Investigating indoor concentrations of PM<Subscript>10</Subscript> in an underground loading dock in Malaysia

Risky air contaminants including PM₁₀ can accumulate inside underground confined loading docks because of the enclosed nature and limited contacts of loading docks with ambient air. Exposure to PM₁₀ can increase morbidity and mortality rates. Hence, this study aimed to investigate and model PM₁₀ concentrations in an underground loading dock located at Kuala Lumpur city center, Malaysia. For this purpose, a real-time air quality monitoring instrument was used for measuring PM₁₀ concentrations for 20 consecutive weeks starting from November 8, 2014. After that, the Statistical Package for Social Sciences (SPSS) software was used to analyze measured PM₁₀ concentrations through series of statistical analyses, whereas MATLAB R2013a was employed for developing prediction models of future PM₁₀ concentrations. Moreover, PM₁₀ temporal variation was examined using time series plots. The results showed that short-term PM₁₀ concentrations did not exceed the Malaysian indoor allowable limit of 150 μg/m³. Despite that, PM₁₀ had 8 % probability of exceedance of WHO standard concentration of 50 μg/m³. This indicates that the occupants will be under the risk of prolonged exposure to PM₁₀ even at low concentrations. The results confirmed a strong correlation between PM₁₀ concentrations and diesel-powered vehicles flow. Contrarily, the flow of gasoline-powered vehicles was poorly correlated. Finally, future daily-averaged PM₁₀ concentrations were predicted for the three weekdays that followed the measurement period using single exponential smoothing. The obtained accuracy was at 70 % of measured PM₁₀ concentrations. Future hourly-averaged PM₁₀ concentrations were estimated using single linear regression with an accuracy of 53 %.     

Effects of Elevated CO<Subscript>2</Subscript> and O<Subscript>3</Subscript> on Phenolic Compounds in Spring Wheat and Maize Leaves

C₃ crops are generally considered more sensitive than C₄ crops to the elevated CO₂ and O₃, but it is unclear whether the concentrations of phenolic compounds in them are affected. In this paper, an enrichment experiment with open-top chamber was conducted to examine the effects of elevated CO₂, O₃, and their combination on the contents of total phenolic compounds and flavone in the leaves of spring wheat (C₃ crop) and maize (C₄ crop). The results showed for spring wheat, the total phenolic contents in its leaves at jointing stage was significantly higher under elevated CO₂ and/or O₃, with the sequence of CO₂ plus O₃ > O₃ > CO₂ > ambient, while at grain-filling stage, the total phenolic content was lower under CO₂ plus O₃ than under CO₂, O₃, and ambient. The total phenolic content in maize leaves at jointing stage had the similar variation trend with that for wheat, but at grain-filling stage, the total phenolic content was slightly affected by elevated CO₂ and/or O₃. The flavone content in spring wheat leaves was significantly lower under CO₂ and/or O₃ stress at jointing stage, but had lesser difference at grain-filling stage under the stress. The same variation trend was observed in the flavone content in maize leaves at jointing and grainfilling stages, i.e., CO₂ plus O₃ > CO₂ > ambient > O₃. C₃ plant was more sensitive than C₄ plant to the CO₂ and/or O₃ stress. Foundation item: The National Natural Science Foundation of China (No. 30570348 and 30500069).     

Explaining the high PM<Subscript>10</Subscript> concentrations observed in Polish urban areas

