Empirical calibration Martijn J. Schuemie, Marc A. Suchard In observational studies, there is always the possibility that an effect size estimate is biased. This can betrue even for advanced, well thought out study designs, because of unmeasured or unmodeled confounding.Negative controls (test-hypotheses where the exposure is not believed to cause the outcome) can be usedto detect the potential for bias in a study, and with enough negative controls we can start to estimatethe systematic error distribution inherent in an observational analysis. We can then use this estimateddistribution to compute a calibrated p-value, which reflects the probability of observing an effect size estimate
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ArticleVolume 2, Number 1, June 2009 ISSN 1995-6681 Pages 1 -6 Jordan Journal of Earth and Environmental Sciences
Diurnal and Seasonal Variation of Air Pollution at Al-Hashimeya Sana'a Abed El-Raoof Odat * Department of Earth Science and Environment, Faculty of Natural Resources and Environment,Hashemite University, Jordan Abstract
This study aimed at using the statistical methods to assess air quality at Al-Hashimeya town in Zarqa Governorate. Three main sources himeya are contributing to air pollution; Jordan Petroleum Refinery, Al-Hussein Thermal Power Station, and Assamra waste water treatment plant. Reports and data relating to pollution in al-Hashimeya were collected from different sources that measured the level of pollution in this area during spring season of the year 1992. Sets of data were processed, using statistical analysis. The results of the study indicated that Jordan Petroleum Refinery and al-Hussein Thermal Power Station were the two main sources of SO2 because of the combustion of fuel that contains sulphur and SO2 concentration that violated Jordanian standards. The study also showed that Assamra Station was the main source of H2S and its concentration had exceeded the Jordanian standards throughout the monitoring months. CO and NOx concentrations were within Jordanian standard. Ozone was in violation of Jordanian standards in more than 90% of the field measurements. Examination of the levels of TSP has shown that they exceeded the national standards with different degr conditions (air Temperature, wind speed, rainfall, wind direction, cloud and relative humidity) have contributed to the high levels of air pollution. 2009 Jordan Journal of Earth and Environmental Sciences. All rights reserved Keywords: Statistical Analysis; Air Pollution; ANOVA; SO2; TSP; CO.
Different studies have been performed to understand source and level of air pollu n in Al-Hashimeya. Most 1. Introduction*
studies are restricted to water and soil .This study aims to use statistical analysis to give both qualitativ In the last 200 ye the growth in the world quantitative information about air pollution for the primar population and the industrial revolution has resulted in an study for Al-Hashimeya during spring season in the year increased demand for energy. Until now these energy 1992, and to determine the impact of polluti requirements have been supplied largely by the parameters (wind speed, wind direction, temperature, combustion of fossil fuels, the plant's resources of rainfall, solar radiation and relative humidity) on the conventional carbonaceous fuel, coal, and oil, have been behaviour of noxious gases in this town. used for heating purposes, power industry, transport and synthesis of chemicals. The by-products of these 2. Methodology
operations (particulates, the oxides of carbon, nitrogen and sulphur) have been emitted to the atmosphere in enormous 2.1. Study Site quantities (Reida and John, 1988). Air becomes polluted when it contains substances in quantities that could harm Al-Hashimeya area is located north of Zarqa city, 35km the comfort or health of both humans and animals, or northeast of Amman It is bounded by Longitude 36° 04′ to could damage plants or materials. These substances are 39º 09′ east and Latitude 32º 04′ to 32 10 north (F called air pollutants and can be solid particles, liquid This town is the most polluted city in Jordan. The air droplets or gases, and they occur naturally or as a result of pollution has resulted from many factories and companies human activity (Seinfeld, 1985). in the area .Potential air pollution sources include, Jordan Al-Hashimeya area is located north to Zarqa city about Oil Refinery, Khirbit Al-Samra Waste water treatment 35km northeast to Amman. This town is the most polluted plant and Al-Hussein Thermal Power station. These city in Jordan; the air pollution has resulted from many sources are called "Triangle of Pollution". And every one factories and companies in the area, most important of of these has a different impact on air quality. A which are Jordan Petroleum Refinery, al-Hussein Thermal Mediterranean type climate is dominant in Al- Hashimey Power Station, and Assamra wastewater treatment plant. town which is characterized by hot and dry cond summer and lack of rain in winter. The average annual ra of rainfall is 142 mm. The low precipitation rate the air quality in Al-Hashimeya because rain is natural * Corresponding author. 