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Continuous haze monitoring was conducted from 12:00 3 April to 12:00 8 April 2016 in Beijing, China to develop a more detailed understanding of spring haze characteristics. The PM 2.5 concentration ranged from 6.30 to 165 μg m −3 with an average of 63.8 μg m −3 . Nitrate was the most abundant species, accounting for 36.4% of PM 2.5 , followed by organic carbon (21.5%), NH 4 + (19.3%), SO 4 2− (18.8%), and elemental carbon (4.10%), indicating the key role of nitrate in this haze event. Species contribution varied based on the phase of the haze event. For example, sulfate concentration was high during the haze formation phase, nitrate was high during the haze, and secondary organic carbon (SOC) had the highest contribution during the scavenging phase. The secondary transition of sulfate was influenced by SO 2 , followed by relative humidity (RH) and O x (O 3 +NO 2 ). Nitrate formation occurred in two stages: through NO 2 oxidation, which was vulnerable to O x ; and by the partitioning of N (+5) which was susceptible to RH and temperature. SOC tended to form when O x and RH were balanced. According to hourly species behavior, sulfate and nitrate were enriched during haze formation when the mixed layer height decreased. However, SOC accumulated prior to the haze event and during formation, which demonstrated the strong contribution of secondary inorganic aerosols, and the limiting contribution of SOC to this haze case. Investigating backward trajectories showed that high speed northwestern air masses following a straight path corresponded to the clear periods, while southwesterly air masses which traversed heavily polluted regions brought abundant pollutants to Beijing and stimulated the occurrence of haze pollution. Results indicate that the control of NO 2 needs to be addressed to reduce spring haze. Finally, the correlation between air mass trajectories and pollution conditions in Beijing reinforce the necessity of inter-regional cooperation and control. [ABSTRACT FROM AUTHOR]

Abstract: Background and objective: The Southeast Asia (SEA) haze is an annual problem and at its worst could produce respirable particles of concentrations up to 500 μg/m3 which is five times the level considered as ‘unhealthy’. However, there are limited reports examining the direct clinical impact of the annual haze. This study examines the effects of the SEA haze on respiratory admissions. Methods: Data from all respiratory admissions in Universiti Kebangsaan Malaysia Medical Centre (UKMMC) from 1st January 2014 to 31st December 2015 were collected retrospectively from chart and electronic database. A total of 16 weeks of haze period had been formally dated by the Department of Environment using the definition of weather phenomenon leading to atmospheric visibility of less than 10 km. Multivariable regression analyses were performed to estimate rate ratios and 95% CI. Results: There were 1968 subjects admitted for respiratory admissions in UKMMC during the study period. Incidence rates per week were significantly different between the two groups with 27.6 ± 9.2 cases per week during the haze versus 15.7 ± 6.7 cases per week during the non‐haze period (P < 0.01). A total of 4% versus 2% was admitted to the intensive care unit in the haze and the non‐haze groups, respectively (P = 0.02). The mean ± SD lengths of stay was 12.1 ± 5.2 days; the haze group had a longer stay (18.2 ± 9.7 days) compared to the non‐haze groups (9.7 ± 3.9) (P < 0.001). Conclusion: The annual SEA haze is associated with increased respiratory admissions. [ABSTRACT FROM AUTHOR]

Stagnation weather affects atmospheric diffusion ability, and hence causes the occurrence of haze events, which have been happening frequently in northern China (NC). This work puts forward an air stagnation index (ASITS) to characterize the stagnation weather in NC, in which the processes of ventilation, vertical diffusion, and wet deposition potency are concerned. ASITS can be applied to analyze air stagnation conditions with daily to monthly time scale. It is shown that the ASITS and particulate matter smaller than 2.5 μm in diameter (PM2.5) concentrations own similar lognormal probability distribution functions on both daily and monthly time scales. And the correlation analyses between the ASITS and PM2.5 concentrations indicate that the ASITS can reflect the monthly and daily variations in PM2.5 concentrations in NC. In addition, ASITS could be used as a leading predictor of haze events since correlation coefficients of ASITS leading PM2.5 concentrations by 1 day were significant and were larger than simultaneous correlation coefficients in almost all areas in NC. The robust relationship between ASITS and PM2.5 concentrations exists possibly because the index can reflect the activities of synoptic systems. ASITS could be a useful statistical indicator for variations in PM2.5 concentrations and haze events, and a good tool in analyzing the relationship between climate change and long-term variations in haze in NC. [ABSTRACT FROM AUTHOR]

In recent years, haze pollution of China has become increasingly serious. Outdoor particles can enter the room through the building crack. Therefore, it is of great significance to study the indoor and outdoor penetrating and transport characteristics of fine particles. In this paper, the main factors affecting the penetration coefficient are quantitatively analyzed by combining theoretical and experimental research. The results indicate that there is no obvious function between the pressure difference and the penetration coefficient when the crack height 1 mm, but they can be unified with a linear function when the crack height 0.25 mm. The effect of the crack height and length on penetration coefficient is related to the maximum net displacement of particles. The smaller the crack height (H), the longer the crack length (L) and the smaller the pressure difference (ΔP) would cause the greater the decrease of the penetration coefficient as the particle size increases. Temperature and relative humidity have no significant correlation with the penetration coefficient. The semi-empirical formula of penetration coefficient is established based on the correlation analysis and the theory of penetrating coefficient, which has the advantages of high accuracy, simple form and easy to measurement. [ABSTRACT FROM AUTHOR]

