Distribution of 10 Micron Sized Particulate Matter

(PM10) in the Air-Shed of Port Harcourt Metropolis

and Environs

1Ini U. Ubong,

2Ifenyi C. Anunuso,

3Emmanuel J. Ejike,

4Uwem U. Ubong and

5Etim U. Ubong

1 Institute of Pollution studies (IPS)

Rivers State University of Science and Tech.

Port Harcourt, Rivers State. Nigeria.

iniubong12@hotmail.com 2,3Dept. of Chemistry

Federal University of Technology, (FUTO)

0werri, Nigeria. 4Dept of Chemistry

Akwa Ibom State University of Science & Technology

Mkpat Enin

Akwa Ibom State. Nigeria. 5Center for Fuel Cell Systems Research & Powertrain Integrations

Kettering University

1700 University Avenue, Flint, MI 48504, USA.

Abstract: PM10 (Particulate Matter with ten

microns size) concentrations were determined

and evaluated in Port Harcourt, (Nigeria)

Metropolis and Environs. The sampling was

performed with well calibrated equipment (A

Multi-RAE PLUS (PGM – 50) a programmable

Multi Gas monitor with an electrochemical

sensor). The parameter assessed was particulate

matter with, 10µm size fraction (PM10). The

temporal distributions of PM10 for all the

sampling sites show data range at Igwuruta

(Control) varied from 27.3 – 1642.4 µg/m3 with a

mean of 188.1 ± 458.7 µg/m3. Seasonal Variation

for PM10 concentrations were catalogued into

dry and wet seasons. Dry season was observed

as the season with highest particulate PM10,

while the wet had the lowest PM10. Test of

significance showed dry to be significantly

different from the wet [tstat (4.3532).05 ≥ tcri

(2.0017).05].

Keywords: PM10, Particulate Matter with ten

microns size, Temporal Variation, Air Basin,

Port Harcourt, Nigeria.

1 INTRODUCTION

Particulate matter is a natural part of the

atmosphere, where the solid or liquid particles

are suspended in the air [1]. These suspended

particles, also known as suspended particulate

matter represents a dispersion aerosol system. In

the air, there are many types of microscopic

airborne particles originated from both natural

and anthropogenic processes, such as

atmospheric clouds of water droplets, photo-

chemically generated particles, re-suspended

particulates, fumes arising from the production

of energy, etc. [1]. Increase in PM10 particulate

matter air contamination and the negative impact

on human health have led to efforts to monitor,

quantify and document this pollutant in this

study.

The effects of inhaling particulate matter have

been widely studied in humans and animals as

documented effects include: asthma, lung

cancer, cardiovascular issues, and premature

death [2]. The size of the particle is a main

determinant of where in the respiratory tract the

particle will rest when inhaled. Larger particles

are generally filtered in the nose and throat and

do not necessarily cause problems, but

particulate matter smaller than 10 micrometers

(µm), referred to as PM10, can settle in the

bronchi and lungs and cause health problems.

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© 2015 IJAIR. All Rights Reserved 232

Seinfeld and Pandis [3] reported that the 10

micrometer (μm) particle size does not represent a

strict boundary between respirable and non-

respirable particles, but has been agreed upon for

monitoring of airborne particulate matter by most

Regulatory agencies.

JOKSIĆ, et al. [4], studied daily deposits of PM10,

PM2.5 and PM1 aerosol fractions which were

collected during spring and autumn sampling

periods in 2007. Gwinn and Vallyathan [5], also

reported that comprehensive toxicological and

epidemiological studies conducted over the last

decades have implicated human exposure with

small airborne particles (PM10 and less). These

have adverse health effects and may be a cause of

a number of respiratory and cardiovascular

inflammations.

In another study, Reiss, et al. [6], and Heal, et al.

[7], reported that during inhalation, the coarse

particulate fraction usually remains in the upper

part of the airways and lungs but, the fine

particles penetrate deeper and reach the alveolar

region. The chemical composition of air

particulate matter fractions thus becomes very

important and engrosses both scientific and public

auditory.

In a number of studies, investigators have

observed an increased incidence of respiratory

diseases in association with PM10 air pollution.

