Showing papers on "Haze published in 2014"
TL;DR: The results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from 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: 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.
3,372 citations
TL;DR: A periodic cycle of PM episodes in Beijing is demonstrated that is governed by meteorological conditions and characterized by two distinct aerosol formation processes of nucleation and growth, but with a small contribution from primary emissions and regional transport of particles.
Abstract: As the world’s second largest economy, China has experienced severe haze pollution, with fine particulate matter (PM) recently reaching unprecedentedly high levels across many cities, and an understanding of the PM formation mechanism is critical in the development of efficient mediation policies to minimize its regional to global impacts. We demonstrate a periodic cycle of PM episodes in Beijing that is governed by meteorological conditions and characterized by two distinct aerosol formation processes of nucleation and growth, but with a small contribution from primary emissions and regional transport of particles. Nucleation consistently precedes a polluted period, producing a high number concentration of nano-sized particles under clean conditions. Accumulation of the particle mass concentration exceeding several hundred micrograms per cubic meter is accompanied by a continuous size growth from the nucleation-mode particles over multiple days to yield numerous larger particles, distinctive from the aerosol formation typically observed in other regions worldwide. The particle compositions in Beijing, on the other hand, exhibit a similarity to those commonly measured in many global areas, consistent with the chemical constituents dominated by secondary aerosol formation. Our results highlight that regulatory controls of gaseous emissions for volatile organic compounds and nitrogen oxides from local transportation and sulfur dioxide from regional industrial sources represent the key steps to reduce the urban PM level in China.
1,291 citations
TL;DR: In this paper, a detailed characterization of the sources and evolution mechanisms of this haze pollution with a focus on four haze episodes that occurred during 10-14 January in Beijing was presented, where the main source of data analyzed is from submicron aerosol measurements by an Aerodyne Aerosol Chemical Speciation Monitor.
Abstract: China experienced severe haze pollution in January 2013. Here we have a detailed characterization of the sources and evolution mechanisms of this haze pollution with a focus on four haze episodes that occurred during 10–14 January in Beijing. The main source of data analyzed is from submicron aerosol measurements by an Aerodyne Aerosol Chemical Speciation Monitor. The average PM1 mass concentration during the four haze episodes ranged from 144 to 300 µg m−3, which was more than 10 times higher than that observed during clean periods. All submicron aerosol species showed substantial increases during haze episodes with sulfate being the largest. Secondary inorganic species played enhanced roles in the haze formation as suggested by their elevated contributions during haze episodes. Positive matrix factorization analysis resolved six organic aerosol (OA) factors including three primary OA (POA) factors from traffic, cooking, and coal combustion emissions, respectively, and three secondary OA (SOA) factors. Overall, SOA contributed 41–59% of OA with the rest being POA. Coal combustion OA (CCOA) was the largest primary source, on average accounting for 20–32% of OA, and showed the most significant enhancement during haze episodes. A regional SOA (RSOA) was resolved for the first time which showed a pronounced peak only during the record-breaking haze episode (Ep3) on 12–13 January. The regional contributions estimated based on the steep evolution of air pollutants were found to play dominant roles for the formation of Ep3, on average accounting for 66% of PM1 during the peak of Ep3 with sulfate, CCOA, and RSOA being the largest fractions (> ~ 75%). Our results suggest that stagnant meteorological conditions, coal combustion, secondary production, and regional transport are four main factors driving the formation and evolution of haze pollution in Beijing during wintertime.
614 citations
TL;DR: In this article, the formation and evolution of haze pollution episodes were observed by the "Forming Mechanism and Control Strategies of Haze in China" group using an intensive aerosol and trace gases campaign that simultaneously obtained data at 11 ground-based observing sites in the CARE-China network.
