Mask use among pedestrians during the Covid-19 pandemic in Southwest Iran: an observational study on 10,440 people.

BACKGROUND: Many countries have recommended the use of face masks for general population in public places to reduce the risk of COVID-19 transmission. This study aims to estimate the prevalence of face mask usage and investigate about different types of face mask and their distribution among pedestrians in southwest Iran during the Covid-19 pandemic. METHODS: This cross-sectional study was conducted in August 2020 in Ahvaz, southwest Iran. Using a multistage sampling method, a total of 10,440 pedestrians selected from 8 urban districts and 92 neighborhoods of the city. The data gathered by observation method. Percentage, mean and standard deviation were used to describe the variables. Chi-square test, fisher exact test and Chi-square for trend used to assess relationship between two categorical variables. We used unconditional logistic regression model to control confounders. RESULTS: The most common age group was 10 to 39 years and 67.9% of the participants were male. The overall prevalence of face mask usage was 45.6% (95% CI, 44.6-46.5). In general, as the age increased, the prevalence of face mask use significantly increased (p for trend < 0.001). Women used face masks significantly higher than men (60.2% vs. 38.7%, p < 0.001). Among the pedestrians who used the mask, 75.6% wore facemask correctly. The most common type of facemask used by the pedestrians were surgical (medical) masks (63.8%). In total, the prevalence of facemask usage was significantly higher during a.m. (49.4%) compared to p.m. (43.9%), (p < 0.001). Besides, in our study, 1.7 and 0.3% of Pedestrians had worn gloves and shielded respectively. Women used shields and gloves significantly higher than men (3.6% vs. 0.7%, p < 0.001). Also, women used shields more than men (0.5% vs. 0.3%, p = 0.036). CONCLUSION: We concluded that the prevalence rate of face mask use in Ahvaz was fairly low especially in men and younger people. Hence, the observed rates probably cannot protect the community against COVID-19 spread. Therefore, it is important to implement educational programs as well as to establish laws and regulations governing the use of face masks in public places.

Capture - recapture based study on the completeness of smear positive pulmonary tuberculosis reporting in southwest Iran during 2016.

BACKGROUND: Tuberculosis (TB) is one of the ten leading causes of death in infectious diseases and one of the ten leading causes of death in the world. For any TB control program, a valid surveillance is essential. In order to assess the status of the assessment, the quality of the record and the completeness of reporting should be assessed. The purpose of this study was to investigate the completeness of smear positive pulmonary tuberculosis reporting in Ahvaz, south west of Iran. METHODS: This cross-sectional study was conducted in 2016 in Ahvaz, southwest Iran. The study was conducted through a three-source Capture recapture method by collecting laboratory, hospital, physician prescription data; including patient referral to the health care center, prescriptions of patients receiving anti-tuberculosis drugs and prescriptions of medical TB diagnostic laboratories, and laboratory prescriptions. Percentage, mean and standard deviation were used to describe the variables. Data analysis was performed using log-linear model in Rcapture package R software. RESULTS: Generally, 134 new cases of smear-positive pulmonary tuberculosis patients were reported through three sources from urban and rural regions during 2016. Pulmonary tuberculosis was reported through three sources from urban and rural regions during 2016. The most common age group was 25 to 44 years and 79.1% of the patient were man. The overall prevalence of new cases of smear-positive pulmonary tuberculosis was in persons that lived urban areas (97.8%). The completeness of reporting the disease estimated by log-linear model was 87.5% and the incidence rate was estimated to be 11.8 disease per 100,000 persons. Completeness of reporting of laboratory, hospital and physician resources were 79%, 30% and 16.3%, respectively. CONCLUSIONS: The present study shows the necessity of evaluating the quality, completeness and linkage between data. Linking between data sources can improve the accuracy and completeness of TB surveillance.

Assessment of types of bacterial bio-aerosols and concentrations in the indoor air of gyms.