For example, in a study conducted in the United

Kingdom, an association between emergency

hospital admissions for respiratory and

cardiovascular disease and PM10 was found [8].

Similarly, another study conducted in Seattle,

Washington, demonstrated association with

emergency room visits for asthmatics and PM10

air pollution [9]. In addition, PM10 was associated

with an increase in hospital admission of the

elderly for Chronic Obstructive Pulmonary

Disease, COPD and asthma and lower respiratory

tract infections including bronchitis and

pneumonia [8, 11, 12].

In addition, a study conducted in Canada by

Burnett et al., (13), found that increases of 10

mg/m3 in PM10 and PM2.5 were associated with

1.9% and 3.3% increases in respiratory and

cardiac hospital admission respectively.

Epidemiological studies have shown the

relationship between PM10 exposure and an

increase in bronchitis, chronic cough, and

respiratory symptoms in persons with COPD [14,

15].

The objective of this study was to quantify levels of

PM10 fraction in ambient air in Port Harcourt and the

environs and document possible levels in this region.

Location and Description

The study areas were located in Port Harcourt

metropolis and the others in Igwuruta and Onne

towns. These two (Port Harcourt and Igwuruta) are

in Ikwerre Local Government area, while Onne town

is in Eleme Local Government area, in the outskirt of

Port Harcourt, all in Rivers State, Nigeria. Port

Harcourt is an industrialized cosmopolitan city

located in the heart of the Niger Delta. The study

areas lie south east of the Niger Delta within

Latitudes 4o 31’ - 4

o 40’N and Longitudes 7

0 0’ - 7

o

10’E. It has an elevation of about 10 – 15 m above

sea level.

2. MATERIALS and METHODS

Ten sampling sites were selected for the collection of

air quality measurements. The sampling was

performed with well calibrated equipment (A Multi-

RAE PLUS (PGM – 50). The parameter measured

was particulate matter of 10 micron size (PM10). This

was monitored 1.5m above ground level from January

to December. These study locations were selected

based on the wind rose of Port Harcourt city and

certain other criteria like accessibility, ease of sample

collection, and nature of activities within the location

and low risk of vandalism.

3. RESULTS

Temporal Distribution

(a) Diobu, Agip and UST (Diobu Air Basin)

Three sites (University of Science and Technology),

UST campus, Diobu residential and Agip estate)

made up the Diobu air basin because they are in the

same regional airshed, sharing residential and

commercial characteristics. Looking at the individual

sites, for example, UST, it is clear that some

characteristics were lost in the air basin. UST had the

lowest monthly distributions with only one prominent

peak in January while other peaks were generally less

than 50 µg/m3. The temporal distributions of PM10 for

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© 2015 IJAIR. All Rights Reserved 233

the three sites that made up the Diobu Air Basin

showed peak in January, with other peaks in

March May and October. Each peak is more than

100 µg/m3. The highest of the peaks occurred in

January and exceeded 1000 µg/m3 followed by

May (Fig. 1). The lowest peak was in September

followed by June and July.

Fig.1: PM 10 distribution in Diobu air basin

As an air basin (Diobu Air Basin), PM10 ranged

from 10.3 – 1147.9 µg/m3 with a mean of 167.0 ±

306.9µg/m3. Very high peaks were generally

observed in January both in the individual sites

and in the air basin. A slight peak was obtained in

March, May and October. Low peaks were

obtained in August, June, and July with a

minimum in September (Fig. 1).

(b) City Center Air Basin (Rumuola, Rumuomasi

and Stadium Road)

This air basin also displayed temporal variation with

a prominent peak in January and one other peak

exceeding 100 µg/m3, which occurred only in March.

Other observations showed a sharp drop in February

with the lowest coming in September and other low

peaks in June and July. Of interest was the August

peak which was higher than those of June, July and

September (Fig. 2).

