Ambient NO2 Research Articles

Association between ambient air pollution and pregnancy outcomes in patients undergoing in vitro fertilization in Shanghai, China: A retrospective cohort study

BackgroundThe effects of ambient air pollutants on adverse pregnancy outcomes have been reported. However, studies about air pollutants exposure and pregnancy outcomes in patients undergoing IVF were limited and inconclusive. To date Shanghai has been the only city in China to implement a compulsory single embryo transfer policy for all patients undergoing their first embryo transfer procedure effective from January 2019. We aimed to investigate the associations between exposure to ambient air pollutants and biochemical pregnancy and live births, and to identify potential vulnerability characteristics of patients undergoing IVF in Shanghai, China. MethodsA retrospective cohort study was conducted on 2766 infertile patients aged ≤ 45 years who underwent first fresh or frozen-thawed cleavage stage embryo transfer in the Shanghai First Maternity and Infant Hospital during April 2016 and December 2019. Daily average ambient levels of six air pollutants (PM2.5, PM10, NO2, SO2, CO and O3 max-8h) were obtained from fixed air monitors located in closest proximity to patients’ residences. The cumulative average level was calculated during three different exposure periods (period1: three months before oocyte retrieval to serum hCG test; period 2: from serum hCG test to live birth outcome; period 3: from three months before oocyte retrieval to live birth). Multiple logistic regression model was performed to investigate associations between exposure to ambient air pollutants and pregnancy outcomes. Stratified analyses were conducted to explore the potential effects modifier. ResultsThe biochemical pregnancy rate and live birth rate were 54.2% and 36.4%, respectively. The ambient NO2 exposure was significantly associated with a 14% lower pregnancy rate during period 1 (aOR = 0.86, 95%CI: 0.75–0.99). The ambient PM10 was related to significantly increased risk of lowering live birth rate among the patients during period 3 [aOR = 0.88(0.79–0.99)]. Stratified analysis showed that ambient PM10 was also significantly associated with a reduced pregnancy rate (aOR = 0.82, 95% CI: 0.69–0.97) in patients who underwent single embryo transfer during period 1. Subjects who underwent single embryo transfer also had a decreased likelihood of a live birth when exposed to ambient SO2 and O3 during period 3 [aOR = 0.74(0.57–0.95), and 0.92 (0.83–0.98), respectively]. Moreover, O3 exposure was associated with decreased live birth rates in patients living in non-urban areas. Sensitivity analyses indicated robust negative association between PM10 exposure and live birth outcomes. ConclusionsOur study suggested that exposure to ambient air pollutants, in particular NO2 and PM10, was associated with an increased risk of lower rates of pregnancy and live birth respectively in patients undergoing IVF. Stratified analyses indicated that ambient SO2 and O3 levels were related to adverse pregnancy outcomes in some subgroups of IVF patients in this study. Notably, patients who underwent single embryo transfer were more susceptible to ambient air pollution exposure. Thus, prospective cohort studies are needed to investigate the underlying mechanisms and the susceptibility windows for women undergoing IVF treatment.

"Freedom to Breathe": Youth Participatory Action Research (YPAR) to Investigate Air Pollution Inequities in Richmond, CA.

Air pollution is a major contributor to human morbidity and mortality, potentially exacerbated by COVID-19, and a threat to planetary health. Participatory research, with a structural violence framework, illuminates exposure inequities and refines mitigation strategies. Home to profitable oil and shipping industries, several census tracts in Richmond, CA are among the most heavily impacted by aggregate burdens statewide. Formally trained researchers from the Center for Environmental Research and Children’s Health (CERCH) partnered with the RYSE youth justice center to conduct youth participatory action research on air quality justice. Staff engaged five youth researchers in: (1) collaborative research using a network of passive air monitors to quantify neighborhood disparities in nitrogen dioxide (NO2) and sulfur dioxide (SO2), noise pollution and community risk factors; (2) training in environmental health literacy and professional development; and (3) interpretation of findings, community outreach and advocacy. Inequities in ambient NO2, but not SO2, were observed. Census tracts with higher Black populations had the highest NO2. Proximity to railroads and major roadways were associated with higher NO2. Greenspace was associated with lower NO2, suggesting investment may be conducive to improved air quality, among many additional benefits. Youth improved in measures of empowerment, and advanced community education via workshops, Photovoice, video, and ”zines”.