The presence of airborne microorganisms in indoor air (home and work) is a serious public health concern. Bio-aerosols have a significant role in indoor air pollution as they can be pathogenic or cause an allergic reaction following inhalation, ingestion or skin absorption. This study aimed to assess bacterial bio-aerosols in the indoor air concentration of gyms, and its relationship with gym area per person, temperature, and relative humidity. Sampling was performed by the National Institute for Occupational Safety and Health (NIOSH) method 0800-0999 and using an Anderson single-step sampler. Fifty-five gyms were selected with simple random sampling method and 165 samples collected for evaluation of bacterial bio-aerosols. The concentrations of airborne bacteria were measured as colony-forming units per cubic meter of air (CFU/m3) collected by impaction on to tryptic soy agar plates. The maximum and minimum densities of bacteria in the air of gyms were 877 and 117 CFU/m3, respectively. Pseudomonas, Staphylococcus and Escherichia Coli had an order of the highest to lowest frequency among the microorganisms, respectively. Generally, with increasing temperature and humidity, the density of bacteria was increased. The higher amount of the microorganisms was observed in the air of gyms in the lower available area per person. Athletes are at risk of high exposure to the bacterial bio-aerosol that can affect their health.

Assessment of carbon monoxide concentration in indoor/outdoor air of Sarayan city, Khorasan Province of Iran.

Nowadays, air pollution by humans is considered a serious problem. One of the main sources of air pollution is carbon monoxide which is called the silent killer. With the increasing rate of population growth in Iran and subsequent acceleration of vehicle and fossil fuel usage, the mortality rate of carbon monoxide has increased. The aim of this study is assessment of the concentration of carbon monoxide in indoor and outdoor air of Sarayan city, Khorasan Province of Iran. In this descriptive-analytic study, the air condition of a residential area and outdoor environment of Sarayan city has been monitored for determining the carbon monoxide concentration during a 3-month period from January to March 2017. Overall, 25 stations with uniform distribution were located in the city. Fifty samples were taken monthly and by considering 3-month period, a total of 150 samples were gathered. The samples were taken in kitchens between 11 a.m. and 3 p.m., and by considering the respiratory height of the human body, the carbon monoxide meters (TES model, Taiwan) were placed at a height of 75-150 cm. The descriptive statistics were presented after entering data into SPSS-16, and, by applying Mann-Whitney and Kruskal-Wallis tests in the case of α = 0.05, the data were analyzed. The average concentrations of carbon monoxide in indoor and outdoor environments were 0.84 ± 3.21 ppm and 0.27 ± 0.92 ppm, respectively. The maximum carbon monoxide concentration in February in an outdoor environment was 6 ppm (station no. 4) and the least one was 0 ppm. In March, for an indoor area, the maximum carbon monoxide concentration was 41 pm for station no. 11. The indoor-to-outdoor (I-to-O) ratio in March was higher than other months, and in January, was less than others. The study reveals that the indoor and outdoor carbon monoxide indices of Sarayan city are at acceptable levels.

Ambient particulate matter concentration levels of Ahvaz, Iran, in 2017.

Dust storm in Khuzestan region is strongly influenced by transportation and influx of large amount of particulate matter from internal sources (Hawizeh Marshes and East Ahwaz) and external sources (the Arabian Desert in Saudi Arabia, Jordan, Syria and the Sahara Desert). Particulate matter is one of the main components of indoor and outdoor air quality that can be very dangerous for human. The principal objective of this study was the pinpoint of the source of airborne particulate matter by the NOAA HYSPLIT model in Ahvaz City, southwest of Iran. The investigation of dust storm and their origin was performed by the GFSG Meteorological Data (backward trajectories ending analysis of the NOAA HYSPLIT model) and collecting particulate samples with high-volume air samplers during the fall and winter seasons. The results showed the average ambient particulate matter concentration in the cold and warm seasons was 158 and 161 µg/m3, respectively. Moreover, the average particulate matter concentration in the cold season was significantly higher than the standard level as presented in the National Ambient Air Quality Standard. Consequently, it seems essential to develop green space, decrease particulate emission from source and make determined efforts to control dust at governmental and international scales.

Assessment of microbial quality of household water output from desalination systems by the heterotrophic plate count method.