Haze and cloud contamination is a common problem in optical remote-sensing imagery, as it can lead to the inaccurate estimation of physical properties of the surface derived from remote sensing and reduced accuracy of land cover classification and change detection. Haze optimized transform (HOT) is a methodology applicable to radiometric compensation of additive haze effects in visible bands that exhibits a spatially complex distribution over an image. The generic approach of HOT allows for the use of older satellite imaging sensors that include at least two visible bands (e.g. Landsat Thematic Mapper (TM) and Landsat Multispectral Scanner (MSS) sensors). This study proposes modifications to extend HOT applicability to new sensors. The improvements and extended functionality adapt the method to the higher radiometric resolution specifications of newer generation sensors and use percentile-based minimum in the correction procedure to avoid causing fake minimum. Alternative filters are also evaluated to smooth raw HOT output and the cloud mask is generated as an additional output. A Landsat 8 scene of Los Angeles is used to demonstrate the improved methodology. The methodology is applicable to sensors such as QuickBird, Worldview 2/3. More than 20 additional scenes were used to evaluate the effectiveness of the methodology. [ABSTRACT FROM PUBLISHER]

This study explores the implications of the digital network society for public health communication and management through an empirical study on communication related to the transboundary haze crisis in Singapore. Using the Social Amplification of Risk Framework (SARF), the authors applied sentiment and thematic analysis on haze-related posts on an online discussion forum (HardwareZone) and a social networking site (Facebook), and to haze-related articles in The Straits Times (a newspaper). The study shows that the medium matters in social amplification of risk: Facebook had an effect on the amplification of emotions, while HardwareZone and The Straits Times did not. In addition, the results show that spikes in online risk amplification were strongly influenced by unprecedented events. They also suggest that anger expressed online may be linked to a sense of futility. Implications for practice and recommendations for future research are provided in the conclusion. [ABSTRACT FROM AUTHOR]

Transboundary haze pollution from land and forest fires is considered one of the most serious environmental problems in Southeast Asia. Almost every year, haze pollution risks the health and lives of people living in the region, especially children, elderly people and people who already suffer from asthma. The international law of the atmosphere plays an important role in reducing the air pollution problem. The current trends in addressing transboundary environmental harm show that States prefer to adopt and implement a prevention and cooperation regime, as shown in Southeast Asia. This article explores how international law responds to transboundary pollution. Particularly, it examines how the Association of Southeast Asian Nations ( ASEAN) addresses transboundary haze pollution, and the effectiveness of its regional legal measures. This article argues that international law, particularly the State responsibility principle, plays an important role in pushing States to exercise due diligence. Nevertheless, State responsibility and civil liability regimes appear particularly difficult to implement in Southeast Asia due to the non-interference principle in the ASEAN Charter. Therefore, improving cooperation is the only viable option for addressing the haze pollution problem. [ABSTRACT FROM AUTHOR]

Transboundary air pollution is a complex, multi-faceted and multi-jurisdictional issue that affects many nation states. In Southeast Asia, this environmental hazard (also known as haze) is a recurring affair that has a tremendous effect on a handful of nation states; in particular, Indonesia, Singapore, Malaysia and Brunei. The Association for Southeast Asian Nations ('ASEAN') has made various attempts at regulating this menace, one of which is the ASEAN Agreement on Transboundary Air Pollution, 2002 (ATHP). While it has achieved a measure of success, one of its key weaknesses is the failure to provide for a successful means of dispute resolution. This article considers several issues in the light of this, including the relationship between Article 27(1) of the ATHP and Article 23(1) of the ASEAN Charter; whether a way forward can be found for the use of mediation as the alternative means of dispute settlement; and the principle of non-interference in the ASEAN way vis-à-vis the use of mediation. [ABSTRACT FROM AUTHOR]

To better understand the characterization and secondary organic aerosol (SOA) formation of volatile organic compounds (VOCs) during non-haze and haze days, ambient VOCs were continuously measured by a vehicle-mounted online thermal desorption system coupled with a gas chromatography-mass spectrometry (TD-GC/MS) system in Shanghai, China. The average concentrations of VOCs in haze episodes (193.2 μg m) were almost 50% higher than in non-haze periods (130.8 μg m). VOC concentrations exhibited a bi-modal pattern in the morning and evening rush hour periods on both non-haze and haze days. The ratios of toluene to benzene (T/B) and m,p-xylene to ethylbenzene (X/E) indicated that VOCs were aged air mass transported from nearby areas. The estimated SOA yields were 12.6 ± 5.3 and 16.7 ± 6.7 μg m for non-haze and haze days, respectively, accounting for 9.6 and 8.7% of the corresponding PM concentrations, which were slightly underestimated. VOCs-sensitivity (VOCs-S) based on a PM-dependent model was used to investigate the variation between VOCs and PM concentrations in the morning rush hour. It was found that VOCs were more sensitive to PM on clean days than during periods of heavy particulate pollution. VOCs-sensitivity was significantly correlated with the ratio of specific PM to background PM, with a simulated equation of y = 0.84x ( r = 0.93, p < 0.001). Our findings suggest that strategies to mitigate VOC emissions and further alleviate haze episodes in Shanghai based on reducing gasoline vehicle-related sources would be very efficient. [ABSTRACT FROM AUTHOR]