A plot of the temporal distribution is shown in Fig. 2

for the City Centre Air Basin. Temporal distribution,

like in Diobu, showed the highest peak in January with

a sharp drop in February. Other peaks were observed in

March, August and November. However, low peaks

were obtained in June, July with a minimum in

September

Fig. 2 PM 10 distribution in City Center air basin

Onne Air Basin (IITA, RIAT and Onne town)

Temporal variation exhibited by this air basin followed

the trend exhibited by other air basins in that, the

highest peak came in January. Contrary to observation

at other air basins, there was a peak in September about

100 µg/m3. All other peaks were less than 100 µg/m

3.

The lowest peak occurred in August rather than

September (Fig. 3).

Onne Air Basin (IITA, RIAT and Onne town)

Temporal variation exhibited by this air basin followed

the trend exhibited by other air basins in that, the

highest peak came in January. Contrary to observation

at other air basins, there was a peak in September about

100 µg/m3. All other peaks were less than 100 µg/m

3.

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The lowest peak occurred in August rather than

September (Fig. 3).

Fig. 3: PM 10 distribution in Onne air basin

. As an air basin, mean PM10 varied from 15.1 –

1134.5 µg/m3 with a mean of 154.1 ± 308.2 µg/m

3

with a very high variability. Three peaks were

easily observable in January, March and

September (Fig. 3). In this air basin, lows were

observed in April, May, June, July and August

with a minimum in April.

d) Igwuruta (Control)

The data varied from 27.3 – 1642.4 µg/m3 with a mean

of 188.1 ± 458.7 µg/m3 (Fig. 4). The temporal variation

was marked with a rise and falling pattern like in other

air basins. The highest peak was obtained in January

other peaks were less than 100 µg/m3 in April and

September. Low values were in May, November with a

minimum in August. There was no August break.

Fig.4: PM 10 distribution in Igwuruta control air

basin

4 SEASONAL VARIATIONS

(a) Two Seasons

PM10 concentrations were catalogued into dry and

wet seasons (Fig. 5). Dry season was observed as

the season with the higher particulate PM10 level,

while the wet had the lower PM10 (Fig. 5). The

Test of significance showed dry to be significantly

different from the wet (p≥).05.

(b) Four Seasons

PM10 variations, during the four seasons are

shown in Fig. 6. Dry season PM10 was the highest

while wet had the lowest peak. Test of

significance showed that differences in means

were significant for dry and wet (p≥).05; for dry

and early dry (p ≥.05)

Fig. 5: Seasonal variation of PM 10 in dry and wet Seasons

Fig. 6: Seasonal variation of PM10 in four seasons

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© 2015 IJAIR. All Rights Reserved 235

Fig. 7: Comparison of PM 10 in hamattan

season with other seasons.

(c) Hamattan and Four other Seasons

Hamattan had the highest PM10 followed by dry

season. The wet season had the lowest peak. Test

of significance showed mean differences were

significant between hamattan and early dry (p

≥).05; hamattan and early wet [p≥1).05]; hamattan

and wet (p≥1)05; hamattan and dry [p ≥ 1] 05.

5 SPATIAL DISTRIBUTIONS

PM10 distributions across all ten sites are

presented in Fig. 8. Spatial differences were

observed with the highest maximum and mean at

Stadium Road and lowest at RIAT.

Fig. 8: Spatial distribution of PM 10 in all study

sites

Mean differences as tested for test of significance

showed that Igwuruta, the control, was not

different from Onne air basin (p≤.1)01; Igwuruta

was not also different from City Centre [(p≤ 1).01];

Igwuruta and Diobu (p≤ 1).

6 ANALYSIS of VARIANCE (ANOVA)

Analysis of variance is shown in Table 1. There

was no variance arising from stations. This is

confirmed by the values of F as Fstat (1.0606).01 <

Fcri (2.59).01. Conversely, Fstat (157.8) .01 ≥ Fcri

(2.4).01 in months. The F factor showed

significant interaction even at 95%: Fstat (157.8) .05

≥ Fcri (1.8).05 for the months (Table 2).

