Research Article IJAER (2017); 3(1): 33-48

Citation: EL-Shakoura, A.A., A.S. EL-Ebiarieb, Y.H. Ibrahima, A.E.A. Moniemb and A.M. EL-Mekawya. 2017. A

comparative study of indoor and outdoor polycyclic aromatic hydrocarbons (pah) levels in residential homes in

Helwan, Egypt. Int. J. Agri and Env. Res., 3(1): 33-48.

A COMPARATIVE STUDY OF INDOOR AND OUTDOOR POLYCYCLIC

AROMATIC HYDROCARBONS (PAH) LEVELS IN RESIDENTIAL

HOMES IN HELWAN, EGYPT

ALIA ABD EL-SHAKOURA, AHMAD SALEM EL-EBIARIEB, YASSER HASSAN IBRAHIMA,

AHMAD ESMAT ABDEL MONIEMB, ASMAA MOHAMED EL-MEKAWYA

Air Pollution Department, National Research Centre, Giza, Egypt

Zoology and Entomology Department, Faculty of Science, Helwan University, Cairo, Egypt

Corresponding author’s email: asmaamekawy75@gmail.com

Abstract

Air quality data of polycyclic aromatic hydrocarbons (PAHs) indoors are sparse or lacking in Egypt. The

concentration of 16 PAHs in particulate matter of both indoor and outdoor air of Helwan city (south Cairo,

Egypt) were measured simultaneously by high-performance liquid chromatography during one year, started

from September 2010 to August 2011. Helwan City is characterized by the presence of industrial activities

beside traffic and commercial activities. The source identification of PAHs in airborne particulate matter was

performed by diagnostic ratios. The outdoor annual mean concentration of PAHs over Helwan city was 708.9

ng/m3, while the indoor PAHs levels ranged from 694.7 ng/m3 at site 2 to 1038.7 ng/m3 at site 3. The average

annual mean concentration of B[a]P over Helwan city was 34.8 ng/m3. The mean annual concentration of

B[a]P in all homes was 70 ng/m3. B[a]P-equivalent carcinogenic power (BAPE) in outdoor air were 99.96,

162.31, 71.1 and 36.75 at sites 1, 2, 3 and 4, respectively. On the other hand, indoor BAPE were 193.04,

92.91, 145.91 and 106.47 at sites 1, 2, 3 and 4, respectively.

Key words: Polycyclic aromatic hydrocarbons, Indoor PAHs, Outdoor PAHs, air quality and Helwan Egypt.

INTRODUCTION

Indoor concentrations of some pollutants

generally exceed outdoor concentrations by up to

about five times (Mitchell et al., 2007; Jia et al.,

2008; Demirel et al., 2014). However, human spends

about 90% of their time indoor (Li, 2013; Gao et al.,

2014; Wetzel and Doucette, 2015). When indoor air

contains elevated concentrations of pollutants (e.g.

volatile organic compounds and carcinogenic

polycyclic aromatic hydrocarbons) they pose serious

risk of adverse health effects, so it is important to

monitor indoor air quality and maintain it at the non-

harmful level for human beings (Naeher et al., 2007;

Chaigneau, 2012). Polycyclic aromatic hydrocarbons

(PAHs) are among the most important compounds,

they are a widespread class of environmental

pollutants of semi-volatile organic compounds that

consist of two or more fused benzene rings. They are

produced as a result of incomplete combustion of

organic matter (Slezáková, 2009; Hrustinszky, 2012).

PAHs are emitted from both natural and

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34

anthropogenic processes. PAHs are widely detected

air pollutants in particulate and gaseous phases, both

indoor and outdoor. PAHs have low volatility and

low aqueous solubility, and are mainly adsorbed to

particles, such as house dust, rather than existing in

the gaseous phase (IARC, 2010; Lu et al., 2011).

Although several hundred PAHs exist, , only a

subset of 16 PAHs are measured by the US

Environmental Protection Agency (USEPA), which

were selected based on their toxicity, distribution in

the environment, and potential risk to human health

(Hrustinszky, 2012).

This study was carried out for assessing the

concentrations and sources of PAHs in the indoor and

the outdoor air ; and for studying the relation between

indoor and outdoor PAHs in Helwan City.