Abstract: In January 2013, a long-lasting episode of severe haze occurred in central and eastern China, and it attracted attention from all sectors of society. The process and evolution of haze pollution episodes were observed by the "Forming Mechanism and Control Strategies of Haze in China" group using an intensive aerosol and trace gases campaign that simultaneously obtained data at 11 ground-based observing sites in the CARE-China network. The characteristics and formation mechanism of haze pollution episodes were discussed. Five haze pollution episodes were identified in the Beijing-Tianjin-Hebei (Jing-Jin-Ji) area; the two most severe episodes occurred during 9-15 January and 25-31 January. During these two haze pollution episodes, the maximum hourly PM2.5 mass concentrations in Beijing were 680 and 530 μg m-3, respectively. The process and evolution of haze pollution episodes in other major cities in the Jing-Jin-Ji area, such as Shijiazhuang and Tianjin were almost the same as those observed in Beijing. The external cause of the severe haze episodes was the unusual atmospheric circulation, the depression of strong cold air activities and the very unfavorable dispersion due to geographical and meteorological conditions. However, the internal cause was the quick secondary transformation of primary gaseous pollutants to secondary aerosols, which contributed to the "explosive growth" and "sustained growth" of PM2.5. Particularly, the abnormally high amount of nitric oxide (NO x ) in the haze episodes, produced by fossil fuel combustion and vehicle emissions, played a direct or indirect role in the quick secondary transformation of coal-burning sulphur dioxide (SO2) to sulphate aerosols. Furthermore, gaseous pollutants were transformed into secondary aerosols through heterogeneous reactions on the surface of fine particles, which can change the particles size and chemical composition. Consequently, the proportion of secondary inorganic ions, such as sulphate and nitrate, gradually increased, which enhances particle hygroscopicity and thereby accelerating formation of the haze pollution.
584 citations
TL;DR: This work introduces a novel transparent paper made of wood fibers that displays both ultrahigh optical transparency and ultrahigh haze, thus delivering an optimal substrate design for solar cell devices.
Abstract: Solar cell substrates require high optical transparency but also prefer high optical haze to increase the light scattering and consequently the absorption in the active materials. Unfortunately, there is a trade-off between these optical properties, which is exemplified by common trans- parent paper substrates exhibiting a transparency of about 90% yet a low optical haze (<20%). In this work, we introduce a novel transparent paper made of wood fibers that displays both ultrahigh optical transparency (∼96%) and ultrahigh haze (∼60%), thus delivering an optimal substrate design for solar cell devices. Compared to previously demonstrated nanopaper composed of wood-based cellulose nanofibers, our novel transparent paper has better dual performance in transmittance and haze but also is fabricated at a much lower cost. This high-performance, low-cost transparent paper is a potentially revolutionary material that may influence a new generation of environmentally friendly printed electronics.
412 citations
TL;DR: In this paper, the authors investigated meteorological conditions for this FHE by diagnosing both its atmospheric background fields and daily evolution in January 2013 and showed that the effect of meteorological factors on the variance of the daily fog and haze evolution reached 0.68.
Abstract: In January 2013, a severe fog and haze event (FHE) of strong intensity, long duration, and extensive coverage occurred in eastern China. The present study investigates meteorological conditions for this FHE by diagnosing both its atmospheric background fields and daily evolution in January 2013. The results show that a weak East Asian winter monsoon existed in January 2013. Over eastern China, the anomalous southerly winds in the middle and lower troposphere are favorable for more water vapor transported to eastern China. An anomalous high at 500 hPa suppresses convection. The weakened surface winds are favorable for the fog and haze concentrating in eastern China. The reduction of the vertical shear of horizontal winds weakens the synoptic disturbances and vertical mixing of atmosphere. The anomalous inversion in near-surface increases the stability of surface air. All these meteorological background fields in January 2013 were conducive to the maintenance and development of fog and haze over eastern China. The diagnosis of the daily evolution of the FHE shows that the surface wind velocity and the vertical shear of horizontal winds in the middle and lower troposphere can exert dynamic effects on fog and haze. The larger (smaller) they are, the weaker (stronger) the fog and haze are. The thermodynamic effects include stratification instability in middle and lower troposphere and the inversion and dew-point deficit in near-surface. The larger (smaller) the stratification instability and the inversion are, the stronger (weaker) the fog and haze are. Meanwhile, the smaller (larger) the dewpoint deficit is, the stronger (weaker) the fog and haze are. Based on the meteorological factors, a multi-variate linear regression model is set up. The model results show that the dynamic and thermodynamic effects on the variance of the fog and haze evolution are almost the same. The contribution of the meteorological factors to the variance of the daily fog and haze evolution reaches 0.68, which explains more than 2/3 of the variance.
