Research Article, Issue 1

Analytical Methods in Environmental Chemistry Journal

Journal home page: www.amecj.com/ir

AMECJ

1. Introduction

In recent decades, the various pollutants are

being detected in urban areas which are mainly

caused by fossil fuel components. They include

a wide spectrum of hydrocarbons. The aromatic

hydrocarbons are either bio-chemically or

biologically active and are potentially carcinogenic

or are by-products of benzene. Many of the recent

researches indicate the adverse effects of benzene

on human health. Although VOCs are quite

important, there have been few studies conducted in

this regard in Tehran metropolitan [1-2]. The main

emphasis has been on measurement, monitoring

and control of VOCs in the last 10 years. The

concentration of hydrocarbons in Tehran is much

higher than other cities in the world (the benzene

and butadiene 1 & 3 levels in Tehran are 10 and 18

times the permissible standards). [2].

Amongst the hydrocarbons, benzene due

* Corresponding Author:A. Mirzahosseini

E-mail: mirzahosseini@gmail.com

https://doi.org/10.24200/amecj.v2.i01.47

Seyed Alireza Hajiseyed Mirzahosseinia,*

a Department of Environmental Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University,

Tehran, Iran

Environmental Health Analysis: Assessing the emission levels of

benzene from the fuel tanks doors of the vehicles in Tehran city

A R T I C L E I N F O:

Received 16 Nov 2018

Revised form12 Feb 2019

Accepted 30 Feb 2019

Available online 19 Mar 2019

------------------------

Keywords:

Volatile Organic Compounds

Benzene emission

PhoCheck

Domestic cars

Analysis of benzene in Air

A B S T R A C T

In this study, 350 vehicles in 20 different models were examined in one

of Tehran’s Automobile Technical Inspection Centers. The laboratory tests

indicate that longtime exposure to benzene has destructive effects on the

blood cells, especially the bone-marrow cells. The concentration levels of

benzene caused by the emission of gasoline vapors from fuel tanks doors

were measured by PhoCheck EX5000 during a 5 to 15-minute interval for

each car. The results indicate that the concentration of benzene caused by

the emission of gasoline vapors from the fuel tanks door of the domestic

cars was 10 times higher than the imported cars. In most of the imported

cars, the amount of benzene in the three measured areas was negligible. This

is due to the use of new technology and adaptation of strict environmental

standards by the manufacturing country.

Emission levels of benzene from the fuel tanks; Seyed Alireza Hajiseyed Mirzahosseini

Analytical Methods in Environmental Chemistry Journal Vol 2 (2019) 49-54

50 Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)

to its carcinogenic effects has an especial

importance. The main sources of benzene

emission in Tehran are the motor vehicles

and the gas stations (due to the evaporation

of fuel and lack of the fume control system).

Majority of the vehicles in Tehran are run

on gasoline and regrettably, their consumed

gasoline has high benzene content (about

5% of the weight). Moreover, most of the

automobiles manufactured domestically lack

environmental standards. They can only attain

Euro 2 Standard that was ratified in 1996.

This is done through modifications in their

appearance and the pollution control systems.

Meanwhile, the production lines of reference

companies like Peugeot 405 and Kia Pride

have stopped abroad more than a decade ago.

It is important to point out that the two major

auto manufactures of Iran, namely SAIPA and

Iran Khodro assemble the decade-old products

of the aforesaid companies. [2]

Various studies are conducted on the effect

of domestically produced fuel and vehicles’

quality on air pollution. Similar researches

are conducted in Brazil and Pakistan.[ 3-4].

Batterman in 2005 studied the amount of

benzene emitted from the fuel tank. Based on

his measurements, the average level of benzene

emission was 2 milligrams per hour. For old

vehicles, this amount reached 62 milligrams

per hour. In this study, the replacement of the

gas cap and the washer of the fuel tank were

regarded as measures to reduce the amount of

evaporated fumes [5]. It is important to point

out that the Iranian and international standard

level of benzene in ambient air is 1.56 ppb

and in advanced countries like Japan is 0.69

ppb. For most countries in the world, the Euro

4 standard was used in 2005[6].

