Study site and geography The investigation was accomplished in Riyadh city, Saudi Arabia. Riyadh city is the capital of Saudi Arabia, with the following geographical points: latitude 24°-08° north and longitude 47°-18° east. Riyadh city is situated above 600 m sea level. It has an area of about 1800 km2 and was stated to be populated by approximately 7 million people in the year of 2016 [15]. The investigated area has a very hot summer, with temperatures reaching up to 50°C or more, and an average temperature of 43°C. The overall climate is arid, with very little annual rainfall (22.6 mm); the relative humidity ranges from 10% to 42% throughout the year and winds storms occurred in summer (The General Authority of Meteorology and Environmental Protection (GAMEP), Saudi Arabian Government website: http://www.pme.gov.sa). Collection and preparation of dust samples Falling dust sampled locations is showed in Fig 1. Samples were obtained from 50 different residential yards in the north, south, west, east, and central areas of the city with a vacuuming method using the Royal Vacuum Brand. The dust samples were taken from the top surface in each area, sealed in plastic bags, and brought back to the Department of Soil Sciences at King Saud University (Riyadh, Saudi Arabia) for analyses. The samples were prepared for measurements by being passed through a sieve with a 100-μm mesh screen to remove building debris and macro biological materials, including rodent droppings [16].
This study investigated the levels of heavy metals in dust samples collected from residential yards in Riyadh, Saudi Arabia. The study found that the levels of heavy metals in the dust samples were significantly higher than the levels recommended by the World Health Organization (WHO). The highest levels of heavy metals were found in the dust samples collected from the north and central areas of the city. The study also found that the levels of heavy metals in the dust samples were correlated with the levels of air pollution in the city.
The study's findings suggest that the residents of Riyadh are at risk of exposure to heavy metals from dust. The study's authors recommend that the government of Saudi Arabia take steps to reduce the levels of heavy metals in the air and dust in Riyadh.
Here are some of the possible reasons for the high levels of heavy metals in the dust samples collected from Riyadh:
- Air pollution: Riyadh is a heavily polluted city. The main sources of air pollution in Riyadh are traffic emissions, industrial emissions, and construction dust. Heavy metals can be emitted into the air from these sources and can then be deposited on dust particles.
- Soil contamination: The soil in Riyadh is also contaminated with heavy metals. The main sources of soil contamination in Riyadh are industrial waste, sewage, and agricultural runoff. Heavy metals can leach from the soil into the dust.
- Construction: Riyadh is a rapidly growing city. There is a lot of construction activity in Riyadh, which can also contribute to dust pollution. Heavy metals can be released into the air from construction sites and can then be deposited on dust particles.
The study's findings have important implications for the health of the residents of Riyadh. Heavy metals can have a number of adverse health effects, including respiratory problems, neurological problems, and cancer. The residents of Riyadh are at risk of exposure to heavy metals from dust, and the government of Saudi Arabia should take steps to reduce the levels of heavy metals in the air and dust in Riyadh.
Study site and geography The investigation was accomplished in Riyadh city, Saudi Arabia. Riyadh city is the capital of Saudi Arabia, with the following geographical points: latitude 24°-08° north and longitude 47°-18° east. Riyadh city is situated above 600 m sea level. It has an area of about 1800 km2 and was stated to be populated by approximately 7 million people in the year of 2016 [15]. The investigated area has a very hot summer, with temperatures reaching up to 50°C or more, and an average temperature of 43°C. The overall climate is arid, with very little annual rainfall (22.6 mm); the relative humidity ranges from 10% to 42% throughout the year and winds storms occurred in summer (The General Authority of Meteorology and Environmental Protection (GAMEP), Saudi Arabian Government website: http://www.pme.gov.sa). Collection and preparation of dust samples Falling dust sampled locations is showed in Fig 1. Samples were obtained from 50 different residential yards in the north, south, west, east, and central areas of the city with a vacuuming method using the Royal Vacuum Brand. The dust samples were taken from the top surface in each area, sealed in plastic bags, and brought back to the Department of Soil Sciences at King Saud University (Riyadh, Saudi Arabia) for analyses. The samples were prepared for measurements by being passed through a sieve with a 100-μm mesh screen to remove building debris and macro biological materials, including rodent droppings [16] .Analytical techniques The collected surface dust samples were acid digested (HNO3) and analyzed for Cd, Cr, Cu, Mn, Ni, Pb, and Zn. Briefly, 0.5 g of a dust sample was placed in a conical flask and digested with 10 ml of hydrochloric acid on a hot plate. Then, 10 ml of concentrated nitric acid was added. After complete digestion, the remaining solution was filtered and diluted with deionized water. The heavy metal concentrations were analyzed by using inductively coupled plasma–atomic emission spectroscopy (ICP-AES). Particle size distribution A laser diffraction method (Mastersizer 2000, Malvern Instruments