Carbon footprint of shopping (grocery) bags in China, Hong Kong ...

Carbon footprint of shopping (grocery) bags in China, Hong Kong and India
Subramanian Senthilkannan Muthu, Y. Li *, J.Y. Hu, P.Y. Mok
Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
article info
Article history:
Received 8 July 2010
Received in revised form
28 August 2010
Accepted 23 September 2010
Keywords:
Plastic bags
Paper bags
Non-woven bags
Woven bags
Life cycle impact assessment
SIMAPRO
IPCC 2007
Carbon footprint
Recycle
Reuse
Disposal to landfill
1. Introduction
abstract
Human beings exert tremendous pressure on our earth, from
which there has been a severe damage caused to the natural
environmental system, and global environmental change due to
excessive carbon emissions is one of the most important changes.
The impact of global environmental change has been a topic of
interest for many researchers in different fields. Among the various
effects, the impact of climate change on human health is of greatest
concern and has attracted close attention (McMichael et al., 2006;
* Corresponding author. Tel.: þ852 2766 6479; fax: þ852 2773 1432.
E-mail address: tcliyi@inet.polyu.edu.hk (Y. Li).
1352-2310/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.atmosenv.2010.09.054
Atmospheric Environment 45 (2011) 469e475
Contents lists available at ScienceDirect
Atmospheric Environment
journal homepage: www.elsevier.com/locate/atmosenv
Carbon footprint has become a term often used by the media in recent days. The human carbon footprint
is professed to be a very serious global threat and every nation is looking at the possible options to
reduce it since its consequences are alarming. A carbon footprint is a measure of the impact of human
activities on earth and in particular on the environment; more specifically it relates to climate change
and to the total amount of greenhouse gases produced, measured in units of carbon dioxide emitted.
Effort of individuals in minimizing the carbon footprint is vital to save our planet. This article reports
a study of the carbon footprint of various types of shopping bags (plastic, paper, non-woven and woven)
using life cycle impact assessment (LCIA) technique in two stages. The first stage (baseline study),
comprised the study of the impact of different types of shopping bags in the manufacturing phase,
without considering their usage and disposal phases (cradle to gate stage). The LCIA was accomplished by
the IPCC 2007 method, developed by the Inter Panel on Climate Change in SIMAPRO 7.2. The GWP (Global
Warming Potential) values calculated by the IPCC 2007 method for 100 years were considered as
a directive to compare the carbon footprint made by the different types of shopping bags under
consideration. The next stage was the study of the carbon footprint of these bags including their usage
and disposal phases (cradle to grave stage) and the results derived were compared with the results
derived from the baseline study, which is the major focus of this research work. The values for usage and
end-of-life phases were obtained from the survey questionnaire performed amongst different user
groups of shopping bags in China, Hong Kong and India. The results show that the impact of different
types of shopping bags in terms of their carbon footprint potential is very high if no usage and disposal
options were provided. When the carbon footprint values from different disposal options were
compared, the carbon footprint values were lower in the case where a higher percentage of reuse is
preferred to recycling and disposing to landfill. The results indicate that a higher percentage of reuse
could significantly scale down the carbon footprint. Once the shopping bags reached the point where
they can no longer be reused, they must be forwarded to recycling options, rather than being disposed to
landfill. At this juncture, consumer’s perceptions and behaviours in connection with the respective
government’s policies in promoting & facilitating recycling systems could be critical in reducing the
carbon footprint of various shopping bags.
Ó 2010 Elsevier Ltd. All rights reserved.
Haines et al., 2006). The major risks posed by climatic change to
human health may have both direct and indirect causes and the
major possible health risks could be: 1. Effects of heat waves and
other extreme events (cyclones, floods, storms, wildfires);
2. Changes in patterns of infectious disease; 3. Effects on food
yields; 4. Effects on freshwater supplies; 5. Impaired functioning of
ecosystems (for example, wetlands as water filters); 6. Displacement
of vulnerable populations (for example, low lying island and
coastal populations); 7. Loss of livelihoods (McMichael et al., 2008).
