An Analysis of Heavy Metals of Atmospheric Aerosols in Makkah
Journal of Natural Sciences and Mathematics
Heavy metals in atmospheric aerosols make an important group of air pollutants, which adversely affect human health, building materials and the natural environment. In this study the levels of six heavy metals are assessed in Mina, Makkah during the Hajj season of 2010 (1431 H). The heavy metals considered in this study are lead (Pb), nickel (Ni), cadmium (Cd), chromium (Cr), vanadium (V) and arsenic (As), which are the most predominant heavy metals in the atmosphere. The concentrations of
... centrations of Total Suspended Particulate (TSP), PM10 and PM2.5 are compared and their heavy metals contents are analysed. The concentration of TSP was much greater than that of PM10 and PM2.5, which probably indicate resuspension of particles being the predominant source of particles in the study area. However, the difference in their heavy metal content was relatively less prominent, indicating a high proportion of heavy metal in PM2.5, which pose potentially greater health risk due to their ability to penetrate deeper into the respiratory system. Correlation analysis revealed two distinct clusters in heavy metals: (a) Pb, Ni, Cd and Cr; (b) V and As. Elements in each group had stronger correlation with each other and relatively weaker correlation with the elements in the other cluster. V was negative, whereas As was positively correlated with Pb, Cd, Cr and Ni. Variations in TSP, PM10 and PM2.5 concentrations during different days of the Hajj and their possible reasons have been discussed. Further work is recommended to analyse spatial and temporal variations in heavy metals concentrations over longer periods of time and to quantify the contribution of each source of emission, which is part of the ongoing research project for the improvement of air quality in Makkah. The term heavy metal covers a wide range of elements, which constitute an important class of air pollutants, for example, Arsenic (As), Lead (Pb), Cadmium (Cd). These pollutants have received the attention of researchers all over the world, mainly due to their harmful effects on human health (Schwartz et al., 2010) . Human biology is full of instances where heavy metal toxicity has led to mass deaths (Donaldson and MacNee, 1998) . Some of them are toxic even at very low concentrations; hence they are of particular health concern (Schwartz et al., 2010). Heavy metals may enter the human body through food, water, air, or absorption through the skin when they come in contact with humans. Heavy metals could induce various diseases because they act as systemic toxins with specific neurotoxic, nephrotoxic, fetotoxic and teratogenic effects (Obiria et al., 2010; Thakur et al., 2010) . Bhattacharya et al. (2006) mentioned that (As) is considered as one of toxic elements found in the environment. Ferner (2001) and Dupler (2001) reported a list of health damages related to (As)exposure, including damage to stomach and intestines, reduction in the production of red and white blood cells, causing infertility and abortion in women, disordered of the skin, poor resistance to infection, and affecting heart muscles, and atrophy of the brain cells. (Cd) can destroy the lungs and cause death (Ferner, 2001) . (Pb) causes impairments in intellectual functioning, kidney damage, infertility, miscarriage, and hypertension. Furthermore, heavy metals can cause damage to the natural environment, contaminate food materials, erode materials (e.g., zinc), and reduce visibility as part of the particulate matter. Langmuir (1997) reported that the processing of minerals, incineration of metallic objects, motor vehicle combustion of fuel containing metal additives, and the wearing out of motor vehicle tires and brake pads resulted in the emission of heavy metals associated with particulate matter. The best known example of a heavy metal emission and the international to tackle its emission is probably Pb from motor vehicle engines before unleaded fuel was introduced (Aburas et al., 2011). It is generally accepted that zinc (Zn) and (Pb) in urban atmospheric particles are due to tyre wear and motor exhaust fumes respectively (Sabbak, 1995) . Other heavy metals emitted by combustion processes include copper (Cu), zinc (Zn), mercury (Hg), (As) and (Cd). Industry emits traces of heavy metals from most combustion processes. These heavy metal emissions can arise from trace concentrations in fuels that are burnt or from raw materials (Aburas et al., 2011) . Re-suspension of soil dust, enriched with heavy metals can also be a major source of heavy metals at urban roadsides (Maher et al., 2008; Gunawardena et al, 2012) . The heavy metals concentrations in the atmosphere have been studied in different parts of the world. Finlayson-Pitts and Pitts (1986) reported that metals such as (As), (Cd) and (Pb) enriched the fine fraction of particulate matter. However, VEPA (1998) mentioned that heavy metals such as (V), (Cr) and (Ni) were found in both coarse and fine fractions in ambient air. Schroeder et al. (1987) reported that (As), (Cd), (Pb), (Cr), (Ni) and (V) represent the most commonly heavy metals found in the pollution sources.