How does a 10-fold pulse increase of aircraft-related NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> impact the global burdens of O<Subscript>3</Subscript> and secondary organic aerosol (SOA)?

Aircraft emissions are an important and growing global source of nitrogen oxides (NO _x ). At cruising altitude, the atmosphere is particularly NO _x -sensitive and aircraft emissions contribute to ozone (O₃) production and oxidation of volatile organic pollutants that ultimately produce secondary organic aerosol (SOA). Rapid growth of the global fleet of aircraft and the number of flights require a careful investigation on the atmospheric impact of potential increases in total aircraft-emitted NO _x . In this study, we simulated atmospheric composition before, during and after two 10× pulses of total aircraft NO _x emissions, one in winter and one in summer of 2007. Results showed that the initial NO _x enhancement (up to 3.25% averaged over the globe) was removed after the first 2 months and the change in O₃ burden increases for 5 months (up to 3.1 and 2.7% averaged over the globe, respectively, for winter and summer perturbations). The NO _x and O₃ enhancements follow previously observed temporal patterns, but SOA showed strong season-specific results. During the summer, the NO _x pulse decreased total secondary organic gases (SOGs) and SOA burdens, suggesting an inverse relationship with enhanced oxidation. During the winter, the NO _x pulse increased the SOG and SOA burdens with SOA lagging SOG. The SOG enhancement has a spatio-temporal pattern similar to NO _x . The highest changes in SOA and SOG burdens of different regions during the summer and winter pulse increases were below 1.6%. However, O₃ pollution with burden increases as high as 8% in the winter months and 6% in the summer months of the northern hemisphere may even represent an air quality concern.     

Concentrations of Mercury and Other Inorganic Ions in Wet Precipitation Collected from a Mountain Mining Zone and an Urban Area in Central Mexico

We measured and compared mercury (Hg) and other ions in rainwater collected in San Joaquin (mining zone) and Juriquilla (urban area), central Mexico, from 2009 to 2012. A total of 274 rainwater samples were collected and analyzed for pH, electrical conductivity, \({\text{NO}}_{3}^{ - },\;{\text{SO}}_{4}^{{2 - }},\) Cl^?, \({\text{NH}}_{4}^{+},\) Na⁺, K⁺, Ca²⁺, Mg²⁺ and Hg. Mercury concentrations in rainwater varied from 24.21 to 248.89 (x-bar?=?86.97?±?10.77)?µg?L^??1 in San Joaquin (mining zone) and 11.26 to 176.91 (x-bar?=?81.51?±?10.24)?µg?L^??1 in Juriquilla (urban area). Rainwater sample were collected over periods 1–3?days, depending upon precipitation frequency. Significant correlations (p?<?0.05) were found between \({\text{SO}}_{4}^{{2 - }},\) Cl^?, \({\text{NO}}_{3}^{ - },\) Na⁺, K⁺, Ca²⁺, Mg²⁺ and Hg at the San Joaquin site. Significant correlations were obtained between \({\text{SO}}_{4}^{{2 - }},{\text{NO}}_{3}^{ - },\;{\text{NH}}_{4}^{+},\) Na⁺, K⁺, Ca²⁺, Mg²⁺ and Hg at the Juriquilla site. In order to determine if there were significant differences among each measured parameter in rainwater collected in San Joaquin and Juriquilla, Kruskal–Wallis test was applied to data. We emphasized that the distribution and concentrations of Hg and the studied ions in rainwater samples were affected by atmospheric dust and local meteorological conditions of wind-speed and direction.     