A carbon footprint is a measure of the impact of human activities
on the environment (in particular climate change) in terms of the
amount of greenhouse gases produced through burning of fossil
fuels for electricity, heating and transportation, etc. and has units of
tonnes (or kg) of carbon dioxide equivalent (Carbon footprint;

470
Hertwich and Peters, 2009). There are two types of carbon footprints
- primary and secondary. Primary footprints, which are
under our direct control, are the result of direct emissions of CO2
from the burning of fossil fuels including domestic energy
consumption and transportation (Ex: Usage of electricity and
transportation, etc.). The secondary footprints are related to the
indirect CO2 emissions from the whole life cycle of the products
human beings use - those associated with their manufacture and
eventual breakdown (Ex: Usage of clothes and other products,
recreation and leisure, etc) (Hertwich and Peters, 2009). Human
beings are the major source of carbon emissions and they will be
the most affected by the emissions, particularly those deemed
serious.
Production, usage and consumption of any product pose a threat
to carbon footprint. Shopping bags, a symbol of the throw-away
society, exacerbate the seriousness of the human carbon footprint.
It is worthwhile studying the entire life cycle phase of different
types of shopping bags from the manufacturing stage to the
disposal stage. Once the product is decided to be disposed of, there
may be three possibilities: reuse of the product for the same or for
different purposes; recycle the product; dispose it off to landfill.
Human dimensions in consumer behaviour rule the decision of
a product’s disposal phase and consequently the environmental
impact. Apart from human dimensions, governmental policies also
assume greater significance in the environmental impact. There are
many dimensions of environmental impact caused by shopping
bags; of which global environmental change is one of the prime
concerns and this is discussed in detail in this article. Out of all the
phases of a product’s life cycle, the disposal phase is very critically
related to the environmental issues and is solely decided by the
consumer’s attitude and the governmental policies to facilitate
recycling of the product.
There are different types of shopping bags available to cater for
the shopping needs of people. A variety of raw materials and
technologies are employed to manufacture them, the most popular
of those are plastic, paper, non-woven and woven bags.
Plastic bags are made from non-renewable resources, where the
key ingredients are petroleum and natural gas. Polyethylene-high
density (HDPE), low density (LDPE), linear low-density polyethylene
(LLDPE) are the raw materials widely used for the
manufacture of plastic bags (Lajeunesse, 2004). The shopping bags
used by super markets are ideally produced out of LLDPE to get the
desired thickness and glossy look. And if one needs very thin and
gauzy bags then LDPE would be an ideal choice (Dilli, 2007). A very
detailed explanation of plastic bags manufacturing process can be
referred from (Muthu et al., 2009).
Paper bags are made out of pulpwood from trees, which is
a renewable source. However, we get paper bags from felling trees,
which destroys both plants and animals and the production process
engrosses energy created by coal or natural gas. The created pulp
will be converted into a paper bag by different processes and
machines after consuming a tremendous amount of energy from
fossil fuels, electricity, various chemicals, etc. (Decker and Graff).
Further details about the paper bag manufacturing process can be
referred from (Muthu et al., 2009).
Although non-woven bags made from many different types of
raw materials are available today in the market, the ones made of
polypropylene (PP) are most commonly seen for shopping
purposes (Muthu et al., 2010b). The production process of a woven
bag made out of cotton is cumbersome compared to that of
a non-woven bag and further details of this process can be referred
from (Muthu et al., 2010b).
All products have an impact on the planet. Quantifying
the impact is crucial to reduce it. Among many techniques to study
the eco-impact of a product, life cycle assessment (LCA) is one
S.S. Muthu et al. / Atmospheric Environment 45 (2011) 469e475
of the most widely used and popular ones. LCA examines the
product from its initial (cradle stage) to final stage (grave stage),
covers its entire life cycle, and also evaluates the product in terms of
the environmental impact during its life time.
A life cycle assessment (LCA) is an analytical tool which can help
to understand the environmental impacts from the acquisition of
raw materials to final disposal (SETAC, 1993).