Investigation of the Effect of Aerosolized TiO2 Nanoparticles on the NO2 Concentrations under UVA Exposure

ABSTRACT Engineered nanomaterials (ENM) are utilized and produced during many engineering processes. However, they may generate airborne nanoparticles during different phases of their life cycles. TiO2, which is known for its photocatalytic properties, especially in terms of degrading NO2, is one of the most widely produced ENM. Ambient NO2 stems mainly from vehicular and industrial combustion processes and potentially harms human health upon inhalation. This study investigated the photocatalytic reduction of NO2 due to varying concentrations of aerosolized TiO2 nanoparticles during varying levels of ultraviolet A (UVA) exposure. Additionally, we evaluated the effects of low (5%), moderate (35%), and high (70%) relative humidity. Our results demonstrated that the decrease in NO2 depended on both the TiO2 concentration and the UVA intensity. However, when the former was high (> 3.23E+06 cm–3), the contribution of the latter was negligible. On the other hand, when the latter was high, the influence of the former was minimal. Furthermore, as the UVA exposure increased in duration, its effect became dominant over that of the TiO2 concentration. Finally, we found the relative humidity to be an insignificant factor during conditions with strong UVA (6328 W s m–2).

From South Asia to the world: embracing the challenge of global sustainable nitrogen management

From South Asia to the world: embracing the challenge of global sustainable nitrogen management

Covid-19 mobility restrictions: impacts on urban air quality and health.

In 2020, Covid-19-related mobility restrictions resulted in the most extensive human-made air-quality changes ever recorded. The changes in mobility are quantified in terms of outdoor air pollution (concentrations of PM2.5 and NO2) and the associated health impacts in four UK cities (Greater London, Cardiff, Edinburgh and Belfast). After applying a weather-corrected machine learning (ML) technique, all four cities show NO2 and PM2.5 concentration anomalies in 2020 when compared with the ML-predicted values for that year. The NO2 anomalies are –21% for Greater London, –19% for Cardiff, –27% for Belfast and –41% for Edinburgh. The PM2.5 anomalies are 7% for Greater London, –1% for Cardiff, –15% for Edinburgh, –14% for Belfast. All the negative anomalies, which indicate air pollution at a lower level than expected from the weather conditions, are attributable to the mobility restrictions imposed by the Covid-19 lockdowns. Spearman rank-order correlations show a significant correlation between the lowering of NO2 levels and reduction in public transport (p < 0.05) and driving (p < 0.05), which is associated with a decline in NO2-attributable mortality. These positive effects of the mobility restrictions on public health can be used to evaluate policies for improved outdoor air quality.Policy RelevanceFinding the means to curb air pollution is very important for public health. Empirical evidence at a city scale reveals significant correlations between the reduction in vehicular transport and in ambient NO2 concentrations. The results provide justification for city-level initiatives to reduce vehicular traffic. Well-designed and effective policy interventions (e.g. the promotion of walking and cycling, remote working, local availability of services) can substantially reduce long-term air pollution and have positive health impacts.

Absorption Efficiency Assessment and Uncertainty Measurement of the Sodium Arsenite Method for Ambient NO2 Determination

The absorption efficiency and uncertainty involved in the sodium arsenite method (modified Jacobs and Hochheiser method) of NO2 measurement were studied using two standard gas concentrations (4.86 ± 0.10 µmol mol–1 (ppm) and 1.95 ± 0.10 µmol mol–1 (ppm)). An average of 71 ± 3% and 71 ± 6% absorption efficiencies, respectively were observed against reported efficiency of 82% in the published standard (IS 5182 (Part 6): 2006, BIS, 2006a) in 1-impinger system at sampling flow rate of 1 L min–1 and absorbing solution temperature of 10–15°C during gas absorption in impinger. The difference is accounted for by the variation in flow rate used in present study (1 L min–1) and that in standard method (0.2 L min–1). Uncertainty involved in the method was calculated considering a range of factors directly or indirectly affecting the measurement and was found to be 15%. Based on the comparison study performed for NO2 ambient measurements using an equivalent method (chemiluminescence continuous method) and 1-impinger system reference method, the present study highlights the importance of accurate determination of absorption efficiency factor in the NO2 pollutant measurement at laboratory level. Variations observed in the absorption efficiency and the data from inter-comparison study between manual and real-time method warranted this study to be taken up to provide solutions for improvement of the method. The use of at least three absorbers/impingers (connected in series) instead of one to obtain absorption efficiency close to unity is proposed to make the reference method independent from the use of absorption efficiency factor thus ensuring the improved data quality and comparability.