To identify the characteristics of air pollutants and factors attributing to the formation of haze in Wuhan, this study analyzed the hourly observations of air pollutants (PM2.5, PM10, NO2, SO2, O3, and CO) from March 1, 2013, to February 28, 2014, and used hybrid receptor models for a case study. The results showed that the annual average concentrations for PM2.5, PM10, NO2, SO2, O3, and CO during the whole period were 89.6 μg m−3, 134.9 μg m−3, 54.9 μg m−3, 32.4 μg m−3, 62.3 μg m−3, and 1.1 mg m−3, respectively. The monthly variations revealed that the peak values of PM2.5, PM10, NO2, SO2, and CO occurred in December because of increased local emissions and severe weather conditions, while the lowest values occurred in July mainly due to larger precipitation. The maximum O3concentrations occurred in warm seasons from May to August, which may be partly due to the high temperature and solar radiation. Diurnal analysis showed that hourly PM2.5, PM10, NO2, and CO concentrations had two ascending stages accompanying by the two traffic peaks. However, the O3concentration variations were different with the highest concentration in the afternoon. A case study utilizing hybrid receptor models showed the significant impact of regional transport on the haze formation in Wuhan and revealed that the mainly potential polluted sources were located in the north and south of Wuhan, such as Baoding and Handan in Hebei province, and Changsha in Hunan province.Implications: Wuhan city requires a 5% reduction of the annual mean of PM2.5concentration by the end of 2017. In order to accomplish this goal, Wuhan has adopted some measures to improve its air quality. This work has determined the main pollution sources that affect the formation of haze in Wuhan by transport. We showed that apart from the local emissions, north and south of Wuhan were the potential sources contributing to the high PM2.5concentrations in Wuhan, such as Baoding and Handan in Hebei province, Zhumadian and Jiaozuo in Henan province, and Changsha and Zhuzhou in Hunan province. [ABSTRACT FROM PUBLISHER]

The newly released MODIS Collection 6 aerosol products have been widely used to evaluate fine particulate matter with a 10 km Dark Target aerosol optic depth (DT AOD) product, a new 3 km DT AOD product and an enhanced Deep Blue (DB) AOD product. However, the representativeness of MODIS AOD products under different air quality conditions remains unclear. In this study, we obtained all three types of MODIS Terra AOD from 2001 to 2015 and Aqua AOD from 2003 to 2015 for the Beijing region to study the performance of the different AOD products (Collection 6) under different air quality situations. The validation of three MODIS AOD products suggests that DB AOD has the highest accuracy with an expected error (EE) envelope (containing at least 67% of the matchups on a scatter plot) of 0.05 + 0.15τ, followed by 10 km DT AOD (0.08 + 0.2τ) and 3 km DT AOD (0.35 + 0.15τ), specifically for Beijing. Near-surface PM2.5 concentrations during the passage of MODIS from 2013 to 2015 were also obtained to categorize air quality as unpolluted, moderately, and heavily polluted, as well as to analyze the performance of the different AOD products under different air quality conditions. Very few MODIS 3 km DT retrievals appeared on heavily polluted days, making it almost impossible to play an effective role in air quality applications in Beijing. While the DB AOD allowed for considerable retrievals under all air quality conditions, it had a coarse spatial resolution. These results demonstrate that the MODIS 3 km DT AOD product may not be the appropriate proxy to be used in the satellite retrieval of surface PM2.5, especially for those areas with frequent haze-fog events like Beijing. [ABSTRACT FROM AUTHOR]

Long-range transported (LRT) haze can affect the regional radiation budget and the air quality in areas downwind of the Asian continental outflow. Because in situ observations of spectral aerosol optical properties of the LRT haze are rare, an intensive characterization of aerosol optical properties is needed. This study characterized the spectral optical properties of the LRT haze and Asian dust originating from the Asian continent. Integrated chemical and optical measurements of aerosol particles were carried out in a downwind area of the Asian continental outflow (Daejeon, South Korea) during winter 2014. High concentrations of PM10 (particulate matter with a diameter⩽10 μm) and light scattering coefficients at 550 nm, σs,550, were observed during a long-range transport (LRT) haze episode (PM10 = 163.9±25.0 μgm-3; σs,550 = 503.4±60.5Mm-1) and Asian dust episode (PM10 = 211.3±57.5 μgm-3; σs,550 = 560.9±151Mm-1. During the LRT haze episode, no significant change in the relative contribution of PM2:5 (particulate matter with a diameter ⩽2.5 μm) chemical components was observed as particles accumulated under stagnant atmospheric conditions (13-17 January 2014), suggesting that the increase in PM2:5 mass concentration was caused mainly by the accumulation of LRT pollutants. On the other hand, a gradual decrease in Ångström exponent (Å) and a gradual increase in single scattering albedo (ω) and mass scattering efficiency (MSE) were observed during the stagnant period, possibly due to an increase in particle size. These results imply that a change in particle size rather than chemical composition during the stagnant period is the dominant factor affecting the aerosol optical properties. During the Asian dust episode, a low PM2:5/PM10 ratio and Å(450/700) were observed with average values of 0.59±0.06 and 1.08±0.14, respectively, which were higher than those during the LRT haze episode (0.75±0.06 and 1.39±0.05, respectively), indicating that PM2:5/PM10 mass ratios and Å(450/700) can be used as tracers to distinguish aged LRT haze and Asian dust under the Asian continental outflow. [ABSTRACT FROM AUTHOR]