MATERIAL AND METHODS

Area under Investigation: Helwan is a city in Egypt

located on the bank of the Nile river. It is situated

about 24 km south east of Cairo city. Helwan is a

residential area surrounded from its north and south

by industrial activities (cement, automobiles, iron and

steel, lead and zinc smelting, foundries, ceramics,

chemicals, coke, fertilizers, spinning and weaving,

starch, and other miscellaneous activities). In

addition, there are two big power stations, one in the

north and the other in the south of Helwan city.

Helwan is impacted by emissions from nearby

industrial activities beside traffic and commercial

activities.

Site Characterization and Sampling Strategy:

Homes were chosen in order to adequately cover the

various sections and activities taking place in the area

under investigation. Participants were recruited on a

voluntarily basis. According to building surroundings

and road configuration, four residential buildings in

Helwan city were selected, and represented as sites 1,

2, 3 and 4 as shown in table (1) and figure (1). Table

(2) represents questionnaire items defining the factors

affecting presence of pollutants and their levels in the

homes under investigation.

Figure (1): Map of Helwan city showing sampling sites.

35

Table (1): Description of sampling sites and their characteristics.

Site Description

Site 1 ❖ Located in Helwan city center

❖ A flat on the fourth floor with about 16 m high from ground level.

❖ With medium road traffic.

❖ built in 1975.

❖ Downwind of Cairo city.

❖ Represents residential area.

Site 2 ❖ Located in Helwan city center.

❖ A flat on the second floor with about 5 m high from ground level.

❖ Adjacent to a busy road with heavy traffic.

❖ built in 1972.

❖ Downwind of Cairo city.

❖ about 900m away from site1.

❖ Represents commercial /residential area with high traffic.

Site 3 ❖ Located in Wady Hoff at the north of Helwan city.

❖ A flat on the second floor with about 5 m high from ground level.

❖ no main traffic roads, but the relatively narrow lanes for residents and private

cars in and out.

❖ built in 1989.

❖ Downwind of Cairo city.

❖ Represents residential area with light traffic.

Site 4 ❖ Located in Torra (cement factory located close to residential area) at the

northern part of Helwan city.

❖ A flat on the first floor.

❖ built in 1985.

❖ Downwind of Cairo city.

❖ Represents a popular residential area (buildings are close to each other).

Table (2): Questionnaire items defining the factors affecting presence of pollutants and their levels.

Questions Site 1 Site 2 Site 3 Site 4

Cooking (hour) 4 2 3 6

Using ventilation fan Yes No Yes Yes

Type of fuel natural gas natural gas natural gas *LPG

Presence of smokers Yes (1) No No No

Floor type of living room Carpet Carpet Carpet Carpet

Use of air conditioner Yes

(only bed room) No

Yes

(only bed room) No

Duration of opening windows in

living room (hour) 5 1 3 0.5

Use of pesticides Few No No No

Liquefied Petroleum Gas: Sixteen PAHs

identified as priority pollutants by USEPA

(Hrustinszky, 2012) were selected for quantification

in Suspended Particulate Matter: Naphthalene,

36

Acenaphthylene, Acenaphthene, Fluorene,

Phenanthrene, Anthracene, Fluoranthene, Pyrene,

Benz[a]Anthracene, Chrysene,

Benzo[b]Fluoranthene, Benzo[k]Fluoranthene,

Benzo[a]Pyrene, Dibenz[a,h] Anthracene,

Benzo[ghi]Perylene, Indeno[1,2,3-c,d] Pyrene.

Sampling of PAHs in outdoor and indoor air:

Samples were collected in outdoor and indoor,

simultaneously at all sites under investigation

through glass fiber filter paper of whatman GFA type

(12cm in diameter) with 99% collection efficiency

(NAS, 1973; Samara et al., 1990). The sampling flow

rate was 14 liter/min. for 24 hours once per week.

Sampling started from September 2010 to August

2011. Indoor samples were collected at height about

1.5 meters from the floor of living room, while

outdoor samples were taken at 1.5–2m high in the

balcony, for at least 1m from the house wall and

about 4 to 10m above ground level (figure 4). The

glass fiber filters were impregnated in acetone before

sampling to remove all organic compounds for 24h

then heated in furnace oven at 400C° for 4h. The

cleaned glass fiber filters were stored in desiccators

until sampling (Thrane and Mikalsen, 1981;

Yamasaki et al., 1982).

