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Characterization of size–fractionated PM10 and associated heavy metals at two semi–arid holy sites during Hajj in Saudi Arabia

Mohammad J. Pasha, Badr H. Alharbi

National Center for Environmental Technology, King Abdulaziz City for Science and Technology (KACST), PO BOX: 6086, Riyadh 11442, Saudi Arabia

ABSTRACTThe size–fractionation of inhalable particles and their heavy metal content during the Hajj season have yet to beexplored. The principal objective of this study is to evaluate the concentration of heavy metals associated with sixdifferent PM10 fractions to which pilgrims are exposed during Hajj. Two holy sites (Mina and Arafat) characterized bythe simultaneous obligatory stay of all pilgrims and concomitant intense vehicular emissions were selected forsampling. Characterization of inhalable PM, their fractional size distribution and concentration of heavy metals wereinvestigated. The sum of total fractions (coarse+fine) as PM10 was recorded at an average of 181.3 μg/m³ at Mina and289.6 μg/m³ at Arafat during peak days of the Hajj period, corresponding to Arabic (8–12 Dhu Al–Hijjah). The averageconcentration (μg/m³) of coarse (3.0 to 10.0 μm) and fine fractions (3.0 to 0.49 μm), and their relative percentageswere recorded [Mina: 62.2, 34.2% (fine), 119.1, 65.8% (coarse); Arafat: 114.5, 35.9% (fine), 175.1, and 64.1% (coarse)].The metal concentrations associated with these fractions, their enrichment factor, and possible adverse effects onpilgrims were assessed. Cd and Se were highly enriched, followed by Cr, Pb, Cu, Ni and Co, indicating vehicularemissions as the likely anthropogenic source. Air Quality indices were calculated based on PM10 and PM2.5 particulateconcentrations in ambient air during the Hajj period, and the days were categorized in relation to health impacts. Thiswork provides crucial information and alerts about the possible impact of PM on ambient air quality, and datasuggests pilgrims, particularly susceptible groups, should adopt suitable precautionary preventive measures during theHajj period.

Keywords: Particulate matter, metals, Hajj, AQI

Corresponding Author:Mohammad J. Pasha

: +966 508455443: +966 114813611:[email protected]

Article History:Received: 21 April 2014Revised: 23 August 2014Accepted: 24 August 2014

doi: 10.5094/APR.2015.019

1. Introduction

Air borne particulate matter (PM) consists of a complexmixture of particles of varying size and chemical composition. Thebehavior of PM in the atmosphere and its potential to affecthuman health and atmospheric visibility are dependent on itsphysical and chemical characteristics (Boueres and Orsini, 1981; deMiranda et al., 2002; Toledo et al., 2008). These characteristics aredependent on the source type and on the formation processes thatparticles undergo at the sources or in the atmosphere (Willeke andWhitby, 1975; Sweet et al., 1993; Pacyna, 1998; Spurny, 1998;CEPA, 1999). The hazardous effects of particulates on humanhealth are usually associated with the presence of inhalableparticulates in the range of 10 μm at high concentration levels inthe ambient air. Several epidemiological studies have indicatedthat short– and long–term exposure to fine PM have associatedadverse health effects, including excess instances of respiratoryand cardiovascular diseases (NRC, 2001; Pope et al., 2002; HEI,2010). Inhalable PM in the atmosphere can be categorized in threemodes based on formation (size) and source: nuclei (Aitken) mode,accumulation mode, and coarse mode. Nuclei mode (ultrafine)particles <0.1 μm are principally formed from the condensation ofhot vapors during high temperature combustion processes andresult in the nucleation of atmospheric species and formation ofnew particles that contribute little to overall particle mass loading.Nuclei mode particles are subject to random motion and collidequickly in coagulation processes to yield larger particles with shortatmospheric residence times. Accumulation mode particles (0.1 to2.0 μm) result from the coagulation of particles in the nuclei modeand condensation of vapors on existing particles, which subsequently grow to this size range (Clark and Whitby, 1967; CEPA,

1999; Weckwerth, 2001; de Kok et al., 2006). These particlesaccount for most of the surface area and much of the particle massin the atmosphere and can remain in the atmosphere for days toweeks. Particles >2.5 μm in size are considered as coarse mode andare typically associated with mechanical processes such as winderosion, grinding operations, and wind–blown soil. These particlesare efficiently removed by gravitational settling and remain in theatmosphere for periods of hours to a few days (Willeke et al., 1974;Willeke and Whitby, 1975; Danielsson et al., 1999; Shu et al., 2001;Vassilakos et al., 2007; Fang et al., 2010; Zheng et al., 2010).

The Hajj pilgrimage is the world’s largest Muslim religiousritual, where approximately 2–3 million pilgrims from various partsof the world visit and perform a sequence of rituals at two holysites, Mina and Arafat in the province of Makkah Al Mukarramah inSaudi Arabia. The Hajj pilgrimage is held between 8–12 Dhual–Hijjah according to the Arabic calendar annually. Among theserituals, the Day of Arafat (9th Dhual–Hijjah) is the most significantevent, where all pilgrims stay together from sunrise to sunsetwithin the defined area at Arafat. On day 1 of the pilgrimage (8th ofDhul–Hijjah) millions of pilgrims gather at Mina and spend the dayand night in tents, and typically depart on day 2 (9th of Dhul–Hijjah)just after dawn to travel to the ground of Arafat by various formsof motor vehicles (as well as on foot). The pilgrims spend the entireday at Arafat and after sunset they depart for the nearby openplace (Muzdalifah) situated between Arafat and Mina, where theyperform an obligatory night stay. In the following three days (from10–12 of Dhul–Hijjah), pilgrims remain at Mina to complete allrituals. Due to enormous vehicular and pedestrian movementsduring the activities of Hajj, pilgrim’s exposure to various gaseousand particulate pollutants is inevitable. Determining the load of