Point-of-use household water desalination systems (HWDSs) are becoming popular in Iran because of the deterioration of drinking water. This study aimed to determine the microbial quality of output water from HWDSs in Qom, Iran by using the heterotrophic plate count (HPC) method. Samples of input and output water from 30 HWDSs were collected over a six-month period. Heterotrophic bacteria were tested using the pour plate technique. At the first sampling stage, the HPC level in 23% of samples exceeded the 500 CFU/ml threshold level. On average, for 50% of samples, the HPC level of input samples was 0-10 CFU/ml, for 42% it was 10-100 CFU/ml and for 8% it was 100-500 CFU/ml. For output samples, for 25%, the level of HPC was 0-10 CFU/ml, for 43% it was 10-100 CFU/ml, for 24% it was 100-500 CFU/ml and for 8% it exceeded 500 CFU/ml. For total coliforms the most probable number test was positive for the first and third stages of sampling (3% input samples). The comparison of the averages with national standard values shows that in some cases, the contamination of output water from HWDSs in the city of Qom has been above the standard values.

Health risk assessment on human exposed to heavy metals in the ambient air PM10 in Ahvaz, southwest Iran.

Heavy metals (HM) are one of the main components of urban air pollution. Today, megacities and industrial regions in southwest of Iran are frequently suffering from severe haze episodes, which essentially caused by PM10-bound heavy metals. The purpose of this study was to evaluate the health risk assessment on human exposed to heavy metals (Cr, Ni, Pb, and Zn) in the ambient air PM10 in Ahvaz, southwest Iran. In this study, we estimated healthy people from the following scenarios: (S3) residential site; (S2) high-traffic site; (S1) industrial site in Ahvaz metropolitan during autumn and winter. In the current study, high-volume air samplers equipped with quartz fiber filters were used to sampling and measurements of heavy metal concentration. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was utilized for detection of heavy metal concentration (ng m-3). Also, an estimate of the amount of health risk assessment (hazard index) of Cr, Ni, Pb, and Zn of heavy metal exposure to participants was used. Result of this study showed that the residential and industrial areas had the lowest and the highest level of heavy metal. Based on the result of this study, average levels of heavy metal in industrial, high-traffic, and residential areas in autumn and winter were 31.48, 30.89, and 23.21 µg m-3 and 42.60, 37.70, and 40.07 µg m-3, respectively. Based on the result of this study, the highest and the lowest concentration of heavy metal had in the industrial and residential areas. Zn and Pb were the most abundant elements among the studied PM10-bound heavy metals, followed by Cr and Ni. The carcinogenic risks of Cr, Pb, and the integral HQ of metals in PM10 for children and adults via inhalation and dermal exposures exceeded 1 × 10-4 in three areas. Also, based on the result of this study, the values of hazard index (HI) of HM exposure in different areas were significantly higher than standard. The health risks attributed to HM should be further investigated from the perspective of the public health in metropolitans. The result of this study showed increasing exposure concentrations to heavy metal in the studied scenarios have a significant potential for generating different health endpoints, while environmental health management in ambient air can cause disorders in citizenship and causing more spiritual and material costs.

Association between cancer risk and polycyclic aromatic hydrocarbons' exposure in the ambient air of Ahvaz, southwest of Iran.

Nowadays, a large number of health endpoints such as disease rates, treatment costs, and death, by air pollutants, have been a serious health problem for humans. One of the most hazardous air pollutants, which is highly dangerous for human health, is polycyclic aromatic hydrocarbons (PAHs). The existence of the emission of industries' pollutants and seasonal variations are the primary agents affecting PAHs' concentration. The purposes of this study were to calculate the cancer risk and measure PAHs' exposure in the ambient air of Ahvaz, southwest of Iran, during 2017. Three distinct areas ((S1) industrial, (S2) high traffic, and (S3) residential) of Ahvaz metropolitan were selected. Omni sampler equipped with polytetrafluoroethylene (PTFE) filters were used for active sampling of PAHs. To detect the level of PAHs, gas chromatography with mass spectrometry (GC/MS) was used. Incremental lifetime cancer risk (ILCR) and lifetime average daily dose (LADD) were used to estimate the health risk caused by PAHs. The results showed that the residential and industrial areas had the lowest and highest level of PAHs. Moreover, the average levels of PAHs in industrial, high traffic, and residential areas were 8.44 ± 3.37, 7.11 ± 2.64, and 5.52 ± 1.63 ng m-3, respectively. Furthermore, ILCR in autumn and winter was higher than EPA standard, 0.06307 and 0.04718, respectively. In addition, ILCR in different areas was significantly higher than standard. Research findings imply that the levels of exposure to PAHs can increase ILCR and risk of health endpoint. The cancer risk attributed to PAHs should be further investigated from the perspective of the public health in metropolitans.