2009 Jordan Journal of Earth and Environmental Sciences . All rights reserved - Volume 1, Number 2 (ISSN 1995-6681) Figure 1. the Location of the Study Area. processes that help washing out soluble substances Table1. Monitoring sites and their position from pollution sources from the air (Shehadeh and Noaman, 1991). in Al-Hashimeya. 2.2. Data Collection Distance and direction of station Monitoring sites There have been several stud from pollution sources Royal Scientific Society (RSS) and the Ministry of 6 km south west from SWTP Environment to monitor basic pollutants in the area during IBN EL Anbary School 0.5 km north from HTPS 1992 (Table 1 and Fig.1). Instruments installed in the 1.5km east from JOR monitoring sites sample ambient air continuously and analyze it automatically, (Table 2 illustrate the 3 km from al hashymia town 5.5km southwest from SWTP 2.3. Preparing for Data Analysis 0.5 km south /southeast fro The yearly mean concentra tion of s ven criteria 2km southeast from JOR pollutants PM10,, TSP, CO, NOx SO2, H2S and Pb was 4 km west from SWTP used obtained from unpublished sources (RSS). Missing ELEMENTARY SCHOOL values were substituted. If the value was missing, for SECONDARY SCHOOL 1 km northeast from JOR example, for a particular year, then it was substituted by taking the average of the preceding and succeeding years. ELECTRICAL TRAINING 0.5 km south from HTPS was done to preserve the seasonal patterns (as opposed to the effect of the procedure of substituting by Main highway of Irbid- Al the annual average.). POLICE STATION/ZARQA Main highway Zarqa Amman 2.4. Statistical Methods 2km south east from SWTP to deal with data, using 2 km north from HTPS the statistical package (SPSS) version 11 and JMP and 2km northeast from JOR 2 km from south east from JMP IN Software version 4. The descriptive statistics of E. SCHOOL/ KHERBEH 6.8 km from northeast HTPS the variables: Mean, standard deviation, median and others 7 km northeast from JOR of dependent variable were calculated, student t-test detect 2 km south /southwest fro for significant between pairs of a variable (p<0.05) unpaired data, One-way-ANOVA and Two-way ANOVAs 2.5 km north from HTPS were used to results. 3km from northeast JOR 2009 Jordan Journal of Earth and Environmental Sciences . All rights reserved - Volume 1, Number 2 (ISSN 1995-6681) 3. Result
3.2. Diurnal and monthly variation of Sulphur dioxide (SO2) The average of SO 3.1. Univariate Statistical Analysis 2 concentrations at Al- Hashimeya region registered was 0.062 ppm. This average exceeded The first step in the data analysis involved the the Jordanian standards and the directions of WHO for 46 s (e.g. Minimum, Maximum, days out of 80 sampled days. The highest monthly average Mean, Medians and Standard de shown in (Table for SO2 was 0.071 ppm for April. The average was yet 3). These statistics are useful in the description of the similar to March and May 0.059ppm. This rise of the distribution and to know the degree of pollution in the air. concentrations in April is due to the low air temperatures, The concentrations of pollutants were compared with humidity, lack of rainfall, and the lack of Ozone (O3 standard values recommended by WHO (Table 4). helps a lot in the process of SO2 removal through Table 2. Instruments and their uses. oxidization. It was noted that the levels of concentrations were not affected during we ekends and other formal Instruments name Sulphure Dioxide Analyser Analyse Sulphure Dioxide Table 3. Minimum ,Maximum ,Mean and St. Dev. of pollutants at Hydrogen Sulfide Analyser Analyse Hydrogen Sulfide Al -Hashimeya in 1992 Carbon Monoxide Analyser Carbon Monoxide continuously Minimum Maximum Mean St. Dev. Non- Dispersive Infrared High Volume Sampler with Selective PM10 Inlet, Portable Calibrator Calibrate instruments of pollutants Permeation Oven. Wind Recorder Mechanical. Measured of wind direction and Table 4 . Monthly average of pollutants and no. of exceeding according to WHO standard for 1992.