395 citations
TL;DR: In this paper, a comprehensive measurement was carried out to analyze the heavy haze events during 2012-2013 winter in Beijing, where the measured variables include some important meteorological parameters, such as wind directions, wind speeds, relative humidity (RH), planetary boundary layer (PBL), solar radiation, and visibility.
275 citations
TL;DR: In this article, a nested-grid GEOS-Chem model reproduces the distribution of PM2.5 and simulates up to 364 εg/m3 of daily maximum PM 2.5.
Abstract: A regional haze with daily PM2.5 (fine particulate matters with diameters less than 2.5 µm) exceeding 500 µg/m3 lasted for several days in January 2013 over North China, offering an opportunity to evaluate models. Observations show that inorganic aerosols (sulfate, nitrate, and ammonium) are the largest contributor to PM2.5 during the haze period, while sulfate shows the largest enhancement ratio of 5.4 from the clean to haze period. The nested-grid GEOS-Chem model reproduces the distribution of PM2.5 and simulates up to 364 µg/m3 of daily maximum PM2.5. Yet on average, the model is a factor of 3 and 4 lower in PM2.5 and fails to capture the large sulfate enhancement from the clean to haze period. A doubling of SO2 emissions over North China, along with daily meteorology corrections, would be required to reconcile model results with surface SO2 observations, but it is not sufficient to explain the model discrepancy in sulfate. Heterogeneous uptake of SO2 on deliquesced aerosols is proposed as an additional source of sulfate under high-relative humidity conditions during the haze period. Parameterizing this process in the model improves the simulated spatial distribution and results in a 70% increase of sulfate enhancement ratio and a 120% increase in sulfate fraction in PM2.5. Combined adjustments in emissions, meteorology, and sulfate chemistry lead to higher sulfate by a factor of 3 and 50% higher PM2.5, significantly reducing the model's low bias during the haze.
272 citations
TL;DR: In this article, the role of reduction of atmospheric relative humidity in the transition process from fog into haze has been further investigated, which implies that it is more difficult for the haze particles to transform into fog drops.
Abstract: Our analysis of fog and haze observations from the surface weather stations in China in recent 50 years (from 1961 to 2011) shows that the number of fog days has experienced two-stage variations, with an increasing trend before 1980 and a decreasing trend after 1990. Especially, an obvious decreasing trend after 1990 can be clearly seen, which is consistent with the decreasing trend of the surface relative humidity. However, the number of haze days has demonstrated an increasing trend. As such, the role of reduction of atmospheric relative humidity in the transition process from fog into haze has been further investigated. It is estimated that the mean relative humidity of haze days is about 69%, lower than previously estimated, which implies that it is more difficult for the haze particles to transform into fog drops. This is possibly one of the major environmental factors leading to the reduction of number of fog days. The threshold of the relative humidity for transition from fog into haze is about 82%, also lower than previously estimated. Thus, the reduction of the surface relative humidity in China mainly due to the increase of the surface temperature and the saturation specific humidity may exert an obvious impact on the environmental conditions for the formations of fog and haze. In addition, our investigation of the relationship between haze and visibility reveals that with the increase of haze days, the visibility has declined markedly. Since 1961, the mean visibility has dropped from 4-10 to 2-4 km, about a half of the previous horizontal distance of visibility.
270 citations
TL;DR: In this paper, the authors used Cimel sunphotometer measurements at seven sites over rural, suburban and urban regions of North China Plain from 1 to 30 January 2013 were used to further understand of spatial-temporal variation of aerosol optical parameters and aerosol radiative forcing (ARF).