Accountability assessment of regulatory impacts on ozone and PM<Subscript>2.5</Subscript> concentrations using statistical and deterministic pollutant sensitivities

Since the 1990 Clean Air Act Amendments, the USA has seen dramatic decreases in air pollutant emissions from a wide variety of source sectors, which have led to changes in pollutant concentrations: both up and down. Multiple stakeholders, including policy-makers, industry, and public health professionals, seek to quantify the benefits of regulations on air pollution and public health, a major focus of air pollution accountability research. Two methods, one empirical, the other based on a chemical transport model (CTM), are used to calculate the sensitivities of ozone (O₃) and particulate matter with diameters less than 2.5 μ m (PM_2.5) to electricity-generating unit (EGU) and mobile source emissions. Both methods are applied to determine impacts of controls on daily concentrations (which are important in assessing acute health responses to air pollution), accounting for nonlinear, meteorologically, and emission-dependent responses of pollutant concentrations. The statistical method separates contributions of nearby EGU, regional EGU, and mobile source emissions on ambient city-center concentrations. Counterfactual emissions, an estimate of emissions under a scenario where no new controls were implemented on local EGU sources after 1995, regional EGUs after 1997, and mobile sources after 1993, are combined with these sensitivities to estimate counterfactual concentrations that represent what daily air quality in Atlanta, GA would have been had controls not been implemented and other emissions-reducing actions not been taken. Regulatory programs are linked with reduced peak summertime O₃, but have had little effect on annual median concentrations at the city-center monitoring site, and led to increases in pollutant levels under less photochemically-active conditions. The empirical method and the CTM method found similar relationships between ozone concentrations and ozone sensitivity to anthropogenic emissions. Compared to the counterfactual between 2010 and 2013, the number of days on which O₃ (PM_2.5) concentrations exceeded 60 p p b (12.0 μ g m ^?3) was reduced from 396 to 200 (1391 to 222). In 2013, average daily ambient O₃ and PM_2.5 concentrations were reduced by 1.0 p p b (2 %) and 9.9 μ g m ^?3 (48 %), respectively, and fourth highest maximum daily average 8-h O₃ was reduced by 14 p p b. Comparison of model-derived sensitivities to those derived using empirical methods show coherence, but some important differences, such as the O₃ concentration where the sensitivity to NO_x emissions changes sign.     

Influence of different complexity levels of road traffic models on air quality modelling at street scale

Urban mobility accounts for 38 and 19% of nitrogen oxide (NO_x) and particulate matter (PM) emissions at European urban areas, respectively. Despite of all the technological development around automobile industry, urban areas are still facing problems related to exposure to high levels of air pollutants. Increasing the accuracy of both emissions and air quality modelling from road traffic is a key-issue for the management of air pollution in road transport sector. This study assessed the influence of using different road traffic emission models on the accuracy of air quality modelling with street-level resolution, having as a case study an urban area located on the centre region of Portugal. Two emission models, with different complexity levels regarding the ability to characterise the traffic dynamics were analysed, namely, transport emission model for line sources (TREM) and vehicle-specific power (VSP), based on data obtained in an experimental campaign. To perform the air quality simulations, the pollutant dispersion in the atmosphere under variable wind conditions (VADIS) model was used and two pollutants were analysed: NO_x and PM10. The results showed that the magnitude of PM10 and NO_x concentrations were result of a conjoint influence of traffic dynamics and meteorological conditions. Comparison between measured and modelled data showed that the VADIS model could track the evolution of NO_x levels, for both emission models considered, displaying a high correlation (>?0.8) between traffic-related NO_x emissions and NO_x concentrations. For PM10, VADIS model is more sensitive to the differences in the emissions calculation; however, it was observed that the traffic-related PM10 emissions accounts 1.3–8.4% to the PM10 concentration levels at the study area.     

Dynamic interaction of trace gases (VOCs,ozone, and NO<Emphasis Type="Italic">x</Emphasis>) in the rural atmosphere of sub-tropical India

