, height, year of inclusion, center, investigator, smoking status, body mass index, educational level and occupational exposure to dusts and fumes were conducted.An increase of 5 µg/m3 in NO2 was associated with lower FEV1 (&amp;#8211;1.37%, 95%CI &amp;#8211;2.05 to &amp;#8211;0.69), lower FVC (&amp;#8211;0.84%, 95%CI &amp;#8211;1.45 to &amp;#8211;0.23), lower FEV1/FVC (&amp;#8211;0.47%, 95%CI &amp;#8211;0.77 to &amp;#8211;0.17) and lower FEF25-75 (&amp;#8211;2.71%, 95%CI &amp;#8211;4.20 to &amp;#8211;1.21). An increase of 2 µg/m3 in PM10 was associated with lower FEV1 (&amp;#8211;1.31%, 95%CI &amp;#8211;2.06 to &amp;#8211;0.55), lower FVC (&amp;#8211;0.81%, 95%CI &amp;#8211;1.49 to &amp;#8211;0.13), lower FEV1/FVC (&amp;#8211;0.43%, 95%CI &amp;#8211;0.77 to &amp;#8211;0.10) and lower FEF25-75 (&amp;#8211;2.44%, 95%CI &amp;#8211;4.10 to &amp;#8211;0.78). An increase of 2 µg/m3 in SO2 was associated with lower FEV1 (&amp;#8211;1.33%, 95%CI &amp;#8211;2.27 to &amp;#8211;0.39), lower FEV1/FVC (&amp;#8211;0.52%, 95%CI &amp;#8211;0.92 to &amp;#8211;0.11), lower FEF25-75 (&amp;#8211;2.70%, 95%CI &amp;#8211;4.82 to &amp;#8211;0.59), but was not significantly associated with lower FVC (&amp;#8211;0.77%, 95%CI &amp;#8211;1.62 to 0.09).Our results add evidence of the impact of urban and industrial outdoor air pollution on lung function in adults from northern France.

Optimization-aided calibration of an urban microclimate model under uncertainty

Simulation models play an important role in the design, analysis, and optimization of modern energy and environmental systems at building or urban scale. However, due to the extreme complexity of built environments and the sheer number of interacting parameters, it is difficult to obtain an accurate representation of real-world systems. Thus, model calibration and uncertainty analysis hold a particular interest, and it is necessary to evaluate to what degree simulation models are imperfect before implementing them during the decision-making process. In contrast to the extensive literature on the calibration of building performance models, little has been reported on how to automatically calibrate physics-based urban microclimate models. This paper illustrates a general methodology for automatic model calibration and applies it to an urban microclimate system. The Urban Weather Generator (UWG) is selected as the underlying simulation engine for an optimization-aided calibration based on the urban outdoor air temperature in an existing district area located in downtown Abu Dhabi (UAE) during 2017. In particular, given the time-constrained nature of engineering applications, an online hyper-heuristic evolutionary algorithm (EA) is proposed and developed in order to accelerate the calibration process. The validation results show that, in single-objective optimization, the online hyper-heuristics could robustly help EA produce quality solutions with smaller uncertainties at much less computational cost. In addition, the resulting calibrated solutions are able to capture weekly-average and hourly diurnal profiles of the urban outdoor air temperature similar to the measurements for certain periods of the year.

Outdoor environment, ozone, radionuclide-associated aerosols and incidences of infantile eczema in Minsk, Belarus.

The early occurrence of atopic dermatitis in infants may be influenced by urban air pollution. The aim of this study was to determine the relationship between incidences of infantile eczema in children under 2years of age and urban outdoor environmental factors. A 11-year population-based study was conducted in retrospective design. The age/gender-adjusted incidence rates of infantile eczema were determined using the data of outpatient visits. We analysed 1965 cases with atopic dermatitis including infantile eczema in relation to the annual means of outdoor monitoring data from 2005 through 2015 in Minsk. Logistic regression and principal component analysis were performed to determine association between the annual means of air pollutants, meteorological variables and incidences of infantile eczema. Higher mean annual carbon monoxide, ammonia, formaldehyde, lead, particulate matter and ground-level ozone were associated with high incidence rates of infantile eczema both in boys and girls. Higher nitrogen dioxide was associated with high incidence rates of infantile eczema in girls 1-2years of age and boys 0-2years of age. There were identified by principal component analysis five combinations of pollutants and meteorological factors. High incidence rates of infantile eczema were associated with the combinations contained higher levels of air pollutants and ultraviolet index, or lower β-activity of the radionuclide-associated aerosols. The higher phenol and formaldehyde levels the higher incidence rates of infantile eczema were observed among boys 0-1years of age and girls 1-2years of age. The higher total column ozone with lower lead level was associated with low incidence rates of infantile eczema among boys and girls 1-2years of age. Urban outdoor air pollutants and their combination with meteorological conditions may impact onset of infantile eczema in both genders.