Abstract: . In January 2013, North China Plain experienced several serious haze events. Cimel sunphotometer measurements at seven sites over rural, suburban and urban regions of North China Plain from 1 to 30 January 2013 were used to further our understanding of spatial-temporal variation of aerosol optical parameters and aerosol radiative forcing (ARF). It was found that Aerosol Optical Depth at 500 nm (AOD500 nm) during non-pollution periods at all stations was lower than 0.30 and increased significantly to greater than 1.00 as pollution events developed. The Angstrom exponent (Alpha) was larger than 0.80 for all stations most of the time. AOD500 nm averages increased from north to south during both polluted and non-polluted periods on the three urban sites in Beijing. The fine mode AOD during pollution periods is about a factor of 2.5 times larger than that during the non-pollution period at urban sites but a factor of 5.0 at suburban and rural sites. The fine mode fraction of AOD675 nm was higher than 80% for all sites during January 2013. The absorption AOD675 nm at rural sites was only about 0.01 during pollution periods, while ~0.03–0.07 and 0.01–0.03 during pollution and non-pollution periods at other sites, respectively. Single scattering albedo varied between 0.87 and 0.95 during January 2013 over North China Plain. The size distribution showed an obvious tri-peak pattern during the most serious period. The fine mode effective radius in the pollution period was about 0.01–0.08 μm larger than during non-pollution periods, while the coarse mode radius in pollution periods was about 0.06–0.38 μm less than that during non-pollution periods. The total, fine and coarse mode particle volumes varied by about 0.06–0.34 μm3, 0.03–0.23 μm3, and 0.03–0.10 μm3, respectively, throughout January 2013. During the most intense period (1–16 January), ARF at the surface exceeded −50 W m−2, −180 W m−2, and −200 W m−2 at rural, suburban, and urban sites, respectively. The ARF readings at the top of the atmosphere were approximately −30 W m−2 in rural and −40–60 W m−2 in urban areas. Positive ARF at the top of the atmosphere at the Huimin suburban site was found to be different from others as a result of the high surface albedo due to snow cover.
262 citations
TL;DR: In this paper, the authors used the Nested Air Quality Prediction Model System (NAQPMS) to investigate the temporal and spatial variations of PM 2.5 over tropospheric central eastern China in January 2013.
Abstract: The Nested Air Quality Prediction Model System (NAQPMS) was used to investigate the temporal and spatial variations of PM 2.5 over tropospheric central eastern China in January 2013. The impact of regional transport and its implications on pollution prevention and control were also examined. Comparison between simulated and observed PM 2.5 showed NAQPMS was able to reproduce the evolution of PM 2.5 during heavy haze episodes. The results indicated that regional transport of PM 2.5 played an important role in regional haze episodes in the city cluster including Hebei, Beijing and Tianjin (HBT). The cross-city clusters transport outside HBT and transport among cities inside HBT contributed 20%-35% and 26%-35% of PM 2.5 as compared with local emission, in HBT respectively. To meet the Air Quality Standards for Grade Ⅱ, 90%, 90% and 65% of emissions would have to be cut down in Hebei, Tianjin and Beijing, if non-control strategy was taken in the surrounding city clusters of HBT. This implicated that control of emissions in one city cluster is not sufficient to reduce regional haze events, and joint efforts among city clusters are essential. Besides regional transports, two-way feedback between boundary-layer evolution and PM 2.5 also significantly contributed to the formation of heavy hazes, which contributed 30% of monthly average PM 2.5 concentration in HBT.
TL;DR: Deposition of inhaled potentially toxic trace elements in various regions of the human respiratory system was estimated using a Multiple-Path Particle Dosimetry model, finding that particle depositions in the respiratory system tend to be more severe during hazy days than those during nonhazy days.
Abstract: Recurring biomass burning-induced smoke haze is a serious regional air pollution problem in Southeast Asia (SEA). The June 2013 haze episode was one of the worst air pollution events in SEA. Size segregated particulate samples (2.5–1.0 μm; 1.0–0.5 μm; 0.5– 0.2 μm; and 60%) of the elements was present in oxidizable and residual fractions while the bioavailable (exchangeable) fraction accounted for up to 20% for most of the elements except K and Mn. Deposition of inhaled potentially toxic trace elements in various regions of the h...
TL;DR: In this article, the authors quantified the contribution of open biomass burning to air pollution in China and globally using both ambient monitoring data and the WRF/CMAQ (Weather Research and Forecasting and Community Multiscale Air Quality) model simulation.
