Determination Of Mercury Levels Research Articles

ANALYSIS OF MERCURY (HG) CONTENT IN URINE AND ITS IMPACT ON HEALTH DISORDERS OF ILLEGAL GOLD MINING WORKERS IN MALOMBA VILLAGE, DONDO SUB-DISTRICT, TOLITOLI DISTRICT

Mercury is a heavy metal element that very easily enters the bodies of living creatures and joins the food chain. The living creatures most likely to be directly exposed to mercury are traditional miners who use the amalgam method to extract gold ore. The danger of poisoning posed by mercury for humans can be diagnosed through analysis of mercury levels in urine. Furthermore, this research aims to determine mercury levels in the urine of gold mine workers and to obtain information regarding the mercury content in the urine and the health problems of gold mine workers. The method used in this research was the calibration curve method with Cold Vapor Atomic Absorption Spectophotometry (CV-AAS) analysis and descriptive methods from the results of questionnaire interviews. The results show that the mercury levels in mine workers have exceeded the threshold value set by WHO of 4 ppb while the highest mercury level obtained is 44.1 ppb, the lowest mercury level is 8.38 ppb and the control sample is 6.32 ppb, and there are 2 respondents that have symptoms of mercury exposure, namely respondent OP showing symptoms of mercury exposure in the form of frequent tingling, itching, easy fatigue, headache and eye irritation, and respondent YP showing symptoms of mercury exposure in the form of tremors, frequent tingling, itching, weakness of taste buds, difficulty swallowing, diarrhea, and headache. Based on the research results, it is found that the bodies of mining workers in Malomba Village show symptoms of exposure to mercury.

Potential of Corn Stalk Biomass as Biosorbent in Adsorption of Mercury (Hg) Metal Contaminants

Corn stalks are an agricultural waste that is commonly found in Indonesia. Corn stalks have a high enough cellulose content which has functional groups that can be used as biosorbents. This study aims to optimize the adsorption of corn stalk waste to mercury metal ions and then determine the adsorption capacity and adsorption constant of the Langmuir and Freundlich isotherm model. This research begins with corn stalk preparation, delignification, characterization using FTIR and SEM, determination of optimization of biosorbent weight, pH of Hg solution, contact time, and concentration of Hg solution, then applied to mercury metal contamination waste. Optimization of the weight of biosorbent in the range 0.4-1.2 grams, pH of the Hg solution is 2-4, contact time is 60-120 minutes, and concentration of the Hg solution of 30-100 g/L with a solution volume of 50 mL. Furthermore, determination of mercury levels, manufacture of standard series, and testing using ICP-OES. Followed by the determination of Langmuir and Freundlich's adsorption isothermal model. The results of this study indicate that the optimum conditions for the adsorption process occur at the weight of the biosorbent 1.2 grams, pH of the Hg 3 solution, contact time of 90 minutes, and concentration of Hg solution of 40 ppb with a solution volume of 50 mL. The application of biosorbent to metal contamination waste with adsorbed Hg concentration obtained 27.5772 ppb in 50 mL of waste solution with an adsorption efficiency of 88.44%. In the determination of Langmuir and Freundlich isotherms, a match was found for Langmuir adsorption isothermals with an adsorption capacity of 0.00333 mg Hg/g biosorbent and b = 176.8256.

Determination of Total Mercury (THg) and Methylmercury (MeHg) in Samples of Crabs (Callinecte amnicola)

This work was initiated with the aim of evaluating the mercury content in crabs Callinectes amnicola at three sites in the Ebrié lagoon. The crabs were taken from the landing sites in the different areas. A total of ninety (90) crabs were graded to obtain a representative sample of all landings. The analyzes focused on the levels of total mercury and methyl mercury in the Callinectes amnicola crabs. The analysis of variance showed that the site with the highest mercury content is the most urban site, namely the Boulay Island site in Abobodoumé. The results obtained showed that the total mercury content varies according to the mass and size of the crab. Furthermore, mercury, at all the sites of our study presents concentrations well below the threshold values ​​set by the WHO and the EU. The determination of mercury levels in crabs from different landing sites in the Ebrié lagoon makes it possible to assess the risks of contamination of the food chain, incurred by the top predator at the end of the chain, which is human beings, the main consumer of seafood products.