The main goal of this paper is to identify the drivers responsible for the high particulate matter concentrations observed in recent years in several urban areas in Poland. The problem was investigated using air quality and meteorological data from routine monitoring network, air mass back trajectories and multivariate statistical modelling. Air pollution in central and southern part of the country was analysed and compared with this in northern-eastern “The Green Lungs of Poland” region. The analysis showed that in all investigated locations, there is a clear annual cycle of observed concentrations, closely following temperature-heating cycles, with the highest concentrations noted in January. However, the main drivers differ along the country, being either connected with regional background pollution (in the central part of the country) or with local emission sources (in the southern part). The occurrence of high PM₁₀ concentrations is most commonly associated with the influence of high-pressure systems that brought extremely cold and stable air masses form East or South of Europe. During analysed episodes, industrial point sources had the biggest (up to 70–80 %) share in PM₁₀ levels on the days with maximum PM pollution, while remote and residential/traffic sources determined the air quality in the early stages of the episodes. Principal component analysis (PCA) shows that secondary inorganic aerosols account for long-range transported pollution, As, Cd, Pb and Zn for industrial point sources, while Cr and Cu for residential and traffic sources of PM₁₀, respectively.     

Estimation of on-road NO<Subscript>2</Subscript> concentrations,NO<Subscript>2</Subscript>/NO<Subscript>X</Subscript> ratios,and related roadway gradients from near-road monitoring data

This paper describes a new regression modeling approach to estimate on-road nitrogen dioxide (NO₂) and oxides of nitrogen (NO_X) concentrations and near-road spatial gradients using data from a near-road monitoring network. Field data were collected in Las Vegas, NV, at three monitors sited 20, 100, and 300 m from Interstate-15 between December 2008 and January 2010. Measurements of NO₂ and NO_X were integrated over 1-h intervals and matched with meteorological data. Several mathematical transformations were tested for regressing pollutant concentrations against distance from the roadway. A logit-ln model was found to have the best fit (R ² = 94.7 %) and also provided a physically realistic profile. The mathematical model used data from the near-road monitors to estimate on-road concentrations and the near-road gradient over which mobile source pollutants have concentrations elevated above background levels. Average and maximum on-road NO₂ concentration estimates were 33 and 105 ppb, respectively. Concentration gradients were steeper in the morning and late afternoon compared with overnight when stable conditions preclude mixing. Estimated on-road concentrations were also highest in the late afternoon. Median estimated on-road and gradient NO₂ concentrations were lower during summer compared with winter, with a steeper gradient during the summer, when convective mixing occurs during a longer portion of the day. On-road concentration estimates were higher for winds perpendicular to the road compared with parallel winds and for atmospheric stability with neutral-to-unstable atmospheric conditions. The concentration gradient with increasing distance from the road was estimated to be sharper for neutral-to-unstable conditions when compared with stable conditions and for parallel wind conditions compared with perpendicular winds. A regression of the NO₂/NO_X ratios yielded on-road ratios ranging from 0.25 to 0.35, substantially higher than the anticipated tailpipe emissions ratios. The results from the ratios also showed that the diurnal cycle of the background NO₂/NO_X ratios were a driving factor in the on-road and downwind NO₂/NO_X ratios.     

Indoor and outdoor air quality analysis for the city of Nablus in Palestine: seasonal trends of PM<Subscript>10</Subscript>, PM<Subscript>5.0</Subscript>, PM<Subscript>2.5</Subscript>, and PM<Subscript>1.0</Subscript> of residential homes

Nablus city is an important urban and industrial center in the West Bank, Palestine. The topography of the city, combined with multiple sources of air pollution, creates a potential air quality problem that might affect human health. The indoor and outdoor particle concentration distributions of PM₁₀, PM_5.0, PM_2.5, and PM_1.0 were measured using a Grimm aerosol spectrometer from December 2014 to November 2015, at four roadsides and four urban homes in Nablus. The results of the annual averages of PM₁₀ and PM_2.5 concentrations were found to be at least three times higher than that of the European Air Quality Standards both in indoors and outdoors. The difference in the results between both the roadside and the urban areas was attributed to human and industrial activities in Nablus. The results revealed that the highest concentrations of the particulate matters are during summer, especially June and July, in the roadside areas due to heavy industrial activities during these months. The same behavior was noticed for urban areas during summer and due to other human activities. The results of indoor/outdoor (I/O) ratios were found to be less than, but very close to, 1 for both roadside and urban areas in summer and winter months. In winter times, areas with poor ventilation indicated the existence of additional sources of PM within the indoor environments, especially when smoking cigarettes and using fuel-based heaters such as fireplaces gas and kerosene heaters.     

