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  1. Ghazali NA, Ramli NA, Yahaya AS, Yusof NF, Sansuddin N, Al Madhoun WA
    Environ Monit Assess, 2010 Jun;165(1-4):475-89.
    PMID: 19440846 DOI: 10.1007/s10661-009-0960-3
    Analysis and forecasting of air quality parameters are important topics of atmospheric and environmental research today due to the health impact caused by air pollution. This study examines transformation of nitrogen dioxide (NO(2)) into ozone (O(3)) at urban environment using time series plot. Data on the concentration of environmental pollutants and meteorological variables were employed to predict the concentration of O(3) in the atmosphere. Possibility of employing multiple linear regression models as a tool for prediction of O(3) concentration was tested. Results indicated that the presence of NO(2) and sunshine influence the concentration of O(3) in Malaysia. The influence of the previous hour ozone on the next hour concentrations was also demonstrated.
    Matched MeSH terms: Ozone/analysis*
  2. Abdul Aziz FAB, Abd Rahman N, Mohd Ali J
    Comput Intell Neurosci, 2019;2019:6252983.
    PMID: 31239836 DOI: 10.1155/2019/6252983
    Due to the rapid development of economy and society around the world, the most urban city is experiencing tropospheric ozone or commonly known as ground-level air pollutants. The concentration of air pollutants must be identified as an early precaution step by the local environmental or health agencies. This work aims to apply the artificial neural network (ANN) in estimating the ozone concentration forecast in Bangi. It consists of input variables such as temperature, relative humidity, concentration of nitrogen dioxide, time, UVA and UVB rays obtained from routine monitoring, and data recorded. Ten hidden layer is utilized to obtain the optimized ozone concentration, which is the output layer of the ANN framework. The finding showed that the meteorology condition and emission patterns play an important part in influencing the ozone concentration. However, a single network is sufficient enough to estimate the concentration despite any circumstances. Thus, it can be concluded that ANN is able to give reliable and satisfactory estimations of ozone concentration for the following day.
    Matched MeSH terms: Ozone/analysis*
  3. Khokhar MF, Nisar M, Noreen A, Khan WR, Hakeem KR
    Environ Sci Pollut Res Int, 2017 Jan;24(3):2827-2839.
    PMID: 27838904 DOI: 10.1007/s11356-016-7907-3
    This study emphasizes on near surface observation of chemically active trace gases such as nitrogen dioxide (NO2) over Islamabad on a regular basis. Absorption spectroscopy using backscattered extraterrestrial light source technique was used to retrieve NO2 differential slant column densities (dSCDs). Mini multi-axis-differential optical absorption spectroscopy (MAX-DOAS) instrument was used to perform ground-based measurements at Institute of Environmental Sciences and Engineering (IESE), National University of Sciences and Technology (NUST) Islamabad, Pakistan. Tropospheric vertical column densities (VCDs) of NO2 were derived from measured dSCDs by using geometric air mass factor approach. A case study was conducted to identify the impact of different materials (glass, tinted glass, and acrylic sheet of various thicknesses used to cover the instrument) on the retrieval of dSCDs. Acrylic sheet of thickness 5 mm was found most viable option for casing material as it exhibited negligible impact in the visible wavelength range. Tropospheric NO2 VCD derived from ground-based mini MAX-DOAS measurements exceeded two times the Pak-NEQS levels and showed a reasonable comparison (r (2) = 0.65, r = 0.81) with satellite observations (root mean square bias of 39 %) over Islamabad, Pakistan.
    Matched MeSH terms: Ozone/analysis
  4. Bais AF, Bernhard G, McKenzie RL, Aucamp PJ, Young PJ, Ilyas M, et al.
    Photochem Photobiol Sci, 2019 Mar 01;18(3):602-640.