Pasha and Alharbi – Atmospheric Pollution Research (APR) 163

inhalable PM of aerodynamic diameter 10 m (PM10) in theambient air, and its chemical characterization, are importantaspects of potential health impacts on pilgrims during the event.The PM under 2.5 μm diameter (PM2.5) is of great concern andearlier studies demonstrated that PM2.5 can efficiently penetrateinto the lungs (Wilson and Spengler, 1996). Furthermore, particlescoated with first row transition metals play a significant role increating inflammatory responses in the lungs (Amdur, 1996; Utelland Samet, 1996). Dockery and Pope (1994) and Pope et al. (1995)illustrated the health effects associated with short–term exposureto 10 μg/m³ increases in PM10 concentration, such as cardiovascular, respiratory morbidity, hospital admission for respiratoryproblems and symptom exacerbation among asthmatics. Epidemiological studies are considered useful for recognizing the possiblehealth effects of particulate exposure. However, accurate identification of ambient fine PM in toxicological studies is a challenge, asthey commonly consist of a mixture of different components withwide toxicological characteristics. Various studies have revealedthat diesel exhaust and other vehicular emissions cause lungfunction deficiencies in humans and animals (Scheepers and Bos,1992a; Scheepers and Bos, 1992b; Mauderly, 1994). Fine particlesfrom vehicular sources had a higher mutagenic effect than samplesfrom other sources (Stevens et al., 1990; Bronzetti et al., 1997).The increases in cardiovascular deaths were found to be morerelevant and frequent (Samet et al., 2000; Wichmann et al., 2000;U.S. EPA, 2003). Kappos et al. (2004) reported that short–termexposure to PM had associated health repercussions, such ashospital admissions, and that these were associated with asthma,chronic obstructive pulmonary disease, pneumonia, cardiovascularand other respiratory causes. In pre–existing asthmatics, a smallimpairment of lung function and an increase of respiratorysymptoms (cough, phlegm, shortness of breath) are found inassociation with particulate exposure. Reduced heart ratevariability (HRV) in patients with cardiovascular complications anddiabetics also seem to be affected by exposure to ambient PM(Peters et al., 1996; Peters et al., 1997; Schwela and Zali, 1999).There is growing concern over the environmental and healtheffects on pilgrims as a result of contaminants release andexposures. PM10 load, fractionations and toxic chemical contentand associated potential health impacts during Hajj, have yet to beinvestigated. The findings reported here is part of an air qualitymonitoring study characterizing the inhalable PM and its fractionsas well as the associated concentrations of selected heavy metals.

2. Material and Methods

2.1. Study locations

Makkah (21°25'19" and 39°49'46") is a great holy city approximately 80 km inland from the Red Sea and at an elevation of 277 mabove sea level. Sources of PM in the area are mostly high volumeof traffic, construction and minor industrial activities, re–suspensionof particulates and geographical conditions. Mina (21°41'33" and39°89'33") and Arafat (18°79'14" and 42°89'37") are located inMakkah Province in Western Saudi Arabia, and are separated by22.1 km (Figure 1).

2.2. Sample collection

PM samplings were performed at the premises of King FahadHajj Research Institute, on the top of a metallic shed at Arafat, andover the roof of a Health Care Center in Mina simultaneously.Samplings were done using a volumetric flow controlled (VFC) HighVolume Air sampler (Model: TE–6070V) equipped with a PM10 sizeselective inlet and a cascade impactor, model: SE–230 (TischEnvironmental, Inc.USA,) particle size cutoffs (μm) at 50%collection efficiency for spherical particles with unit mass densityat 25 °C 760 mm Hg comprised of 5 stages which separate 7.2–10;3.0–7.2; 1.5–3.0; 0.95–1.5; and 0.49–0.95 μm size particles. Thesampler was placed at a height of 3.0 m above ground level andsamplings were carried out between the 5th and 14th of Dhul–

Hijjah, 1425H (January 15–24, 2005). Five fractions of PM wascollected over pre–weighed slotted Quartz fiber filter substrate(SAC–230–QZ) and Whatman QM–A micro–quartz fiber filter (8"x10" size) used for back–up (<0.49 μm) filter to capture all finestparticles. Each sampling was performed continuously for 24 hours;from midnight 0:00 to 0:00 next day at a flow rate of between67.8–70.2 m³/hr. Meteorological data were simultaneously recordedduring sampling days. The samples were preserved separately inpolyethylene bags until delivery to the laboratory. Final weights ofeach sample, including from the various filters size fractions, weretaken and particulate concentrations in the ambient air werecalculated.

Figure 1. Location of Mina area where pilgrims stay in tents for five daysand Arafat area where pilgrims performs obligatory stay from sunrise to

sunset on the 9th day of Hajj.