The laboratory tests indicate that longtime exposure

to benzene has destructive effects on the blood cells,

especially the bone-marrow cells. These effects

cause the reduction in production of bone-marrow

cells and anemia. The long term effect of benzene is

leukemia. Environment Protection Agency (EPA)

categorizes benzene in group A of carcinogenic

substances. Also, the International Agency for

Research on Cancer (IARC) refers to benzene as a

carcinogenic substance for humans[7-9].

2. Material and Methods

In this research, the benzene concentration is

measured by PhoCheck EX5000 equipment.

This device is portable and with the aid of Photo

Ionization Detector (PID) mechanism can measure

the benzene concentration level with high precision

(± 1 ppb). The PhoCheck takes samples from the

gasoline fumes with the flow rate of 220 millimeters

per minute. This device with its high precision

(ppb level) samples the benzene through a portable

laboratory chromatograph. It is important to point

out that Krypton lamp of 10.6 eV is used in this

device. One of the most important advantages of this

equipment is its approved technology to determine

the benzene concentration with the accuracy of 1

ppb to 10000 ppm as well as its good performance

in weathers ranging from -20 to 60 degrees[10].

In this study, 350 automobiles encompassing

20 models are examined in the Automobile

Technical Inspection Center of Tehran. The

benzene concentration due to the gasoline fume

is measured at three important spots namely,

the gas cap, muffler and inside the cabin during

a period of 5 to 10 minutes (for each car). It

Emission levels of benzene from the fuel tanks; Seyed Alireza Hajiseyed Mirzahosseini

is important to point out that all the cars were

tested for the fume emission, after they received

their certificate from the Technical Inspection

Center. All the Iranian made cars are required

to be inspected annually after the 2nd years of

production and obtain the certificate. For the

ease of study, 350 automobiles were divided

into two categories’ of imported and domestic

vehicles.

In most of the studied cars, there were three

protective valves for the gas cap (except the

Peugeot 206). The protective valve has a physical

function without being in direct contact with the

gasoline and its fumes. However, if the first valve

(which is in direct contact with the gasoline and the

fumes) fails, the leaked fumes would enter the small

chamber of the protective valve for subsequent

release to the atmosphere.

The second valve plays its role in controlling the

fumes and the overflow of gasoline. In most of the

domestically manufactured cars (except Renault

L90), this valve does not exist. Figure1 illustrates

the position of the three valves and the means to

measure benzene. During measurement, the engine

is off and only the protective valve is open. Since the

valve in Peugeot 206 is in one piece, only the space

between the chassis and the gas cap is sampled.

Unfortunately, in Peugeot 405 with carburetor, the

Table 1. The minimum, maximum and average concentration levels of benzene in 12 models of imported cars (the

amounts are in ppb)

Car Type Hyundai Nissan Mazda Gol Kia Zantia Roniz Cielo Toyota Prado Benz BMW

Average 0.03 0.98 0.21 0.86 0.16 0.34 2.34 0.57 0.68 0.12 0.15 0.1

Max 0.397 3.6 0.83 9.4 0.98 0.97 6.9 2.3 4.3 0.3 0.73 0.7

Min 0 0 0 0.82 0 0 0 0 0 0 0 0

Fig. 1. Sampling method of the fuel tank, the protective valve, primary and secondary valves (if present)

3-Primary valve

2-Secondary valve

1-Protective valve

Protective valve

52 Analytical Methods in Environmental Chemistry Journal; Vol. 2 (2019)

gasoline fume was emitted from other parts of the

car (underneath the fuel tank and the engine).

3. Results and Discussion

3.1. concentration levels of benzene in 12 models

of imported cars

The imported automobiles consisted of 116

vehicles from 12 company models. The results

indicated that Gol (manufactured by Volkswagen)

has the highest amount of benzene leakage from

the gas cap. The average concentration of benzene

in this group is 86.5 ppb. The lowest concentrations

of benzene were detected in Hyundai, Kia,

Mercedes Benz, BMW and Prado in amounts of

0.03 ppb, 0.16 ppb, 0.15 ppb, 0.01 ppb and 0.12

ppb, respectively. It is important to point out that

Mercedes Benz and BMW models in 70 percent of

the cases registered zero concentrations (the best

condition). With respect to the fuel type (super and

regular gasoline), 28 percent of the samples used

were super unleaded gasoline (Octane number of

95) and 72 percent were regular unleaded gasoline

(Octane number of 87). The average age of the

vehicles in this classification was 3.8 years. About

65 percent of the sampled automobiles had less

than 3 years of operation.