High-efficiency nitrate electroreduction to ammonia on electrodeposited cobalt-phosphorus alloy film.

Electrocatalytic eight-electron nitrate (NO3-) reduction is a sustainable strategy to degrade NO3- and convert it into high value-added ammonia (NH3) but needs efficient catalysts with high activity and selectivity. Our study shows the use of Ti plate supported cobalt-phosphorus alloy film (Co-P/TP) as a highly active and selective electrocatalyst for ambient NO3--to-NH3 conversion. In 0.2 M Na2SO4 with 200 ppm NO3-, Co-P/TP offers an NH3 yield rate of 416.0 ± 7.2 μg h-1 cm-2 and a high faradaic efficiency of 93.6 ± 3.3% at -0.6 V and -0.3 V vs. reversible hydrogen electrode, respectively, with good durability. Noticeably, a conversion rate of 86.9% is achieved after 10 h bulk electrolysis.

Associations between total mortality and personal exposure to outdoor-originated NO2 in 271 Chinese cities

Epidemiological studies have reported significant associations of outdoor NO2 with daily mortality. These studies used ambient NO2 concentrations as a proxy of personal exposure of outdoor-originated NO2 (PEO NO2), which may lead to biased health effect estimates. This study was aiming to explore whether modified outdoor NO2 exposure can reduce this error. We performed a Monte Carlo simulation to estimate the outdoor-originated NO2 concentration in residential buildings in 271 Chinese cities from 2013 to 2015, and then PEO NO2 was obtained according to time-activity-location patterns of people. We adopted a typical time-series analysis to compare the mortality associations between PEO and outdoor NO2. The averaged concentrations of PEO and outdoor NO2 were 16.5 μg/m3 and 31.6 μg/m3, respectively. PEO NO2 showed a better model fitting and larger effect for its daily mortality association. A 10 μg/m3 increase in two-day moving average concentration of PEO and outdoor NO2 was associated with a 2.08% (1.70%, 2.45%) and 1.03% (0.83%, 1.22%) increase in total mortality, respectively. Our study revealed that personal exposure to NO2 modified from outdoor NO2 concentrations may better reflect the health effects of air pollutants, and such evidence might be useful for future policy making and air pollution regulations.

Lockdowns and reduction of economic activities during the COVID-19 pandemic improved air quality in Alexandria, Egypt.

Parallel reductions in atmospheric aerosols (particulate matter (PM)) and nitrogen dioxide (NO2) accompanied the drastic measures that were adopted to limit the spread of COVID-19. The results of this preliminary study conducted in northern Egypt revealed that ambient PM10, PM2.5, and NO2 levels decreased by 22.8%, 29.3%, and 25.9%, respectively, after the lockdown started on March 13, 2020. These reductions in concentrations significantly (p ˂ 0.01) correlated with the decrease in transportation and industrial and other economic activities. Furthermore, PM and NO2 concentrations radically reduced during the full lockdown on Easter, Ramadan, and Eid Al-Fitr. The findings of this study will help the World Health Organization (WHO) and other health regulators to combat COVID-19 in the world. This study is part of an ongoing research related to the current pandemic.

The effect of weather, air pollution and seasonality on the number of patient visits for epileptic seizures: A population-based time-series study

ObjectiveThe objective of the study was to explore the influences of seasonality, meteorological conditions, and air pollution exposure on the number of patients who visit the hospital due to seizures. MethodsOutpatient and inpatient data from the National Health Insurance Database of Taiwan from 2009 to 2013, meteorological data from the Meteorological Bureau, and air pollution exposure data from the Taiwan Air Quality Monitoring Stations were collected and integrated into daily time series data. The following data processing and analysis results are based on the mean of the 7 days' lag data of the 18 meteorological condition/air pollution exploratory factors to identify the critical meteorological conditions and air pollution exposure factors by executing univariate analysis. The average hospital visits for seizure per day by month were used as an index of observation. The effect of seasonality has also been examined. ResultsThe average visits per day by month had a significant association with 10 variables. Overall, the number of visits due to these factors has been estimated to be 71.529 (13.7%). The most obvious factors affecting the estimated number of visits include ambient temperature, CH4, and NO. Six air pollutants, namely CH4, NO, CO, NO2, PM2.5, and NMHC had a significantly positive correlation with hospital visits due to seizures. Moreover, the average daily number of hospital visits was significantly high in January and February (winter season in Taiwan) than in other months (R2 = 0.422). ConclusionThe prediction model obtained in this study indicates the necessity of rigorous monitoring and early warning of these air pollutants and climate changes by governments. Additionally, the study provided a firm basis for establishing prediction models to be used by other countries or for other diseases.