f pollutants and no. of Average monthly of SO2 0.059 0.071 0.056 Number of exceeding Average monthly of TSP 183.25 169.7 221.8 Number of exceeding Average monthly of H2S 0.006 0.006 0.007 Number of exceeding Average monthly of O3 (ppm) Number of exceeding 3.3. Diurnal and Monthly Variation of Hydrogen Sulphide (H2 The Concentrations of H2S for all monitoring days ranged from 0.002 -0.030 ppm with mean of 0.0064 ppm and standard deviation of 0.004. This average exceeds WHO standards. Royal Scientific Society (RSS) recorded 33 violations of the standards in 88 days, with 28% of all samples. The Average Concentrations of H2S in May was 0.007 ppm with 15 violations, i.e., 50% of the total samples. This average decreased in March to 0.006 ppm with 12 violations that gave rise to 43% of the total, and this monthly average is the same as in April but with about 6 days, (Table.3). 3.4. Diurnal and Mo y Variation of Ozone (O3) Figure 2. Concentration of O3 and WHO Standard at Al- The Concentrations of O ashimeya in 1992. 3 vary between 0.0 -0.65 ppm with a mean value that equals 0.074 ppm and a standard The Average Concentrations of O3 in March was 0.07 deviation of about 0.082. This average exceeds WHO ppm in 28 days ,i.e., 100% , but the concentration standards. It violated the standard 46 times out of 51 days, decreased in April to 0.06 ppm , 18 sample exceeded which means that the violation is 90% from all the standards, that mean 78% of the samples in this month samples (Figure 2). .The high concentration of O3 might correspond to increases in sunlight that helps nitrogen oxides and 2009 Jordan Journal of Earth and Environmental Sciences . All rights reserved - Volume 1, Number 2 (ISSN 1995-6681) volatile organic compounds reacting with each other to form photochemical oxidants (also known as photochemical smog) of which ozone is the principal component. Whereas the values ranged in April between 0.030 - 0.084 ppm, (Table 3). 3.5. Diurnal And Monthly Variation of Total Suspended Particles (TSP):- The monthly average of Total Suspended Particles (TSP) exceeded the 120 µg/m³ ppm WHO Standard days out of 31 day i.e. 77%. The average concentrations of TSP in May reached 221.8 µg/m³ ppm with 12 days violations, 92 %, this is due to low wind speed and humidity and west wind direction. In April, the average exceeded WHO standards with a mean value of about 169.7 µg/m³ ppm with 8 days violation, i.e., 80%. But in Figure 4. Variation in TSP levels at Al- Hashimeya and Um Suleh March the average monthly of TSP reached to 138.25 µg/m³ ppm with 4 days that reach ed to 50% of all the samples (Figure 3). The average exceeds WHO standards 4. the Factors Affecting the Concentration of Air
with a mean value of about (84.4 µg/m³) with 37 days Pollutants At Al –Hashimeya
violate from all the samples. Meteorology plays a great role in influenc pollutants at Al-Hashimeya ,where the total explanation caused by these factors reach 43% of the percentage pollution during spring season (March ,April and May).This percentage varies from 22% in March to 52% in April and 21% in May. 4.1. Meteorological Impact on SO2 Concentration:- (Table 5) shows the most important metrological factors that influenced SO2 concentration in the air. These factors explained 37% of dissimilarity in March, 84% in April and 29% in May. Table 5. Metrological Factors affect on the Concentration of SO2 at Al-Hashimeya in 1992. Variables R² R² Correlation Significant Figure 3. Concentration of TSP and WHO Standard at Al- Adjusted coefficient Hashimeya in 1992. The highest monthly average of TSP is that of May at ranges from 108 – 455 µg/m³ ppm, and the lowest average April Temperature 0.58 was found in March which ranged from 56 – 352 µg/m³, and this concentrations exceeds WHO standards. In April, it was 62 –316 μg/m³. These percentages exceed the international standards. This is more obvious when we compare these results with Umm Soleh, 3kms far from the study area. Studies indicate that the percentage of concentrations reached one third of the total percentage i.e., 38% of the whole exceedings. Figure (4) shows that the comparison of the TSP concentration in Ibn el-anbari (inside Al- Hashimeya area) and Um Suleh, (far 3Km west from Al- Hashimeya). TSP concentration in Ibn el-anbari is higher and exceeds to one-third, compared to Um suleh. 