Acute myocardial infarction and COPD attributed to ambient SO2 in Iran.

Acute myocardial infarction (MI) and chronic obstructive pulmonary disease (COPD) are important diseases worldwide. Inhalation is the major route of short-term exposure to air sulfur dioxide (SO2) that negatively affect human health. The objective of this study was to estimate the health effects of short-term exposure to SO2 in Khorramabad, Iran using the AirQ software developed by the World Health Organization (WHO). Daily mean SO2 concentrations were used as the estimates of human short-term exposure and allow calculation of the attributable excess relative risk of an acute MI and hospital admissions due to COPD (HACOPD). The annual mean SO2 concentration in Khorramabad was 51.33µg/m3. Based on the relative risk (RR) and baseline incidence (BI) approach of WHO, an increased risk of 2.7% (95% CI: 1.1-4.2%) of acute MI and 2.0% (95% CI: 0-4.6%) of HACOPD, respectively, were attributed to a 10µg/m3 SO2 increase. Since the geographic, demographic, and climatic characteristics are different from the areas in which the risk relationships were developed and not evaluated here, further investigations will be needed to fully quantify other health impacts of SO2. A decreased risk for MIs and COPD attributable to SO2 could be achieved if mitigation strategies and measures are implemented to reduce the exposure.

Health benefits of PM10 reduction in Iran.

Air pollution contains a complex mixture of poisonous compounds including particulate matter (PM) which has wide spectrum of adverse health effects. The main purpose of this study was to estimate the potential health impacts or benefits due to any changes in annual PM10 level in four major megacities of Iran. The required data of PM10 for AirQ software was collected from air quality monitoring stations in four megacities of Iran. The preprocessing was carried out using macro coding in excel environment. The relationship between different presumptive scenarios and health impacts was determined. We also assessed the health benefits of reducing PM10 to WHO Air Quality Guidelines (WHO-AQGs) and National Ambient Air Quality Standards (NAAQSs) levels with regard to the rate of mortality and morbidity in studied cities. We found that the 10 µg/m3 increase in annual PM10 concentration is responsible for seven (95% CI 6-8) cases increase in total number of deaths per 2 × 105 person. We also found that 10.7, 7.2, 5.7, and 5.3% of total death is attributable to short-term exposure to air pollution for Ahvaz, Isfahan, Shiraz, and Tehran, respectively. We found that by attaining the WHO's proposed value for PM10, the potential health benefits of 89, 84, 79, and 78% were obtained in Ahvaz, Isfahan, Shiraz, and Tehran, respectively. The results also indicated that 27, 10, 3, and 1% of health impacts were attributed to dust storm days for Ahvaz, Isfahan, Shiraz, and Tehran, respectively.

Cardiovascular and respiratory mortality attributed to ground-level ozone in Ahvaz, Iran.

Ahvaz, the capital city of Khuzestan Province, which produces Iran's most oil, is on the rolls of fame in view of air pollution. It has also suffered from dust storm during the recent two decades. So, emissions from transportation systems, steel, oil, black carbon, and other industries as anthropogenic sources and dust storm as a new phenomenon are two major concerns of air pollution in Ahvaz. Without any doubt, they can cause many serious problems for the environment and humans in this megacity. The main objective of the present study was to estimate the impact of ground-level ozone (GLO) as a secondary pollutant on human heath. Data of GLO in four monitoring stations were collected at the first step and they were processed and at the final step they were inserted to a health effect model. Findings showed that cumulative cases of cardiovascular and respiratory deaths which attributed to GLO were 43 and 173 persons, respectively. Corresponding RR for these two events were 1.008 (95% CI) and 1.004 (95% CI), respectively. Although we did not provide a distinction between winter and summer in case of mentioned mortalities attributed to GLO, ozone concentrations in winter due to more fuel consumption and sub adiabatic condition in tropospheric atmospherewere higher than those GLO in summer.

A digital image analysis approach to understand the microscopic and macroscopic phenomena in dissolved air flotation.