In vitro investigation of the Flusso™ Bypass adapter efficiency upon ventilator circuit disconnect in a clinical simulated environment.

RationaleMechanically ventilated patients must be disconnected from the ventilator during intra-facility transfers. Intentional and accidental circuit disconnections represent a potential hazard to patients (sudden collapse and re-expansion of the alveoli) as well as to clinical staff (exposure to patient’s unfiltered exhalation). Therefore, avoiding abrupt circuit disconnections could better protect the patient’s health and reduce or eliminate contamination risks around clinical staff.ObjectiveThe purpose of this in-vitro work was to investigate and evaluate the potential for environmental exposure of Nitric Oxide (NO, as an indicator of any contamination exposure) before and after implementing the novel Flusso™ Bypass adapter during the disconnect procedure of a mechanical ventilator system.MethodsA mechanical ventilator delivering NO was connected to a breathing simulator with and without the Flusso™ Bypass adapter. The ambient NO concentration was measured when the circuit was briefly disconnected (3 s) during inhalation and exhalation. Both volume and pressure ventilation modes were used.Measurements and main resultsDisconnecting the standard ventilator circuit (pressure-controlled mode) without the Flusso™ Bypass adapter produced higher NO escape to the surroundings (compared with the volume-controlled mode), leading to a longer NO dissipation time. No ambient NO traces were detected when the Flusso™ adapter was used.ConclusionThe usage of the Flusso™ adapter drastically decreases the unwanted exposure among clinical staff dealing with potentially hazardous airborne biological aerosols emanating from the circuit. Avoiding abrupt disconnection in the ventilator circuit could reduce lung injuries and alveolar over distension and collapse.

NO2 Removal by Adsorption on Transition-Metal-Based Layered Double Hydroxides

The emission of nitrogen dioxide (NO2) has caused severe air pollution and threatened the safety of the environment and people’s health. Various techniques have been intensively explored for the abatement of NO2, mostly on the basis of catalytic reduction at elevated temperature, but few have shown satisfactory NO2 removal efficiency at ambient conditions. The use of solid porous adsorbents is a promising approach for NO2 removal due to their high capacity and low energy penalty for regeneration. Here, we report the uncalcined transition-metal-based layered double hydroxides (TM–Al–CO3 LDHs) as ambient NO2 adsorbents. The dynamic breakthrough experiments demonstrated that Ni–Al–CO3 LDH showed a superior NO2 adsorption capacity above 5.3 mmol g–1 and the lowest NO generation ratio (∼31.7% of the total NO2 input) among the four TM–Al–CO3 adsorbents. The in situ diffuse reflectance infrared Fourier transform spectroscopy disclosed the reactive adsorption mechanism between NO2 and LDHs via acid–base interaction. The reversibility of active adsorption sites in Ni–Al–CO3 LDH could maintain over 74% after six adsorption–desorption cycles, suggesting a decent regenerability of Ni–Al–CO3 as the NO2 adsorbent.

Short-Term Associations of Nitrogen Dioxide (NO2) on Mortality in 18 French Cities, 2010–2014

We present an analysis of short-term associations between ambient NO2 and mortality according to cause, age-group, and period (cold and warm) in 18 areas in metropolitan France for the 2010–2014 period. Associations were estimated in each area using a generalized additive Poisson regression model, and effects were summarized in a meta-analysis. The percentage increase in mortality rate was estimated for a 10 µg m−3 increase in the NO2 level in each area for each complete calendar year and for cold (November to April) and warm periods (May to October) in each year. We found that the NO2 increase (lag of 0–1 days) was associated with a 0.75% increase of non-accidental mortality for all age-groups (95% confidence interval (CI): (0.4; 1.10)). During the warm period, this NO2 increase was associated with a 3.07% increase in non-accidental mortality in the ≥75 years old group (95% CI: 1.97; 4.18). This study supports the short-term effects of NO2 as a proxy of urban traffic pollution on mortality, even for concentrations below the maximum guideline of 40 µg m−3 set down by the European Air Quality Standards and the World Health Organization (WHO).