The Nested Air Quality Prediction Model System (NAQPMS) was used to investigate an extreme regional haze episode persisting over the Beijing-Tianjin-Hebei megacity cluster from November 26 to December 1, 2015. During this extreme haze event, the regional daily mean PM 2.5 exceeded 500 μg/m3. We found that local emissions were the main source of haze over Beijing and Hebei in the early formational stage of this episode. The accumulation of regionally transported, highly aged secondary inorganic aerosols (SIA) along the foot of the mountains was responsible (60%) for the rapid increase of surface PM 2.5 in Beijing between November 30 and December 1, although PM 2.5 concentrations in the source regions of Hebei province were lower. The height of regional transport ranged from 200 to 700 m above ground level, with a slow increase with increasing distance of the source regions from Beijing. This indicates that more attention should be given to point sources at heights of 200–500 m in order to reduce the contribution of transport. The contribution of local emissions to haze in Beijing was mostly concentrated below 300 m above ground level, and was more significant for black carbon (BC) and organic matter (OM) than SIA. Tagging of pollutants by emission time showed that PM 2.5 had been aged before it arrived at Beijing, and PM 2.5 formed one or more days prior to arrival was twice that formed on the arrival day. This suggests that control measures would be more effective if they were implemented two days prior to haze episodes. In contrast to Beijing, haze in Tianjin was governed by transport from outside sources, whereas in cities located in Hebei province this episode resulted from local emissions. [ABSTRACT FROM AUTHOR]

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To investigate the characteristics of polycyclic aromatic hydrocarbons (PAHs) during haze episodes in warm seasons, daily PM and gaseous samples were collected from March to September 2015 in Hangzhou, China. Daily samples were further divided into four groups by the definition of haze according to visibility and relative humidity (RH), including non-haze (visibility, >10 km), light haze (visibility, 8-10 km, RH <90 %), medium haze (visibility, 5-8 km, RH <90 %), and heavy haze (visibility, <5 km, RH <90 %). Significantly higher concentrations of PM-bound PAHs were found in haze days, but the mean PM-bound PAH concentrations obviously decreased with the aggravation of haze pollution from light to heavy. The gas/particle partitioning coefficients of PAHs decreased from light-haze to heavy-haze episodes, which indicated that PM-bound PAHs were restricted to adhere to the particulate phase with the aggravation of haze pollution. Absorption was considered the main mechanism of gas/particle partitioning of PAHs from gaseous to particulate phase. Analysis of air mass transport indicated that the PM-bound PAH pollution in haze days was largely from regional sources but also significantly affected by long-range air mass transport. The inhalation cancer risk associated with PAHs exceeded the acceptable risk level markedly in both haze and non-haze days. [ABSTRACT FROM AUTHOR]

The article discusses the measurements of spectral ultraviolet attenuation in a severe dust event in Australia. It refers to the solar ultraviolet attenuation during the Red Dawn dust event on September 23, 2009. The Australian storm affected the major population centers of Sydney and Brisbane which were blanketed with a thick reddish haze and reduced visibility.

Haze-fog pollution has been one of the major atmospheric pollution problems in China. This study is aimed at understanding spatial distribution and spatial correlation of haze-fog pollution in China from 2001 to 2010 using exploratory spatial data analysis technique. The results show that spatial distribution of haze-fog pollution is not changed obviously in the 10 years, and the most serious polluted region is distributed in Beijing-Tianjin-Hebei region. The values of global Moran's I vary from 0.4066 to 0.4842, which indicates that haze-fog pollution is not distributed randomly, but has spatial agglomeration effects. The High-High agglomeration type is mainly distributed in central China, which contains 15, 14, 14, and 13 regions for the years of 2001, 2004, 2007, and 2010, respectively, while the Low-Low agglomeration type is concentrated in western and eastern China, which contains 11, 10, 10, and 8 regions for the years of 2001, 2004, 2007, and 2010, respectively. The results should provide policy guidance for public authorities to control haze-fog pollution. Further researches are still needed because of the complexity of haze-fog pollution and variety of influence factors. [ABSTRACT FROM AUTHOR]