Effects of Elevated Atmospheric CO<Subscript>2</Subscript> and O<Subscript>3</Subscript> on Hill Activity and Ca<Superscript>2+</Superscript>/Mg<Superscript>2+</Superscript>-ATPase Activity of <Emphasis Type="Italic">Pinus tabulaeformis</Emphasis> Carr.

The main photo-physiological characteristics of Pinus tabulaeformis Carr. were analyzed in open-top chambers under elevated carbon dioxide and ozone concentrations. The results indicated that the leaves net photosynthetic rates (p < 0.05), Hill activity, Ca²⁺/Mg²⁺-ATPase activity, soluble sugar and starch contents all increased under elevated carbon dioxide concentration in whole growing season. While under elevated ozone concentration, the leaves net photosynthetic rates, Hill activity, Ca²⁺/Mg²⁺-ATPase activity, soluble sugar and starch contents all decreased. Under elevated carbon dioxide and ozone concentration, the leaves net photosynthetic rates, Hill activity, soluble sugar and starch contents all increased, but Ca²⁺-ATPase activity increased during the earlier growing season, decreased in later growing season, while Mg²⁺-ATPase activity responded contrarily.     

Impact of Elevated CO<Subscript>2</Subscript> and O<Subscript>3</Subscript> Concentrations on Biogenic Volatile Organic Compounds Emissions from <Emphasis Type="Italic">Ginkgo biloba</Emphasis>

In natural environment with ambient air, ginkgo trees emitted volatile organic compounds 0.18 μg g⁻¹ h⁻¹ in July, and 0.92 μg g⁻¹ h⁻¹ in September. Isoprene and limonene were the most abundant detected compounds. In September, α-pinene accounted for 22.5% of the total. Elevated CO₂ concentration in OTCs increased isoprene emission significantly in July (p < 0.05) and September (p < 0.05), while the total monoterpenes emission was enhanced in July and decreased in September by elevated CO₂. Exposed to elevated O₃ increased the isoprene and monoterpenes emissions in July and September, and the total volatile organic compounds emission rates were 0.48 μg g⁻¹ h⁻¹ (in July) and 2.24 μg g⁻¹ h⁻¹ (in September), respectively. The combination of elevated CO₂ and O₃ did not have any effect on biogenic volatile organic compounds emissions, except increases of isoprene and Δ3-carene in September. Foundation item: The National Natural Science Foundation of China (No. 90411019).     

On the relation between capsaicin sensitivity and responsiveness to CO<Subscript>2</Subscript>: detection sensitivity and event-related brain potentials

Objective  Sensory hyperreactivity (SHR) with predominantly airway symptoms is a subgroup of chemical intolerance to various environmental substances with pungent/odorous properties. The hallmark of SHR is sensitivity to capsaicin inhalation, resulting in extensive coughing likely to be mediated by a C-fiber hyperreactivity of the airway sensory neurons. However, it is not clear whether capsaicin sensitivity implies a greater sensitivity to chemosomatosensory substances in general. Therefore, the present study tested the hypothesis of an association between capsaicin cough sensitivity and sensitivity to CO₂ with respect to detection sensitivity and electrophysiological brain response. Methods  A correlational study was employed to investigate the relation between capsaicin cough sensitivity and detection thresholds and chemosomatosensory event-related potentials (ERPs) for CO₂ presented in the nasal cavity in 35 persons varying in capsaicin cough sensitivity. Results  Number of coughs were found to correlate negatively with CO₂ threshold and tended to correlate negatively also with N1 and P2 latencies of the chemosomatosensory ERP for CO₂. No tendencies of correlations were found between number of coughs and latencies for olfactory and auditory ERPs, recorded for comparison, but, unexpectedly, were found between number of coughs and auditory N1 amplitude. Conclusions  The results imply that capsaicin cough sensitivity, such as in SHR, is related to higher detection sensitivity, and tends to be related to faster cortical processing of other chemosomatosensory substances, at least of CO₂.     