Assessment of Ambient Air Quality around Ihetutu Minefield, Ishiagu, Nigeria

This study assessed the levels of physicochemical characteristics and heavy metals in ambient air around Ihetutu community in Ishiagu, Nigeria, to evaluate the impact of prolonged Pb-Zn mining and several other related activities on air quality in the area. Particulates, heavy metals, microclimatic and gaseous parameters in ambient air were analyzed for the assessment. Sampling and quality measurements were done during rainy, late rainy, dry and late dry seasons between 2018 and 2019, from study and control areas. Samples were analyzed for particulates and heavy metals in the laboratory while microclimatic and gaseous parameters were measured in-situ using standard field equipment and procedures. Mean and seasonal concentrations of parameters were determined to evaluate the ambient air quality at various locations in the study area. Results showed high mean values of some parameters including; ambient temperature (35.19oC), Relative Humidity (65.78%), SO2 (0.33ppm), NO2 (0.30ppm), PM10 (89.73µg/m3), Cu (0.03mg/L), Zn (0.06mg/L), Fe (0.39mg/L), Mn (2.28mg/L), Ni (0.04mg/L) and Pb (0.05mg/L). Highest Noise level in the study area was 60.40 dB(A). SO2 and NO2 were below detection limits during the dry seasons, but with mean levels above daily average limits of DPR, NESREA, and WHO, due to their high levels during the rainy seasons, except at Amaonye Square. CO mean levels were above FMEnv daily average limit but within DPR limit. PM10 mean values were within NESREA recommended daily average limit while dry season values were above. Zn and Fe pollution along the stations were in the order of SAS3&gt;SAS4&gt;SAS5, while Pb pollution was SAS3&gt;SAS4=SAS5. Generally, trend of heavy metal pollution was Mn&gt;Fe&gt;Pb&gt;Zn&gt;Cd=Cu=Ni. Highest positive correlation within the heavy metals was between Zn and Fe (r = 1.000). There were also no statistically significant differences in means of the parameters among sampling stations (p&gt;0.05). The results revealed pollution of ambient air in the area by heavy metals and gaseous substances, especially around the mining sites and high traffic areas. Proper monitoring of the operations of mining companies and other artisan activities is recommended, to ensure that ambient air status in the area is excellent and within standard guidelines.

Contrasting stream nitrate and sulfate response to recovery from experimental watershed acidification

Improvements in air quality have led to ecosystem recovery from acidic deposition, but the mechanisms and trajectories of this recovery are not fully understood. Here, we present long-term stream response and recovery data for paired watersheds at the Bear Brook Watershed in Maine (BBWM) during declining ambient SO4 and NO3 in precipitation. East Bear (EB) received ambient deposition from 1989 to 2018; West Bear (WB) received artificially elevated N + S from 1989 to 2016. The WB treatment was discontinued after 2016, the beginning of the recovery from both the experimental N + S and ambient decline. Stream SO4 in WB gradually declined after the treatment ended, from ~147 μeq L−1 in 2010–16 to ~126 μeq L−1 in 2017–18. The declining S inputs induced desorption of SO4 from soil phase surfaces, with stream loss far exceeding precipitation input. At the current rate of recovery, it will be many decades before the WB stream returns to pre-treatment SO4 concentrations. In contrast, NO3 is only weakly adsorbed in soil, and WB stream NO3 concentrations rapidly declined from ~39 μeq L−1 in 2010–16 to ~5 μeq L−1 in 2017–18, comparable to the N-limited EB stream. The acid anions are strongly coupled to base cation chemistry in streams, and there was a distinct hysteretic response of Ca and Mg to the chronic acidification, as (Ca + Mg) increased rapidly during the initial years, followed by declining values due to depletion of the soil exchange complex. This 30-year monitoring study (1989–2019) provides insights into recovery mechanisms from acidic deposition and highlights the role of abiotic processes in soil that mediate nutrient cycling and retention. Documenting the rapid response of N alongside the slower recovery for S identifies the temporal resolution necessary for other whole-watershed recovery studies.

Lower placental iodine concentrations are linked with higher concentrations of ambient PM2.5 exposure during the last trimester of pregnancy.