Haze pollution involving PM2.5 is currently a serious problem in China, and the implementation of tougher measures to further reduce emissions from key air pollution sources such as coal-fired power plants has become an inevitable trend. Wet electrostatic precipitator (WESP) technology is being adopted by an increasing number of power plants because of its ability to remove PM2.5 and other fine particulate matter. In this study, key indicators such as filterable particulate matter (FPM), condensable particulate matter (CPM), SO3, and droplets in the flue gas of Shanghai Changxing Island No.2 Power Plant were measured and analysed. The results indicate that the emission concentrations of total particulate matter (TPM) were 30.31 mg/m³ and 15.74 mg/m³, FPM were 20.31 mg/m³ and 6.09 mg/m³, PM2.5 were 4.06 mg/m³ and 2.50 mg/m³, SO3 were 4.51 mg/m³ and 3.06 mg/m³, and droplets were 114 mg/m³ and 102 mg/m³ at the stack when the WESP was off and on, respectively. Similarly, CPM accounted for 33% and 61% of TPM, respectively. This study demonstrates that the use of WESP technology has a significant effect on the removal of particulate matter and droplets. [ABSTRACT FROM AUTHOR]

The rapid industrial development has led to the intermittent outbreak of pm2.5 or haze in developing countries, which has brought about great environmental issues, especially in big cities such as Beijing and New Delhi. We investigated the factors and mechanisms of haze change and present a long-term prediction model of Beijing haze episodes using time series analysis. We construct a dynamic structural measurement model of daily haze increment and reduce the model to a vector autoregressive model. Typical case studies on 886 continuous days indicate that our model performs very well on next day’s Air Quality Index (AQI) prediction, and in severely polluted cases (AQI ≥ 300) the accuracy rate of AQI prediction even reaches up to 87.8%. The experiment of one-week prediction shows that our model has excellent sensitivity when a sudden haze burst or dissipation happens, which results in good long-term stability on the accuracy of the next 3–7 days’ AQI prediction. [ABSTRACT FROM AUTHOR]

The atmospheric effect greatly affects the quality of satellite data and mostly found in the polluted urban area in the great extent. In this paper, the atmospheric correction has been carried out on IRS-1C LISS-III multispectral satellite image for efficient results for the Raipur city, India. The atmospheric conditions during satellite data acquisition was very clear hence very clear relative scattering model of improved dark object subtraction method for the correction of atmospheric effects in the data has been carried out to produce the realistic results. The haze values (HV) for green band (band 2), red band (band 3), NIR band (band 4) and SWIR (band 5) are 79, 53, 54 and 124, respectively; were used for the corrections of haze effects using simple dark object subtraction method (SDOS). But the final predicted haze value (FPHV) for these bands are 79, 49.85, 21.31 and 0.13 that were used for the corrections of haze effects applying improved dark object subtraction method (IDOS). We found that IDOS method produces very realistic results when compared with SDOS method for urban land use mapping and change detection analysis. Consequently, ATCOR2 model provides better results when compared with SDOS and IDOS in the study. [ABSTRACT FROM AUTHOR]

A WRF-CMAQ modeling system is used to assess the impact of emission control strategies and weather conditions on haze pollution in Zhongshan, Guangdong Province, China. One-month simulations for January 2014 are completed and evaluated with the observational data. The simulations show reasonable agreement with the observations. Several sensitivity studies are completed to quantify the percentage contributions of local emissions versus regional emissions to the PM2.5 concentrations under different weather conditions. The results indicate that the contributions from local emission is higher than those of the emissions from regional transport when there is no intrusion of cold front (i.e., 58% contribution from local emission versus 42% contribution from the regional transport). The contribution of regional transport is increased to 76% when a strong cold front appears. Furthermore, the sensitivity study demonstrates that PM2.5 concentrations on the first, second, and third days are reduced by 47%, 52%, and 58%, respectively, after the local emissions are turned off when there is no intrusion of cold front. Finally, a case study shows that industrial, residential, and mobile emissions account for 24%, 22%, and 15% of the change of PM2.5, respectively, during a heavy haze pollution event in Zhongshan. [ABSTRACT FROM AUTHOR]

Based on the surface meteorological data of Jiangsu Province during 1980–2012, the climatic characteristics and the trends of haze were analyzed. The results indicated that during 1980–2012 haze days increased; in particular, severe and moderate haze days significantly increased. In the northern and coastal cities of Jiangsu Province China, haze days showed a significant increase. Haze often appeared in fall and winter and rarely in summer in the study area. It also occurred more often inland, and less along the coast. Haze occurred more often in June due to straw burning in the harvest time. The haze day increased during the 1990s over southern and southwestern Jiangsu Province; in central and northern Jiangsu, haze day increased after 2000. The continuous, regional, and regional continuous haze days all showed increasing trends. As the urban area expanded each year, industrial emissions, coal consumption, and car ownership increased accordingly, resulting in regional temperature increase and relative humidity decrease, which formed the urban heat island and dry island effects. Hence, haze formation and maintenance conditions became more favorable for more haze days, which led to the increase of haze days, and the significant increases of continuous, regional, and regional continuous haze days. [ABSTRACT FROM AUTHOR]