Practicalities of mapping PM<Subscript>10</Subscript> and PM<Subscript>2.5</Subscript> concentrations on city-wide scales using a portable particulate monitor

Fine particulate matter is considered to be the most significant ambient air pollutant in terms of potential health impacts. Therefore, it is important that regulators are able to accurately assess the exposure of populations to PM₁₀ and PM_2.5 across municipal areas. We report on the practicalities of using a laser light scattering portable particulate monitor (Turnkey Instruments DustMate), in combination with a GPS, to map PM₁₀ and PM_2.5 concentrations on city-wide scales in Newcastle upon Tyne/Gateshead (UK), during a series of walking surveys. A heated inlet is necessary to remove moisture droplets from the sampled air prior to analysis by the instrument, though this also results in the loss of volatile particulate components, particularly from the PM_2.5 fraction. A co-location calibration study was carried out with a reference urban background Tapered Element Oscillating Micro-Balance/Filter Dynamics Measuring System (TEOM-FDMS) system in Newcastle that is part of the UK’s Automatic Urban and Rural Network (AURN) of air quality monitoring stations. For PM₁₀, orthogonal regression of the DustMate against TEOM-FDMS data gave a slope and intercept of 1.02?±?0.06 and ?3.7?±?1.2, respectively (R ²?=?0.73), whereas for PM_2.5, the respective values were 0.78?±?0.06 and ?0.63?±?0.55 (R ²?=?0.79). These parameters are comparable to literature calibration studies using this technology. There was good agreement between simultaneous samples taken using two DustMate instruments: for PM₁₀, a slope and intercept of 1.05?±?0.03 and 0.36?±?0.5, respectively (R ²?=?0.73), were obtained, whereas for the PM_2.5, the respective values were 0.79?±?0.01 and 0.19?±?0.06 (R ²?=?0.86). Correction factors based on the slope and intercepts obtained from the calibration exercise were applied to raw data collected from the DustMate. An annually-normalised correction procedure was then used to account for different background particulate concentrations on different sampling days. These corrected PM₁₀ and PM_2.5 concentrations and corresponding GPS coordinates were displayed on a base map using Google Fusion Tables and Google Earth Professional. Almost all areas surveyed in Newcastle/Gateshead were well below the EU Air Quality Standards for PM₁₀ and PM_2.5.     

Effects of Elevated O<Subscript>3</Subscript> and/or Elevated CO<Subscript>2</Subscript> on Lipid Peroxidation and Antioxidant Systems in <Emphasis Type="Italic">Ginkgo biloba</Emphasis> Leaves

Four-year-old seedlings of Ginkgo biloba were exposed to elevated O₃, elevated CO₂ and elevated O₃ plus elevated CO₂ in open-top chambers (OTCs) to study the responses of antioxidant system in Ginkgo biloba leaves. No significant changes in reactive oxygen production and scavenging systems were detected in seedlings exposed to high CO₂. Significant increase in H₂O₂ and MDA content were induced by elevated O₃. The ascorbate content and antioxidative enzymes activity were increased significantly by exposure to high O₃ as well. But the promoted ability in scavenging did not prevent the increase in H₂O₂ content and cell membrane lipid peroxidation. The increase was mitigated by high CO₂ in the combined exposure, but the effect was hardly significant.     