2.3. Metal analysis

The particulate filter samples obtained from the cascadeimpactor. Five different size fractions and a back–up filter (2.54 cm× 20.32 cm size strip) were digested separately with concentratednitric acid (15 mL) following acid extraction of method for metalicelements (Compendium Method IO–3.1, EPA/625/R–96/010a, U.S.EPA, 1999a) using advanced composite vessels in an MDS–2100microwave digestion system. Aliquots of digested samples wereinitially filtered through filter paper (Whatman 42) followed byGelman Acrodisk (0.45 μm) filters and the volume of the aliquotwere made up to 25 mL as a final extract volume with deionizedwater. The digested samples were finally analyzed for Pb, Cd, Se, V,Ni, Co, Cu, Cr and Mn using ICP–OES (Optima 2000 DV, PerkinElmer, USA), and the blank contents duly subtracted from theanalysis (Davidowski and Grosser, 2000). Each sample was analyzedin triplicate and the mean concentrations were calculated. For theback–up filter substrate, the concentration was calculated following


an EPA procedure (Compendium Method IO–3.4, EPA/625/R–96/010a, U.S. EPA, 1999b). Metal concentration in particulate filtersample (Backup) calculated as follows:

(1)

where C is the concentration in air ( g metal/ m3), g metal/mL isthe metal concentration in the extract, final extraction volume(mL/strip) is the volume of the extract from 1 strip, 9 is the numberof the strips per sample filter, Fm is the average amount in blankfilters ( g), and Vstd is the volume of the sampled air through thefilter (m3).

Enrichment factor (EF) is a useful tool to differentiate betweenmetals originating from anthropogenic activities and those fromnatural sources and to assess the level of anthropogenic influence.It was calculated as follows:

(2)

where, Cref is the concentration of the reference metal in PM andBref was the content of the reference metal in crustal origin. In thisstudy, Mn was taken as the reference metal. EFs close to 1 pointedto a crustal origin, while those greater than 10 were considered tohave a non–crustal (anthropogenic) source. The final results werecomputed and subjected to statistical analysis.

The Air Quality Index (AQI) is used to assess the status of localair quality in relation to health concern, and is divided into sixcategories: good; moderate; unhealthy for sensitive groups;unhealthy; very unhealthy; and hazardous (U.S. EPA, 2009). AQIvalues were calculated based on the concentrations of PM (PM10and PM2.5) following the guideline procedure of U.S. EPA (2006).

2.4. Vehicular traffic count

Vehicular traffic counts were conducted at six main accessroads to the Arafat area at 15 min time intervals for four consecutive days using pneumatic tube counters (McGowen and Sanderson,2011). At Mina this task was not performed due to difficulties inmanaging various road arteries coupled with heavy vehicular trafficand frequent jams.

3. Results and Discussion

3.1. Meteorological conditions

Meteorological conditions recorded during Hajj days aresummarized in Table S1 (see the supporting Material, SM). Averagevalues of wind speed, temperature, relative humidity, solarradiation and rainfall were 0.7 m/s, 24.6 °C, 57.3%, 95.7 W/m² atMina respectively. Due to technical difficulty rainfall data was notrecorded at Mina. Meteorological conditions at Arafat were1.5 m/s, 24.6 °C, 60.2%, 125.0 W/m² and 1.2 mm respectively.These parameters were broadly consistent from 8–11 Dhual–Hijjahat Mina and Arafat; however, there was an abrupt change inweather on 12th Dhual–Hijjah (January 22, 2005) due to a violentdust storm followed by 3.6 mm of rainfall. As indicated in Figure 2and Figure S1 (see the SM), the wind speed range 0 – <0.5 m/sprevailed towards the North–East (NE) with mostly relatively calmconditions or light air in the range of 0.28–1.39 m/s.

3.2. Vehicular traffic count

The traffic count recorded at six main roads accessing theArafat area for four consecutive days (7–10 Dhual–Hijjah, January17–20, 2005) indicated that the maximum traffic of 96 180 vehicleswas recorded on the 9th Dhual–Hijjah (January 19, 2005) followedby 26 458 vehicles on 8th (January 18, 2005), 16 973 vehicles on

10th (January 20, 2005) and 1 954 vehicles on 7th Dhual–Hijjah(January 17, 2005). A total of 141 565 vehicles were moved duringthese four days within the recorded timings across the six selectedroads (see the SM, Table S2).

3.3. Concentration of particulate size fractions in ambient air atMina and Arafat

The distribution of different size fractions and the sum of totalconcentrations at Mina and Arafat during the Hajj period (includingpre– and post–Hajj) are summarized in Table 1. In the ambient air,the overall percentages of coarse and fine fractions were 34.2%and 65.8% respectively (Mina), and 35.9% and 64.08% respectively(Arafat). The sum of total fractions (coarse+fine) as PM10 wasrecorded at an average of 181.3 μg/m³ at Mina and 289.6 μg/m³ atArafat. Due to the sudden occurrence of a dust storm on 12thDhual–Hijja (January 22, 2005), high concentrations of PM10 wererecorded (228.4 and 843.2 μg/m³ at Mina and Arafat respectively).As compared to the Saudi Arabian (Presidency of Meteorology andEnvironment) and USEPA 24 h average standard guidelines(150 μg/m³) of PM10, four exceedances were recorded in theambient air at each location (i.e., on the 10th, 11th, 12th and 14thDhual–Hijjah at Mina and 5th, 9th, 10th and 14th Dhual–Hijjah atArafat) during the Hajj period. However, in comparison to PM2.5guidelines, values exceeded recommended levels on all days (seethe SM, Table S3). There was a strong correlation between PM10and fine fraction of 3 μm (R2=0.946–0.951) and similarly, betweenPM10 and >3 μm (coarse) PM (R2=0.927–0.960) at both Mina andArafat respectively. It clearly indicated that temporal variation ofPM10 under prevailing meteorological conditions; significantlyinfluenced by PM3 size particulates (see the SM, Figures S2 and S3).Although there was variation in proportional distribution of sizefractions across days, the trend of distribution among size fractions(i.e., 3.0–1.5; 1.5–0.95 and 0.95–0.49 μm) observed parallel inambient air at both Mina and Arafat during Hajj days (Figure 3),since the meteorological conditions were broadly consistent withwind speed ranged from 0–<0.5 m/s prevailed towards the North–East (NE) with relatively calm conditions or light air in the range of0.28–1.39 m/s (Figure 2 and Figure S1).