AN ANALYSIS OF MERCURY (HG) LEVELS IN RIVER WATER AROUND THE GOLD MINING AREA IN BANYUWANGI REGENCY

Mercury (Hg) is a metal that is commonly found in water and has toxic properties, so it is very dangerous for human health and the environment. Mercury in the environment can come from gold mining activities such as in Pesanggaran Village, Banyuwangi. Based on information from the surrounding community, the waste disposal flowed into the river and it was feared to affect the quality of river water in this area. This study aimed to analyze the mercury level in the river water using the UV-Visible Spectrophotometer method, where river water samples were taken from the upstream, middle, and downstream parts. Determination of mercury levels was carried out at the STIKES Banyuwangi Laboratory. The results showed that the Hg content in the river water around the gold mining area of Pesanggaran Village, Banyuwangi ranged from 0.031 to 0.033 mg/L. The Hg level of river water in this area was above the threshold and it was not recommended to use as drinking, bathing, cooking or washing. However, it is necessary to analyze Hg levels using other methods, such as the AAS (Atomic Absorption Spectroscopy) method which is more expensive but more accurate results will be obtained.

PENERAPAN METODE SPEKTROFOTOMETRI SERAPAN ATOM (SSA) DALAM MENGANALISIS LOGAM MERKURI (Hg) PADA KRIM PEMUTIH WAJAH

Whitening cream is a mixture of chemicals and or other ingredients with properties that can fade dark spots on the skin. Whitening cream must be safe and must not contain harmful ingredients such as heavy metal mercury because its toxicity to the organs of the kidneys, nerves, and brain is very strong, so its use is prohibited in cosmetic preparations. The purpose of this study was to determine the levels of metallic mercury (Hg) contained in the preparation of facial whitening creams circulating in Sei Sikambing Market, Medan. The sample used in this study was a facial whitening cream that was not registered with BPOM. The method used to determine mercury levels is qualitatively using color reagents and quantitatively using AAS (Atomic Absorption Spectrophotometry). The results obtained were from 2 samples of facial whitening cream that were used positively for heavy metal mercury (Hg) characterized by the formation of a red-orange precipitate with KI reagent, yellow precipitate by NaOH reagent, white precipitate by HCl reagent. The results of the analysis showed that the highest Hg metal content in the sample with code E was 5.0241 ± 0.4064 g/g. The conclusion of this study is that two samples were positive for mercury, where the use of mercury has been prohibited by BPOM.

Validation of Mercury Speciation Analysis in River Around Artisanal Small-Scale Gold Mining Area in West Nusa Tenggara, Indonesia

A method for determining mercury concentration using a mercury analyzer in a river water sample was validated according to ISO/IEC 17025. Analytical performance including linear range, limit of detection, precision and accuracy were evaluated. Mercury speciation profile was obtained from Pelangan River at three areas within Dusun Rambut Petung, an area with the highest amount of artisanal small-scale gold mining (ASGM) in Lombok, West Nusa Tenggara. Then, their concentration in each species was measured using sequential extraction. Good curve linearity was obtained in the concentration range of 0.1-5.0 µg/L and the limit of detection was 0.014 µg/L. The developed method has good precision and accuracy with a RSD value <10% and a recovery of 94.16-101.91%. The detected fraction of mercury in the Pelangan river is organomercury, elemental mercury, and sulfide-bound species with each concentration of 0.732±0.032; 0.350±0.027; and 0.850±0.027 µg/L, respectively. The measurement results showed conformity with the reference method using CV-AAS. Therefore, this method can be applied to determine mercury levels in water for monitoring environmental quality.

Mercury contamination levels in rivers and resident wells in Padesa and Sepukur Villages, Lantung District, Sumbawa Regency, Indonesia