    PMID: 30810565 DOI: 10.1039/c8pp90059k
    This report assesses the effects of stratospheric ozone depletion and anticipated ozone recovery on the intensity of ultraviolet (UV) radiation at the Earth's surface. Interactions between changes in ozone and changes in climate, as well as their effects on UV radiation, are also considered. These evaluations focus mainly on new knowledge gained from research conducted during the last four years. Furthermore, drivers of changes in UV radiation other than ozone are discussed and their relative importance is assessed. The most important of these factors, namely clouds, aerosols and surface reflectivity, are related to changes in climate, and some of their effects on short- and long-term variations of UV radiation have already been identified from measurements. Finally, projected future developments in stratospheric ozone, climate, and other factors affecting UV radiation have been used to estimate changes in solar UV radiation from the present to the end of the 21st century. New instruments and methods have been assessed with respect to their ability to provide useful and accurate information for monitoring solar UV radiation at the Earth's surface and for determining relevant exposures of humans. Evidence since the last assessment reconfirms that systematic and accurate long-term measurements of UV radiation and stratospheric ozone are essential for assessing the effectiveness of the Montreal Protocol and its Amendments and adjustments. Finally, we have assessed aspects of UV radiation related to biological effects and human health, as well as implications for UV radiation from possible solar radiation management (geoengineering) methods to mitigate climate change.
    Matched MeSH terms: Stratospheric Ozone/analysis*
  5. Abdullah L, Khalid ND
    Environ Monit Assess, 2012 Nov;184(11):6957-65.
    PMID: 22160435 DOI: 10.1007/s10661-011-2472-1
    Proper identification of environment's air quality based on limited observations is an essential task to meet the goals of environmental management. Various classification methods have been used to estimate the change of air quality status and health. However, discrepancies frequently arise from the lack of clear distinction between each air quality, the uncertainty in the quality criteria employed and the vagueness or fuzziness embedded in the decision-making output values. Owing to inherent imprecision, difficulties always exist in some conventional methodologies when describing integrated air quality conditions with respect to various pollutants. Therefore, this paper presents two fuzzy multiplication synthetic techniques to establish classification of air quality. The fuzzy multiplication technique empowers the max-min operations in "or" and "and" in executing the fuzzy arithmetic operations. Based on a set of air pollutants data carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone, and particulate matter (PM(10)) collected from a network of 51 stations in Klang Valley, East Malaysia, Sabah, and Sarawak were utilized in this evaluation. The two fuzzy multiplication techniques consistently classified Malaysia's air quality as "good." The findings indicated that the techniques may have successfully harmonized inherent discrepancies and interpret complex conditions. It was demonstrated that fuzzy synthetic multiplication techniques are quite appropriate techniques for air quality management.
    Matched MeSH terms: Ozone/analysis
  6. Abu Amr SS, Aziz HA, Adlan MN, Bashir MJ
    PMID: 23445415 DOI: 10.1080/10934529.2013.744611
    The objective of this study was to investigate the performance of employing Fenton's reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and Fenton dosage, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): chemical oxygen demand (COD), color, NH-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 90 min, 30 g/m³ ozone, 0.01 mol/L₂H₂O,0.02 mol/L Fe²⁺, and pH 5. COD, color, and NH₃-N removal rates of 79%, 100%, and 20%, respectively, and 0.18 kg O₃/kg COD OC were obtained. The predictions correspond well with experimental results (COD, color, and NH-N removal rates of 78%, 98.5%, and 19%, respectively, and 0.29 kg O₃/kg COD OC). This method reduces the treatment time and improves the treatment efficiency relative to a previously published method that used Fenton's reagent prior to ozonation.
    Matched MeSH terms: Ozone/analysis
  7. Awang MB, Jaafar AB, Abdullah AM, Ismail MB, Hassan MN, Abdullah R, et al.
    Respirology, 2000 Jun;5(2):183-96.
