Air Quality Situation Research Articles

GA-BP Air Quality Evaluation Method Based on Fuzzy Theory

With the rapid development of China's economy, the scale of the city has been continuously expanding, industrial enterprises have been increasing, the discharge of multiple pollutants has reached the top of the world., and the environmental problems become more and more serious. The air pollution problem is particularly prominent. Air quality has become a daily concern for people. In order to control air pollution, it is necessary to grasp the air quality situation in an all-round way. It is necessary to evaluate air quality. Accurate results of air quality evaluation can help people know more about air quality. In this paper, refers to previous research results and different evaluation methods, combined with artificial neural network, fuzzy theory, genetic algorithm, GA-BP hybrid algorithm based on fuzzy theory is proposed to evaluate air quality. At the same time, for the problem that the two-level standard of air quality annual evaluation is not suitable for practical application, the four-level standard for annual air quality evaluation has been proposed, and its practicality has been verified through experiments. By setting contrast experiments and comparing the air quality evaluation model based on standard BP algorithm, it is proved that the fuzzy GA-BP evaluation model is better than the standard BP model, both in efficiency and accuracy.

Solving air quality problems in cities by retrofitting - Case studies showing real-world driving performances

Urban air quality has been widely discussed and debated over the last decades. It started mainly with the focus on fine particles and concern was in major cities in certain developing countries. Lately, more and more weight has been put on nitrogen oxides (NOx), also in European cities. Public and political pressure has been increasing over the last years, while additional studies on the current situation of air quality together with health risks have been published. There are multiple sources of nitrogen oxides (NOx) and the whole picture is complex in nature. However, traffic has been shown to be one of the main reasons. As it is known today, older generation diesel vehicles emit a great deal of NOx. It is believed that the situation would improve while a newer fleet is taking place. But, unfortunately the progress has not been as expected there. The current knowledge on the difference between heavy-duty engines laboratory condition homologations, application specific chassis dynamometer tests and lastly real world driving conditions is underlining the importance of improvements in exhaust emission reduction technologies.This study shows the differences between chassis dynamometer and real-world emissions on city busses. Online monitoring and portable measurement technologies together with retrofitting and upgrading the vehicles using state of the art emission reduction technology has been studied for measuring and reducing the harmful exhaust gas compounds, especially NOx in real-drive conditions in city driving. The retrofitting of buses with an improved emission after treatment systems has proven to be a feasible and quick solution for reducing local NOx emissions significantly. The comparison of new buses and the retrofitted ones clarifies the potential of the retrofit approach. Several case studies are presented, and some European city retrofit programs are referred to in this study.

Air Quality Context Information Model for Ubiquitous Public Access to Geographic Information

The advance in Information Communication Technology (ICT) has contributed to global challenges of improving urban air quality. Ubiquitous computing technology enables citizens to easily access air quality information services without spatial or temporal limitations. Citizens are also encouraged to participate in air quality assessment and environmental governance. These societal and technical changes require a new paradigm to develop an air quality information system and its services. An air quality information system needs to integrate varied types of air quality information from heterogeneous data sources as well as allow citizens to express their concerns about air quality. Thus, a standardized manner is necessary to develop an air quality information system. In this regard, an air quality context information model was designed according to the Ubiquitous Public Access (UPA) context information model defined in the International Organization for Standard (ISO) 19154. For validation and verification purposes, the air quality context information model was implemented in a geographic information system (GIS)-based air quality information system. Implementation results showed that spatially relevant air quality information services were generated from the system, depending on the location and air quality situations near a specific user. Also, citizens can contribute air quality information at their current regions.

Proliferation of low-cost sensors. What prospects for air pollution epidemiologic research in Sub-Saharan Africa?