Willeke and Whitby (1975) identified that the accumulationmode (0.08–1.0 μm) features a life time of 4–40 days, and ourresults show that the percentage of fine fraction (in the range of0.95– 0.49 μm) is 82.4% and 89.5% of the total fine fractions (3.0–0.49 μm) at Mina and Arafat respectively. The distribution of fineand coarse fraction of particulates during Hajj days (8th–12thDhual–Hijjah) except pre and post Hajj days, accounted for 67%and 33% of the total at Mina and 59% and 41% at Arafatrespectively (Table1). The time evolved distribution of differentfractions of particulate concentrations (within PM10) during thesedays indicated the dominance of fine fraction ( 0.49 μm size) inthe ambient air (Figure 4). An increase in mass concentration offine PM could occur due to condensation of ultra–fine particulatesemitted from vehicular exhausts. This condensation process takesplace initially by homogeneous nucleation, leading to formation ofa high concentration of fine fraction of particulates (Elshobokshy,1984). In addition, earlier investigators reported that re–suspended dust was found to be contributing nearly 20–25% to thePM2.5 (Mancilla and Mendoza, 2012). However, the amount of re–suspended road dust particles are influenced by a number offactors including vehicle movement, type of road, associatedmeteorological conditions, and traffic speed (Pacyna, 1986;Etyemezian et al., 2003; Gertler et al., 2006; Thorpe et al., 2007;Bhaskar and Sharma, 2008; Thorpe and Harrison, 2008;Kauhaniemi et al., 2011; Majumdar et al., 2012). As evidencedfrom traffic volume counts at six main roads accessing the Arafatarea during four consecutive days (7th–10th Dhual–Hijjah),maximum traffic of 4 008 vehicles per hour was recorded on the 9thDhual–Hijjah, followed by 10th, 8th and 7th Dhual–Hijjah with 1 306,1 102 and 178 vehicles per hour, respectively (Table 2).


Figure 2.Wind speed and its direction during the period of Hajj.

Figure 3.Mean concentration of different size fractional distribution in the ambient air at Mina and Arafatduring Hajj days (January 18 22, 2005, Dhual–Hijjah).

Based on the concentration of fine particulate fractionrecorded during the Hajj days, the phenomena of particulatecondensation leading to formation of a high concentration of fineparticulates is expected to be reasonable because of the largevolume of vehicular traffic movement and frequent jams, whichlead to a greater volume of hot exhaust emissions (particularlyduring idling and acceleration mode of vehicular movement) acrossthe roads of Arafat and Mina. The particulate fraction range of 1.5–0.49 μm exhibited a distinct color variation (black in appearance),indicating that particulates within this range might be composed ofcarbon containing components formed due to interaction ofvolatile carbon compounds and elemental carbon, which ultimatelyleads to soot formation (see the SM, Figure S4). The diesel vehiclesare the major source of soot particles (with average size of 30 nm)and this may explain high concentrations of fine particles withblack color. This color demarcation was consistent at both Minaand Arafat. These observations were consistent with findings of

source characterization of particulates (Kleeman et al., 2000; Murrand Bang, 2003). Coarse particulate fractions (PM2.5–PM10), whichare mostly crustal in origin, might be contributed by rising dustfrom vehicular traffic movement on paved and unpaved roads,movement of pedestrian pilgrims and resuspended road dust(Rogge et al., 1993; Abu–Allaban et al., 2003; Boulter et al., 2005;Tervahattu et al., 2006; Wahlin et al., 2006; Thorpe et al., 2007;Amato et al., 2009; Amato et al., 2010; Gietl et al., 2010; HEI, 2010;Barmpadimos et al., 2011; Hays et al., 2011; Harrison et al., 2012;Masiol et al., 2012). The relatively high concentration of finefractions of particulates (3.0 – 0.45 μm) during peak Hajj days,both at Mina and Arafat, reflected the fact that these particulatesare of secondary origin and appear to be mainly due to combustionof fossil fuels (gasoline and diesel in automobile engines), which isconsidered to be the major source of fine PM in the ambient air atMina and Arafat.

Concen

tration(μg/m

)


Table 1. Concentration of different particulate size (μm) fractions and their concentrations (μg/m³) in ambient air at Mina and Arafat during Hajj days

Hajj PeriodParticle Size Fraction (μm)

10.0–7.2 7.2–3.0 Sum % 3.0–1.5 1.5–0.95 0.95–0.49 Backup0.49 Sum % PM10 Conc.

(μg/m3)Mina

01.15.2005 a 20.17 32.60 52.78 47.90 8.56 6.83 3.92 38.10 57.41 52.10 110.1901.18.2005 14.15 17.78 31.93 24.07 7.18 3.64 0.73 89.20 100.74 75.93 132.6701.19.2005 12.36 6.51 18.87 25.04 5.22 4.95 0.59 45.72 56.47 74.96 75.3401.20.2005 27.03 54.89 81.92 44.65 19.86 8.92 44.92 27.85 101.55 55.35 183.4701.21.2005 37.77 53.33 91.10 31.40 14.72 8.89 2.02 173.44 199.07 68.60 290.1701.22.2005 25.58 50.12 75.70 33.14 15.28 18.45 1.23 117.79 152.74 66.86 228.4401.24.2005 b 28.82 54.14 82.96 33.36 13.91 8.78 4.30 138.70 165.69 66.64 248.65Average 23.7 38.5 62.2 34.2 12.1 8.6 8.2 90.1 119.1 65.8 181.3SD 8.9 19.8 5.2 4.8 16.2 55.7 78.8Percentage 13.1 21.2 6.7 4.8 4.5 49.7