The atmospheric chemistry and health implications of pollutants are important scientific concerns in the rural atmosphere. The current study investigates the estimation of seasonal and diurnal variability of VOCs, ozone, and NOx in the rural area located in a tropical region of India during the year 2013–2014. Results showed that most of the targeted VOCs were higher in winter followed by summer and autumn. The diurnal variability of aromatic hydrocarbons showed similar pattern with different amplitudes as maxima and minima during morning (07:00–10:00 h) or evening (16:00–19:00 h) and daytime (10:00–16:00 h), respectively. The sum of aromatic VOCs are found to be in the range from 27.3 to 87.9 μg/m³. In addition to this, O₃ and NOx were observed as 45.04 ± 15.19 μg/m³ and 12.41 ± 3.49 μg/m³, respectively, during the observation period. The estimated VOC/NOx ratios (ranged from 3.4 to 3.7) indicated that the selected rural area was VOC limited in terms of ozone sensitivity. The sources of the VOCs have been explained by characteristic ratios, correlation, and principal component analysis. Further, ozone-forming potential (OFP) of the targeted aromatic VOCs has been evaluated using maximum incremental reactivity which suggested toluene (benzene) contributed the largest (lowest) in the ozone formation. Exposure assessment in terms of lifetime cancer and non-cancer risks lies within the acceptable range of USEPA guidelines.     

Physicochemical Characterization of Ambient Air Particulate Matter in Tabriz,Iran

Atmospheric particulate matter (PM) was measured concurrently from September, 2012, to June, 2013, at two sites, urban and industrial suburban, in Tabriz, Iran. The annual average concentration of total suspended particulates (TSP), PM₁₀, PM_2.5, and PM₁ at the urban site were 142.2 ± 76.3, 85.3 ± 43.9, 39 ± 19.1, and 28.4 ± 14.9 µg/m³ (mean ± SD), respectively. A total of 11 inorganic water-soluble ions in the TSP and PM₁₀ were identified by ion chromatography. In the urban site, concentrations of total water-soluble ions in TSP and PM₁₀ were 20.3 ± 20.8 and 16.0 ± 14.1 µg/m³, respectively. In this sampling site, secondary inorganic aerosols (i.e., Σ $ {\text{SO}}_{4}^{2 - } $ , $ {\text{NO}}_{3}^{ - } $ , and $ {\text{NH}}_{4}^{ + } $ concentrations) were the main measured water-soluble ions, which collectively accounted for 13.9 % of TSP mass and 17.7 % of PM₁₀ mass. Correlations between $ {\text{NH}}_{4}^{ + } $ with $ {\text{NO}}_{3}^{ - } $ and $ {\text{SO}}_{4}^{2 - } $ indicated that the main source of these ions in PM was the combustion processes. Results of elemental analysis in the industrial suburban site showed that natural sources were the dominant source of PM in this area.     

Significance of volatile organic compounds and oxides of nitrogen on surface ozone formation at semi-arid tropical urban site,Hyderabad, India

The chemistry and variation in light molecular weight (C₂–C₅) volatile organic compounds (VOCs) and nitrogen oxides (NO _x ?=?NO?+?NO₂) over the formation of tropospheric ozone (O₃) was studied for a time period of 1 year (2013) at a tropical urban site located in Deccan plateau region of Hyderabad, India, with semi-arid climate. Diel pattern of hydrocarbons showed maxima in the morning and night and minima in the afternoon. Ethylene and propylene showed relatively larger diurnal amplitude than other hydrocarbons. Among the analyzed hydrocarbons, acetylene was the most abundant with an annual mean of 5.5?±?1.3 ppbv. All the VOCs exhibited a seasonal variation with monsoon and summer minimum and winter maximum. Ozone formation potentials (OFP) and propylene-equivalents (propy-equiv.) were calculated to account the contribution of individual hydrocarbons towards formation of O₃. Propylene had the highest contribution of propy-equiv. (34 %) and OFP (28.4 %) among the VOCs observed. The concentrations of VOCs and their reactivity with hydroxyl radicals played a significant role on the levels of propy-equiv. and OFP. Strong correlations 0.65 and 0.77 were observed between O₃ vs. propy-equiv. and O₃ vs. OFP, respectively. The crossover point relationship between NO _x , VOCs, and O₃ showed enhancement of O₃ at lower levels and decreased at higher levels of NO _x in the range of VOCs concentrations studied. Among hydrocarbons, propylene (10) and ethane (6.5) showed the highest and lowest crossover points, respectively.     