Analysis of CO<Subscript>2</Subscript> monitoring data demonstrates poor ventilation rates in Albanian schools during the cold season

Poor ventilation in schools is associated with accumulation of indoor-generated pollutants, which is associated with “stuffy” air, elevated risk of infectious diseases and impaired learning outcomes. This survey in Albania was conducted as part of WHO’s efforts to facilitate assessments of indoor air quality and other environmental factors in schools in the European Region. The survey was conducted in 36 classrooms in 12 middle schools (eight urban and four rural) from December 2011 through March 2012. In each school, carbon dioxide (CO₂) was continuously measured in three classrooms during one school week. Ventilation rates during classes were estimated using the build-up and steady-state mass balance equations utilizing CO₂ concentration data, classroom occupancy and classroom volume. All 12 schools had gravimetric ventilation systems. Heating systems were absent or not operational in most schools. Average classroom temperatures during lessons varied from 9.1 to 14.4 °C (median 11.7 °C) with lower temperature associated with poorer ventilation. Weekly average CO₂ levels during classes ranged from 1286 to 5546 ppm (median 2776 ppm) while average ventilation rates ranged from 0.8 to 3.6 (median 1.8) litres per second per person. Classrooms with indoor combustion heaters had higher indoor temperature, lower CO₂ levels and higher levels of carbon monoxide (CO). WHO guidelines on 1- and 8-h CO exposure levels were exceeded in one classroom. Classroom CO₂ levels were substantially above and ventilation rates below existing national and international guidelines. Detrimental impacts of poor ventilation on health and learning outcomes are likely to be substantial in Albanian schools during the cold season. Indoor temperature in most classrooms was below the commonly recommended levels.     

Variability of tropospheric columnar NO<Subscript>2</Subscript> and SO<Subscript>2</Subscript> over eastern Indo-Gangetic Plain and impact of meteorology

Long-term analyses of monthly mean tropospheric NO₂ and SO₂ were performed over a period of January 2005 to December 2014, around few industrial areas (power plant clusters) in the Indo-Gangetic Plains. Alongside, similar studies have been conducted over some background mountain and rural sites, forest areas and small urban locations without large industries—all located in and around the Indo-Gangetic Plains. In these locations, the trend analyses of columnar NO₂ and SO₂ using satellite-based measurements from Ozone Monitoring Instrument (OMI) were performed to study their spatial, seasonal and long-term behaviour. Distribution of NO₂ shows a large variation with major hot spots and average monthly values ranging between 0.03 and 0.35 Dobson Unit (DU), whereas the same for SO₂ illustrates the range of average monthly values in between 0.13 to 1.00 DU. All the columnar values have been further correlated to meteorological parameters like cloud fraction, rainfall, outgoing longwave radiation flux and planetary boundary layer height. Analysis of the results indicates the influence of meteorology on the columnar concentration of these gases. Anomalous behaviour of SO₂ during 2008 and 2011 were observed due to the long-range transport of volcanic SO₂ over India from Dalaffilla and Nabro volcanoes, respectively. SO₂/NO₂ ratio was also observed to elicit the contribution of stationary (power plants and industries) source origins over mobile (automobile) sources towards the columnar burdens of these gases.     

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.     

The Effect of Anthracene and Phenanthrene on the Growth,Photosynthesis, and SOD Activity of the Green Alga <Emphasis Type="Italic">Scenedesmus armatus</Emphasis> Depends on the PAR Irradiance and CO<Subscript>2</Subscript> Level