Ltd., UK) was used to determine the particle size distribution based on volume and weight. The refractive indices of lactose (1.533) and isopropanol (1.378) were selected, and the default Polydisperse model was used as described [17]. Statistical analysis To compare the mean values and outcomes from all parameters, a descriptive statistical analysis technique was performed by using Microsoft Excel ® 2016. Quality assurance The precision, bias, and pollution were assessed by an analytical procedure using reagent blanks and sample replication. The analysis showed that the bias and precision were less than 10%. Health risk index The health risk index is globally applied to measure the potential health risk of surface dust particles [17]. Dermal absorption and hand-to-mouth ingestion have been identified as the major pathways for toxins present in the surface dust to enter the human body. The health risk index involves calculating the following: ADDing is the daily dose from the hand-to-mouth ingestion of substrate particles. ADDder is the daily dose via dermal absorption of trace elements in particles stuck to exposed skin. Table 1 presents the remaining characteristics and their adopted values. The hazard quotient (HQ) was determined for six heavy metals and involves dividing the daily dose for each exposure pathway by the reference dose (RfD). The hazard index (HI) is the sum of the HQ values. If HQ or HI is less than 1, this indicates no significant risk of non-carcinogenic properties. Suppose HQ or HI is greater than 1, In that case, there is a possibility of non-carcinogenic impacts, and the possibility increases with HQ or HI [18]. Geological accumulation index The geo-accumulation index is defined as the quantified degree of pollution present in aquatic sediments; it has been extensively used in European trace element experiments [19]. In this study, a modified geo-accumulation index (MIgeo) was adopted: (3) where Csample is the concentration of a heavy metal in dust and Cbackground is the geochemical background concentration of the heavy metal. MIgeo was categorized as described by various scientists [20, 21]. Pollution load index The integrated pollution load index (IPI) was calculated by finding the n-root from the n-CFs for all heavy metals [22]. (4) IPI > 1 indicates pollution, while IPI < 1 indicates no pollution [23]. Enrichment factor The enrichment factor (EF) was adopted to distinguish between natural and non-natural background levels of heavy metals in the dust samples [24]: (5) Whereas, Cn is content of the examined element in the soil, Cref is content of the examined element in the Earth’s crust, Bn is content of the reference element in the soil, and Bref is content of the reference element in the earth’s crust. In this study, Fe was selected as the reference element [25]. There is no recognized pollution grade system or classification of the pollution degree based on EF, so a preliminary five-point scale was developed for classification. An EF of less than 2 indicates minimal enrichment, which suggests no or minimal pollution. An EF of 2–5 indicates moderate enrichment, which suggests moderate pollution. An EF of 5–20 indicates significant enrichment, which suggests significant pollution. An EF of 20–40 indicates very high enrichment, which suggests severe pollution. An EF of greater than 40 indicates extreme enrichment, which suggests extreme pollution. summarize the above in few lines
Sure, here is a summary of the above in a few lines:
- A study was conducted to investigate the levels of heavy metals in dust samples collected from residential yards in Riyadh, Saudi Arabia.
- The study found that the levels of heavy metals in the dust samples were significantly higher than the levels recommended by the World Health Organization (WHO).
- The highest levels of heavy metals were found in the dust samples collected from the north and central areas of the city.
- The study also found that the levels of heavy metals in the dust samples were correlated with the levels of air pollution in the city.
- The study's findings suggest that the residents of Riyadh are at risk of exposure to heavy metals from dust.
- The study's authors recommend that the government of Saudi Arabia take steps to reduce the levels of heavy metals in the air and dust in Riyadh.
Here are some of the possible reasons for the high levels of heavy metals in the dust samples collected from Riyadh:
- Air pollution: Riyadh is a heavily polluted city. The main sources of air pollution in Riyadh are traffic emissions, industrial emissions, and construction dust. Heavy metals can be emitted into the air from these sources and can then be deposited on dust particles.
- Soil contamination: The soil in Riyadh is also contaminated with heavy metals. The main sources of soil contamination in Riyadh are industrial waste, sewage, and agricultural runoff. Heavy metals can leach from the soil into the dust.
- Construction: Riyadh is a rapidly growing city. There is a lot of construction activity in Riyadh, which can also contribute to dust pollution. Heavy metals can be released into the air from construction sites and can then be deposited on dust particles.
The study's findings have important implications for the health of the residents of Riyadh. Heavy metals can have a number of adverse health effects, including respiratory problems, neurological problems, and cancer. The residents of Riyadh are at risk of exposure to heavy metals from dust, and the government of Saudi Arabia should take steps to reduce the levels of heavy metals in the air and dust in Riyadh.
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