Intra-urban variability of ozone in a tropical city—characterization of local and regional sources and major influencing factors

Tropospheric ozone (O₃), a secondary air pollutant, was assessed to evaluate the intra-urban variability of O₃, its local and distant sources, and the influence of O₃ precursor gases and meteorological variables on seasonal and temporal trends of O₃ from 2013 to 2017 in a tropical urban city located in the middle Indo-Gangetic Plains of India. Passive samplers and data from real-time air quality monitoring station were considered. Trajectory statistical models, multivariate statistical methods, and geographic information system were further used to identify spatial-temporal variability and source apportionment. O₃ concentrations showed significant intra-urban variability with higher concentrations in suburban or background regions of the city, which were mostly attributed to the transport of O₃ at high wind speed from distant and rural areas away from the city, while lower concentrations in traffic and commercial areas were due to titration of O₃ by nitric oxide (NO). Variations in meteorological variables (temperature, relative humidity, wind speed) and planetary boundary layer height were responsible for seasonal variations in O₃ concentrations. Long-range and regional transport of O₃ and its precursors such as volatile organic compounds and NO_x from the northwestern and eastern directions of the city significantly influenced O₃ variability with distinct seasonal patterns. A negative trend in O₃ levels was recorded during the study period which may be due to increase in NO_x emission in the city. The observed outcomes suggest significant intra-urban variability of O₃ in the city which is influenced by traffic as well as by distant and local sources.     

Determination of <Superscript>226</Superscript>Ra Contamination Depth Around Phosphogypsum Pit Using In-Situ Gamma Spectrometer

The feasibility of applying multiple photopeak method (MPM) and peak to valley ratio (PVRM) method to determine Radium-226 contamination depth (²²⁶Ra h_c) has been investigated. Gamma spectra in eight positions around phosphogypsum disposal pit has been measured using portable NaI(Tl) gamma spectrometer. MPM was investigated by calculating the ratio \(\left( {\mathop R\nolimits_{{609,352}} } \right)\) of 609 keV gamma line net counts to the corresponding value of 352 keV. PVRM was investigated by calculating the ratio \(\left( {\mathop Q\nolimits_{{609}} } \right)\) of net counts of 609 keV gamma line to the corresponding valley counts. ²²⁶Ra h_c in the positions has been determined using traditional soil coring. It was found that, \(\mathop R\nolimits_{{609,352}}\) and \(\mathop Q\nolimits_{{609}}\) have good linear correlations with ²²⁶Ra h_cTherefore, ²²⁶Ra h_c can be determined by MPM and PVRM. These methods save a lot of time, costs and efforts in comparison with the traditional one.     

Do Varying Aquatic Plant Species Affect Phytoplankton and Crustacean Responses to a Nitrogen-Permethrin Mixture?

Hydraulically connected wetland microcosms vegetated with either Typha latifolia or Myriophyllum aquaticum were amended with an NH₄NO₃ and permethrin mixture to assess the effectiveness of both plant species in mitigating effects of the pollutant mixture on phytoplankton (as chlorophyll a) and Hyalella azteca. Phytoplankton grew in response to increased NH₄NO₃ in the presence of all plant species, but was unaffected by exposure to permethrin. H. azteca responses occurred rapidly (0.17 days), was mitigated within 1–2 days, and aqueous toxicity was unaffected by plant species type. A toxic unit model approach ascertained primary toxicity was permethrin with minimal additional toxicity from NH₄NO₃. Varying aquatic plant species had only modest influences on phytoplankton responses and no observable influence on animal responses during nitrogen-permethrin mixture exposures. As a result, both T. latifolia and M. aquaticum can be used as part of an effective agricultural best-management practice system for mitigating pollutant impacts of agricultural run-off.     