Dissolved air flotation (DAF) is an effective method for separating suspended oil and solid particles from wastewater by utilizing small air bubbles. This study aims to investigate the impact of key factors, such as saturating pressure and water flow rate, on the separation of fine oil droplets from a water stream. The macroscopic flow patterns within the cell were analyzed using particle image velocimetry (PIV), while Digital Image Analysis (DIA) was employed to study microscopic phenomena, including oil droplet rising velocity and oil-bubble contact mechanisms. Our findings propose a safe operating window (specifically, water flow rate and saturation pressure) for the effective separation of oil droplets without any oil escaping into the clean water stream. It was found that the oil droplet rising velocity increases with the saturation pressure up to 200 kPa. However, a further increase in the pressure of the air saturating chamber leads to a decrease in oil droplet rising velocity. Additionally, we identified a peak in rising velocity at an oil droplet size of approximately 200 µm. Below this threshold, the rising velocity increases with droplet size, while for droplet sizes exceeding 200 µm, the rising velocity decreases with size. This behavior can be explained by the conflicting effects of droplet size increment according to the Stokes law for the rising velocity of oil droplets. As the droplet size increases, the average density of the bubbles/droplet aggregate rises, reducing the ∆ρ in the Stokes law and subsequently lowering the aggregate rising rate. However, as per the Stokes law, the oil droplet rising velocity increases proportionally to the square of its size.

Evaluation of carcinogenic risk of heavy metals due to consumption of rice in Southwestern Iran.

Pollution by heavy metals is a serious global problem due to its toxicity, abiotic characteristics, abundant sources, and cumulative behavior. On the other hand, considering the importance of rice consumption as an important part of nutrition in Lordegan and Ahvaz cities, this study was conducted to evaluate the carcinogenic risk of heavy metals lead, cadmium, zinc, nickel and in local Champa rice cultivated in these two cities. 16 Champa rice samples were collected from the fields of Lordegan and Ahvaz cities. The elements were read in three replicates by Varian 710-ES atomic emission device. The results showed that the concentration of cadmium and nickel in the cultivated rice in the two studied cities was within the range of the national standard of Iran and the Codex standard. Carcinogenic risk values for lead, cadmium and nickel in Champa Lordegan and Ahvaz rice were within the safe range. Also, the non-carcinogenic risk for these heavy metals in the two studied areas was less than 1 and was in the safe range. Rice pollution in Champa in Ahvaz can be due to the industrial nature of this city, and in Lordegan, it is due to pollution through pesticides, chemical fertilizers, and transportation. Long-term consumption of contaminated rice may endanger the health of residents of these areas. It is recommended to carry out regular and up-to-date monitoring strategies in these two cities to prevent the entry of these toxic heavy metals into the human food chain. Also, more studies are needed to evaluate the complete scenario and make definitive decisions.

The concentration of phthalates in drinking water in Iran: A systematic review and meta-analysis.

PAE and PC polymers, such as BPA, are utilized to make water bottles. Due to the lack of polymer-chemical interaction, PAE can enter drinking bottles during production, wrapping, and keeping. Phthalates can transfer from the bottle to the water depending on keeping conditions (temperature, time, sunlight intensity), pH, and bottle capacity. Since there haven't been previous studies published on the subject, the aim of this meta-analysis and systematic review research is to determine the level of phthalates in drinking water consumed in Iranian cities. Web of Science, Science of Direct, Scopus, and PubMed, databases have been used in this study. Eight studies were selected from 556 initial publications after screening for duplication and irrelevant information. Articles from January 1, 2000, to February 10, 2024, were found in the mentioned databases. Among the types of phthalates, the concentration of DEHP was reported higher than the others Because its concentration has been reported in seven out of eight studies. The highest concentration of DEHP was reported by Mehraie(2.22 µg/l), Zare Jeddi (0.8 µg/l), Yousefi (0.77 µg/l), Abtahi (0.76 µg/l), Zare Jeddi (0.42 µg/l), Abdolahnejad(0.15 µg/l), and Pourzamani (0.08 µg/l). The highest concentration of DEP, DBP, BBP, and PA was reported by Abtahi (0.77 µg/l) and Esteki (2.25 µg/l), Mehraie(0.93 µg/l), and Pourzamani (0.83 µg/l). The results of this study showed that the most important phthalates measured in drinking water include DEP, DEHP, DBP, BBP, and PA. According to the results of the present studies, the most important factor in the increase of phthalates is the storage conditions of drinking water (temperature, sunlight, and the type of pipe or bottle).