Addressing the worsening urban air quality situation in Sub-Saharan Africa (SSA) is proving increasingly difficult owing to paucity of data on air pollution levels and also, lack of local evidence on the magnitude of the associated health effects. There is therefore the urgent need to expand air quality monitoring (AQM) networks in SSA to enable the conduct of high quality epidemiologic studies to help inform policies aimed at addressing air pollution and the associated health effects. In this commentary, I explore the prospects that the proliferation of low-cost sensors in recent times holds for air pollution epidemiologic research in SSA. This commentary is timely because most SSA governments do not see investments in air pollution control that requires assembling a network of sophisticated and prohibitively expensive instrumentation for AQM as necessary for improving and protecting public health. I conclude that, in a region that is bereft of air pollution data, the growing influx of low-cost sensors represents an excellent opportunity for bridging the data gap to inform air pollution control policies and regulations for public health protection. However, it is essential that only the most promising sensor technologies that performs creditably well in the harsh environmental conditions of the region are promoted.

Performance of MODIS C6 Aerosol Product during Frequent Haze-Fog Events: A Case Study of Beijing

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.

Air Quality: Missing the wood for the trees by Ivo Vegter published by the South African Institute of Race Relations, September 2016

This report of just under 20 pages into South Africa’s air quality situation comes out with its conclusion right on the front page as a subtitle: “Indoor pollution is SA’s most serious air quality problem”. The title, Air Quality: Missing the wood for the trees, itself is clearly polemic. Upon reading the title, one wonders exactly who it is that is missing the wood for the trees. The answer becomes apparent in the first line of the introduction section, namely that when examining air quality media and activists focus of industrial pollution but loose sight of what the author regards as the real problem, namely indoor air pollution.

Review of Air Quality Monitoring: Case Study of India

Air pollution is one of the foremost and grave public health and environmental anxiety in most of evolving countries. Objectives: The objective of this paper is to provide insight details about current situation of air quality across various cities present in India, along with countless origins and effects of air pollution. An attempt is made to make people aware about various types of gases and particulate matter present in air highlighting their effects on environment along with the various ways of overcoming this situation. Methods: The National Air Quality Index (NAQI) ensures comparison amongst various cities so that new measures can be formulated in order to decrease the quantity of particulate matter present in air. In this paper concentration of various pollutants along with various harmful gases for various cities of India are analyzed based on past NAQI data thereby highlighting those areas which are under extensive menace of pollution. Findings: It has been perceived from past few years that the rate at which Urban Air Pollution across India has grown is alarming due to severe unsafe web of particulate matter (PM) and harmful gases present in air that living organism’s breath. Levels of particulate matter are extremely higher in all cities of India. Only few cities are such that can be emphasized where Air Quality Monitoring (AQM) has started due to which they show some enhancement in quality of air but mostly affected areas are small and medium sized towns which suffer from phenomenal spurt in pollution in very critical manner. Due to increase in immense number of vehicles, industries and manufacturing units has resulted in excess assembly of pollutants in air making air pollution as a state of national emergency across various cities around the country.

SITUAÇÃO ATUAL DA QUALIDADE DO AR DAS PRINCIPAIS CIDADES DA AMÉRICA LATINA

In this paper was done the compilation of Particulate Matter (PM) concentrations for the largest cities in Latin America, with over 1 million inhabitants in order to investigate the air quality situation in this region. For this study were obtained data from 28 cities of 13 countries from the World Health Organization reports (WHO), government agencies and monitoring stations. The results shows that, in most cities, the levels established by WHO guidelines, both PM10 and PM2.5, are exceeded, providing conditions that threaten the public health of citizens.

Air quality assessment using a weighted Fuzzy Inference System

Air pollution is a current monitored problem in areas with high population density such as big cities. In this sense, environmental modelling should be accurate in order to generate better air quality evaluations; but in consequence they are complex. Nowadays, the artificial intelligence based on heuristic methods allows assessing air quality parametres, providing a partial solution to this problem. Accordingly, this paper proposes a new evaluation model using fuzzy inferences combined with an Analytic Hierarchy Process, providing a new air quality index. Environmental parametres (PM2.5, PM10, O3, CO, NO2 and SO2) are evaluated according to toxicological levels and then, a fuzzy reasoning process assesses different air quality situations. Additionally, individual weights are computed and assigned according to the pollutant importance on the air evaluation. Finally, the model proposed considers five score stages: excellent, good, regular, bad and dangerous, based on data from the Mexico City Atmospheric Monitoring System (SIMAT). Experimental results show a good performance of the proposed air quality index against those in literature, providing better assessments when weights are assigned according to an importance level in atmosphere pollution.