    PMID: 10894109
    OBJECTIVE: Observations have been made on the long-term trends of major air pollutants in Malaysia including nitrogen dioxide, carbon monoxide, the ozone and total suspended particulate matter (particularly PM10), and sulfur dioxide, emitted from industrial and urban areas from early 1970s until late 1998.

    METHODOLOGY: The data show that the status of atmospheric environment in Malaysia, in particular in highly industrialized areas such as Klang Valley, was determined both by local and transboundary emissions and could be described as haze and non-haze periods.

    RESULTS: During the non-haze periods, vehicular emissions accounted for more than 70% of the total emissions in the urban areas and have demonstrated two peaks in the diurnal variations of the aforementioned air pollutants, except ozone. The morning 'rush-hour' peak was mainly due to vehicle emissions, while the late evening peak was mainly attributed to meteorological conditions, particularly atmospheric stability and wind speed. Total suspended particulate matter was the main pollutant with its concentrations at few sites often exceeding the Recommended Malaysia Air Quality Guidelines. The levels of other pollutants were generally within the guidelines. Since 1980, six major haze episodes were officially reported in Malaysia: April 1983, August 1990, June 1991, October 1991, August to October 1994, and July to October 1997. The 1997 haze episode was the worst ever experienced by the country. Short-term observations using continuous monitoring systems during the haze episodes during these periods clearly showed that suspended particulate matter (PM10) was the main cause of haze and was transboundary in nature. Large forest fires in parts of Sumatra and Kalimantan during the haze period, clearly evident in satellite images, were identified as the probable key sources of the widespread heavy haze that extended across Southeast Asia from Indonesia to Singapore, Malaysia and Brunei. The results of several studies have also provided strong evidence that biomass burning is the dominating source of particulate matter. The severity and extent of 1997's haze pollution was unprecedented, affecting some 300 million people across the region. The amount of economic costs suffered by Southeast Asian countries during this environmental disaster was enormous and is yet to be fully determined. Among the important sectors severely affected were air and land transport, shipping, construction, tourism and agro-based industries. The economic cost of the haze-related damage to Malaysia presented in this study include short-term health costs, production losses, tourism-related losses and the cost of avertive action. Although the cost reported here is likely to be underestimated, they are nevertheless significant (roughly RM1 billion).

    CONCLUSIONS: The general air quality of Malaysia since 1970 has deteriorated. Studies have shown that should no effective countermeasures be introduced, the emissions of sulfur dioxide, nitrogen oxides, particulate matter, hydrocarbons and carbon monoxide in the year 2005 would increase by 1.4, 2.12, 1.47 and 2.27 times, respectively, from the 1992 levels.

    Matched MeSH terms: Ozone/analysis
  8. Othman M, Latif MT, Yee CZ, Norshariffudin LK, Azhari A, Halim NDA, et al.
    Ecotoxicol Environ Saf, 2020 May;194:110432.
    PMID: 32169727 DOI: 10.1016/j.ecoenv.2020.110432
    It is important to have good indoor air quality, especially in indoor office environments, in order to enhance productivity and maintain good work performance. This study investigated the effects of indoor office activities on particulate matter of less than 2.5 μm (PM2.5) and ozone (O3) concentrations, assessing their potential impact on human health. Measurements of indoor PM2.5 and O3 concentrations were taken every 24 h during the working days in five office environments located in a semi-urban area. As a comparison, the outdoor concentrations were derived from the nearest Continuous Air Quality Monitoring Station. The results showed that the average 24 h of indoor and outdoor PM2.5 concentrations were 3.24 ± 0.82 μg m-3 and 17.4 ± 3.58 μg m-3 respectively, while for O3 they were 4.75 ± 4.52 ppb and 21.5 ± 5.22 ppb respectively. During working hours, the range of PM2.5 concentrations were 1.00 μg m-3 to 6.10 μg m-3 while for O3 they were 0.10 ppb to 38.0 ppb. The indoor to outdoor ratio (I/O) for PM2.5 and O3 was <1, thus indicating a low infiltration of outdoor sources. The value of the hazard quotient (HQ) for all sampling buildings was <1 for both chronic and acute exposures, indicating that the non-carcinogenic risks are negligible. Higher total cancer risk (CR) value for outdoors (2.67E-03) was observed compared to indoors (4.95E-04) under chronic exposure while the CR value for acute exposure exceeded 1.0E-04, thus suggesting a carcinogenic PM2.5 risk for both the indoor and outdoor environments. The results of this study suggest that office activities, such as printing and photocopying, affect indoor O3 concentrations while PM2.5 concentrations are impacted by indoor-related contributions.