The carbonaceous aerosol concentrations in coarse particle (PM: Dp ≤ 10 μm, particulate matter with an aerodynamic diameter less than 10 μm), fine particle (PM: Dp ≤ 2.5 μm), and ultrafine particle (PM: Dp ≤ 0.133 μm) carbon fractions in a rural area were investigated during haze events in northwestern China. The results indicated that PM contributed a large fraction in PM. OC (organic carbon) accounted for 33, 41, and 62 % of PM, PM, and PM, and those were 2, 2.4, and 0.4 % for EC (elemental carbon) in a rural area, respectively. OC3 was more abundant than other organic carbon fractions in three PMs, and char dominated EC in PM and PM while soot dominated EC in PM. The present study inferred that K, OP, and OC3 are good biomass burning tracers for rural PM and PM, but not for PM during haze pollution. Our results suggest that biomass burning is likely to be an important contributor to rural PMs in northwestern China. It is necessary to establish biomass burning control policies for the mitigation of severe haze pollution in a rural area. [ABSTRACT FROM AUTHOR]

Using the daily records derived from the synoptic weather stations and the NCEP/NCAR and ERA-Interim reanalysis data, the variability of the winter haze pollution (indicated by the mean visibility and number of hazy days) in the Beijing–Tianjin–Hebei (BTH) region during the period 1981 to 2015 and its relationship with the atmospheric circulations at middle–high latitude were analyzed in this study. The winter haze pollution in BTH had distinct inter-annual and inter-decadal variabilities without a significant long-term trend. According to the spatial distribution of correlation coefficients, six atmospheric circulation indices (I1 to I6) were defined from the key areas in sea level pressure (SLP), zonal and meridional winds at 850 hPa (U850, V850), geopotential height field at 500 hPa (H500), zonal wind at 200 hPa (U200), and air temperature at 200 hPa (T200), respectively. All of the six indices have significant and stable correlations with the winter visibility and number of hazy days in BTH. In the raw (unfiltered) correlations, the correlation coefficients between the six indices and the winter visibility (number of hazy days) varied from 0.57 (0.47) to 0.76 (0.6) with an average of 0.65 (0.54); in the high-frequency (< 10 years) correlations, the coefficients varied from 0.62 (0.58) to 0.8 (0.69) with an average of 0.69 (0.64). The six circulation indices together can explain 77.7% (78.7 %) and 61.7% (69.1 %) variances of the winter visibility and the number of hazy days in the year-to-year (inter-annual) variability, respectively. The increase in Ic (a comprehensive index derived from the six individual circulation indices) can cause a shallowing of the East Asian trough at the middle troposphere and a weakening of the Siberian high-pressure field at sea level, and is then accompanied by a reduction (increase) of horizontal advection and vertical convection (relative humidity) in the lowest troposphere and a reduced boundary layer height in BTH and its neighboring areas, which are favorable for the formation of haze pollution in BTH winter, and vice versa. The high level of the prediction statistics and the reasonable mechanism suggested that the winter haze pollution in BTH can be forecasted or estimated credibly based on the optimized atmospheric circulation indices. Thus it is helpful for government decision-making departments to take action in advance in dealing with probably severe haze pollution in BTH indicated by the atmospheric circulation conditions. [ABSTRACT FROM AUTHOR]

Haze caused by high particulate matter loadings is an important environmental issue. PM 2.5 was collected in Nanjing, China, during a severe haze–fog event and clear periods. The particulate-bound elements were chemically fractionated using sequential extractions. The average PM 2.5 concentration was 3.4 times higher during haze–fog (96–518 μg/m 3 ) than non-haze fog periods (49–142 μg/m 3 ). Nearly all elements showed significantly higher concentrations during haze–fog than non-haze fog periods. Zn, As, Pb, Cd, Mo and Cu were considered to have higher bioavailability and enrichment degree in the atmosphere. Highly bioavailable fractions of elements were associated with high temperatures. The integrated carcinogenic risk for two possible scenarios to individuals exposed to metals was higher than the accepted criterion of 10 −6 , whereas noncarcinogenic risk was lower than the safe level of 1. Residents of a city burdened with haze will incur health risks caused by exposure to airborne metals. [ABSTRACT FROM AUTHOR]

Recently, PM2.5 (particulate matter with diameter of 2.5 micron or less) has become a major health hazard from the polluted air in many cities in China. The regular gauze masks are used to prevent inhaling the PM2.5 fine particles; however, those masks are not able to filter out the PM2.5 because of the large porosity of the mask materials. Some well-prevented masks usually have poor breathability, which increases other health risks. In this study, a polysulfone based nanofiber for mask filtration material was synthesized by electrospinning. That nanofiber mask material was characterized by SEM, air permeability test, and PM2.5 trapping experiment. The results indicate that nanofiber mask material can efficiently filter out the PM2.5 particles and simultaneously preserve a good breathability. We attribute such improvement to the nanoscaled fibers, having the same porosity as that of regular gauze mask but with extremely reduced local interfiber space. [ABSTRACT FROM AUTHOR]