Urban air quality evaluations under two versions of the national ambient air quality standards of China

The air quality of urban areas is of a great concern for residents living in cities. China has released a new National Ambient Air Quality Standard (NAAQS) in 2012 to improve the air quality evaluation index because the reported air quality situation from governments is inconsistent with public sensing. In total, 190 cities' hourly monitoring data are publicized in the national web platform. By using the above data, the air pollution indexes (APIs) under the previous NAAQS and air quality indexes (AQI) for all 190 cities' were calculated. With the new NAAQS, the national attainment rate has fallen from 73.63% to 59.62% with regional differences. 8 of the 10 cities with the worst air quality are located in North China around Beijing, while 9 of the 10 cities with the best air quality are located in South China. These results indicate that cities in North China, including Beijing, need to address the air pollution together as the pollution in North China is a regional issue and not a local issue.

Field testing of natural ventilation in college student dormitories (Beijing, China)

Human health demands and thermal comfort both require sufficient amounts of fresh outdoor air. Many university student dormitories in China have high residential density with no individual fresh air systems. In this kind of physical environment, natural ventilation is the primary way to obtain fresh outdoor air. However, few studies have explored ventilation under these conditions. In this paper, the ventilation rate in student dormitories (Beijing, China) was field-tested using carbon dioxide as a tracer gas. The test conditions were selected in accordance with the behavioral patterns of the occupants (students) throughout different seasons of the year. A stable CO2 release source was obtained from students in the sleep state. The results were used to create an empirical equation that could estimate the air change rate in a room. The CO2 concentration change in different dormitories was also discussed to evaluate the current ventilation and indoor air quality situation in the tested university student dormitories. Although sufficient outdoor air can be provided to dilute the indoor CO2 through single-sided natural ventilation in 82% of the testing period, nevertheless, for infiltration the indoor CO2 concentration exceeded the IAQ standard in 76% of the recorded times. The results were also factored into the design of student dormitories for better ventilation and indoor air quality.

Seasonal and Temporal Variation of Volatile Organic Compounds (VOCs) Pollution in Isolo Industrial Areas of Lagos State, Southwestern-Nigeria

Spatial and temporal variations of volatile organic compounds in ambient air in Isolo Industrial Area during May, 2010 to April, 2011 are presented. The results were analysed in other to present information about the detailed nature of air quality situation in the sampled areas. The air samples were collected by passive sampler (ORSA 5). The air samplers were exposed to a height of 1.5 - 2.0 m and sampling was carried out four times a month for a period of 12 months. The adsorbed VOCs were desorbed with carbondisulphide (CS 2 ) and the solution analysed using Gas Chromatography (GC) fitted with Flame Ionization Detector (FID). The results from analysis of the air samples collected showed that twenty (26) VOCs were captured. There is a significant difference (P < 0.05) between the levels of VOCs in Isolo. Despite comparatively higher concentrations of VOCs at the studied sites, there is a significant difference in the spatial distribution. At lower wind speed, the VOCs concentrations tend to increase and become uniformly distributed around the industrial Areas. The temporal distribution shows a decrease in ambient concentrations of VOCs from May to July due to Atmospheric (dilution)/wash down by rain. The results of two-way factor ANOVA analysis of the monthly average of total volatile organic compounds revealed that there is significant difference (P < 0.05) in seasonal and temporal variations of TVOC concentrations in the studied areas. The meteorological parameters showed significant correlations with the ambient concentrations of VOCs. The principal component analysis revealed that the major sources of VOCs in Isolo are mainly Anthropogenic and four (4) factors were identified as sources of VOCs in the studied area with Industrial and emissions from traffic dominating. Key words: Significant, Pollution, Spatial, Anthropogenic, Temporal

Fuzzy Comprehensive Evaluation of Air Quality in Home

Based on the indoor air quality and the evaluation index, utilize the fuzzy mathematical theory, comprehensively consider on the three important factors which influence the air quality, and through the calculation and determination the weight vector, divide the air quality into four levels as "qualified"," mild overweight"," overweight", "severe overweight". Through sampling the indoor air in a family, according to the fuzzy comprehensive evaluation method and the maximum membership degree principle, get every sample point levels from data. It will provide the method of getting a more objective evaluation of indoor air quality situation.