3.6. Diurnal and Monthly Variation of Carbon Monoxide (CO) 4.2. Metrological Impact on H2S Concentration:- Levels of this gas were low at the observance period, The most important meteorological factors that affected where it didn't exceed WHO standards, 9 ppm i.e., 8 hours the H2S concentration in spring was Wind Direction. Calm as an average in the light of the day where the highest winds are prevailing in Al –Hashimeya region, 38.6%. concentration of this gas reached 5 ppm in April. Also West winds blow on the region in 31.8%, south winds with 18.2% .The Eastern winds blow reached 2.3%, southeast reached 4.5%, southwest 2.3% and northwest reached 1.1%. 2009 Jordan Journal of Earth and Environmental Sciences . All rights reserved - Volume 1, Number 2 (ISSN 1995-6681) Clearly, winds play a big role in affecting the 4.4. Metrological Impact on TSP Concentration:- percentage of H2S gas ,14% of distraction in H2S value The main factors affecting TSP are temperature and with -0.32 negative correlated with coefficient value are clouds (Table 8). The mean average of temperature at Al – explained at 99% reliability (Table 6). This relation is Hashimeya is approximately 17.3 Cº with a maximum mainly due to the increase in the percentage of calm value of 29.30 Cº and a minimum of 7.2Cº. Thus such winds, and west winds, which increased the air pollution temperatures have an effect on on the concentration of level in the study area, wind in carrying these pollutants TSP. It therefore explains 22% of the dissimilarity in the from their resources (Petroluem Refinery and Al-Sammra values of this gas with a negative correlation coefficient – station) to the sampling location. 0.50. The reason behind the negative correlation is that It is clear that the speed of the wind plays a big role in high temperatures enhance convection currents, which increasing the H2S concentrations in March. It explains helps in good air mixing and reducing TSP concentration 31% of the dissimilarity of the gas values with a negative Low air temperatures results in stable atmosphere and correlation of -0.56 at the 99% significance level. i.e., when the wind speed is decreased, the level of air pollution The amount of clouds affects the percentage of TSP is increased in Al-Hashimeya. concentration; it explains 14% of dissimilarity in the The average relative humidity in Al –Hashimeya is values of TSP at a positive correlation of 0.37 at 99 % . approximately 81.3% for the month of April. Humidity is Table 8: Metrological Factors that Affect the Increase Of TSP in an important factors that decreases the H2S concentration. It explains 27% of the dissimilarity in the gas value with a negative correlation –0.52, at 99% of confidence. When Variables R² R² Correlation Significant Adjusted coefficient there is an increase in relative humidity in the atmosphere, the concentration value decreases. The negative correlation is attributed to the role of humidity in increasing the chemical interactions for the gases and water vapour in order to form droplets, as well as forming the photochemical smog . Table 6. most important metrological factors that affect the increase of H2S in the air. 5. Discussion