Extraction of PAHs: Filters were placed in

glass vial and extracted with 10ml of

dichloromethane (DCM)/n-hexan (1:1) extra pure

HPLC grade, vials were placed in ultrasonic bath for

10min at room temperature, this process was repeated

three times. The extract was filtered and concentrated

to about 2ml using rotary evaporator (loborota 4003

control rotary evaporator with G3 glassware,

heidolph, Germany) (Nielsen, 1996-a; Nielsen et al.,

1996-b; Escriva et al.,.1991; Fromme et al.,1998).

The concentrated extracts were passed through

column chromatography. PAHs were eluted with

20ml of DCM/n-hexane (1:1) extra pure HPLC

grade. The volume of elutes were concentrated using

a gentle flow of dry nitrogen gas to a volume of

approximately 2ml. according to (Omar et al., 2002;

Sharma et al., 2007).

Instrument Analysis: Qualitative and quantitative

determination of individual PAHs was done using

High Performance Liquid Chromatograph (HPLC).

The HPLC was calibrated with a diluted standard

solution of 16 PAHs compounds (Supleco, Inc.,

Bellefonte, PA). The standard PAHs mixture

(2000µg/ml for each) was containing Sixteen PAHs

identified as priority pollutants by USEPA. The

peaks in the chromatogram were identified by

comparing retention times (from HPLC

chromatogram) with those of standards and they were

quantified by comparing the integrated peak area

with that of the nearest standard. The concentrations

of individual PAHs were calculated and expressed in

ng/m3.

Detection Limits: The detection limit of each

compound was calculated from the data of duplicate

measurements of low concentration samples and

observed from their standard deviation. The method

detection limits ranged from 0.4 to 2 ng/m3 for the

target PAHs.

Quality Assurance /Quality Control: The quality

assurance and quality control (QA/QC) procedure

included laboratory and field blanks, parallel samples

and duplicate measurements of samples. The

laboratory blanks and the field blanks were tested

with no significant contamination found for any of

target PAHs. Duplicate field samples were collected

at all the sampling locations. The relative standard

deviation (RSD) for duplicate analyses of all the field

samples varied from 10 to 15% for all the measured

PAHs.

The recovery test was done by spiking known

amounts of PAH onto pre-extracted SPM retained on

glass fiber filters and extracted using the same

analytical method. A recovery of better than 90% for

most PAHs components was obtained. In the present

study, all laboratory tools used in sample collection

analysis, and storage were soaked in 10% HNO3 for

two days and then rinsed thoroughly with distilled

and double distilled water, respectively, before use.

RESULTS AND DISCUSSION

Polycyclic Aromatic Hydrocarbons (PAHs) in

Ambient Air

Annual and Seasonal Mean Concentration of

∑PAHs in Ambient Air: From figure (2) it can be

noticed that the outdoor annual mean concentration

37

of ∑PAHs (the summation of 16 PAHs) over Helwan city was 708.9ng/m3.

Figure (2): The annual mean concentration of ∑PAHs (ng/m3) in outdoor air of the investigated sites.

This concentration is much higher than the

concentration found in other studies around the world

e.g. Tian et al. (2009) in Harbin (100±94ng/m3);

Drooge et al. (2010) in Tyrolean Alps, Europe,

Tenerife and in Central Norway (0.20, 0.00 ,0.38

ng/m3, respectively); Ma et al. (2011) reported that

the mean total ΣPAHs was 104 ± 130ng/m3 at

Beijing during the 29th Olympic Games; Liu et al.

(2013) found a concentration of (0 ± 6.6 ng/m3 and

20 ± 15 ng/m3) in two different sites in summer and

Chen et al. (2014) reported that the range of PAHs

was (0.06–2.53ng/m3 with average 0.59ng/m3) in

Lulang, Tibet; Krugly et al. (2014) found a

concentration ranged from 40.7 to 121.2 ng/m3) in

outdoors. The maximum annual mean concentration

of ∑PAHs in outdoor air was 921 ng/m3 at site 2.

High PAHs concentration at site 2 may be due to

vehicular emissions near this site.