Observational studies of the meteorological characteristics associated with poor air quality over the Pearl River Delta in China

Abstract. The structure of the atmospheric boundary layer (ABL) and its influence on regional air quality over the Pearl River Delta (PRD) were examined through two intensive observations in October 2004 and July 2006. Analytical results show the presence of two types of typical weather conditions associated with poor air quality over the PRD. The first is the warm period before a cold front (WPBCF) and the second is the subsidence period controlled by a tropical cyclone (SPCTC). Two typical low air quality situations, which are affected by WPBCF and SPCTC, and one high air quality situation were analysed in detail. Results showed that continuously low or calm ground winds resulted in the accumulation of pollutants, and sea-land breezes had an important role during low air quality conditions. Data on recirculation factors showed that recirculation was significant during low air quality conditions, and steady transportation occurred during high air quality conditions. The ventilation index and the 24 h average ventilation index during high air quality conditions were significantly higher than those during low air quality conditions. Deep and stable inversion layers inside the ABL remarkably affected low air quality. Surface and low-altitude inversions were usually observed during WPBCF, contrary to during SPCTC, during which only the low-altitude inversion appeared frequently.

Modelled air pollution levels versus EC air quality legislation - results from high resolution simulation

An appropriate method for evaluating the air quality of a certain area is to contrast the actual air pollution levels to the critical ones, prescribed in the legislative standards. The application of numerical simulation models for assessing the real air quality status is allowed by the legislation of the European Community (EC). This approach is preferable, especially when the area of interest is relatively big and/or the network of measurement stations is sparse, and the available observational data are scarce, respectively. Such method is very efficient for similar assessment studies due to continuous spatio-temporal coverage of the obtained results. In the study the values of the concentration of the harmful substances sulphur dioxide, (SO2), nitrogen dioxide (NO2), particulate matter - coarse (PM10) and fine (PM2.5) fraction, ozone (O3), carbon monoxide (CO) and ammonia (NH3) in the surface layer obtained from modelling simulations with resolution 10 km on hourly bases are taken to calculate the necessary statistical quantities which are used for comparison with the corresponding critical levels, prescribed in the EC directives. For part of them (PM2.5, CO and NH3) this is done for first time with such resolution. The computational grid covers Bulgaria entirely and some surrounding territories and the calculations are made for every year in the period 1991–2000. The averaged over the whole time slice results can be treated as representative for the air quality situation of the last decade of the former century.

The Situation of Air Quality in Kumpawapi District Udon Thani Province

The Situation of Air Quality in Kumpawapi District Udon Thani Province

Intra-urban air pollution in a rapidly growing Sahelian city

In this paper we analyze spatial and temporal variations of air pollution (PM1, PM2.5, PM10, CO, NOx, O3, Toluene and Benzene) and climate in areas of different development typology in Ouagadougou, Burkina Faso. Analyses are based on measurements from fixed sites and car traverse measurements during field studies in 2007 and 2010. Large spatial and temporal variations were found, showing a generally poor air quality situation, with extreme levels of PM10, commonly exceeding air quality guidelines of WHO. Pollution levels increase considerably with increased atmospheric stability. Important sources were transported dust and re-suspension of dust from unpaved roads, but also traffic emissions and biomass burning. The spatial variations are examined with focus on effects for variations in potential exposure depending on for example area of residence and daily activity pattern, showing that great differences are likely to exist. Ouagadougou, like most developing countries worldwide, currently experiences an extremely rapid population growth in combination with limited financial means. This is likely to create increasingly harmful air pollution situations for the rapidly growing populations of these areas, and shows an urgent need for increased understanding of the pollution situation as well as development of mitigation strategies.