Traditional mining business activities for processing gold ore in Lantung District are amalgamated using mercury (Hg) from 2015 to 2021 and are still ongoing. On average, there are ten to fifteen logs in each village, the waste being discharged only through ditches or small streams leading to rivers. Mercury that enters the aquatic environment will experience precipitation, dilution, and dispersion, absorbed by organisms living in these waters. Mercury water will be converted into methyl mercury by certain bacteria called biomethylation. In methyl-mercury (MeHg), mercury has toxic properties, firm binding, and high solubility. If consumed by biota, it will experience bioaccumulation in the body, and if consumed by humans for a long time, it can cause various types of diseases up to death. This study aims to determine mercury levels in the rivers and wells of residents in Sepukur Village and Lantung District. The research method is a survey with a sampling technique that is purposive sampling based on the distance from the logs to the residents' wells and rivers. The results showed that mercury levels in the Padesa Village river and springs were 0.002 mg/L. The average mercury level in the Sepukur Village River is 0.0004 mg/L, dug wells are 0.0014 mg/L, and drilled wells are 0.0024 mg/L. It can be concluded that the mercury levels in the springs in the village of Sepukur exceed the standard, and the river is classified in class 3. Mercury levels in the drilled wells of the residents of Sepukur Village exceed the standard, and the dug wells are still within the safe limits of the standard. Meanwhile, the river level in the Village of Sepukur is still relatively safe.

Potential of Cassia alata and Cassia multijuga to Phytoremediate Mined-out Soils in the Puruni Mining Area

Phytoremediation is a technology that uses plants to remove contaminants such as mercury from soil. This research examined phytoremediation as an option to remove mercury from mined out soils in the Puruni mining area, Mazaruni (Region VII). The study examined the phytoextractive capabilities of the Cassia alata (Carrion Crow Bush) and Cassia multijuga (False Sicklepod). Soil sampling was conducted to determine mercury levels at five mined out sites: Jubilee Creek Nos. 1 & 2, Chinese Creek, Tiger Creek, and the Takatu area. A tube auger and sieve were used to extract soil samples and remove debris.

Health Risk Assessment of Mercury Exposure from Fish Consumption in Munduruku Indigenous Communities in the Brazilian Amazon.

Fish serves as the principal source of animal protein for the indigenous people of the Amazon, ensuring their food and nutritional security. However, gold mining causes mercury (Hg) contamination in fish, and consequently increases health risks associated with fish consumption. The aim of this study was to assess the health risk attributed to the consumption of mercury-contaminated fish by Munduruku indigenous communities in the Middle-Tapajós Region. Different fish species were collected in the Sawré Muybu Indigenous Land to determine mercury levels. The health risk assessment was carried out according to the World Health Organization (WHO 2008) methodology and different scenarios were built for counterfactual analysis. Eighty-eight fish specimens from 17 species and four trophic levels were analyzed. Estimates of Hg ingestion indicated that the methylmercury daily intake exceeds the U.S. EPA (United States Environmental Protection Agency) (2000) reference dose from 3 to 25-fold, and up to 11 times the FAO (Food and Agriculture Organization)/WHO (2003) dose recommendation. In all situations analyzed, the risk ratio estimates were above 1.0, meaning that the investigated Munduruku communities are at serious risk of harm as a result of ingestion of mercury-contaminated fish. These results indicate that, at present, fish consumption is not safe for this Munduruku population. This hazardous situation threatens the survival of this indigenous population, their food security, and their culture.

Pakistan Karachi sahillerinden Holothuria (Mertensiothuria) leucospilota türünde (Brandt, 1835) Hg değerlendirmesi

The aim of the present study was to determine mercury levels in sediments, surface sea water and Holothuria leucospilota muscles and skin in two selected sites from Karachi coast. Samples were collected during two seasons south-west monsoon (August-September) and north-east monsoon (December-January). The concentrations of Hg in sediment ranged from 0.0012 to 0.0023 mg kg-1, and in surface water from 0.00018 to 0.00034 (µg l-1), while in muscle and skin of black sea cucumber ranged from LOD to 0.0034 and LOD to 0.0046 mg kg-1 dry wt., respectively. Moreover, Hg showed the highest accumulation rate in the skin tissue with BSAF values ranging between 2 in Buleji and 2.69 in Sunehri at north-east monsoon. The BSAF values in the muscles of the black sea cucumber ranged from 1.44 at south-west monsoon in Buleji to 1.63 at north-east monsoon in Sunehri, respectively. Since BSAF value is higher than 2 on the skin of sea cucumber, it is evaluated as macro-concentrator. However, the BSAF value varies between 1 and 2 in muscle, it has been determined as micro-concentrator. Hg in the black sea cucumbers from Buleji and Sunehri sites of the Karachi coasts is “very bio-accumulative” (BCF > 5000) during both sampling seasons.