Background - The essential trace element iodine is needed for an optimal (neuro)-development of the fetus via the production of thyroid hormones. Recent findings indicate that exposure to ambient air pollution was linked with mild thyroid dysfunction during pregnancy. We hypothesize that air pollution might alter the placental iodine concentrations during gestation. Methods -We determined the placental iodine concentrations in 470 mother newborn pairs included in the ENVIRONAGE birth cohort. Maternal residential PM2.5 (particulate matter with a diameter &lt; 2.5 µm), NO2, and black carbon concentrations were determined during the pregnancy using a high-resolution air pollution model. Using distributed lag nonlinear models (DLNM), we modeled the gestational week-specific association between placental iodine concentrations and air pollutants. Results - Significant inverse associations were observed between gestational exposure to PM2.5 at weeks 28 to 35 and placental iodine concentrations. Cumulative estimates over the trimesters of pregnancy showed that in the third trimester of pregnancy (week 27 until delivery) an increase of 5 µg/m³ in PM2.5 exposure was associated with a decrease of 0.85 µg/kg in placental iodine concentration (95%CI: -1.56 to -0.14). These associations were adjusted for maternal pre-pregnancy BMI, gestational weight gain, household smoking behavior, maternal alcohol consumption, maternal education, maternal age, vitamin use, gestational age, date and season at delivery, and newborns’ sex. No significance was found between placental iodine load and the ambient NO2 or black carbon exposure.Conclusions- Gestational exposure to PM2.5 is linked with a lower placental iodine concentration. This decrease indicates that ambient air pollution might interfere with the normal uptake mechanisms of iodine, which could results in worse neurocognitive health outcomes later in life.

Long-term trends in NO2 exposure and associated pediatric asthma impacts in urban areas worldwide

Recent meta-analyses of epidemiological studies conducted in North America, Latin America, Europe, and East Asia show that traffic-related nitrogen dioxide (NO2) pollution is associated with pediatric asthma incidence. Using concentration-response relationships from these meta-analyses, traffic-related NO2 has been estimated to be responsible for 13% (~4 million) of new pediatric asthma cases globally. The objective of this study is to estimate surface ambient annual average NO2 concentrations and associated pediatric asthma burdens from 2005 to 2019 in urban areas worldwide. We estimate 15-year trends in population exposure to NO2 with global coverage at 1km resolution using 2010-2012 NO2 concentrations from a previously published land use regression model, along with satellite remote sensing observations of NO2 columns from the Ozone Monitoring Instrument. We use epidemiologically-derived concentration-response factors to estimate temporal trends in NO2-attributable pediatric asthma incidence in hundreds of cities worldwide. Results include 2005-2019 trends in NO2 concentrations and the associated burden on pediatric asthma incidence in major cities around the world, including major reductions in places with strong emission regulations and increases in areas experiencing rapid economic growth without effective emission controls. Results may be informative for data-driven decision-making about mitigating the public health impacts of air pollution in urban areas, where two-thirds of the global population is expected to live by 2050.

Prenatal Ambient Air Pollutants Influence Fetal Blood Flow and Shunting to the Brain in the Third Trimester

Background: Prenatal exposure to air pollutants has been associated with numerous adverse fetal outcomes.Objectives: We tested whether air pollutants affect umbilical venous perfusion of the fetal liver and shunting of blood from liver to brain in the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort. We hypothesized prenatal air pollution exposure contributes to an adverse intrauterine environment and alters fetal blood flow by shunting less blood to the liver and more to the brain. Methods: Daily estimates of ambient air pollutants NO2, PM10, PM2.5 and O3 were spatially interpolated at each participant’s residence. Prenatal average exposures were calculated from the date of conception to the date of ultrasound. Doppler ultrasound measurements were performed between 30-34 weeks’ gestation for 102 participants by a certified obstetrics sonographer to determine the proportion of umbilical vein (UVf) blood flowing to the ductus venosus (DVf) or the fetal liver (FLf) in ml/min. Shunting was calculated as the proportion of blood flow, DVf/ UVf. Linear regression models were used to evaluate the associations between single pollutants and UVf, DVf, FLf, and DVf/ UVf adjusting for covariates.Results: Mean maternal age was 28 (6) years and gestational age at study visit was 31.7 (1.1) weeks. PM10 and PM2.5 were significantly associated with DVf (β = 9.4 and 5.1, p &lt; 0.0001, p=0.04 for a 1 SD change in pollutant) and with shunting (β = 3.3 and 0.20, p &lt; 0.0001, p=0.02). Daily 8hr maximum O3 and 24hr average O3 were associated with DVf (β = 7.1, 5.8, p =0.003, 0.02) and 8hr maximum O3 with shunting (β =1.7, p= 0.04).Conclusions: Prenatal air pollutant exposure was associated with blood flow in the ductus venosus and shunting of blood from liver to brain, the long-term consequences of which remain unknown.