Short-term (24-h) experiments were performed to examine the effect of phenanthrene (PHE) and anthracene (ANT) on algae grown in a batch culture system at irradiances of 12, 33, 48, and 64 W m^–2 of the PAR range. Cultures were aerated (0.1 or 2% CO₂) or nonaerated. As a result of aeration the concentration of ANT dropped from 0.45 mg L^–1 at the beginning of the experiment (t₀) to an undetectable value after 10 h. The PHE concentration dropped from 9.36 mg L^–1 at t0 to 0.17 mg L^–1 after 24 h. ANT at nominal concentrations exceeding 0.05 mg L^–1 inhibited the growth of the algae in a concentration- and irradiance-dependent manner. The algistatic effect of ANT observed at 64 and 48 W m^–2 was independent of the CO₂ level, whereas the growth inhibition at 33 and 12 W m^–2 was much greater in cultures aerated with 2% than with 0.1% CO₂. PHE inhibited the growth only at a concentration of 10 mg L^–1 (about 50% of the control) regardless of the irradiance or the CO₂ concentration. The toxicity of both PHE and ANT was similar in aerated (0.1% CO₂) and nonaerated cultures. ANT and PHE had a distinct effect on the photosynthesis. At 0.1% CO₂, the irradiance-dependent inhibition (ANT) and stimulation (PHE) of the photosynthesis was observed. The inhibitory effect of ANT was enhanced when algae were grown at 2% CO₂, but at the same CO₂ concentration PHE did not affect the photosynthesis. ANT stimulated the total superoxide dismutase (SOD) activity in the cells, this effect being generally more pronounced at elevated CO₂ levels and increasing with the irradiance. The total SOD activity was 250–300% higher in cells treated with PHE aerated with 0.1% CO₂. At 2% CO₂ no effect of PHE on the enzymes activity was noted. The results obtained indicate that ANT acts as a photosensitizer causing an oxidative damage of cells, while PHE seems to affect the macromolecular synthesis.     

Selective detection of the inorganics NO<Subscript>x</Subscript>, SO<Subscript>2</Subscript>, and H<Subscript>2</Subscript>S in the presence of volatile BTEX contaminants toluene,benzene, and xylene

We demonstrate the highly selective detection of the inorganics NO_x (NO, NO₂), SO₂, and H₂S in the presence of toluene, benzene, and xylene using nanostructure metal-oxide-decorated interfaces. This selectivity can be obtained for sensors whose sensitivities are varied for a diversity of nanostructured metal oxides which are applied to a porous silicon (PS) interface. We focus on NO_x and SO₂ and include additional new evaluations for the response to H₂S. In all cases, the response to these inorganic analytes strongly dominates that for toluene, benzene, and xylene. The responses are also consistent with the recently developing inverse hard/soft acid/base concept. The nanostructure metal-oxide-decorated PS conductometric sensors are found to have selectivity ratios well in excess of 10⁴:1 for toluene and benzene and well in excess of 10³:1 for xylene. The dominance of the response of these small inorganic sulfur and nitrogen compounds has important implications for the monitoring of significant contaminants associated with the venting and flaring of natural gas pits, as they can be present in oil and gas formations.     

Mortality risk and PM<Subscript>2.5</Subscript> air pollution in the USA: an analysis of a national prospective cohort

Epidemiologic evidence indicates that exposure to fine particulate matter air pollution (PM_2.5) contributes to global burden of disease, primarily because of increased risk of cardiovascular morbidity and mortality. This study evaluates associations between long-term PM_2.5 exposure and mortality risk in national, representative cohorts of the US adult population, constructed from public-use National Health Interview Survey (NHIS) data. Two cohorts consisting of 392,807 and 162,373 individuals (without and with individual smoking data) were compiled from public-use NHIS survey data (1986–2001) with mortality linkage through 2011. Cohorts included persons who lived in a metropolitan statistical area (MSA) were 18–84 years of age and had individual risk factor information. Modeled PM_2.5 exposures were assigned as MSA-level mean ambient concentration for 1999 through 2008. Mortality hazard ratios (HRs) were estimated using Cox proportional hazard regression models, controlling for age, race, sex, income, marital status, education, body mass index, and smoking status. Estimated HRs for all-cause and cardiovascular mortality, associated with a 10-μg/m³ exposure increment of PM_2.5 were 1.06 (1.01–1.11) and 1.34 (1.21–1.48), respectively, in models that controlled for various individual risk factors, including smoking. This study provides evidence that elevated risks of mortality, especially cardiovascular disease mortality, are associated with long-term exposure to PM_2.5 air pollution in US nationwide adult cohorts constructed from public-use NHIS data.