The seasonal variations in the concentrations of

total PAHs (∑PAH16) compounds are represented

graphically in figure (3). The ∑PAH16 mean

concentrations showed seasonal variation with the

highest level during summer and spring seasons,

while the lower were measured during winter and

autumn season at most of the investigated sites,

except for site 3 which had higher PAHs

concentration during autumn season. Partitioning

Characteristics of PAHs in Outdoor Air: Figure (4)

shows the percentages contribution of low molecular

weight (LMW) (two and three rings PAHs), middle

molecular weight (MMW) (four and five rings PAHs)

and high molecular weight (HMW) (six rings PAHs)

PAH compounds to ∑PAH in the outdoor air of sites

1, 2, 3 and 4, during the period of study. It can be

noticed that the most abundant PAHs during the

period of study were LMW (2 and 3 rings) at sites 1,

3 and 4, with relative higher percentage of the LMW

at site 3.

On the other hand, the most abundant PAHs

compounds at site 2 were MMW (4 and 5 rings).

38

There was a higher percent of HMW at sites 2 and 4 than that reported at sites 1 and 3

.

Figure (3): Seasonal mean concentrations of total PAH compounds (ng/m3) in outdoor air of sites under investigation.

Figure (4): Percentage of LMW, MMW and HMW PAH compounds in outdoor air of sites under investigation.

39

LMW PAHs at sites 1, 3 and 4 may be due to its

emission from industrial activities (such as coke and

iron and steel) and the traffic emissions especially

from diesel engines. These results are in agreement

with Randolph et al. (2003) who reported that coke

production was marker for anthracene, phenanthrene,

benzo(a)pyrene and benzo(ghi) perylene. On the

other hand, there was a higher percent of MMW and

HMW PAHs at site 2 this may be attributed to

vehicular emissions beside the industrial one, higher

molecular weight PAHs are emitted especially from

vehicular emissions (Pandey et al., 1999).

Percentage of the Total Carcinogenic Compounds to

the ∑ PAHs in Outdoor Air: EPA has clssified

benz[a]anthracene (BAA), benzo[b]fluoranthene

(BBF), benzo[a]pyrene (BAP), dibenz

[a,h]anthracene (DBA) and indeno[1,2,3-cd]pyrene

(IND) as probable human carcinogens (USEPA,

1995).

From figure (5) it can be noticed that percentage of

the total carcinogenic compounds to the ∑ PAH16 at

all sites are almost similar. The maximum

percentages of the total carcinogenic compounds to

the ∑ PAH16 were during spring and summer

seasons at almost all sites under investigation.

Figure (5): Annual percentage of the total carcinogenic compounds.

The annual average concentrations of the total

carcinogenic compounds in outdoor air were 235.9,

469.3, 248.6 and 138.9 ng/m3 at sites 1, 2, 3 and 4,

respectively. The annual average concentration of the

total carcinogenic compounds in outdoor air of

Helwan city was 273.1 ng/m3. The highest annual

percentage of the total carcinogenic compounds to

the ∑ PAH16 was at site 2 reaching 50.9% of the

total concentration of PAHs (469.3ng/m3), while, the

minimum annual percentage of the total carcinogenic

compounds to the ∑ PAH16 was at site 3 reaching

29.5% of the total concentration of PAHs (248.6

ng/m3). Higher annual percentage of the total

carcinogenic compounds to the ∑ PAH16 at site 2

may be attributed to the presence of heavy traffice in

this site.

Benz[a]pyrene Carcinogenic Fraction of PAHs in

Ambient Air of Helwan City: Benz[a]pyrene (B[a]P)

is one of the most important PAHs because of its

carcinogenic properties. It has been regarded as the

40

compound with the most important consequences for

human health because it is probable carcinogenic to

humans classified in group-1 (IARC, 2002; IARC,

2009a). B[a]P was considered to be a sufficient index

for PAH carcinogenicity. B[a]P has been widely used

as an indicator of air quality and for overall PAH

carcinogenicity (WHO, 2000).

In the present study, the annual mean

concentrations of B[a]P were 51.6, 39.01, 43.59 and

5.01ng/m3 at sites 1, 2, 3 and 4, respectively. The

average annual mean concentration of B[a]P over

Helwan city was 34.8ng/m3, this concentration is

about thirty four times higher than the Italian

standard for B[a]P (1ng/m3), it exceeded both the

upper limit (2.5ng/m3) of the Chinese AAQS, and the

annual standard of the Chinese AAQS (1.0ng/m3)

(Delgado-Saborit et al., 2011), and the value of 0.25

ng/m3 set by the UK air quality standard (EPAQS,

1999). It is also much higher than concentration

reported by Delgado-Saborit et al. (2011) in outdoor

air of UK (0.19ng/m3).