Abstract: . Open biomass burning is an important source of air pollution in China and globally. Joint observations of air pollution were conducted in five cities (Shanghai, Hangzhou, Ningbo, Suzhou and Nanjing) of the Yangtze River delta, and a heavy haze episode with visibility 2.9–9.8 km was observed from 28 May to 6 June 2011. The contribution of biomass burning was quantified using both ambient monitoring data and the WRF/CMAQ (Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ)) model simulation. It was found that the average and maximum daily PM2.5 concentrations during the episode were 82 and 144 μgm−3, respectively. Weather pattern analysis indicated that stagnation enhanced the accumulation of air pollutants, while the following precipitation event scavenged the pollution. Mixing depth during the stagnant period was 240–399 m. Estimation based on observation data and CMAQ model simulation indicated that biomass open burning contributed 37% of PM2.5, 70% of organic carbon and 61% of elemental carbon. Satellite-detected fire spots, back-trajectory analysis and air quality model simulation were integrated to identify the locations where the biomass was burned and the pollutants transport. The results suggested that the impact of biomass open burning is regional, due to the substantial inter-province transport of air pollutants. PM2.5 exposure level could be reduced 47% for the YRD region if complete biomass burning is forbidden and significant health benefit is expected. These findings could improve the understanding of heavy haze pollution, and suggest the need to ban open biomass burning during post-harvest seasons.
TL;DR: Although significant improvement has occurred in China, change the development mode of "high growth, high pollution" and balance environmental conservation with the well-being of the population remains a challenge for China.
TL;DR: In this paper, an online coupled meteorology-chemistry model was employed to simulate the impacts of aerosol?meteorology interactions on fine particles (PM2.5) pollution during this haze episode.
Abstract: In January 2013, a severe regional haze occurred over the North China Plain. An online-coupled meteorology-chemistry model was employed to simulate the impacts of aerosol?meteorology interactions on fine particles (PM2.5) pollution during this haze episode. The response of PM2.5 to meteorology change constituted a feedback loop whereby planetary boundary layer (PBL) dynamics amplified the initial perturbation of PM2.5. High PM2.5 concentrations caused a decrease of surface solar radiation. The maximal decrease in daily average solar radiation reached 53% in Beijing, thereby leading to a more stable PBL. The peak PBL height in Beijing decreased from 690 m to 590 m when the aerosol extinction was considered. Enhanced PBL stability suppressed the dispersion of air pollutants, and resulted in higher PM2.5 concentrations. The maximal increase of PM2.5 concentrations reached 140 ?g m?3 in Beijing. During most PM2.5 episodes, primary and secondary particles increased simultaneously. These results imply that the aerosol?radiation interactions played an important role in the haze episode in January 2013.
TL;DR: In this paper, the authors examined the horizontal distribution and decadal trends of low visibility, haze and fog events in the North China Plain (NCP) during the past 30 years.
Abstract: . Frequent low visibility, haze and fog events were found in the North China Plain (NCP). Data throughout the NCP during the past 30 years were examined to determine the horizontal distribution and decadal trends of low visibility, haze and fog events. The impact of meteorological factors such as wind and relative humidity (RH) on those events was investigated. Results reveal distinct distributions of haze and fog days, due to their different formation mechanisms. Low visibility, haze and fog days all display increasing trends of before 1995, a steady stage during the period 1995–2003 and a drastically drop thereafter. All three events occurred most frequently during the heating season. Benefiting from emission control measures, haze and fog both show decreasing trends in winter during the past 3 decades, while summertime haze displays continuous increasing trends. The distribution of wind speed and wind direction as well as the topography within the NCP has determinative impacts on the distribution of haze and fog. Weakened south-easterly winds in the southern part of the NCP have resulted in high pollutant concentrations and frequent haze events along the foot of the Taihang Mountains. The orographically generated boundary layer wind convergence line in the central area of the southern NCP is responsible for the frequent fog events in this region. Wind speed has been decreasing throughout the entire southern NCP, resulting in more stable atmospheric conditions and weaker dispersion abilities, calling for harder efforts to control emissions to prevent haze events. Haze events are strongly influenced by the ambient RH. RH values associated with haze days are evidently increasing, suggesting that an increasing fraction of haze events are caused by the hygroscopic growth of aerosols, rather than simply by high aerosol loadings.