Spatial-temporal levels, variations and sources of NO2/NOx in the sub-Saharan African city of Accra, Ghana

Background. As the world’s fastest urbanizing region, rapid economic growth in Sub-Saharan Africa (SSA) is raising levels of urban air pollution from diverse local and regional sources. While measurement data are now emerging from SSA on particulate matter pollution, there is limited information on major combustion related gaseous pollutants. We examined the levels, spatial, seasonal, and socioeconomic patterns as well as sources of oxides of nitrogen (NOx: NO2/NO) in Accra, Ghana’s capital and one of SSA’s largest metropolitan cities.Methods. We collected weekly integrated ambient NO2 and NOx samples using OGAWA passive samplers at 150 sites, consisting of a year-long (n=10) and week-long (n=140) averages which included a range of land-uses and emissions sources (traffic, biomass).Results. Annual mean NO2 across all sites was 52 µg/m3. Both NO2 and NOx concentrations were highest between November and February, the ‘Harmattan’ period when local and regional meteorology is altered, with means of 73 and 218 µg/m3, respectively, comparing to 47 and 116 µg/m3 during non-Harmattan period. The mean NO2 and NOx levels were highest at roadside sites (82 and 285 µg/m3), followed by residential (46 and 102 µg/m3) and sub-urban background sites (27 and 67 µg/m3). There was no difference between high-density (i.e. low-income and high biomass use) and low-density (i.e. high-income and low biomass use) residential sites. The overall sample mean NO2/NOx ratio was 0.53, varying from 0.35 at roadside sites to 0.63 at residential sites.Conclusions. Traffic is the most important contribution for NOx in Accra, while contribution from biomass burning shows no difference at high- and low-income neighborhoods. NO2/NOx ratios are significantly lower than in North American, European and East Asian cities, indicating a less oxidative atmospheric condition in Accra, especially among traffic sites. “Harmattan” increases local pollution level significantly, possibly by altering local and regional meteorology conditions.

Prenatal Ambient Air Pollutants and Maternal Depressive Symptoms at 12 months Postpartum

Background: Depression is the leading cause of mental health-related morbidity, particularly among women. Ambient air pollutants are modifiable exposures that have increasingly been associated with depression and pregnancy is a period that may increase maternal susceptibility to environmental exposures. We examined whether exposures to prenatal ambient air pollutants are associated with maternal depressive symptoms at 12 months postpartum. Methods: Women participating in the MADRES cohort—an ongoing cohort of predominantly low income, Hispanic women in Los Angeles—were followed from pregnancy through 12 months postpartum with a series of visits and phone calls. At the 12-month study visit, women were orally administered the Center for Epidemiologic Studies-Depression (CES-D) scale as part of a questionnaire on home exposures, social stressors, sociodemographics, and health history. Residential address histories were recorded from one year prior to conception through 12 months postpartum and average ambient pollutant estimates of NO2, PM10, PM2.5 and O3 were spatially interpolated at participants’ residential locations. Logistic regression models were fitted to evaluate associations between trimester-specific and 9-month average levels across pregnancy of ambient air pollutants and probable depression (score of ≥16 on the CES-D) at 12 months postpartum, adjusting for maternal age and recruitment site (N=101). Results: We found that second trimester ambient NO2 levels were associated with a two-fold increased odds of probable depression at 12 months (OR=2.03 per SD increase in NO2 exposure, 95% CI: 1.24, 3.33). Similar results were found for 9-month prenatal average NO2 (OR=1.88, 95% CI: 1.07, 3.32). Prenatal ambient PM10, PM2.5, and O3 levels were not significantly associated with depressive symptoms at 12 months postpartum. Conclusions: Prenatal ambient NO2 levels were associated with increased maternal depressive symptoms at 12 months postpartum. These results underscore the need to better understand the contribution of modifiable environmental risk factors during critical susceptible exposure periods.