The determination of mercury levels in the blood and hair of rabbits with amalgam fillings

Purpose: This study was conducted to investigate the level of blood and hair mercury transition in rabbits depending on the number of amalgam filled teeth in the mouth.
 Material and Methods: A total of 18 male rabbits from New Zealand were used in the study. The rabbits were separated into three groups in this study. The first group was named as control group, the second group was named as dichotomous filled group, and the third group was named as quadruple amalgam filled group. Blood samples were collected from filler animals before the filling, at 24 hour, at the first week and month and also hair samples were taken before the filling and at the first month. The transfer of mercury, taken by the blood and feather samples of rabbits in the study, was made with the hydride system in the absorption spectrophometer.
 Results: The data’s, obtained from the study, were evaluated by using the SPSS 21 package program. Compared by the control group at the 24th hour, any statically difference wasn’t seen between dichotomous and quadruple amalgam filling groups in terms of blood mercury level. (P>0.05). However, the level of blood mercury, one week and one month later was significantly higher than the control group.(P<0.05) In the all periods, the level of blood mercury was found similar between dichotomous and quadruple amalgam filling groups (P>0.05).
 Conclusions: Mercury couldn’t be detected in hair samples. As a result, it was revealed that amalgam filling affects the blood mercury level.
 
 How to cite this article: Yerebasan Ü, Servi K, Ataş O, Doğan MS. The determination of mercury levels in the blood and hair of rabbits with amalgam fillings. Int Dent Res 2020;10(1):12-16. https://doi.org/10.5577/intdentres.2020.vol10.no1.3
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Perbandingan kadar merkuri, kreatinin, dan urea pada pekerja industri di Kotagede dan Banguntapan, Yogyakarta sebagai indikator pencemaran

Study from the Environmental Office of Yogyakarta, indicates in Kotagede found the pollution of mercury from the environment because of improper disposal of wastewater. This study aims to assess the levels of mercury, creatinine and urea in the serum and urine of people working in several industries in Kotagede and Banguntapan. Subjects of this study were 52 employees in several industries in Kotagede Yogyakarta with a range of ages between 20 - 71 years and length of work between 3 - 38 years. A total of 42 people with the age range was 21 - 63 years and the length of work between 1 - 20 years were taken from industrial employees in Bantul who have almost the same geographical conditions as Kotagede. Determination of mercury levels using the Atomic Absorption Spectrophotometry (AAS) method while the determination of urea and creatinine levels by a Dyasis kit. In Kotagede, there were 3 people (5.8%) with the average mercury serum of 0.217 ppb and no mercury in the urine was found in all subjects. In Banguntapan, one person (2.4%) had 0.200 ppb mercury serum and 6 people (14.3%) had an average mercury urine level of 0.395 ppb. Urine creatinine and urea levels in subjects from Kotagede were higher than those from Banguntapan (p<0.05), despite being on the normal range. The presence of mercury in several industrial employees in Kotagede and Banguntapan is still on the low range even though it was correlated to creatinine levels.

A case study on the development of representative sampling procedure to determine mercury levels in a lot of tuna caught by static trap.

Mercury contamination in fish products, and in large pelagic predatory fish in particular, is a remarkable food safety issue that affects fish industry. A lot made up by Bluefin tunas caught at Porto Paglia − in the south-western coast of Sardinia − was subject to several sessions of fish meat official sampling, as disputable results of mercury level determination suggested a potential non-compliance to maximum allowable limit. Local competent Veterinary Service reviewed the sampling procedure introducing more rigorous details including the identification of a specific muscular portion as sampling site, after having taken into account both statutory provisions laid down by Regulation (EC) No 333/2007 and available scientific evidence on variables affecting uneven distribution of mercury across tuna carcasses. This case-study aims to provide an initial contribution in order to ensure an appropriate and representative field sampling protocol of tuna lots that are to be analysed for mercury content.

Urinary Mercury Levels Among Workers in E-waste Shops in Nakhon Si Thammarat Province, Thailand.