TL;DR: In this article, the authors present a regional insight into characteristics and formation process of the widespread extreme haze pollution in northern China during January of 2013 using integrated satellite observations and ground measurements.
TL;DR: It is demonstrated that particles with aerodynamic diameter larger than 2.1μm cannot be neglected during severe haze events, and secondary inorganic aerosols and organic matter dominated the fine particle mass on heavily polluted days, while their contribution reduced to 29% and 18%, respectively, on clear days.
TL;DR: In this article, the authors employ meteorological observation data from surface and high-balloon stations, China Meteorological Administration (CMA) model T639 output data, NCEP reanalysis data, PM2.5 observations and modeled HYSPLIT4 trajectory results to study the meteorological causes, including large-scale circulation and planetary boundary layer features.
TL;DR: Investigation of the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon ((14)C) and biomass burning/secondary organic aerosol (SOA) tracers during winter in Guangzhou, China found that haze episodes were formed either abruptly by local emissions or through the accumulation of particles transported from other areas.
Abstract: We conducted a source apportionment and investigated the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon (14C) and biomass burning/secondary organic aero...
TL;DR: It is demonstrated that haze pollution was associated with total and cardiovascular illnesses and NO2 was the sole pollutant with the largest risk of hospital admissions for total and respiratory diseases in both single- and multi-pollutant models.
Abstract: Guangzhou is a metropolitan in south China with unique pollutants and geographic location. Unlike those in western countries and the rest of China, the appearance of haze in Guangzhou is often (about 278 days per year on average of 4 years). Little is known about the influence of these hazes on health. In this study, we investigated whether short-term exposures to haze and air pollution are associated with hospital admissions in Guangzhou. The relationships between haze, air pollution, and daily hospital admissions during 2008-2011 were assessed using generalized additive model. Studies were categorized by gender, age, season, lag, and disease category. In haze episodes, an increase in air pollutant emissions corresponded to 3.46 (95 % CI, 1.67, 5.27) increase in excessive risk (ER) of total hospital admissions at lag 1, 11.42 (95 % CI, 4.32, 18.99) and 11.57 (95 % CI, 4.38, 19.26) increases in ERs of cardiovascular illnesses at lags 2 and 4 days, respectively. As to total hospital admissions, an increase in NO2 was associated with a 0.73 (95 % CI, 0.11, 1.35) and a 0.28 (95 % CI, 0.11, 0.46) increases in ERs at lag 5 and lag 05, respectively. For respiratory illnesses, increases in NO2 was associated with a 1.94 (95 % CI, 0.50, 3.40) increase in ER at lag 0, especially among chronic obstructive pulmonary disease. Haze (at lag1) and air pollution (for NO2 at lag 5 and for SO2 at lag3) both presented more drastic effects on the 19 to 64 years old and in the females. Together, we demonstrated that haze pollution was associated with total and cardiovascular illnesses. NO2 was the sole pollutant with the largest risk of hospital admissions for total and respiratory diseases in both single- and multi-pollutant models.
TL;DR: The dark-object subtraction method is further developed to calculate a haze thickness map, allowing a spectrally consistent haze removal on calibrated and uncalibrated satellite multispectral data.
Abstract: Haze degrades optical data and reduces the accuracy of data interpretation. Haze detection and removal is a challenging and important task for optical multispectral data correction. This paper presents an empirical and automatic method for inhomogeneous haze detection and removal in medium- and high-resolution satellite optical multispectral images. The dark-object subtraction method is further developed to calculate a haze thickness map, allowing a spectrally consistent haze removal on calibrated and uncalibrated satellite multispectral data. Rare scenes with a uniform and highly reflecting landcover result in limitations of the method. Evaluation on hazy multispectral data (Landsat 8 OLI and WorldView-2) and a comparison to haze-free reference data illustrate the spectral consistency after haze removal.