    Matched MeSH terms: Ozone/analysis*
  9. Ng KY, Awang N
    Environ Monit Assess, 2018 Jan 06;190(2):63.
    PMID: 29306973 DOI: 10.1007/s10661-017-6419-z
    Frequent haze occurrences in Malaysia have made the management of PM10 (particulate matter with aerodynamic less than 10 μm) pollution a critical task. This requires knowledge on factors associating with PM10 variation and good forecast of PM10 concentrations. Hence, this paper demonstrates the prediction of 1-day-ahead daily average PM10 concentrations based on predictor variables including meteorological parameters and gaseous pollutants. Three different models were built. They were multiple linear regression (MLR) model with lagged predictor variables (MLR1), MLR model with lagged predictor variables and PM10 concentrations (MLR2) and regression with time series error (RTSE) model. The findings revealed that humidity, temperature, wind speed, wind direction, carbon monoxide and ozone were the main factors explaining the PM10 variation in Peninsular Malaysia. Comparison among the three models showed that MLR2 model was on a same level with RTSE model in terms of forecasting accuracy, while MLR1 model was the worst.
    Matched MeSH terms: Ozone/analysis
  10. Nadzir MSM, Ashfold MJ, Khan MF, Robinson AD, Bolas C, Latif MT, et al.
    Environ Sci Pollut Res Int, 2018 Jan;25(3):2194-2210.
    PMID: 29116536 DOI: 10.1007/s11356-017-0521-1
    The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009-2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O3 mixing ratio during MASEC'16 increased from a minimum of 5 ppb to ~ 10-13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O3 cycle has a maximum during the winter of 30 to 35 ppb between June and August and a minimum during the summer (January to February) of 10 to 20 ppb. The surface O3 mixing ratio during the summer was controlled by photochemical processes in the presence of sunlight, leading to the depletion process. During the winter, the photochemical production of surface O3 was more dominant. The NOAA-AIRS and ECMWF-MACC analysis agreed well with the MASEC'16 data but twice were higher during the expedition period. Finally, the CO past data showed the surface O3 mixing ratio was influenced by the CO mixing ratio over both the Ushuaia and Antarctic regions. Peak surface O3 and CO hourly mixing ratios reached up to ~ 38 ppb (O3) and ~ 500 ppb (CO) over Ushuaia. High CO over Ushuaia led to the depletion process of surface O3 over the region. Monthly CO mixing ratio over Antarctic (South Pole) were low, leading to the production of surface O3 over the Antarctic region.
    Matched MeSH terms: Ozone/analysis*
  11. Tan KC, Lim HS, Mat Jafri MZ
    Environ Sci Pollut Res Int, 2014 Jun;21(12):7567-77.
    PMID: 24599658 DOI: 10.1007/s11356-014-2697-y
    This study aimed to predict monthly columnar ozone (O3) in Peninsular Malaysia by using data on the concentration of environmental pollutants. Data (2003-2008) on five atmospheric pollutant gases (CO2, O3, CH4, NO2, and H2O vapor) retrieved from the satellite Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) were employed to develop a model that predicts columnar ozone through multiple linear regression. In the entire period, the pollutants were highly correlated (R = 0.811 for the southwest monsoon, R = 0.803 for the northeast monsoon) with predicted columnar ozone. The results of the validation of columnar ozone with column ozone from SCIAMACHY showed a high correlation coefficient (R = 0.752-0.802), indicating the model's accuracy and efficiency. Statistical analysis was utilized to determine the effects of each atmospheric pollutant on columnar ozone. A model that can retrieve columnar ozone in Peninsular Malaysia was developed to provide air quality information. These results are encouraging and accurate and can be used in early warning of the population to comply with air quality standards.