In accordance with the definition given by The Society of Environmental
Toxicology and Chemistry (SETAC), LCA is an iterative
process for evaluating the environmental burdens associated with
a product, process or activity by identifying and quantifying energy
and materials used and wastes released to the environment. LCA
can also be used to assess the impact of those energy and materials
used and released to the environment and can help to identify and
evaluate opportunities to effect environmental improvements. The
assessment includes the entire life cycle of the product, process or
activity, encompassing extracting and processing raw materials;
manufacturing, transportation and distribution, use, reuse, maintenance,
recycling and final disposal (Fava et al., 1991). According to
ISO 14040, an LCA study essentially consists of four interconnected
steps/phases (ISO 14040, 2006):
Goal and scope definition
Inventory analysis
Impact Assessment
Interpretation
Further details about life cycle assessment (LCA) can be found in
(Muthu et al., 2009; SETAC, 1993; Fava et al., 1991; ISO 14040, 2006;
ISO 14044, 2006).
Shopping bags, as an example of unnecessary waste, require LCA
to assess the environmental impact in terms of their carbon footprint.
A large number of studies have been conducted to investigate
the LCA of various shopping bags (Muthu et al., 2009, 2010b;
Brower et al., 1999; Chaffee and Yaros, 2007; Ecobilan, 2008;
Nolan ITU et al., 2002; ExcelPlas Australia et al., 2004; James
and Grant, 2005; FRIDGE; Los Angeles County Department of
Public Works, 2007; Paper vs. Plastic Bags, 1990; Ellis et al., 2005;
www.sustainability-ed.org). Most of the studies focused on plastic
and paper bags. However, very little work has been done on nonwoven
and woven bags compared to plastic and paper bags. And
also there have been no published articles till date focusing
primarily on the carbon footprint created by shopping bags.
Research into the influence of the consumer’s attitude and
governmental policies on this is entirely lacking. This article bridges
the gaps identified above and also describes the impact of different
types of shopping bags on the human carbon footprint and also
how consumer and policy dimensions influence it.
Consumer behaviour and governmental policies play an
important role in the disposal stage of shopping bags. Notwithstanding
the capability of certain types of bags to be recycled and
reused, it is in the hands of customers to reuse a bag until it can be
discarded or recycled, i.e. to reuse the shopping bags many times
till they can be disposed of and to keep them in recycling bins
provided by the government, rather than dispose to landfill, which
is detrimental to the environment as far as eco-impact is concerned.
It is the responsibility of government to provide more
recycling options and viable policies to set things in place in terms
of recycling. Frequent promotion of recycling options by government
and the behaviour of the consumer to reuse the shopping
bags till they can be discarded is crucial in reducing the carbon
footprint.
To determine the attitude of users of shopping bags and to
understand the disposal scenarios, a questionnaire survey was
conducted in China, Hong Kong and India among different user

groups of shopping bags and the findings are reported in (Muthu
et al., 2010a). These three territories were particularly chosen,
since the authors are from these territories and they intend to
create awareness and consequently educate people of the country
to which they belong to. The aims of the survey lie in comprehending
how different user groups use and dispose plastic, paper,
non-woven and woven bags. Usage and disposal behaviors are
defined as how many times people reuse different shopping bags,
what percentage of shopping bags can be recycled/sent to landfill
with the existing possibilities of recycling in their own country and
what percentage of shopping bags people perceive can be reused/
recycled/sent to landfill. Also this survey intends to comprehend
the existing recycling options provided by the government and the
willingness of people to support the government’s policies further
to improve the possibilities of recycling.
2. Research methodology
2.1. Study of impact of various shopping bags on carbon footprint
This paper revolves around the study of global climate change
due to the production, usage and disposal phases of various types of
shopping bags in China, Hong Kong and India. The initial step of this
study is the collection of secondary data for Life cycle inventory
(LCI) for various types of shopping bags for the three countries
under consideration in this present study. For different types of
shopping bags such as plastic (HDPE), paper (Kraft), non-woven
(PP) bags and woven cotton bags, the data were obtained from the
final report prepared for Environment Australia in 2002 (Nolan ITU
et al., 2002). An LCI of different types of shopping bags under
consideration in this study also appears in an updated version of
this study published in 2004 (ExcelPlas Australia et al., 2004). The
basic data referred from these sources were converted to the
functional unit assumed for China, Hong Kong and India.
The data arising from this study included the total energy
consumed by a bag to get it manufactured, where total energy
represents process and feedstock energy and the quantity of
pollutants emitted to the atmosphere during the manufacturing
process.