Arafat01.15.2005 a 30.88 66.80 97.68 45.24 16.47 10.15 9.24 82.35 118.21 54.76 215.8901.18.2005 24.50 26.19 50.69 52.92 4.79 3.99 2.77 33.56 45.10 47.08 95.8001.19.2005 59.20 41.95 101.15 36.23 7.71 9.25 5.12 155.93 178.01 63.77 279.1601.20.2005 13.02 27.46 40.48 23.62 7.10 5.71 5.26 112.82 130.89 76.38 171.3701.21.2005 21.58 44.91 66.49 26.37 7.56 6.25 7.02 164.79 185.61 73.63 252.0901.22.2005 222.44 192.53 414.97 49.22 32.94 16.20 19.66 359.40 428.20 50.78 843.1801.24.2005 b 8.99 21.26 30.26 17.81 6.96 4.56 1.53 126.62 139.66 82.19 169.92Average 54.37 60.16 114.53 35.92 11.93 8.02 7.23 147.92 175.10 64.08 289.63SD 75.9 60.4 10.0 4.3 6.0 103.4 251.4Percentage 18.8 20.8 4.1 2.8 2.5 51.1a Pre Hajj Dayb Post Hajj Day

Figure 4. Distribution of different particulate size (μm) fractions at (a)Mina and (b) Arafat during Hajjdays(January 18 22, 2005, Dhual–Hijjah).

0

20

40

60

80

100

120

140

160

180

200

10.0 7.2 7.2 3.0 3.0 1.5 1.5 0.95 0.95 0.49 Backup 0.49

PMCo

ncen

tration(μg/m³)

Particle size fraction (μm)

(a) 01.18.2005 01.19.2005 01.20.2005 01.21.2005 01.22.2005

0

50

100

150

200

250

300

350

400

10.0 7.2 7.2 3.0 3.0 1.5 1.5 0.95 0.95 0.49 Backup 0.49

PMCo

ncen

tration(μg/m³)

Particle size fraction (μm)

(b) 01.18.2005 01.19.2005 01.20.2005 01.21.2005 01.22.2005


Table 2. Concentration of heavy metal elements in the ambient air during Hajj days at Mina

Date Size FractionConcentration of Heavy Metal Elements (ng/m³)

Mn Cr Cu Co Ni V Se Cd Pb

Mina(Pre Hajj day)01.15.2005

(7.2–10.0 μm) 5.775 16.496 1.811 0.385 0.844 0.328 ND 0.095 1.974(3.0–7.2 μm) 8.349 17.242 3.768 0.447 0.989 0.706 ND 0.072 2.791(1.5–3.0 μm) 3.457 9.654 1.648 0.213 0.551 0.042 0.058 0.154 1.649(0.95–1.5 μm) 2.538 23.097 1.128 0.257 0.706 ND 0.160 0.247 1.625(0.49–0.95 μm) 1.791 12.701 0.648 0.206 0.490 ND 0.317 0.133 1.372

Back–Up (<0.49 μm) 6.777 100.674 3.445 0.461 3.255 ND 0.614 0.374 4.795Total 28.686 179.865 12.448 1.969 6.833 1.076 1.149 1.075 14.207

Enrichment Factor 1.0 62.9 7.1 3.0 2.6 0.2 529.5 158.2 8.9

(Hajj Days)01.18.2005

(7.2–10.0 μm) 4.151 8.020 1.621 0.158 0.556 0.066 0.002 0.258 1.721(3.0–7.2 μm) 4.943 4.150 1.953 0.177 0.536 0.173 ND 0.130 2.028(1.5–3.0 μm) 2.262 3.835 1.072 0.095 0.399 ND 0.201 0.125 0.645(0.95–1.5 μm) 1.973 14.013 1.148 0.092 0.501 ND 0.103 0.214 1.490(0.49–0.95 μm) 2.085 24.889 0.889 0.077 0.599 ND 0.037 0.060 0.656



01.19.2005

(7.2–10.0 μm) 4.201 18.395 1.802 0.181 0.765 ND 0.014 0.100 1.805(3.0–7.2 μm) 4.898 29.719 1.966 0.240 0.926 0.123 ND 0.086 2.098( 1.5–3.0 μm) 3.469 31.212 1.356 0.169 0.878 ND ND 0.083 1.800(0.95–1.5 μm) 2.036 15.086 0.924 0.130 0.670 ND 0.253 0.126 1.771(0.49–0.95 μm) 1.565 14.727 0.763 0.109 0.636 ND 0.310 0.225 1.845

Back–Up (<0.49 μm) 11.529 197.709 4.917 0.185 4.688 ND ND 0.536 6.449Total 27.699 306.847 11.728 1.014 8.562 0.123 0.577 1.155 15.769


01.20.2005

(7.2–10.0 μm) 7.843 24.321 2.746 0.332 1.060 0.658 ND 0.072 1.486(3.0–7.2 μm) 2.750 6.964 0.602 0.142 0.338 0.212 ND 0.071 0.635(1.5–3.0 μm) 7.003 21.571 2.477 0.253 1.137 0.622 ND 0.152 1.659(0.95–1.5 μm) 4.924 30.451 2.114 0.189 1.043 0.327 ND 0.106 5.577(0.49–0.95 μm) 2.039 24.198 0.684 0.116 0.609 ND ND 0.167 0.747

Back–Up (<0.49 μm) 16.648 122.276 21.903 0.375 4.881 0.650 ND 0.495 23.921Total 41.207 229.781 30.525 1.407 9.067 2.469 ND 1.063 34.025