Improving road transport-related air quality in England through joint working between Environmental Health Officers and Transport Planners

In this paper the necessity for effective joint working arrangements between Environmental Health Officers and Transport Planners is demonstrated as a fundamental prerequisite for successful management of traffic-related air quality in English local government areas. Current approach to joint working and collaboration between the officers was examined based on the evidence from a three-year study which involved questionnaire surveys and case study interviews. The findings show that despite good administrative devolution and policy integration, the chance of improving specific local air quality situations through the Local Transport Planning process is dependent on other overriding factors which influence the capabilities of the authorities to integrate policies across departments and tiers of governments. Implicit in these findings is the need for a shared paradigm of continuous engagement by all the policy actors and stakeholders if proper integration and the possibility of tangible results in future policy development are to be achieved. The paper proposes a new framework through which such collaborations can be developed and within which solutions to the issues identified can be evaluated.

Evaluation of a multiple regression model for the forecasting of the concentrations of NOx and PM10 in Athens and Helsinki

Forecasting models based on stepwise multiple linear regression (MLR) have been developed for Athens and Helsinki. The predictor variables were the hourly concentrations of pollutants (NO, NO2, NOx, CO, O3, PM2.5 and PM10) and the meteorological variables (ambient temperature, wind speed/direction, and relative humidity) and in case of Helsinki also Monin-Obukhov length and mixing height of the present day. The variables to be forecasted are the maximum hourly concentrations of PM10 and NOx, and the daily average PM10 concentrations of the next day. The meteorological pre-processing model MPP-FMI was used for computing the Monin-Obukhov length and the mixing height. The limitations of such statistical models include the persistence of both the meteorological and air quality situation; the model cannot account for rapid changes (on a temporal scale of hours or less than a day) that are commonly associated, e.g., with meteorological fronts, or episodes of a long-range transport origin. We have selected the input data for the model from one urban background and one urban traffic station both in Athens and Helsinki, in 2005. We have used various statistical evaluation parameters to analyze the performance of the models, and inter-compared the performance of the predictions for both cities. Forecasts from the MLR model were also compared to those from an Artificial Neural Network model (ANN) to investigate, if there are substantial gains that might justify the additional computational effort. The best predictor variables for both cities were the concentrations of NOx and PM10 during the evening hours as well as wind speed, and the Monin-Obukhov length. In Athens, the index of agreement (IA) for NOx ranged from 0.77 to 0.84 and from 0.69 to 0.72, in the warm and cold periods of the year. In Helsinki, the corresponding values of IA ranged from 0.32 to 0.82 and from 0.67 to 0.86 for the warm and cold periods. In case of Helsinki the model accuracy was expectedly better on the average, when Monin-Obukhov length and mixing height were included as predictor variables. The models provide better forecasts of the daily average concentration, compared with the maximum hourly concentration for PM10. The results derived by the ANN model where only slightly better than the ones derived by the MLR methodology. The results therefore suggest that the MLR methodology is a useful and fairly accurate tool for regulatory purposes.

Introduction of hydrogen vehicles in Kathmandu Valley: A clean and sustainable way of transportation

Air quality of Kathmandu Valley, the capital of Nepal, was one of the worse among the big cites in the world. The air quality situation was becoming more critical due to the substantial increase in the conventional fueled vehicles in the valley each year. The bowl-like topography and generally low speeds of wind during the dry seasons create poor dispersion conditions, augmenting the air pollution problem further. The pollution is expected to quadruple by 2020 from the 2005 level in as business as usual scenario. The main source of the pollution in the valley is motor vehicle emissions. The paper highlights the different level of air pollution and emission reductions by introducing hydrogen fuel vehicles in Kathmandu Valley. The entire fleet of vehicles in the valley can be fueled by hydrogen produced from the national hydroelectricity of Nepal using only less than 50% of its surplus energy. This will reduce about 700,000 tonnes of carbon emission in the valley in 2020. In addition, production of hydrogen using the surplus hydroelectricity of Nepal will improve load factor of the grid, and save a substantial amount of hard currency used to import the petroleum fuel in the country. As Nepal is one of the most hydropower potential countries in the world, with a 80,000 MW potential capacity, hydrogen production is renewable, sustainable and pollution free.