The goal of the study under discussion is to analyse the carbon
footprint of these four types of bags in China, Hong Kong and India
with the available data from a secondary source (cradle to gate) in
the first step and in the second step, to study the effect of
consumer’s attitude and policy dimensions in the carbon footprint
of these four types of shopping bags (cradle to grave). The scope of
this study includes the comparative investigation of carbon footprint
of plastic, paper, non-woven and woven shopping bags in
both cradle to gate and grave states from the data sources
mentioned above in China, Hong Kong and India. The cradle to gate
assessment phase of this study considers impacts at each life cycle
stage of four types of shopping bags under consideration which
includes extraction/processing or growing/harvesting of resources;
the process of manufacturing; transport from the manufacturer to
the wholesaler/retailer as indicated in the secondary data sources
from which the cradle to gate data were referred. For cradle to grave
stage, public opinion from China, Hong Kong and India on
percentage of reuse, recycle and disposal to landfill were considered
to build the end-of-life scenarios in addition to the above
mentioned areas in cradle to gate stage.
To derive the functional unit which suits better for the three
territories considered, the consumption statistics of shopping bags
was referred from the literature pertaining to China, Hong Kong
and India. Among the four bags under consideration in this present
study, statistics were readily available on the consumption of
plastic bags. As per our currently available literature survey on
S.S. Muthu et al. / Atmospheric Environment 45 (2011) 469e475 471
statistics on shopping bags consumption, an average Chinese and
a Hong Kong resident, on an average uses 3 plastic bags per day
(EPD, HK, 2009; Environmental News Network, 2008). Although
there is no readily available statistics for the usage of plastic bags in
India compared to Hong Kong and China (Businessgreen.com, 2010;
The Times of India, 2009), as per one of the references pertaining to
the consumption of plastic bags in India, India’s per capita
consumption is 150 plastic bags a year (Online Edition of The Hindu,
2010).
The functional unit of this present study is the, “number of
shopping bags used for grocery shopping per year by an average
Chinese/Indian/HK resident”. For the territories considered for this
study, we assume that plastic and paper bags are comparable and
they are equivalent to each other in their functional front. When it
comes to non-woven and woven bags, we assume that 1 nonwoven
and 2 woven cotton bags will replace 100 single use plastic
and paper bags. Further, our above said assumptions can be validated
from the relevant literature also (Nolan ITU et al., 2002;
ExcelPlas Australia et al., 2004; James and Grant, 2005; Reusable
shopping bags; Envirosax; Alburyenvirobags). Hence 1095 plastic
and paper bags, 10.95 non-woven and 21.9 woven bags are required
to fulfill the functional unit assumed for this study for an average
Chinese and HK residents. For Indians, 150 plastic and paper bags,
1.5 non-woven and 3 woven bags are needed to fulfill this study’s
functional unit.
The end-of-life values were derived from a survey conducted in
China, Hong Kong and India as reported in the references in detail
(Muthu et al., 2010a). Results from the survey were used in Life
cycle impact calculations in the usage and disposal states were
compared with the life cycle stage without usage and disposal
criteria.
2.2. Life cycle inventory (LCI) of shopping bags
The energy and pollutants data for the functional unit considered
for different shopping bags under consideration in this present
study was taken from the previous studies (Nolan ITU et al., 2002;
ExcelPlas Australia et al., 2004) and is tabulated in Table 1 for China
and Hong Kong and Table 2 for India.
2.3. Survey results of usage and disposal behaviour
of shopping bags
The major focus of this study is to investigate the influence of
human behaviour and governmental policies on the carbon footprint
of various types of shopping bags. A survey was conducted
among students, home makers and employed professionals in
various professions of different age groups, who are the users of
shopping bags and who have the knowledge on the usage and
disposal behaviour of the same in China, Hong Kong and India. This
survey was mainly aimed at understanding the consumer’s
perception of reuse, recycle and disposal to landfill, recycling
Table 1
Life cycle inventory data of plastic, paper, non-woven and woven bags in China and
Hong Kong.