Enrichment Factor 1.0 56.0 12.2 1.5 2.4 0.4 ND 108.9 14.9

01.21.2005

(7.2–10.0 μm) 6.660 11.907 1.893 0.285 0.757 0.439 0.024 0.003 0.048(3.0–7.2 μm) 18.221 21.509 6.668 0.616 1.524 1.798 ND ND 2.643(1.5–3.0 μm) 7.811 11.810 3.564 0.333 0.989 0.613 ND 0.029 1.675(0.95–1.5 μm) 3.103 5.838 1.736 0.169 0.628 0.090 0.101 0.085 1.175(0.49–0.95 μm) 1.039 4.394 1.307 0.115 0.439 ND 0.304 0.105 0.631



01.22.2005

(7.2–10.0 μm) 7.773 9.142 3.046 0.391 1.027 0.157 0.235 0.141 2.002(3.0–7.2 μm) 16.833 17.160 4.753 0.683 1.689 0.814 ND 0.047 2.288(1.5–3.0 μm) 7.382 16.174 2.296 0.367 1.085 ND 0.278 0.403 1.663(0.95–1.5 μm) 4.289 20.950 1.506 0.403 1.097 ND 0.718 0.238 2.010(0.49–0.95 μm) 2.247 29.820 1.199 0.139 1.030 ND 0.312 0.157 1.634

Back–Up (<0.49 μm) 11.738 140.756 6.933 0.509 6.801 ND ND 0.538 9.165Total 50.263 234.002 19.733 2.492 12.729 0.971 1.544 1.524 18.762


(Post Hajj Day)01.24.2005

(7.2–10.0 μm) 8.722 7.885 2.808 0.386 0.916 0.540 ND 0.034 0.936(3.0–7.2 μm) 15.300 8.634 4.896 0.593 1.287 1.264 ND ND 1.529(1.5–3.0 μm) 6.697 18.459 3.052 0.282 1.015 ND 0.303 0.152 1.066(0.95–1.5 μm) 4.084 11.005 1.753 0.227 0.692 ND ND 0.058 0.919(0.49–0.95 μm 1.977 8.878 0.996 0.127 0.440 ND ND 0.034 0.681

Back–Up (<0.49 μm) 8.935 71.222 7.199 0.299 4.161 ND ND ND 4.595Total 45.714 126.084 20.703 1.914 8.511 1.804 0.303 0.278 9.726



3.4. Concentration of heavy metal elements in the ambient air

Selected particulate filter samples collected on 5th (pre–Hajj),8th–12th (main–Hajj days) and 14th (post–Hajj day) Dhual Hijjah atMina, and similarly on 5th, 8th–10th and 14th Dhual Hijjah at Arafat,

were analyzed for nine targeted metal elements (Mn, Cr, Cu, Co,Ni, V, Se, Cd, and Pb) associated with different size fractions of PM.The concentrations of these metal elements in each fraction areshown in Tables 2 and 3.

Table 3.Concentration of heavy metal elements in the ambient air during Hajj days at Arafat

Date Size FractionConcentration of Heavy Metal Elements (ng/m³)