B[a]P -equivalent carcinogenic power (BAPE) in

Outdoor Air: For other compounds with carcinogenic

properties such as BAA, DBA, BBF and IND the

following equation was used to calculate the B[a]P -

equivalent carcinogenic power (BAPE) (Cecinato,

1997 and Cecinato et al., 1998):

BAPE= BAA×0.06+ DBA×0.6+BAP+

BBF×0.07+ IND×0.08: This index tries to

paramterize the health risk for humans related to

ambient PAH expositions, and is calculated by

multiplying the concentration of each carcinogenic

congener with its carcinogenic factor obtained by

laboratory studies. By this way the contribution of

other carcinogenic compounds was also considered

instead of taking only BAP as a compound

representing carcinogenicty, allowing a better

parameter to be related to the whole PAH fraction.

From table (3), it can be noticed that B[a]P-

equivalent carcinogenic power (BAPE) in outdoor air

were 99.96, 162.31, 71.1 and 36.75 at sites 1, 2, 3 and

4, respectively.

Table (3): Annual means concentration of total carcinogenic PAH concentration (ng/m3) and B[a]P -

equivalent carcinogenic power (BAPE) in outdoor air of the investigated sites

Site BAPE ∑ PAH Carcinogenic

Site 1 99.96 235.93

Site 2 162.31 469.35

Site 3 71.10 248.67

Site 4 36.75 138.91

B[a]P -equivalent carcinogenic power (BAPE) in this

study is much higher than those reported by Ohura et

al. (2004b) in Shizuoka, Japan; Chang et al. (2006) in

urban of Taiwan; Tuntawiroon et al. (2007) in

Bangok, Thailand; Akyuz and Cabuk (2008) in

Turkey and Callen et al. (2008) in Zaragoza, Spain

and.

PAHs in Indoor Air: Annual and Seasonal Variation

of PAHs Concentration in the Indoor Air: Annual

mean concentration of ∑PAHs in the indoor air of the

investigated sites ranged from 694.7ng/m3 at site 2 to

1038.7 ng/m3 at site 3 (as seen from figure (6)).

These concentrations are much higher than

concentration found in other studies, such as the

concentration ranged from n.d. to 62.8 ng/m3 with a

mean of 2.16 ng/m3found by Delgado-Saborit et al.

(2011) in the indoors environments in United

Kingdom; and the concentrations of 8 PAHs

(∑PAHs) ranged from 7.1 to 320 ng/m3 and 0.15 to

32 ng/m3, with an average of 47 ng/m3 and 5.2

ng/m3 in residential air of Hangzhou, China and

Shizuoka, Japane, respectively (Lu et al., 2011); and

more than that recorded by He et al. (2014) (58.19

ng/m3) for tPAHs in Nanjing, China.

It is clear that, PAHs concentration vary according to

the influence of specific source emitter at each site.

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Figure (6): The annual mean concentration of ∑PAHs (ng/m3) in indoor air of the investigated sites.

The particle bound PAH16 mean concentrations

showed seasonal variation with the highest level

during spring and summer, while the lowest values

were reported in winter season for all sites under

investigation except for site 4 (figure 7). These

results are in accordance with Lu et al. (2011) who

found higher PAHs concentration during summer

season in residential air of Hangzhou, China, while

the lower concentration was during winter season.

Figure (7): Seasonal mean concentration of total PAH compounds (ng/m3) in indoor air of sites under investigation.

42

Partitioning Characteristics of PAHs Compounds in

Indoor Air: The most abundant PAHs during the

period of study was LMW (2 and 3rings) at sites 1, 2

and 3, with relative higher percent of HMW at sites 2

and 3 than other sites. On the other hand, the most

abundant PAHs compounds at site 4 were MMW (4

and 5rings) (as shown in figure (8)). Relative higher

ratios of low molecular weight PAHs (two and three

rings) usually indicates that PAHs are originated

from local sources in homes such as cooking and

smoking practices, while higher molecular weight

indicates that PAHs in the indoor air are

accompanied for both indoor and outdoor sources (Lu

et al., 2011). The indoor concentrations of the higher

molecular weight PAHs (five rings and larger) are

dominated by outdoor sources (Naumova et al., 2002;

Delgado-Saborit et al., 2011).