Heavy Metal Contamination and Ecological Risk Assessment of Swine Manure Irrigated Vegetable Soils in Jiangxi Province,China

Heavy metal are often added to animal fodder and accumulate in the soils with swine manure. In this study, heavy metal (Cu, Pb, Cd, Zn, As and Cr) concentrations were determined in agricultural soils irrigated with swine manure in Jiangxi Province, China. Results showed that the average concentrations of Cu, Zn, As and Cr (32.8, 93.7, 21.3 and 75.8 mg/kg, respectively) were higher than the background values, while Pb and Cd (15.2 and 0.090 mg/kg, respectively) were lower than the background values. Contamination factors \(\left( {C_{f}^{i}} \right)\) indicated that they were generally moderate for Cu, Zn, As and Cr and generally low for Pb and Cd. The contamination degree (C _d ) was calculated to be 7.5–10.0 indicating a moderate degree of contamination. The geoaccumulation index (I_geo) indicated that the soils were unpolluted with Zn, Cd and Pb, while unpolluted to moderately pollute with Cr, Cu and As. The single ecological risk factor \(\left( {E_{r}^{i}} \right)\) revealed that the six heavy metals all belonged to low ecological risk. The ecological risk indices suggested that all the sampling sites were at low risk level.     

Preeclampsia and Hypertension During Pregnancy in Areas with Relatively Low Levels of Traffic Air Pollution

Objectives Air pollution exposure may contribute to the development of preeclampsia and hypertension during pregnancy. However, the evidence for such a relation is still limited. We investigated the associations between exposure for moderate to low levels of air pollution during pregnancy and preeclampsia and gestational hypertension in selected urban and county areas of Norway. Methods This study used a sub-group of 17,533 women in the Norwegian Mother and Child Cohort Study. Air pollution levels at residential addresses were estimated using land use regression models and back-extrapolated to the period of each pregnancy. Information on preeclampsia and gestational hypertension were obtained from the Medical Birth Registry of Norway and information on lifestyle factors was collected from questionnaires completed by the women during pregnancy. Results Moderate mean levels of NO₂ (13.6?±?6.9 µg/m³) at residential address during pregnancy were not associated with preeclampsia and pregnancy hypertension. We found no statistically significant associations per 10 µg/m³ change in NO₂ exposure and preeclampsia (adjusted OR 0.89, 95% CI 0.74, 1.08) or hypertension during pregnancy (adjusted OR 0.91, 95% CI 0.78, 1.06). Conclusions for Practice In this large Norwegian pregnancy cohort, we found no statistically significant associations for moderate to low levels of pregnancy NO₂ exposure and preeclampsia or hypertension during pregnancy.     

Cardiorespiratory strain in jobs that require respiratory protection

Summary Twenty-one workers in the construction, foundry, shipyard, and metal industries, and nine firemen were studied in jobs that require the regular use of various industrial respirators. The subjects' heart rates (HR) were continuously recorded during 1 to 2 workshifts or during special tasks. Their oxygen consumption and ventilation rates were measured during main work phases. The subjects' were determined by a submaximal bicycle-ergometer test. In construction and industrial jobs, when a filtering device or an air-line apparatus was worn, the subjects' mean HR-values ranged from 66 to 132 beats min^–1, which is equivalent to a relative aerobic strain of 12 to 57% . In smog-diving and repair and rescue tasks with self-contained breathing apparatus and protective clothing, the corresponding mean values were 142 to 160 beats min^–1 and 54–74% , respectively. The field results were compared with those measured in the laboratory with the same type of respirator. The suitability of different respirators in practical work situations was then evaluated, as were the physical qualifications required of the wearer.     