    Matched MeSH terms: Ozone/analysis*
  12. Masseran N, Razali AM, Ibrahim K, Latif MT
    Environ Monit Assess, 2016 Jan;188(1):65.
    PMID: 26718946 DOI: 10.1007/s10661-015-5070-9
    The air pollution index (API) is an important figure used for measuring the quality of air in the environment. The API is determined based on the highest average value of individual indices for all the variables which include sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and suspended particulate matter (PM10) at a particular hour. API values that exceed the limit of 100 units indicate an unhealthy status for the exposed environment. This study investigates the risk of occurrences of API values greater than 100 units for eight urban areas in Peninsular Malaysia for the period of January 2004 to December 2014. An extreme value model, known as the generalized Pareto distribution (GPD), has been fitted to the API values found. Based on the fitted model, return period for describing the occurrences of API exceeding 100 in the different cities has been computed as the indicator of risk. The results obtained indicated that most of the urban areas considered have a very small risk of occurrence of the unhealthy events, except for Kuala Lumpur, Malacca, and Klang. However, among these three cities, it is found that Klang has the highest risk. Based on all the results obtained, the air quality standard in urban areas of Peninsular Malaysia falls within healthy limits to human beings.
    Matched MeSH terms: Ozone/analysis
  13. Soyiri IN, Reidpath DD, Sarran C
    Int J Biometeorol, 2013 Jul;57(4):569-78.
    PMID: 22886344 DOI: 10.1007/s00484-012-0584-0
    Asthma is a chronic condition of great public health concern globally. The associated morbidity, mortality and healthcare utilisation place an enormous burden on healthcare infrastructure and services. This study demonstrates a multistage quantile regression approach to predicting excess demand for health care services in the form of asthma daily admissions in London, using retrospective data from the Hospital Episode Statistics, weather and air quality. Trivariate quantile regression models (QRM) of asthma daily admissions were fitted to a 14-day range of lags of environmental factors, accounting for seasonality in a hold-in sample of the data. Representative lags were pooled to form multivariate predictive models, selected through a systematic backward stepwise reduction approach. Models were cross-validated using a hold-out sample of the data, and their respective root mean square error measures, sensitivity, specificity and predictive values compared. Two of the predictive models were able to detect extreme number of daily asthma admissions at sensitivity levels of 76 % and 62 %, as well as specificities of 66 % and 76 %. Their positive predictive values were slightly higher for the hold-out sample (29 % and 28 %) than for the hold-in model development sample (16 % and 18 %). QRMs can be used in multistage to select suitable variables to forecast extreme asthma events. The associations between asthma and environmental factors, including temperature, ozone and carbon monoxide can be exploited in predicting future events using QRMs.
    Matched MeSH terms: Ozone/analysis
  14. Hassan NA, Hashim Z, Hashim JH
    Asia Pac J Public Health, 2016 Mar;28(2 Suppl):38S-48S.
    PMID: 26141092 DOI: 10.1177/1010539515592951
    This review discusses how climate undergo changes and the effect of climate change on air quality as well as public health. It also covers the inter relationship between climate and air quality. The air quality discussed here are in relation to the 5 criteria pollutants; ozone (O3), carbon dioxide (CO2), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter (PM). Urban air pollution is the main concern due to higher anthropogenic activities in urban areas. The implications on health are also discussed. Mitigating measures are presented with the final conclusion.