Figure (8): Percentage of LMW, MMW and HMW PAH compounds in indoor air of sites under investigation.

Percentage of the Total Carcinogenic Compounds to

the ∑PAH16 in Indoor Air: Figure (9) shows that the

maximum percentages of the total carcinogenic

compounds to the ∑PAH16 were during spring

season at almost all sites under investigation, except

for site 1 , which had the maximum percentages of

the total carcinogenic compounds to the ∑ PAH16

during summer season.

The highest annual percentage of the total

carcinogenic compounds to the ∑ PAH16 was at site

3 reaching 40.4% of the total concentration of PAHs,

while, the minimum annual percentage of the total

carcinogenic compounds to the ∑ PAH16 was at site

1 reaching 32.2% of the total concentration of PAHs.

The annual average concentrations of the total

carcinogenic compounds in indoor air were 328.96,

229.39, 420.46 and 316.08 ng/m3 at sites 1, 2, 3 and

4, respectively. The average annual concentration of

the total carcinogenic compounds in indoor air of all

sites was 323.72 ng/m3, this concentration is much

higher than the concentration (0.77 ng/m3) reported

by Delgado-Saborit et al. (2011).

Benz[a]pyrene Carcinogenic Fraction of PAHs in

Indoor Air: B[a]P was considered the primary

representative and was regarded by the World Health

Organization (WHO) as a good index for the whole

PAHs carcinogenicity (Shi et al., 2010).

In the present study, the annual mean concentrations

of B[a]P in indoor air were 141.9 ng/m3 at site 1,

43

16.02 ng/m3 at site 2, 59.71 at site 3 and 62.4 at site

4. Higher B[a]P at site 1 may be attributed to the

presence of smoker at this home. Fromme et al.

(2004) and Harrison et al. (2009) reported that homes

in industrialized countries with ETS presented higher

B[a]P levels than homes without the presence of ETS

(0.01–0.58 ng/m3).

Figure (9): Seasonal and annual percentage of the total carcinogenic compounds in indoor air of sites under investigation.

The mean annual concentration of B[a]P in all homes was 70 ng/m3. The value of B[a]P recorded for Egyptian

homes were much higher than concentration found in many studies for B[a]P in the indoor air of many

countries such as the mean concentration value of 3.73 ng/m3 reported by Delgado-Saborit et al. (2011) in the

indoor environments; and 0.01–0.65 ng/m3 recorded for European homes (Fischer et al., 2000; Fromme et al.,

2004; Gustafson et al., 2008; Harrison et al., 2009); it is also higher 0.21–3.4 ng/m3 recorded in Asian urban

homes (Li and Ro, 2000; Chao et al., 2002).

The annual mean concentration of B[a]P in the present study exceeds the Ambient Air Quality Standards

(AAQS) set for B[a]P in many countries. Such as the upper limit (2.5ng/m3) of the Chinese AAQS, and the

annual standard (1.0ng/m3) (Delgado-Saborit et al., 2011), and the value of 0.25 ng/m3 set by the UK air

quality standard (EPAQS, 1999).

BAP-equivalent carcinogenic power (BAPE): Table (4) shows the annual means of B[a]P -equivalent

carcinogenic power (BAPE) and ∑ PAH16 Carcinogenic concentrations at indoor air of the selected houses.

From this table, it is clear that, the highest BAPE value was found at site 1, while the minimum BAPE value

44

was found at site 2. B[a]P -equivalent carcinogenic

power (BAPE) were 193.04, 92.91, 145.91 and

106.47 at sites 1, 2, 3 and 4, respectively. Indoor

BAP-equivalent carcinogenic power (BAPE) in this

study is much higher than those reported by Ohura et

al. (2004b) in Shizuoka (Japan), Chang et al. (2006)

in urban of Taiwan, Tuntawiroon et al. (2007) in

Thailand, Akyuz and Cabuk (2008) in Turkey, Ras et

al. (2009) in Tarragona (Spain) and by Delgado-

Saborit et al. (2011). Relation between PAHs

Concentrations (I/O Ratio) in Indoor and Outdoor:

The average ratios of indoor/outdoor PAHs

concentrations are given in table (5), and the

comparison between indoor and outdoor PAHs

annual mean concentrations at sites under

investigation are shown in figure (10).

