Characterization of Street Dust Nearby the Holy Mosques in Ramadan and Hajj Seasons, Saudi Arabia

Abstract

Street dust is estimated as a main contributor of particualte matter (PM). Resuspension of street dust affects air quality and human health. The present study aims to evaluate concentrations of heavy metals (iron-Fe, lead-Pb, cadmium-Cd, and nickel-Ni), cations (Li+, Na+, NH4+, K+, Mg2+, and Ca2+), anions (F-, Cl-, Br-, NO2-, NO3-, PO43- and SO4-) and microoganisms (bacteria and fungi) associated dust particles ≤ 45 µm. The dust samples were collected by sweeping an arera ~ 1 m2 along both sides of the major streets surrounding Al-Haram mosque, in Makkah, and the Prophet,s mosque in Al Madina Al Manwarrah, Saudi Arabia. The heavy metals and soluble ions were analysed using atomic absortion spectrometer and ion chromatograpgy, respectively. Nutrient agar and Malt extract agar media were used for counting bacteria and fungi associated dust, respectively. The dust size fraction of 1.7 µm constitued the highest percentage (10-25%) among various particles sizes ≤ 45 µm. Fe was found in the highest heavy metal concentration, and lead (Pb) achived high pollution index ≥ 3. The soluble ion profile (%) was: NO3-, SO42-, Na+, Ca2+, Cl-, NO2-, K+, F-, Mg2+, NH4+, Br-, PO43- and Li+. The demolition/ constrcution activities were main contributor of street dust. Bacterial and fungal concentrations ranged between 104-106 and 104-105 CFU/g, respectively, with the highest bio-pollution in the northern street dust at Al-Haram mosque. Bacillus and Aspergillus were the common bacterial and fungal genera, repectively. Microorganisms did not show any significant linear relationships with dust chemical composition. Characterization of street dust allows identifying its sources and consequently developing an appropriate abatement strategy.

Keywords

• street dust
• size fraction
• heavy metal
• microorganisms
• pollution index