Table 1: ANOVA Summary table for PM10 at 99% Source of Variation SS df MS F P-value F crit

Rows 70292.0317 9 7810.226 1.060596 0.398599 2.591747

Columns 12783567.6 11 1162143 157.8141 1.38E-57 2.432147

Error 729035.699 99 7363.997

Total 13582895.3 119

Table 2: ANOVA Summary table for PM10 at 95% Source of

Variation SS df MS F P-value F crit

Rows 70292.0317 9 7810.226 1.060596 0.398599 1.975806

Columns 12783567.6 11 1162143 157.8141 1.38E-57 1.886684

Error 729035.699 99 7363.997

Total 13582895.3 119

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DISCUSSIONS

PM10 Particulate Matter

Temporal and Seasonal Variations

(a) Diobu, Agip and UST (Diobu Air Basin)

Wide variability at all sites is explained by

monthly and seasonal fluctuations. Excessive

particulates in January is attributable to hamattan

effects. Very low particulate level in September

was due to the scavenging effect of precipitation.

September is the month with highest rainfall

amount. Rainfall has been reported to have the

greatest effect on particulate air quality. Of all

meteorological parameters, it has been shown to

have the greatest effect of washing particles out of

the air [15].

Excessive particulates reaching 1,177.9 µg/m3 in

January was due to Hamattan effects; due to the

dry season air masses in operation, etc. North

Easterlies that blow across the Sahara desert (arid

region) coming ladened with dust and particulate

matter; which is excessive in January. January is

also known for hamattan effects, brought about by

the same North Easterlies. A sharp drop in

February was due to the first rainfall which

washed off particulate loading.

Four intervals of peak emergence corresponded

with periods of changing season e.g. dry season,

early wet, wet season and early dry. Differences

in timing of peak emergence depended on varying

meteorology, time of arrival, duration and

intensity of rainfall, terrain type and degree of

shielding.

Minimum concentration corresponded with

periods of highest rainfall which scavenged

particulates off the air. The more the rainfall

amount, the more scavenged the particulates are,

leading to low values. It has been reported that of

all meteorological parameters, rainfall has the

greatest effect on air quality. Rainfall washes

particles out of the air and stops re-entrainment of

particles [15].

Most sites experienced lowest peaks in

September, July or May or August. These are

intense rainy months. Lowest peak occurring in

which month depended on which month received

the highest rainfall. On the average September

and July have the bimodal rainfall peaks.

Sometimes, there are changes due to climatic

variations earlier explained.

(b) Rumuola, Rumuomasi and Stadium Road

(City Centre Air Basin)

The pattern of observation was similar to that of

Diobu. This was characterized by high variability

as usual. The highest peak in January is

attributable to hamattan while a sharp drop in

February is due to effect of first rains.

(c) City Centre

Similar explanation goes for City Centre

observations where highest reading in January is

attributable to hamattan. Sharp drop in February is

attributable to early rains. Other very low peaks

were attributed to the scavenging effect of intense

rainfall. Apart from January and March, peaks

were generally below 80.0µg/m3 except in

October to December when they were below

100.0µg/m3.

(d) IITA, RIAT and Onne (Onne Air Basin)

Apart from January, other peaks were generally

below 50.0µg/m3. Lower monthly particulate

distribution is due to the unique geographically

location of Onne, which allows it enjoy more

rainfall, thus resulting in reduced particulate.

(e) Igwuruta Air Basin

The temporal rising and falling pattern was also

observed here. This is because Igwuruta is

influenced by the same meteorological factors that

govern particulate distribution.

T-test showing significant difference meant that

particulate loading in dry season is statistically

different from that of wet. The results also

showed that even in the four seasons, that dry was

significantly different from all seasons. The

reason is in the absence of rainfall in dry season

resulting in particulate build up during the season.

At other seasons, there is rainfall in varying

intensity scavenging particulate from the

atmosphere, thus low particulate is obtained.

CONCLUSIONS

The study set out to investigate the levels of PM10

in Port Harcourt metropolis and the environs in

Nigeria. The study showed that the air quality,

irrespective of station, is dominated by excessive

particulates (PM10) with maximum reaching

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© 2015 IJAIR. All Rights Reserved 237

almost 2,000 µg/m3 especially in the month of

January. It was further observed that of all

meteorological parameters, rainfall had the

greatest effect on air quality.

ACKNOWLEDGEMENT

The authors are grateful to everyone who

contributed to the successful completion of the

study.

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