Month Variables R² R² Correlation Significant It is observed that the main sources of Sulphur dioxide Adjusted Coefficient emissions in Al- Hashimeya town are Jordanian Petroleum March Wind 0.31 0.31 Refinery and Al –Hussein Ther mal Power station due to burning heavy fuel oil with high Sulphur content. It was also noticed that the areas located north, northeas southeast are mainly affected by SO2 emissions from the refinery, as Al-Husain station's influence is low in comparison with the refinery because the prevailing winds in Al-Hashimeya region are west headed. The study also showed that Assamra Station is the main source for the Months Direction emanation of H2S and the density of this gas has the Jordanian standards in this respect throughout the monitoring months whereas the levels of nitrogen oxides 4.3. Metrological Impacts on Ozone Concentration and CO concentrations are low in the ambient air in this Humidity is considered among the meteorological town, but for TSP the concentration is high and it exc factors that influences O3 concentration. It explains 22% of the WHO standards. the dissimilarity in the gas value with a negative Results have proved that the high concentrations of correlation –0.48, at 99% of confidence (Table 7) . When TSP were attributed to the prevailing Khamasin winds, there is an increase in the relative humidity, the O3 which is common in spring, especially in April and May, concentration decreases, the negative correlation is in addition to the high temperature and the low averag attributed to the role of humidity in increasing the rainfall and low humidity, thus helping responding fugitive chemical interactions for the gases and acid rain as well as forming the photochemical smog. Temperature shows an inverse relation with most of the Table 7. most important metrological factors that affect the pollutants because of the role of the heat in warming up increase of O3 in the air. the surface of the earth by the oncoming radiation from sun which strikes the earth and warms it, thus making the Month Variables R² Correlation Significant air that touches it warm and consequently reducing its Adjusted coefficient density, so it expands and goes upward to be replaced by March Relative 0.22 0.22 cold air and so on. This process increases the amounts of the up going air currents. When the horizontal and vertical air mixing processes increase, they reduce the May Relative 0.
concentration of the pollutants in it. Further, the decrease in temperature for some pollutants increases the production of some pollutants due to an increase in the 2009 Jordan Journal of Earth and Environmental Sciences . All rights reserved - Volume 1, Number 2 (ISSN 1995-6681) burning times and using of the central heating, which  Directorate of Environment in Al- Zarqa.(2000). Reports results in the increase of these pollutants like NO about Al-Hashimeya area 2000. CO. The relation of TSP with temperature is proportional,  Department of public Statistic. (1994 –2004). Unpublished as the increase in temperature leads to generating more air currents and shaping vertical winds, thus causing dust and  Al-awdat G. (1992). Air pollution in Jordan. Ministry of therefore TSP increases in the area. Humidity is low in Al- environment and municipal Affairs, Department of Hashimeya city. It's annual rate amount 65% .The process environment, Amman, Jordan, February. of humidity decrease leads to more concentrations of gas Air Quality at Al- Hashimeya area contaminations and suspended dust in the air, which Zarqa,Final Reports of 2004 ,2003 , 2002, 2001, 2000, 999, results from Oil Refinery, Al- Hussien thermal power 1998, 1997, 1996, 1995, 1 994, 1992.Prepared by Royal station and Al- Kherbh Al- Sammra. Scientific Society (RRS) to the General CORPORATION The relation of relative humidity with the concentration FOR Environmental Production (GCEP). of the pollutants is proportional relation, which could be  Sall J., Lehman A.,and Lee Creighton. (2001). JMP Start attributed to the role of the humidity in causing the heat Statistics, Using JMP and JMP IN Software. Copyright: 2001 discrepancies as the increase