Concentrations and variability of organophosphate esters, halogenated flame retardants, and polybrominated diphenyl ethers in indoor and outdoor air in Stockholm, Sweden

We investigated the concentrations and temporal variability of organophospate esters (OPEs), halogenated flame retardants (HFRs) and polybrominated diphenyl ethers (PBDEs) in indoor and outdoor urban air in Stockholm, Sweden over one year (2014–2015) period. The median concentrations of the three target chemical groups (OPEs, HFRs, PBDEs) were 1–2 orders of magnitude higher in indoor air than outdoor urban air. OPEs were the most abundant target FRs with median concentrations in indoor (Σ10OPE = 340 000 pg/m3) and outdoor urban (Σ10OPEs = 3100 pg/m3) air, being 3 orders of magnitude greater than for HFRs in indoor (Σ15HFRs = 120 pg/m3) and outdoor urban (Σ15HFRs = 1.6 pg/m3) air. In indoor air, PBDE concentrations (Σ17PBDEs = 33 pg/m3) were lower than for the HFRs, but in outdoor urban air, concentrations (Σ17PBDEs = 1.1 pg/m3) were similar to HFRs. The most abundant OPEs in both the indoor and outdoor urban air were tris(2-butoxyethyl)phosphate (TBOEP), tris(chloroisopropyl)phosphate (TCIPP), tris(2-chloroethyl)phosphate (TCEP), tri-n-butyl-phosphate (TnBP), triphenyl phosphate (TPhP) and tris(1,3-dichloroisopropyl)phosphate (TDCIPP). TCIPP in indoor air was found in the highest concentrations and showed the greatest temporal variability, which ranged from 85 000 to 1 900 000 pg/m3 during the one-year sampling period. We speculate that activities in the building, e.g. floor cleaning, polishing, construction, introduction of new electronics and changes in ventilation rate could explain its variation. Some OPEs (TnBP, TCEP, TCIPP, TDCIPP and TPhP), HFRs/PBDEs (pentabromotoluene, 2, 3-dibromopropyl 2, 4, 6-tribromophenyl ether, hexabromobenzene, BDE-28, -47, and -99) in outdoor urban air showed seasonality, with increased concentrations during the warm period (p < 0.05, Pearson's r ranged from −0.45 to −0.91). The observed seasonality for OPEs was probably due to changes in primary emission, and those for the HFRs and PBDEs was likely due to re-volatilization from contaminated surfaces.

Airborne ultrafine particles in a naturally ventilated metro station: Dominant sources and mixing state determined by particle size distribution and volatility measurements

Ultrafine particle number concentrations and size distributions were measured on the platform of a metro station in Athens, Greece, and compared with those recorded at an urban background station. The volatility of the sampled particles was measured in parallel, providing further insights on the mixing state and composition of the sampled particles. Particle concentration exhibited a mean value of 1.2 × 104 # cm−3 and showed a weak correlation with train passage frequency, but exhibited a strong correlation with urban background particle concentrations. The size distribution appears to be strongly influenced by outdoor conditions, such as the morning traffic rush hour and new particle formation events observed at noon. The aerosol in the metro was externally mixed throughout the day, with particle populations being identified (1) as fully refractory particles being more dominant during the morning traffic rush hours, (2) as core-shell structure particles having a non-volatile core coated with volatile material, and (3) fully volatile particles. The evolution of particle volatility and size throughout the day provide additional support that most nanoparticles in the metro station originate from outdoor urban air.

Severe Urban Outdoor Air Pollution and Children's Structural and Functional Brain Development, From Evidence to Precautionary Strategic Action.

According to the latest estimates, about 2 billion children around the world are exposed to severe urban outdoor air pollution. Transdisciplinary, multi-method findings from epidemiology, developmental neuroscience, psychology, and pediatrics, show detrimental outcomes associated with pre- and postnatal exposure are found at all ages. Affected brain-related functions include perceptual and sensory information processing, intellectual and cognitive development, memory and executive functions, emotion and self-regulation, and academic achievement. Correspondingly, with the breakdown of natural barriers against entry and translocation of toxic particles in the brain, the most common structural changes are responses promoting neuroinflammation and indicating early neurodegenerative processes. In spite of the gaps in current scientific knowledge and the challenges posed by non-scientific issues that influence policy, the evidence invites the conclusion that urban outdoor air pollution is a serious threat to healthy brain development which may set the conditions for neurodegenerative diseases. Such evidence supports the perspective that urgent strategic precautionary actions, minimizing exposure and attenuating its effects, are needed to protect children and their brain development.