Examining some potential actions in mitigating gaseous emissions from vehicles,case study: Tehran

Pollutant emission from vehicles is known as a major air pollution source in metropolitan areas. Efficiency of several solutions was quantified and compared to introduce the best solution for decreasing greenhouse gases and air pollutant emissions: (1) inspection and maintenance (I/M) of vehicles, (2) restriction of air conditioner usage, (3) injecting better quality fuel (removing sulfur), and (4) replacing older vehicles with new ones were modeled by International Vehicle Emissions (IVE) model as potential solutions. Restricting air conditioner usage makes an insignificant contribution in pollutants’ emission. The idle inspection/ maintenance system can reduce carbon monoxide (CO) and methane (CH ₄) emission by about 10.7 and 3.8 %, respectively. The loaded I/M system reduces nitrogen oxides (NO _x ), CO, volatile organic carbon (VOC), and CH ₄ emission by 8.6, 11.5, 3.4, and 7.6 %, respectively. Effect of I/M programs depends on the types of vehicles and target pollutants needed to be reduced. Sulfur emission into the atmosphere would be reduced remarkably (about 98 %) if its concentration was reduced in fuels. Substitution of old vehicles with new vehicles makes a noticeable contribution in improving air quality (about 53 % reductions in CO, 52 % in VOC, and 58 % in CH ₄ emission for light-duty vehicles). Analytical hierarchy process (AHP) was utilized to identify the most feasible solution for reducing air pollution. Fuel quality improvement and replacing old cars with newer ones are the most tangible solutions, respectively. This paper demonstrates that each policy has its own impact on emission and we can apply each of them in cases in which the pollutants concentrations are high.     

Effect of exposure to detergents and other chemicals on biomarkers of pulmonary response in exhaled breath from hospital cleaners: a pilot study

Purpose

The main aim of the study was to provide evidence whether professional cleaning was associated with biomarkers of lung damage in non-invasively collected biological fluids (exhaled air and exhaled breath condensate—EBC).

Materials and methods

This cross-sectional study involved 40 cleaners regularly exposed to cleaning detergents and 40 controls. The subjects completed a standard questionnaire from European Community Respiratory Health Survey (ECRHS II) and underwent a spirometry. Fractional exhaled nitric oxide (F_ENO) was measured online, and pH, ammonium (NH₄ ⁺), H₂O₂ and 4-hydroxynonenal (4-HNE) were assayed in EBC.

Results

Among the cleaners, the frequency of asthma and rhinitis was, respectively, 2.5 and 20%. The most frequently reported symptoms were sneezing (27.5%), nasal and/or pharyngeal pruritus (25%), ocular pruritus (22.5%) and cough (22.5%). There were no significant differences in comparison with the control group. Median F_ENO levels were higher in African than in Caucasian cleaners (21.5 [16.5–30.0] ppb and 18.0 [13.5–20.5] ppb; p < 0.05). H₂O₂-EBC (0.26 [0.09–0.53] μM vs. 0.07 [0.04–0.15] μM; p < 0.01), NH₄ ⁺-EBC (857 [493–1,305] μM vs. 541 [306–907] μM; p < 0.01) and pH-EBC (8.17 [8.09–8.24] vs. 8.06 [7.81–8.10]; p < 0.01) were higher in the cleaners than in the controls. Finally, the cleaners showed significant correlations between pH-EBC and NH₄ ⁺-EBC (r = 0.33, p < 0.05) and a weak correlation between 4-HNE-EBC and H₂O₂-EBC (r = 0.37, p < 0.05).

Conclusion

The promising role of EBC analysis in biomonitoring of exposed workers was confirmed. It was also possible to identify the potential biomarkers of exposure to alkaline products (increased ammonium-EBC and pH-EBC levels) and potential biomarkers of oxidative stress (increased H₂O₂-EBC levels correlated with 4-HNE-EBC levels) in workers with no signs of airway diseases.