Abstract: Public concerns about environmental problems create narrative structures that influence policy by allocating roles of blame, responsibility, and appropriate behavior. This paper presents an analysis of public concerns about transboundary haze resulting from forest fires in Indonesia, Singapore, and Malaysia for crises experienced in 1997, 2005 and 2013. The source of the information is content analysis of 2231 articles from representative newspapers in each country. The study shows that newspaper reporting about haze has changed from a discussion of the potential health and economic impacts of fires resulting partly naturally from El Nino-induced droughts, toward an increasing vilification of Indonesia for not ratifying the 2002 Association of South East Asian Nations (ASEAN) Agreement on Transboundary Haze Pollution; plus criticism of Singaporean and Malaysian companies investing in palm oil plantations, and ASEAN. Attention to climate change and potential biodiversity loss linked to haze, however, remains low. The paper argues that newspaper analysis of public concerns, despite political influences on the press, offers insights into how public criticism is voiced in these countries, and how perceived responsibility for action is changing.
TL;DR: The economic value of health impacts of transboundary smoke haze pollution in Kuala Lumpur and adjacent areas in the state of Selangor was assessed and the average annual economic loss due to the inpatient health impact of haze was valued at MYR273,000 ($91,000 USD).
TL;DR: In this article, the authors investigated the effect of biomass smoke emissions on air quality in the city state of Singapore during a haze episode in October 2006, and found that significantly increased levels of airborne particulate matter (PM) and associated chemical species were observed during the haze period.
Abstract: . Biomass burning activities commonly occur in Southeast Asia (SEA), and are particularly intense in Indonesia during the dry seasons. The effect of biomass smoke emissions on air quality in the city state of Singapore was investigated during a haze episode in October 2006. Substantially increased levels of airborne particulate matter (PM) and associated chemical species were observed during the haze period. Specifically, the enhancement in the concentration of molecular tracers for biomass combustion such as levoglucosan by as much as two orders of magnitude and the diagnostic ratios of individual organic compounds indicated that biomass burning emissions caused a regional smoke haze episode due to their long-range transport by prevailing winds. With the aid of air mass backward trajectories and chemical mass balance modeling, large-scale forest and peat fires in Sumatra and Kalimantan were identified as the sources of the smoke aerosol, exerting a significant impact on air quality in downwind areas, such as Singapore.
TL;DR: Wang et al. as mentioned in this paper studied the air pollution condition of a severe haze episode occurred on 6-16 January 2013 over eastern China, and found that this severe pollution episode of large area haze was accompanied with low visibility, high PM10 and AOD in eastern China.
TL;DR: This study clearly indicates that exposure to haze events showed immediate and delayed effects on mortality in the Klang Valley region between 2000 and 2007.
01 Oct 2014
TL;DR: A novel efficient dehazing method with illumination estimation for nighttime haze condition that can achieve both illumination balanced and haze free results and also has good color rendition ability.
Abstract: Nighttime haze removal is important for different applications such as nighttime video surveillance in haze environment. Different from the imaging conditions in the daytime, nighttime haze images may suffer from non-uniform illumination from artificial light sources. In this paper, we proposed a novel efficient dehazing method with illumination estimation for nighttime haze condition. First, we estimate the light intensity and enhance it to obtain an illumination balanced result. Then, we process a color correction step after estimating the color characteristics of the incident light. Finally, we remove the haze by using the dark channel prior along with estimating the pointwise environmental light. Experimental results show that the proposed method can achieve both illumination balanced and haze free results. Moreover, it also has good color rendition ability.
TL;DR: With the limited-dynamics detector used, a maximum fourfold increase in contrast was demonstrated under bright background illumination using polarimetric difference image, and the efficiency of using polarized light for source contrast increase with different signal representations was compared.
Abstract: We report an experimental implementation of long-range polarimetric imaging through fog over kilometric distance in real field atmospheric conditions. An incoherent polarized light source settled on a telecommunication tower is imaged at a distance of 1.3 km with a snapshot polarimetric camera including a birefringent Wollaston prism, allowing simultaneous acquisition of two images along orthogonal polarization directions. From a large number of acquisitions datasets and under various environmental conditions (clear sky/fog/haze, day/night), we compare the efficiency of using polarized light for source contrast increase with different signal representations (intensity, polarimetric difference, polarimetric contrast, etc.). With the limited-dynamics detector used, a maximum fourfold increase in contrast was demonstrated under bright background illumination using polarimetric difference image.