Mn Cr Cu Co Ni V Se Cd Pb

Arafat(Pre Hajj Day)01.15.2005

(7.2–10.0 μm) 7.683 7.616 2.054 0.226 0.657 0.509 ND 0.058 1.122

(3.0–7.2 μm) 15.702 17.038 3.727 0.407 1.522 0.315 0.013 0.079 1.441

(1.5–3.0 μm) 6.717 9.343 1.733 0.091 0.698 0.377 0.082 0.091 0.622

(0.95–1.5 μm) 3.511 6.737 1.256 ND 0.416 0.075 ND 0.022 1.048

(0.49–0.95 μm) 0.836 3.949 0.510 ND 0.150 ND ND 0.015 0.966

Back–Up (<0.49 μm) 13.122 52.129 2.323 ND 3.166 0.007 ND ND 2.185

Total 47.571 96.812 11.603 0.724 6.609 1.283 0.095 0.266 7.384


(Hajj Days)01.18.2005

(7.2–10.0 μm) 6.852 5.362 1.662 0.129 0.440 0.360 ND 0.012 0.870

(3.0–7.2 μm) 8.744 5.685 2.073 0.190 0.567 0.484 ND 0.055 0.788

(1.5–3.0 μm) 1.982 3.226 0.315 ND 0.011 ND 0.028 0.022 0.518

(0.95–1.5 μm) 1.844 5.070 0.820 ND 0.197 ND 0.108 0.065 0.459

(0.49–0.95 μm) 1.567 8.435 0.831 ND 0.278 ND 0.189 0.093 0.644

Back–Up (<0.49 μm) 5.324 33.877 5.296 ND 1.383 ND 0.272 0.318 4.660

Total 26.312 61.655 10.997 0.319 2.875 0.844 0.597 0.564 7.938


01.19.2005

(7.2–10.0 μm) 13.952 8.007 2.832 0.404 0.881 1.211 ND ND 0.648

(3.0–7.2 μm) 13.302 7.121 3.146 0.314 0.760 1.005 ND ND 1.066

(1.5–3.0 μm) 4.508 5.768 1.425 0.028 0.308 ND ND 0.035 0.669

(0.95–1.5 μm) 3.110 5.470 1.128 ND 0.226 ND ND 0.062 0.779

(0.49–0.95 μm) 1.917 5.299 0.691 ND 0.129 ND ND 0.046 0.476

Back–Up (<0.49 μm) 10.611 57.609 2.867 ND 1.327 ND ND 0.065 3.614

Total 47.400 89.274 12.089 0.746 3.630 2.216 ND 0.209 7.251

Enrichment Factor 1.0 18.9 4.2 0.7 0.9 0.3 ND 18.6 2.8

01.20.2005

(7.2–10.0 μm) 2.834 3.650 0.908 0.031 0.205 ND ND 0.061 0.510

(3.0–7.2 μm) 6.387 4.932 1.880 0.107 0.425 0.151 ND 0.005 0.512

(1.5–3.0 μm) 3.689 5.133 1.284 0.040 0.329 ND ND 0.049 0.549

(0.95–1.5 μm) 3.296 8.160 1.080 0.170 0.408 ND 0.226 0.100 0.551

(0.49–0.95 μm) 2.196 9.660 0.643 0.053 0.316 ND 0.194 0.093 0.957

Back–Up (<0.49 μm) 4.741 41.934 1.936 ND 2.399 ND 0.091 0.361 4.420

Total 23.142 73.469 7.731 0.401 4.081 0.151 0.511 0.669 7.499


(Post Hajj Day)01.24.2005

(7.2–10.0 μm) 2.035 3.053 0.510 ND 0.199 ND ND 0.038 0.266

(3.0–7.2 μm) 5.258 4.509 0.922 0.060 0.468 0.145 ND 0.005 0.198

(1.5–3.0 μm) 2.455 4.430 0.495 ND 0.232 ND ND 0.042 0.253

(0.95–1.5 μm) 1.646 3.906 0.748 ND 0.354 ND 0.063 0.069 0.413

(0.49–0.95 μm) 1.061 4.236 0.548 ND 0.201 ND ND 0.003 0.268

Back–Up (<0.49 μm) 5.253 75.700 1.859 ND 1.409 ND ND 0.067 1.724

Total 17.708 95.835 5.083 0.060 2.862 0.145 0.063 0.224 3.122



The concentration of the various size fractions was lower atArafat than at Mina. For a better understanding of the origin(anthropogenic or natural) of the metalic elements, and theirabundance in the PM, the enrichment factors (EF) were calculatedat both monitoring sites. EF is the ratio of chemical concentrationof an element in the particulate samples to that in the crust. Thecrustal concentrations of the metals were obtained from Taylorand McLennan (1995) and the calculated enrichment factors areshown in Table 2. It is presumed that any particular metal elementwith an EF of 1 is of crustal origin, whereas an EF of >1.0 indicatesthat anthropogenic activities are likely to be the major source. Thehighest EFs were obtained for Cd, Se, and Cr, followed by Cu, Pb,and Ni, suggesting that non–crustal sources are predominant, asexpected due to the emissions from traffic, tyre wear, fossil fuelcombustion and other possible non–exhaust source of Mn and Vcontribution was from tyre wear and re–suspension of particulatematter (Rogge et al., 1993; Wahlin et al., 2006; Thorpe andHarrison, 2008; Gietl et al., 2010; Amato et al., 2011; Hays et al.,2011). Earlier investigators reported that higher particle emissionrates from traffic were produced by diesel–soot and analyses ofsoot from vehicular exhausts revealed that enrichment of Ni, Cu,Ag, Cd and Sb as well as for non–metals like Se and Br found to beassociated with diesel soot (Heinrichs and Brumsack, 1997). Otherexplanation for the higher enrichments in diesel soot may be dueto contaminations from the motor and the exhaust where theseelements might also be in use. Most of these elements particularly,Zn, Mo, Cu are known to be used as additives to the oils used aslubricants, anti–oxidants and anti–corrosives. The possibility ofdistinguishing diesel soot from vehicular emissions is through thedifference in particle sizes (<1 μm) as a condensation product(Hirner et al., 1996; Heinrichs and Brumsack, 1997; Weckwerth,2001; Amato et al., 2011). V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pbwere associated with three types of vehicles (gasoline cars, dieselbuses and other vehicles). Their results showed that Zn was themost abundant element, accounting for over 45% of the totalmetal concentration. Cr and Pb were the next most abundantelements. Enrichment factor analysis showed that Cr, Zn, As, Cdand Pb exhibited heavy or extreme contamination and significantenrichment, indicating the influence of anthropogenic sources. Mnand Co were mostly non–enriched and were mainly influenced bycrustal sources. Ni and V presented moderate or heavycontamination, and were influenced by both crustal origin andanthropogenic sources. Selenium is usually of crustal origin butfossil fuel also contains Se, which can contribute to the totalconcentration in ambient air. The lowest EF values were recordedfor V, which is presumed to be of crustal/soil origin, with re–

suspended soil being the dominant source for this element. Themetalic elements originating from anthropogenic sources (i.e., Cr,Cd, Cu, Pb, Co and Ni) exhibited predominant occurrence in finefraction from both locations, whereas, elements such as Mn, V andSe, which typically originate from natural sources and soil dust,were distributed in coarse fractions. The common sourcesattributed to these metals at these sites are re–suspension of roaddust due to vehicular activity and activities such as wear–and–tearof tires, oil burning, abrasion of mechanical parts of road vehicles,and oil lubricants. Bivariate analysis between the metal elementsassociated with PM10 at Mina and Arafat exhibited strong positivecorrelation and were predominantly of anthropogenic origin.However, V showed weak positive to negative correlations with Se,Cd and Pb (see the SM, Table S4). Therefore, aforesaid studies inconformity with present findings associated with vehicular trafficsource of particulate pollution during the period of Hajj.