ObjectivesTo determine urinary mercury levels in e-waste workers in Southern Thailand and the airborne mercury levels in the e-waste shops where they worked, to describe the associations between urinary and airborne mercury levels, and to evaluate the prevalence of mercury exposure-related health effects among e-waste workers.MethodsA cross-sectional study was conducted by interviewing 79 workers in 25 e-waste shops who lived in Nakhon Si Thammarat Province, Thailand. Information on general and occupational characteristics, personal protective equipment use, and personal hygiene was collected by questionnaire. Urine samples were collected to determine mercury levels using a cold-vapor atomic absorption spectrometer mercury analyzer.ResultsThe e-waste workers’ urinary mercury levels were 11.60±5.23 μg/g creatinine (range, 2.00 to 26.00 μg/g creatinine) and the mean airborne mercury levels were 17.00±0.50 μg/m3 (range, 3.00 to 29.00 μg/m3). The urinary and airborne mercury levels were significantly correlated (r=0.552, p<0.001). The prevalence of self-reported symptoms was 46.8% for insomnia, 36.7% for muscle atrophy, 24.1% for weakness, and 20.3% for headaches.ConclusionsPersonal hygiene was found to be an important protective factor, and should therefore be stressed in educational programs. Employers should implement engineering measures to reduce urinary mercury levels and the prevalence of associated health symptoms among e-waste workers.

Mercury in foods from the first French total diet study on infants and toddlers

A very sensitive method using a direct mercury analyser was developed and validated according to the accuracy profile procedure to determine mercury levels in foods mainly consumed by infants and toddlers. Total mercury was not detected (LOD of 0.30µg.kg−1 fresh weight) in 92.4% of the 291 food samples analysed or at relatively low concentrations, lesser than or equal to LB/UB 0.5/1.0µg.kg−1 in all samples, except in fish samples (mean LB/UB 25µg.kg−1 with a maximum of 53µg.kg−1). Levels of total mercury in these foods were in all cases within permitted Regulatory limits of 500 or 1000µg.kg−1 in fishery products and muscle meat of fish.

Determining mercury levels in anchovy and in individuals with different fish consumption habits, together with their neurological effects.

An increase in enviromental pollution may lead to mercury toxicity of fish origin due to the accumulative nature of methylmercury in fish. The main sources of human exposure to organic mercury compounds are contaminated fish and other seafoods. This descriptive study was planned to determine mercury levels in anchovy and in hair samples from individuals with different fish consumption habits, and to evaluate those individuals in terms of toxic effects. For that purpose, we analyzed 100 anchovies from the Black Sea and 100 anchovies from the Sea of Marmara, and assessed 25 wholesale workers in fish markets and 25 cleaning firm employees from both Ankara and Istanbul. Mercury levels in samples were measured using a cold vapor atomic absorption spectrophotometer. Participants were examined neurologically and mini mental state examination was applied to evaluate their cognitive functions. Mercury levels in fish were found to be below the national and international permitted levels. There was no statistically significant relation between mercury levels and the sea from which fish were caught. Hair mercury levels for all participants were within permitted ranges. However, hair mercury levels in both cities increased significantly with amount and frequency of fish consumption. A significant correlation was determined at correlation analysis between levels of fish consumption and hair mercury levels in the fishmongers and in the entire group (r = 0.32, p = 0.025; r = 0.23, p = 0.023, respectively). Neurological examination results were normal, except for a decrease in deep tendon reflexes in some participants in both cities. There was no correlation between Standardized Mini Mental State Examination results and hair mercury levels. We conclude that establishing a monitoring system for mercury levels in fish and humans will be useful in terms of evaluating potential neurotoxic effects.

Determination of Mercury Exposure among Dental Health Workers in Nakhon Si Thammarat Province, Thailand

Objectives. The main objective of this study was to assess the mercury exposure levels in dental health workers that work in dental clinics. The study evaluated the airborne and urinary mercury levels, the type of work done in the clinic, and the effect of mercury exposure on health of dental health workers. Material and Methods. A case-control study was conducted with 124 exposed and 124 matched nonexposed subjects. Personal and area samplings were conducted to quantify mercury concentrations by solid sorbent tube. Urine samples were collected to determine mercury levels by cold-vapor atomic absorption spectrometer mercury analyzer. Results and Discussion. 17.6% (n = 32/182) of the air samples were higher than the occupational exposure limit (OEL). A multiple regression model was constructed. Significant predictors of urinary mercury levels included dietary consumption (fish or seafood), duration of work (yrs), work position, personal protection equipment used (PPE), and personal hygiene behaviors. Significant correlations were observed between mercury levels in urine and mercury in storage areas (r = 0.499, P < 0.05) and between mercury levels in urine and airborne mercury in personal samplings (r = 0.878, P < 0.001). Conclusion. Improvements in working conditions, occupational health training, and PPE use are recommended to reduce mercury exposure.