Images captured in foggy weather conditions often suffer from poor visibility, which will create a lot of impacts on the outdoor computer vision systems, such as video surveillance, intelligent transportation assistance system, remote sensing space cameras and so on. In this paper, we propose a new transmission estimated method to improve the visibility of single input image (with fog or haze), as well as the image's details. Our approach stems from two important statistical observations about haze-free images and the haze itself. First, the famous dark channel prior, a statistics of the haze-free outdoor images, can be used to estimate the thickness of the haze; and second, gradient prior law of transmission maps, which is based on dark channel prior. By integrating these two priors, to estimate the unknown scene transmission map is modeled into a TV-regularization optimization problem. The experimental results show that the proposed approach can effectively improve the visibility and keep the details of fog degraded images in the meanwhile. [ABSTRACT FROM AUTHOR]

Recently, haze has become a great threat to public travel safety, and a major source of damage to physical and mental health in eastern China. More and more research and global media attentions have focused on the harmful influences of the haze weather. From this scrutiny has emerged the fact that haze negatively affects Chinese tourist attractions, and the declining visitor numbers are proof of this. Based on an analysis of the responses of inbound tourists, we discovered that haze as the representative of air pollution, as well as associated food safety, health anxieties, and other risks in China, decrease the quality of tourist experiences. This paper reported a range of haze -related issues that constitute the main aspects of inbound tourists' perceptions of adverse environmental risks in China. To identify how inbound tourists experience and evaluate environmental risks, the researchers designed a questionnaire that covered 27 measures after a literature review and communication with a sample of inbound tourists. After a series of pre-surveys, we incorporated 24 of these measures in our final survey instrument. Finally, we used the IPA technique to analyze the data obtained from the investigation. The IPA technique is a basic diagnostic decision tool that facilitates the identification of improvement prioritization. Because of the negative performance of environmental risk itself, there is a need to adjust the traditional IPA method. The original IPA method was initially used only to analyze positive performance problems. In this context, the research proposes a "negative IPA matrix" to analyze inbound tourists' perception of environmental risk in China. We compared four dimensions of the perception of risks: possible movement restrictions, health threats, security threats, and recreation restrictions. The study found that key features of environmental risks perceived by inbound tourists for China were "poor air quality" and "low visibility", and related issues. Moreover, the study found that inbound tourists generally had high perceptions of environmental risk, and consequently gave low marks to the China's tourism environment. The evaluation of the four dimensions all showed higher negative values than the mean. In particular, the perception of threats to health in risk evaluations is much higher than the perceived actual strength. We believe that there are two main factors that account for this special phenomenon. This paper presents and proves the effectiveness of the negative IPA tool in the study of tourist risk perceptions. We also propose strategies as countermeasures for these perceptions. For example, inbound tourists feel most strongly and give the worst evaluation on poor air quality and low visual amenity, when these are compared to the other seven factors. Our preferred strategy is to "concentrate here". To provide specific strategies to deal with the adverse effects of recent haze on the China's inbound tourism market, governments and marketing organizations should pay attention to this impact, and take measures to deal with it. However, as we were limited by constraints on the research, the study has several shortcomings: first, the survey sample was mainly selected from Suzhou, Jiangsu Province. The research therefore needs to be combined with similar research on other tourist cities in East China; and second, there were few questions on the socio-cultural environmental risk factors for tourism in the questionnaire, and follow-up studies can do better in this respect. [ABSTRACT FROM AUTHOR]

Rapid industrialization and urbanization in developing countries has led to an increase in air pollution, along a similar trajectory to that previously experienced by the developed nations. In China, particulate pollution is a serious environmental problem that is influencing air quality, regional and global climates, and human health. In response to the extremely severe and persistent haze pollution experienced by about 800 million people during the first quarter of 2013 (refs 4, 5), the Chinese State Council announced its aim to reduce concentrations of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 micrometres) by up to 25 per cent relative to 2012 levels by 2017 (ref. 6). Such efforts however require elucidation of the factors governing the abundance and composition of PM2.5, which remain poorly constrained in China. Here we combine a comprehensive set of novel and state-of-the-art offline analytical approaches and statistical techniques to investigate the chemical nature and sources of particulate matter at urban locations in Beijing, Shanghai, Guangzhou and Xi'an during January 2013. We find that the severe haze pollution event was driven to a large extent by secondary aerosol formation, which contributed 30-77 per cent and 44-71 per cent (average for all four cities) of PM2.5 and of organic aerosol, respectively. On average, the contribution of secondary organic aerosol (SOA) and secondary inorganic aerosol (SIA) are found to be of similar importance (SOA/SIA ratios range from 0.6 to 1.4). Our results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from, for example, fossil fuel combustion and biomass burning is likely to be important for controlling China's PM2.5 levels and for reducing the environmental, economic and health impacts resulting from particulate pollution. [ABSTRACT FROM AUTHOR]