Table (4): Annual means of total carcinogenic PAH concentration (ng/m3) and B[a]P - equivalent carcinogenic

power (BAPE) in indoor air of the investigated sites.

Site ∑ PAH Carcinogenic BAPE

Site 1 328.96 193.04

Site 2 229.39 92.91

Site 3 420.46 145.91

Site 4 316.08 106.47

Table (5): Ratio between indoor and outdoor (I/O ratio) PAHs annual mean concentrations at sites under

investigation

I/O ratio for

PAHs

PAHs

Site 1 Site 2 Site 3 Site 4

NAP 1.54* 2.63* 0.93 0.99

ACY 1.98* 0.28 1.06* 3.86*

ACE 1.20* 0.74 1.15* 1.27*

FLU 1.49* 0.34 0.46 4.95*

PHE 4.06* 0.67 0.47 2.30*

ANT 0.31 3.22* 0.99 1.86*

FLT 3.45* 0.27 0.84 11.79*

PYR 4.61* 0.65 0.20 92.20*

BAA 3.44* 0.58 0.62 0.81

CRY 1.51* 0.49 0.71 0.72

BBF 0.18 0.15 2.57* 524.73*

BKF 0.88 0.26 0.13 3.38*

BAP 2.75* 0.41 1.37* 12.44*

DBA 1.24* 17.01* 4.41* 1.21*

BGP 2.82* 0.22 3.29* 1.55*

IND 0.20 2.41* 0.32 1.11*

Mean 1.35* 0.75 1.24* 2.11*

*> I/O is more than 1

45

Figure (10): Comparison between indoor and outdoor PAHs annual mean concentrations at sites under investigation.

From table (5) it can be observed that I/O ratio for

low-molecular-weight PAHs (two and three rings)

are usually higher than 1 at all sites under

investigation (except for site 2) which means that the

concentrations of low-molecular-weight PAHs (two

and three rings) are usually higher indoor air than

outdoor one due to sources inside the building.

I/O concentration ratios for MML such as FLT and

PYR were higher than 3 at sites 1 and 4, while I/O

ratios for BAA and CRY were higher than 3 and 1,

respectively, at site 1. This confirms that indoor air of

homes is highly influenced by local indoor sources

such as generally tobacco smoking, heating or

cooking sources (Vanrooij et al., 1994; Naumova et

al., 2002).

Some HMW I/O concentration ratios were observed

to be more than 1, such as BBF and IND at sites 2

and 4, BKF at site 4, DBA at sites 1, 2, 3 and 4 and

BGP at sites 1, 3 and 4.

The I/O concentration ratios of BAP ranged from

0.41 at site 2 to 12.44 at site 4.

This variety in I/O concentration ratios across

different homes suggesting that ratios are affected by

variables such as differences in combustion sources

and heating systems, climatic conditions and

ventilation habits (Chao et al., 2002)..

From table (5) and figure (10) it can be noticed that

the I/O annual mean concentration ratios for ∑PAHs

were higher than 1 at sites under investigation except

at site 2 (1.35, 1.24 and 2.11 at sites 1, 3 and 4,

respectively).

CONCLUSIONS

The concentration of 16PAHs in particulate matter of

both indoor and outdoor air of Helwan city (south

Cairo, Egypt) were measured simultaneously. The

annual mean concentration of ∑PAHs (the

summation of 16 PAHs) over Helwan city was

708.9ng/m3 while in the indoor air it ranged from

694.7ng/m3 at site 2 to 1038.7 ng/m3 at site 3. The

average annual mean concentration of B[a]P over

46

Helwan city was 34.8ng/m3. The mean annual

concentration of B[a]P in all homes was 70 ng/m3.

B[a]P -equivalent carcinogenic power (BAPE) in

outdoor air were 99.96, 162.31, 71.1 and 36.75 at

sites 1, 2, 3 and 4, respectively. On the other hand , in

indoor air were 193.04, 92.91, 145.91 and 106.47 at

sites 1, 2, 3 and 4, respectively.

The most abundant PAHs in ambient and indoor air

during the period of study were LMW (2 and 3rings)

at all sites except site 2 which had higher

concentration of MMW (4 and 5 rings). This may be

attributed to the presence of heavy traffic near this

site.

ACKNOWLEDGMENT

The authors would like to thank the National

Research Centre, Egypt, and the Air Pollution

Department for the opportunity and support to carry

out this research.

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