     

Factors controlling the lung dose of road traffic-generated sub-micrometre aerosols from outdoor to indoor environments

Estimates of lung dose of submicron particles in the human respiratory system play an essential role in assessing health outcomes of aerosol exposure. The objectives of this study are to calculate the regional lung dose of traffic-generated particles by different metrics from exposure in outdoor and indoor environments and to identify main factors determining the lung dose. Particle number size distributions were collected in both indoor and outdoor environments in two unoccupied apartments from 22nd February to 30th April 2012 in Bologna, Italy. The whole lung doses of outdoor aerosols by number, surface area and mass at a traffic site were 1.0?×?10¹⁰ particles/h, 130 mm²/h and 1.9 μg/h, respectively. A majority of particles by number and surface area were found to deposit in the alveolar region (65%). The physical properties of particles such as shape, hygroscopicity and density play an important role in the calculation of surface area and mass dose due to shifting of the lung deposition curve. Particle number can predict well the regional dose by number, while PM_2.5 and PM₁₀ are good metrics for the prediction of surface area and mass dose. Good correlations between NO_x and the surface areas and mass dose (r²?~?0.8) and number dose (r²?~?0.7) of submicron aerosols suggest that NO_x may be a good indicator for predicting the health outcomes of traffic-generated aerosols. The doses of indoor sub-micrometre aerosols are less than those of outdoor aerosols by factors of 4.1 (for number), 2.7 (for surface area) and 2.1 (for mass). Due to traffic emissions, the lung dose of outdoor aerosols in the traffic area was much higher than that in the residential area by 5 times for number and surface area and 2 times for mass. A different exercise level (standing, walking, running and cycling) has only a slight influence on the whole lung deposition fraction of submicron aerosols but has a large effect on the dose due to differences in ventilation rate.     

Use of an exposure model to explore the impact of residential proximity to a highway on exposures to air pollutants of an ambient origin

Air pollutant exposure models are generally applied to large populations living across wide urban areas, and most do not account for daily variation in activity patterns, which can result in exposure misclassification. Far fewer studies exist where exposure is modeled for specific individuals using detailed time-activity data. We employed a novel application of the US-EPA’s Air Pollution Exposure Model (APEX) to simulate exposure levels for 51 residents living within a small study area (1.5 km²) bisected by a heavily trafficked highway in South Auckland, New Zealand. The model produced daily exposure estimates of nitrogen oxides (NO _x ), carbon monoxide (CO), and particulate matter (PM₁₀) for the month of July, 2010. Inputs included pollutant and meteorological data monitored at sites positioned both upwind and downwind of the highway, as well as city monitoring sites north of the study area to represent work locations. A local resident survey provided time-activity diary input. The simulation was run once using the residents’ home locations and four times with the population artificially placed 50 and 150 m downwind, as well as 50 and 150 m upwind, relative to the highway. For NO _x and CO, the population was 31–36 % more exposed when positioned 50 m downwind and 17–18 % less exposed at the upwind side (p?<?0.001), compared to their actual home locations. An additional 100 m separation downwind resulted in a 56–71 % drop in total mean exposure (p?<?0.001) and the difference in exposure levels for certain occupations varied by up to a factor of eight (p?<?0.05). PM₁₀ exposure was comparatively stable across the area. The effect of residential proximity and position, occupation and work location, were assessed using generalized linear models (GLMs), followed by post hoc testing. This unique application of APEX shows good promise as a planning tool for assessing the potential benefits of a buffer zone between major roads and residential homes, for particular population groups.     

Cardiorespiratory and thermal effects of wearing gas protective clothing

Summary Six healthy men aged 25 to 37 walked on a treadmill at work levels of 21 and 41% of their for 25 to 30 min wearing gas protective clothing (GPC) consisting of an impermeable suit with a self-contained breathing apparatus (total weight 25 kg) or shorts (control tests, CT) in a temperate environment (t _a 24.3°C ± 1.0°C, rh 30–50%). When the GPC was worn at 21 and 41% , the most prominent increases, compared with the CT, were noted in the heart rate ( ± SE, 120 ± 5 vs 76 ± 3 beats min^–1 and 171 ± 5 vs 103 ± 3 beats min^–1), mean skin temperature (36.1 ± 0.2 vs 31.3° C ± 0.1°C and 36.9 ± 0.3 vs 30.9°C ± 0.4°C) and sweat rate (473 ± 51 vs 70 ± 23 g m^–2 h^–1 and 766 ± 81 vs 135 ± 18 g m^–2 h^–1) indicating a high cardiovascular and thermoregulatory strain, which was not decreased by ventilating the suit with an air flow of 281 min^–1 at 41% . The ventilation, oxygen consumption and production of carbon dioxide increased in relation to the extra weight of the GPC, partly dependent on the dynamic work level. It was concluded that the increase in the physiological load caused by the GPC was so high that the work-rest regimens, workers' level of physical fitness, cardiovascular health and heat tolerance should be considered whenever gas protective clothing is used.     