    Matched MeSH terms: Ozone/analysis
  15. Hewitt CN, MacKenzie AR, Di Carlo P, Di Marco CF, Dorsey JR, Evans M, et al.
    Proc Natl Acad Sci U S A, 2009 Nov 3;106(44):18447-51.
    PMID: 19841269 DOI: 10.1073/pnas.0907541106
    More than half the world's rainforest has been lost to agriculture since the Industrial Revolution. Among the most widespread tropical crops is oil palm (Elaeis guineensis): global production now exceeds 35 million tonnes per year. In Malaysia, for example, 13% of land area is now oil palm plantation, compared with 1% in 1974. There are enormous pressures to increase palm oil production for food, domestic products, and, especially, biofuels. Greater use of palm oil for biofuel production is predicated on the assumption that palm oil is an "environmentally friendly" fuel feedstock. Here we show, using measurements and models, that oil palm plantations in Malaysia directly emit more oxides of nitrogen and volatile organic compounds than rainforest. These compounds lead to the production of ground-level ozone (O(3)), an air pollutant that damages human health, plants, and materials, reduces crop productivity, and has effects on the Earth's climate. Our measurements show that, at present, O(3) concentrations do not differ significantly over rainforest and adjacent oil palm plantation landscapes. However, our model calculations predict that if concentrations of oxides of nitrogen in Borneo are allowed to reach those currently seen over rural North America and Europe, ground-level O(3) concentrations will reach 100 parts per billion (10(9)) volume (ppbv) and exceed levels known to be harmful to human health. Our study provides an early warning of the urgent need to develop policies that manage nitrogen emissions if the detrimental effects of palm oil production on air quality and climate are to be avoided.
    Matched MeSH terms: Ozone/analysis*
  16. Tajudin MABA, Khan MF, Mahiyuddin WRW, Hod R, Latif MT, Hamid AH, et al.
    Ecotoxicol Environ Saf, 2019 Apr 30;171:290-300.
    PMID: 30612017 DOI: 10.1016/j.ecoenv.2018.12.057
    Rapid urbanisation in Malaysian cities poses risks to the health of residents. This study aims to estimate the relative risk (RR) of major air pollutants on cardiovascular and respiratory hospitalisations in Kuala Lumpur. Daily hospitalisations due to cardiovascular and respiratory diseases from 2010 to 2014 were obtained from the Hospital Canselor Tuanku Muhriz (HCTM). The trace gases, PM10 and weather variables were obtained from the Department of Environment (DOE) Malaysia in consistent with the hospitalisation data. The RR was estimated using a Generalised Additive Model (GAM) based on Poisson regression. A "lag" concept was used where the analysis was segregated into risks of immediate exposure (lag 0) until exposure after 5 days (lag 5). The results showed that the gases could pose significant risks towards cardiovascular and respiratory hospitalisations. However, the RR value of PM10 was not significant in this study. Immediate effects on cardiovascular hospitalisations were observed for NO2 and O3 but no immediate effect was found on respiratory hospitalisations. Delayed effects on cardiovascular and respiratory hospitalisations were found with SO2 and NO2. The highest RR value was observed at lag 4 for respiratory admissions with SO2 (RR = 1.123, 95% CI = 1.045-1.207), followed by NO2 at lag 5 for cardiovascular admissions (RR = 1.025, 95% CI = 1.005-1.046). For the multi-pollutant model, NO2 at lag 5 showed the highest risks towards cardiovascular hospitalisations after controlling for O3 8 h mean lag 1 (RR = 1.026, 95% CI = 1.006-1.047), while SO2 at lag 4 showed highest risks towards respiratory hospitalisations after controlling for NO2 lag 3 (RR = 1.132, 95% CI = 1.053-1.216). This study indicated that exposure to trace gases in Kuala Lumpur could lead to both immediate and delayed effects on cardiovascular and respiratory hospitalisations.
    Matched MeSH terms: Ozone/analysis
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