Effects of nano and microplastics on the reproduction system: In vitro and in vivo studies review.

Microplastics (MPs) and nanoplastics (NPs), as their name suggest, are tiny plastic particles. The negative impact of MPs as an emerging pollutant on humans is not hidden from anyone. Recent research on how this pollutant affects the reproductive system and how it enters the blood, placenta, and semen has attracted the attention of scientists. This review study deals with the reproductive toxicity of MPs particles in terrestrial animals, aquatic animals, soil fauna, human cells, and human placenta. In vitro and in vivo animal studies showed that MPs can lead to reduced fertility in men, reduced ovarian capacity, apoptosis of granulosa cells, or even reduced sperm motility. They cause oxidative stress and cell apoptosis and inflammatory effects. The results of these animal studies show that MPs may have similar effects on the human reproductive system. However, not much research has been done on human reproductive toxicity by MPs. Therefore, special attention should be paid to the toxicity of the reproductive system by MPs. The purpose of this comprehensive study is to express the importance of the impact of MPs on the reproductive system. These results provide new insight into the potential dangers of MPs.

The effect of long-term exposure to toxic air pollutants on the increased risk of malignant brain tumors.

Toxic air pollutants are one of the most agent that have many acute, chronic and non-communicable diseases (NCDs) on human health under long or short-term exposure has been raised from the past to the present. The aim of this study was investigation effect of long-term exposure to toxic air pollutants on the increased risk of malignant brain tumors. Databases used to for searched were the PubMed, Web of Science, Springer and Science Direct (Scopus) and Google Scholar. 71 papers based on abstract and article text filtered. In the end after sieve we selected 7 papers. Identify all relevant studies published 1970-2022. The literature showed that exposure to toxic air pollutants and their respiration can cause disorders in different parts of the brain by transmission through the circulatory system and other mechanisms. Various unpleasant abnormalities are caused by the inhalation of toxic air pollutants in the human body that some of the most common of them include chronic lung disease, coronary heart disease and heart attacks, strokes and brain diseases (Parkinson's, Alzheimer's and multiple Sclerosis), cancers (liver, blood, prostate and brain) and eventually death. According to the finding brain health and proper functioning can be easily disrupted by various genetic or external factors such as air pollution, causing a wide range of abnormalities in the brain and malignant brain tumors. The results of this study showed that reducing the concentration of toxic pollutants in the air, that exposure to them play an increasing role in the development of brain diseases can slow down the process of abnormalities in the brain and will have significant impacts on reducing the number of people affected by them.

Ecological risk assessment of heavy metals in urban dust in Iran: A systematic review and meta-analysis.

Background: Heavy metals in street dust are one of the most important sources of pollutants in urban areas. This urban dust can be caused by industrial activities, traffic, erosion of buildings, and fossil fuels. The aim of this systematic review is to evaluate the ecological risk of heavy metals in the dust of Iran's provinces. Methods: This study was conducted in February 2023 in order to investigate the environmental risks associated with heavy metals associated with dust particles in Iran. The present study was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Finally, 9 studies were extracted from the search databases. Results: The ecological risk of heavy metals in the present study was as follows: Cd (258.26؛ CI: 83.53, 433) >Pb (52.58؛ CI: 37.15, 68.02) >Cu (24.44؛ CI: 16.74, 32.14)>Ni (14.75؛ CI: 12.68, 16.82)>As (13.53؛ CI: 10.20, 16.85)>Zn (6.32؛ CI: 3.76, 8.87)>V (3.18؛ CI: 2.65, 3.72)>Cr (2.73؛ CI: 2.19, 3.27)>Co (1.94؛ CI: 1.13, 2.74). The mean ranking of the studied Pb ecological risk is as follows: Shiraz.> Tehran > Ahvaz > Ilam > Abadan > Dezful. Conclusion: The ecological risk potential of Cd in Tehran was also much higher than the standard. Therefore, Tehran was the most polluted city studied in terms of the ecological risk potential of Cd (1611.41؛ CI: 1605.98, 1616.84) and Pb (86.54؛ CI: 71.46, 101.62). The average concentration as well as the ecological risk of Cr, Co, and V metals were lower than the standard. Therefore, controlling the sources of heavy metal emissions (especially lead and cadmium) is highly recommended.