In Table (1), the minimum, maximum and average

concentrations of benzene are provided. The

minimum amounts of measured benzene in all

models, except Gol, were zero. Gol model showed

the highest benzene leakage from the gas tank.

It is important to point out that the most important

reasons for the emission of benzene fumes in this

category are lack of tightening the gas cap and

over fueling (pumping too much gasoline into the

fuel tank). The average concentration of emitted

benzene from the fuel tank of the imported vehicles

(116 automobiles) is 0.96 ppb.

3.2. concentration levels of benzene in 8 models of

domestic vehicles

In the domestically manufactured auto category,

a total of 234 cars in eight various models are

investigated. Based on the results, Paykan and

Pride show the highest leakage of benzene from the

gas cap with the average benzene concentrations

of 21.76 and 86.43 ppb, respectively. It should be

pointed out that the average age of the examined

automobiles was 4.8 years, where 65% of the

sampled cars had less than 5 years of age. In regard

to the fuel type consumption, the super and regular

gasoline was used 22.2% and 77.8%, respectively.

The lowest concentrations of benzene are detected

in Rio and Peugeot 206 as 0.43 and 3.09 ppb,

respectively. It is important to mention that Peugeot

206 has registered zero concentration in over 35%

of its samples. Table 2 presents the minimum,

maximum and average benzene concentration.

It reveals that the minimum benzene concentration

in all models except Paykan was zero. The primary

Table 2. The minimum, maximum and average concentration of benzene in domestic vehicles in 8 models (measured

in ppb)

Car Type Tondar 90 Paykan Pars 405 206 Pride Samand Rio

Average 6.59 76.21 26.21 6.83 3.09 43.86 3.94 0.43

Max 38.2 296 151 59.6 51.5 295 7.35 1.95

Min 0 2.06 0 0 0 0 0 0

Emission levels of benzene from the fuel tanks; Seyed Alireza Hajiseyed Mirzahosseini

reasons for the emission of benzene fumes in this

group are technical defects of the primary gas

cap, lack of the secondary gas cap, over fueling

and lack of canister system. Also, about 9% of

the domesticated vehicles run on carburetors

whose average benzene concentration (in 234

automobiles) is 20.89 ppb. As it is shown in Table

2-2, the emission from the gas caps goes up as the

age of the vehicle increases.

4. Conclusions

Majority of the domestic cars emit high levels

of benzene from the gas cap, muffler and the

gas tank. The best and worst domestically

manufactured automobiles are Peugeot 206 and

Pride, respectively. The most prominent reasons for

high concentration of benzene in this category are

the lack of appropriate catalyst system, technical

defects in fuel system, and fuel leakage from the

gas cap. Amongst the imported car category, Kia

and Hyundai groups have the lowest emission of

benzene. In most of the imported cars, the amount

of benzene in the three measured areas was

negligible. This is due to the use of new technology

and adaptation of strict environmental standards by

the manufacturing country.

Based on the research results, the amount of benzene

concentration due to the leakage of gasoline fumes

from the gas cap in domestic cars is approximately

ten times higher than the imported cars. In Pride

models, the level of gasoline fume emission is

considerable and the benzene concentration is

15 times higher than Peugeot 206. Moreover, the

average benzene concentration from the emission

of gasoline fumes from the gas cap of the imported

cars is less than 6 ppb. However, this number for

much of domestic cars was higher than 6 ppb. Pride

is identified as the most polluting vehicle in the

domestic car category. The research results indicate

that the annual inspect of the gas tank, periodical

replacement of washer, and modification of the gas

cap system in the domestic cars have significant

impact on the reduction of gasoline fumes.

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[7] Agency for Toxic Substances and Disease Registry

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