3.5. Air Quality Index (AQI)

AQI was used in this study as an indicator of daily air qualityand its health implications (U.S. EPA, 2009). The AQI was calculatedfor PM2.5 (using PM1 concentration values as conservative andproximate values) and PM10 in Mina and Arafat (Figure 5). Asevidenced from AQI in relation to PM2.5 particulates during theentire Hajj period, in Mina pilgrims were exposed to moderate airquality for 10% of the days, to unhealthy air quality for sensitivegroups for 30% of the days, to unhealthy air quality for 40% of thedays, and very unhealthy air quality for 20% of days. In Arafat theair quality was lower, with pilgrims being exposed to unhealthy airquality for sensitive groups for 8% of days, unhealthy air quality for50% of days, very unhealthy air quality for 34% of days, andhazardous air quality for 8% of days during the entire Hajj period.Considering the case of PM10 at Mina, pilgrims were exposed tomoderate air quality for 20% of the days, to unhealthy air qualityfor sensitive groups for 30% of the days, to unhealthy air qualityfor 20% of the days and to very unhealthy air quality for 30% of thedays. In Arafat for PM10 9% of days were of moderate air quality,8% of unhealthy air quality for sensitive groups, 25% of days ofunhealthy air quality, and 50% of days of very unhealthy air qualityand 8% of days were of hazardous air quality. Consequently,potential health impacts (Mauderly, 1994; Wilson and Suh, 1997;Buckeridge et al., 2002; Fan et al., 2006; HEI, 2010; Masiol et al.,2012; Rissler et al., 2012) were expected among certain groups ofpeople, including respiratory and heart diseases and morbidity inpilgrims with cardio–pulmonary problems during Hajj days,particularly in Arafat.

Figure 5. Air Quality Index represents the quality of ambient air based on PM10 and PM2.5 during Hajj days and its impact on health.

(55 154 g/m3)

(b)(a)(355 424 g/m3)

(255 354 g/m3)

(155 254 g/m3)

(150.5 250.4 g/m3)

(55.5 150.4 g/m3)

(35.5 55.4 g/m3)

(12.1 35.4 g/m3)


Figure 5. Continued.

4. Conclusions

This study provided a clear indication that particulate pollution load is primarily contributed by various activities during theHajj period, including emissions from traffic (comprising of bothlight and heavy motor vehicles), movement of pedestrian pilgrimson paved and unpaved roads during peak Hajj days and large–scalesweeping and cleaning operations during and pre–Hajj days. Majorpart of fine PM and most of the associated metal elementsreported in this study mainly contributed from vehicular trafficemissions from both exhaust (tailpipe), due to and non–exhaust,emissions due to wear and tear of vehicle parts such as brake, tyreand clutch and re–suspension of dust and road surface abrasionsource from both gasoline and diesel vehicles.

The concentration of fine particulate fraction recorded duringthe Hajj days, the phenomena of particulate condensation leadingto formation of a high concentration of fine particulates isexpected to be reasonable because of the large volume ofvehicular traffic movement and frequent jams, which lead to agreater volume of hot exhaust emissions (particularly during idlingand acceleration mode of vehicular movement) across the roads ofArafat and Mina. Non–exhaust emissions including street sweepingoperations and re–suspension street dust contributed mainly tothe coarse mode of PM (PM2.5–10) while exhaust emissionscontribute predominantly to fine PM (<2.5 μm). Based onenrichment factors, the contribution of metalic elements showedmainly from vehicular traffic source (anthropogenic), partially fromnatural source due to windblown dust and re–suspension of roaddust.

The fine fraction of PM recorded at Mina and Arafat werewithin the size range of accumulation mode, and this wouldpresumably have an adverse impact on the health of pilgrims,particularly those with pre–existing asthma or cardiovascularproblems, the elderly, and young children.

The wind speed during the Hajj period was relatively calm [0–0.28 m/s for half of the period and light air (0.28–1.39 m/s) for therest of the time], which might have facilitated particulate accumulation. Prevailing meteorological conditions, topography of thelocations, and atmospheric reactions may also have had direct andindirect influence over the existence and proportional occurrenceof PM in the ambient air.

The characterization of PM of biological origin, which mayinclude pollens, bacteria, and fungal spores, investigations oncumulative and synergistic effects of PM from biological and non–biological origins, together with other organic and inorganicgaseous pollutants, and their complex chemical characteristics and

their impact in relation to health of pilgrims during Hajj period, aresome of the critical issues that need be addressed in furtherresearch.

Further emphasis on research is also needed to address otheraspects such as chemical characterization of fine PM ( 2.5 μm)because the large number of these small particles have a highsurface to volume ratio, providing greater opportunity for surfaceabsorption of toxic substances such as polycyclic aromatic hydrocarbons (PAHs), and other high molecular weight hydrocarbonsand toxic heavy metals generated from vehicular emissions.

Acknowledgments

The authors would like to thank King Abdulaziz City for Scienceand Technology (KACST) for supporting this work.

Supporting Material Available

Wind speed and relative frequency of pattern during theperiod of Hajj (Figure S1), Correlation between PM10 and PM 3.0 μmparticulate matter at Mina and Arafat during Hajj days (Figure S2),Correlation between PM10 and PM>3.0 μm coarse particulatematter at Mina and Arafat during Hajj days (Figure S3), Particulatefraction range of 1.5–0.49 μm (Figure S4), Average meteorologicalconditions at Mina and Arafat during Hajj days (Table S1), VehicularTraffic count recorded during Hajj days at Arafat (Table S2),Standard guideline values of Saudi Arabian (PME), WHO, USEPA forPM10 and PM2.5 particulate matter and number of exceedancesrecorded during Hajj period (Table S3), Bivariate analysis showscorrelation between the metal elements associated with PM10 atMina and Arafat (Table S4). This information is available free ofcharge via the Internet at http://www.atmospolres.com.

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