of humidity in the by SAS Institute Inc.Duxbury Thomson LEARNING. atmosphere reduces the amount of solar radiation that  Jordan Petroleum Refinery. (1960). Report published at the reaches the earth , and when sunshine collides with these opening of the company. drops, then it absorbs these scattered drops in the surro  Jordan Petroleum Refinery. (1991) . Annual reports of unding atmosphere, so they start to evaporate and management committee for 1978, 1988 and 1991 launch their embedded heat in the surrounding air, which contr  Metrology Department. (2004). Amman, Unpublished ibutes in forming heat variations where the air near to the surface of the earth is becoming colder than that in the climatic data, ( 1992 –2004). upper parts, thus reducing the up going air currents and M nistry of municipal affairs. (1993). Monitoring project of air pollution in Al- hashimeya ,Foheis and the city town from dingly increasing the pollutants in the atmosphere. 1st of October ,1991 to 1st February 1993 ,Strategies of Environmental Project in Jordan. 6. Conclusion
 Ministry of Health. (1998). the Experience of The Ministry of The results hav shown that the observed levels of air Health In Air Pollution In Amman, 1988 –1989. pollution exceeded the Jordanian standard for air quality  Ministry of Health. (1987) .Report about Pollution in (HTP) and the study proved that the effect of meteorological and (JRS) in Al- hashimeya. factors play a great role in influencing the air with gases  Ministry of Health. (1983). The Study of the United Nation and dust in Al – Hashimeya area. (UN) about Monitoring and Protecting of Air Pollution in Jordan ,1983.Reports of Sewdian Team about air pollution in Al- Hashimeya area  Ministry of Energy and Mineral Resources. (2002). S cientific Society, Metrology Unpublished annual r por Department, and Ministry of Eenvironment for providing  Ministry of Environment. (1999). Unpublished annual report. us with the data used in this study .  Ministry of Environment.(2003). Unpublished annual report. References
 Ministry of Health. (1973) .Management of licensing vehicles, unpublished annual report.  AARC (Al-Urdun Al-Jadid Research Center), (2001).The  Municipality of Al-Hashimeya. (2003). Reports about Al- State of Environment in Jordan, Annual Report. Hashimeya pollution 2003.  Al- Sammra, J., (1974). A seminar on pollution in the Arab  Reida B, and kutzach J,(1988) . Air pollution, Univer world ,(22/4 -25/4/1974) Arab countries corporation,the Winsconsin mades on association of American geographers, scientific,cultural and educational committee ,Cairo (1974).  Al- Hussein Thermal Plant. (2001). Report for Air Quality  Royal Scientific Society.(1990). Hydrogen sulphide pollution Monitoring for the Selected Site of As samra Power Project in populated Areas of Al- Hashimeya Town ship. Amman, at Al- Hashimeya 2001.  Al-Hasan A., (1986-1990). Air pollution monitoring in  Royal Scientific Society (RSS).(1990) . Air pollution in amman . Environmental research center, Royal scientific Amman, 1986 –1990. society, Amman, Jordan.  Royal Training course on air pollution. (1992). selected  Box, G.E.P., Jenkins, G.M., and Reinsel, G.C. (1994). Time presentations, world health organization (WHO), Ea Series Analysis Forecasting and Control. (3rd Edition). Mediterranean regional Office, Royal center for Prentice Hall Press, Englewood Cliffs, New Jersey. environmental health activities (RCHA), Amman, Jordan., pp  Burnett, R.T., et al.(1999). Effects of particulate and gaseous air pollution on cardio respiratory hospitalisation. Arch.  Seinfed ,J.L.,and Pandis. (1998). Atmospheric Chemistry and Environ. Health, 130. Physics from Air Pollution to climate change ;John Wiley  Department of Statistics. (2004), Reports about Al- and sons: New York ,pp 74 –75,1056 –1057. Hashimeya area 1997,1994 and 2004.
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