Mercury concentration in the milk of mothers living near the southern coast of the Caspian Sea during different stages of lactation period

The aim of this study was to determine mercury levels and changes during lactation in colostrum, transitional milk, and mature milk (1 month and 2 months post partum). The mercury mean concentration in milk samples collected from 18 women was 90 ± 20 and 100 ± 30 ng L−1 for colostrum and transitional milk, respectively. Also, mean concentration of 160 ± 70 and 140 ± 50 ng L−1 for mature milk 1 month and up to 2 months post partum were found. The concentration of mercury did not decline during the lactation period. Mercury daily intake was estimated when the infants were fed human milk only. The intakes ranged from 0.0 to 80 and from 0.0 to 70 ng kg−1 body weight day−1 for colostrum and transitional milk, respectively. For mature milk at the first month and up to 2 months the intakes were estimated from 1 to 200 and from 0.0 to 270 ng kg−1 body weight day−1. Significant difference was found between mothers without amalgam-filled teeth and mothers with one to five amalgam-filled teeth. Fruit and vegetable consumption showed negative correlation with the mercury concentration in human milk.

Mercury Exposure among Garbage Workers in Southern Thailand

Objectives1) To determine mercury levels in urine samples from garbage workers in Southern Thailand, and 2) to describe the association between work characteristics, work positions, behavioral factors, and acute symptoms; and levels of mercury in urine samples.MethodsA case-control study was conducted by interviewing 60 workers in 5 hazardous-waste-management factories, and 60 matched non-exposed persons living in the same area of Southern Thailand. Urine samples were collected to determine mercury levels by cold-vapor atomic absorption spectrometer mercury analyzer.ResultsThe hazardous-waste workers' urinary mercury levels (10.07 µg/g creatinine) were significantly higher than the control group (1.33 µg/g creatinine) (p < 0.001). Work position, duration of work, personal protective equipment (PPE), and personal hygiene, were significantly associated with urinary mercury level (p < 0.001). The workers developed acute symptoms - of headaches, nausea, chest tightness, fatigue, and loss of consciousness at least once a week - and those who developed symptoms had significantly higher urinary mercury levels than those who did not, at p < 0.05. A multiple regression model was constructed. Significant predictors of urinary mercury levels included hours worked per day, days worked per week, duration of work (years), work position, use of PPE (mask, trousers, and gloves), and personal hygiene behavior (ate snacks or drank water at work, washed hands before lunch, and washed hands after work).ConclusionChanging garbage workers' hygiene habits can reduce urinary mercury levels. Personal hygiene is important, and should be stressed in education programs. Employers should institute engineering controls to reduce urinary mercury levels among garbage workers.

Determination Of The Mercury Content Of Lichens and Comparison To Atmospheric Mercury Levels In The South African Highveld Region

The concentration of mercury vapour in ambient air is routinely determined using specialised instruments.As an economical alternative, actively pumped Hopcalite sorbent tubes can be used to trap atmosphericmercury, which is subsequently analysed by cold vapour atomic absorption spectroscopy. Plant materialsare also readily available in most regions and can be analysed to obtain information on time averagedatmospheric mercury levels.Lichen and tree bark samples were collected in the cities of Pretoria and Witbank, dried and acid digestedwith subsequent cold vapour atomic absorption spectroscopy. Average mercury concentrations rangingfrom 74 to 193 μg.kg-1 were found in lichens from three Pretoria suburbs, whilst average Hg levels of 228μg.kg-1 were determined in lichens collected in Witbank. The average mercury concentration in tree barkwas consistently lower than in lichens, with concentrations between 28 and 72 μg.kg-1 determined insamples from three Pretoria suburbs and 75 μg.kg-1 determined in samples taken in Witbank. This study isthe first in South Africa to determine mercury levels in lichens and tree bark.Average total gaseous mercury concentrations in ambient air at the three Pretoria suburban sites, asdetermined by a semi-continuous spectroscopic method using Hopcalite sampling, ranged between 1.6and 2.5 ng.m-3, while an average of 1.7 ng.m-3 was measured in Witbank over the sampling interval.