Transboundary haze pollution is an almost annual occurrence in Southeast Asia. Haze originates from peat and forest fires mostly in Indonesia, with Malaysia and Singapore suffering the worst of its effects. Most of these fires are man-made and linked to land-clearing activities of local and foreign commercial oil palm plantations. The regional nature of the haze has resulted in a concentration of haze mitigation activities at the Association of Southeast Asian Nations (ASEAN) level. However, these initiatives continually fail to effectively mitigate haze. This article argues that this failure is due to the influence of patronage politics in the sector, which is linked to the ASEAN style of regional engagement that prioritises the maintenance of national sovereignty. States are compelled to act in their national interests, as opposed to the collective regional interests. The economic importance of the oil palm sector to the states involved, coupled with the political importance of the clients populating this sector to elite patrons in the governments, meant that the maintenance of the status quo, where clients could continue to clear land using fire, was of crucial national interest. Therefore, the ASEAN style of regional engagement has enabled political elites to shape ASEAN initiatives to preserve the interests of their clients, while the public continue to suffer the haze. This article demonstrates this through a close analysis of the negotiations, outcomes and the implementation of the ASEAN Agreement on transboundary haze pollution, with a special focus on Indonesia's decision to withhold ratification of the treaty. [ABSTRACT FROM AUTHOR]

Fog events almost happened every year in cold season in North China Plain. In this study, hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model was applied to analyze the formation of four fog events occurring in Ji'nan, China, during the period from March 2012 to February 2014. Three types of fog have been distinguished, including radiation fog, advection fog, and frontal fog. When fog events happened, the average surface temperature ranged from near zero to 10°C and the relative humidity was around 90%. Fog events often happened immediately after haze episodes (i.e., fog-haze) and sometimes after light rain. Back trajectory analyses show that the air masses during the fog events mostly came from the local Shandong areas and moved in very slow speed (4-24kmh-1). During the fog events, the humidity along the air trajectories always gradually increased to saturation. The mixed layer depth was small, generally below 400 m at noon and around 100 m at midnight. However, the air temperature exhibited complex variations--sometimes decreased and sometimes kept stable or even increased. [ABSTRACT FROM AUTHOR]

The air-pollution episodes in China in January 2013 were the most hazardous in the Beijing-Tianjin-Hebei (BTH) region. PM25, AOD, and long-term visibility data, along with various climate and meteorological factors and the boundary-layer structure, were used to investigate the cause of the heavy-haze pollution events in January 2013. The result suggests that unfavorable diffusion conditions (weak surface winds and high humidity) and high primary-pollutant emissions have induced heavy-haze pollution in the BTH region over the past two decades. A sudden stratospheric warming (SSW), weak East Asian winter monsoon, a weak Siberian High, weak meridional circulation, southerly wind anomalies in the lower troposphere, and abnormally weak surface winds and high humidity were responsible for the severe haze pollution events, rather than an abrupt increase in emissions. Heavy/severe haze pollution is associated with orographic wind convergence zones along the Taihang and Yanshan Mountains, slight winds (1.7-2.1 m/s), and high humidity (70%~90%), which limits the diffusion of pollutants and facilitates the hygroscopic growth of aerosols. Recirculation and regional transport, along with the poorest diffusion conditions and favorable conditions for hygroscopic growth of aerosols and secondary transformation under the high emission, led to explosive growth and the record high hourly average concentration of PM25 in Beijing. [ABSTRACT FROM AUTHOR]

In addressing transboundary haze pollution, the role of the domestic legal framework is crucial. Despite this importance, literature addressing the problem from a current legal and policy framework in Indonesia is lacking. This article examines the adequacy of that existing legal framework in Indonesia. It argues that a well-structured, integrated legal framework is crucial in addressing land/forest fires. The legislation and policy examined mainly relate to regulation specifically addressing, and other legislation related to, land and forest fires. The approach to analysing the adequacy of legal framework is holistic and includes a broader legal framework; that is, it examines not only regulation specifically addressing land and forest fires, but also legislation and regulation in other sectors related to such fires, such as forestry law, agriculture law, environment protection law, autonomy law, and disaster management law. This broader approach aims to examine the gaps, overlaps and conflicts between these sectoral laws. This article concludes that the existing legal framework in Indonesia to address land and forest fires is inadequate. Stronger legislation in the form of a statute/law is required. [ABSTRACT FROM AUTHOR]

The possibility to obtain reliable data on the chemical and physical characteristics of aerosols and the regularities in the processes of their formation and transportation under the background natural-climatic conditions is a necessary requirement for verification of existing climate models [1, 2]. [ABSTRACT FROM AUTHOR]

Air protection agencies in the United States increasingly confront non-attainment of air quality standards for multiple pollutants sharing interrelated emission origins. Traditional approaches to attainment planning face important limitations that are magnified in the multipollutant context. Recognizing those limitations, the Georgia Environmental Protection Division has adopted an integrated framework to address ozone, fine particulate matter, and regional haze in the state. Rather than applying atmospheric modeling merely as a final check of an overall strategy, photochemical sensitivity analysis is conducted upfront to compare the effectiveness of controlling various precursor emission species and source regions. Emerging software enables the modeling of health benefits and associated economic valuations resulting from air pollution control. Photochemical sensitivity and health benefits analyses, applied together with traditional cost and feasibility assessments, provide a more comprehensive characterization of the implications of various control options. The fuller characterization both informs the selection of control options and facilitates the communication of impacts to affected stakeholders and the public. Although the integrated framework represents a clear improvement over previous attainment-planning efforts, key remaining shortcomings are also discussed. [ABSTRACT FROM AUTHOR]