Space-time mapping of ground-level PM<Subscript>2.5</Subscript> and NO<Subscript>2</Subscript> concentrations in heavily polluted northern China during winter using the Bayesian maximum entropy technique with satellite data

The accurate and informative space-time mapping of air pollutants is a crucial component of many human exposure studies. In the present work, space-time maps of daily distributions of PM_2.5 and NO₂ concentrations were generated in the severely polluted northern China region using the Bayesian maximum entropy (BME) method. This method can incorporate hard PM_2.5 and NO₂ data (obtained at ground-level monitoring sites), and various kinds of soft (uncertain) data, including satellite data processed in terms of machine learning techniques, meteorological variables, and geographical predictors. The BME maps of space-time PM_2.5 and NO₂ concentrations over northern China generated during the winter season (when severe haze episodes occur frequently) were realistic and informative. As regards their numerical accuracy, for the space-time PM_2.5 estimates, the tenfold cross-validation R ² and the RMSE were, respectively, 0.86 and 14.37 μg/m³; for the space-time NO₂ estimates, the R ² and RMSE values were, respectively, 0.85 and 6.93 μg/m³. Lastly, it was shown that the BME method performed better than the mainstream spatiotemporal ordinary kriging technique in terms of the higher R ² values of both the predicted PM_2.5 and NO₂ concentration maps.     

Effect of 8-weeks prebiotics/probiotics supplementation on alcohol metabolism and blood biomarkers of healthy adults: a pilot study

Purpose

Modulating gut bacteria via regular prebiotics/probiotics consumption may improve the metabolism of acute alcohol ingestion. This study investigated the impact of 8-weeks prebiotics/probiotics supplementation on microbiome changes and responses to acute alcohol consumption.

Methods

38 participants (21 females, 23.6?±?3.4 kg m^?2, mean?±?SD) attended the laboratory on two occasions separated by an 8-week intervention period. On each of these visits, a dose of alcohol (0.40?±?0.04 g kg^?1, Vodka?+?Soda-Water) was consumed over 10 min. Breath alcohol concentration was sampled over 5 h and alcohol pharmacokinetics was analysed using WinNonlin non-compartmental modelling (C_max, t_max, AUC_last). For the intervention, participants were randomised to receive Placebo?+?Placebo (PLA), Placebo?+?Prebiotics (PRE), Probiotics?+?Placebo (PRO), or Probiotics?+?Prebiotics (SYN) in a double-blinded manner. Probiotics were a commercially available source of Lactobacillus acidophilus (NCFM^®) and Bifidobacterium lactis (Bi-07). Prebiotics were a commercially available source of Larch Gum (from Larix occidentalis). Placebo was microcrystalline cellulose. Each visit, participants provided a stool sample, which was analysed to determine the presence of L. acidophilus and B. lactis. Differences between trials were analysed using paired samples t tests.

Results

Increased counts for at least one bacterial strain (L. acidophilus or B. lactis) were observed for all participants on SYN (n?=?10) and PRO (n?=?10) trials. No difference in C_max or t_max was observed between trials when analysed by treatment condition or microbiome outcome. A significant decrease in AUC_last was observed between trials for PLA (p?=?0.039) and PRE (p?=?0.030) treatments, and when increases in at least one bacterial strain (p?=?0.003) and no microbiome changes (p?=?0.016) were observed.

Conclusion

Consumption of probiotics appears to alter faecal counts of supplemental bacterial strains in otherwise healthy individuals. However, translation to any possible beneficial impact on alcohol metabolism remains to be elucidated.