Alternative Weight/bag Bags/year Material Green house Primary
consumption gas emissions
(CO2 eq.)
energy
Plastic bag 6 g 1095 6.57 kg 12.8 kg 442.2 MJ
Paper bag 42.6 g 1095 46.65 kg 24.8 kg 1518.3 MJ
PP fibre nonwoven
bag
65.6 g 10.95 718.32 g 5.17 kg 122.2 MJ
Woven
cotton bag
125.4 g 21.9 2.75 kg 6.06 kg 385 MJ

472
Table 2
Life cycle inventory data of plastic, paper, non-woven and woven bags in India.
Alternative Weight/bag Bags/year Material
consumption
possibilities with the existing government provisions/policies for
recycling, willingness to support recycling systems/policies to
reduce the percentage of landfill and so on (Muthu et al., 2010a).
The major results extracted from this survey are presented in
Table 3.
From the survey results, usage and end-of-life scenario values
are deduced to the following categories, which can be seen from
Table 3.
3. Results and discussions
Green house
gas emissions
(CO2-eq.)
3.1. Life cycle assessment analysis and results without
usage and disposal options
Primary
energy
Plastic bag 6 g 150 900 g 1.74 kg 60 MJ
Paper bag 42.6 g 150 6.39 kg 3.41 kg 210 MJ
PP fibre nonwoven
bag
65.6 g 1.5 98.4 g 708 g 16.73 MJ
Woven cotton
bag
125.4 g 3 376.2 g 831 g 52.74 MJ
In this section, energy and pollutants data were processed by
using one of the commercial LCA softwareseSIMAPRO 7.2. The IPCC
2007 method (IPCC method) for LCIA was employed to assess the
carbon footprint, which is expressed in terms of Global Warming
Potential of 20 years, 100 and 500 years. LCIA modelling was done
in three phases: Global Warming Potential of 20 years, 100 and 500
years by using the same method for China and Hong Kong separately
and for India separately as per the functional unit assumption.
Results of these analyses can be seen from Fig. 1 for China and
Hong Kong and Fig. 2 for India. For the functional unit assumed,
non-woven bags made out of polypropylene score out all other
bags, followed by woven cotton bags in the three territories
considered for this study. Plastic bags and paper bags have very
high global warming potential for 20, 100 and 500 years compared
to non-woven and woven bags. Life cycle inventory data presented
in Tables 1 and 2 clearly enumerate these results and indicate that
non-woven bags occupy better position in this comparative analysis.
For the functional unit assumed, non-woven bags consume
lesser energy and fewer amounts of materials and also they emit
lesser green house gas emissions in the production phase of
shopping bags in comparison with its counterparts in China, Hong
Kong and India.
According to the first part of this study, paper bags seem to be
very much detrimental to the environment in terms of more
amounts of carbon emissions compared to its counterparts as per
the secondary data source references. However this can be further
studied with the inclusion of the positive effect of the photo
synthesis effect created by trees, from where the paper is primarily
being made. This part certainly needs to be included in the carbon
footprint modelling part.
Table 3
Values for usage and disposal options from survey results (Muthu et al., 2010a).
S.S. Muthu et al. / Atmospheric Environment 45 (2011) 469e475
3.2. Life cycle assessment analysis and results with usage
and disposal options
The results of the survey findings tabulated in Table 3 were
employed to investigate the impact of plastic, paper bags, nonwoven
and woven bags on carbon footprint in terms of global
warming potential and they were compared with the results
obtained from without usage and disposal options (baseline study).
The GWP results of the same for China, Hong Kong and India are
described in Figs. 3 and 4 respectively. For better clarity and ease of
comparison, only the results from 100 years are considered for this
discussion.
The data tabulated in Figs. 3 and 4 permit a comparative
investigation between, without and with usage and disposal
options according to the existing consumer behaviour and
government policies in China, Hong Kong and India. In all the cases,
the carbon footprint values are less than those of the without usage
and disposal options. When the comparison is made between the
options from three countries under discussion here, one can see
that for plastic bags, the carbon footprint values from India is less
compared to other countries. This is due to the fact that reuse
option is most selected by Indians for plastic bags. For other categories
of shopping bags, the carbon footprint values from China are
less, due to the same fact mentioned above. The influence of reuse
option on reducing carbon footprint values is very much pertinent
in all the cases under discussion here. While looking at the results
in Table 3 for woven bags in China and Hong Kong, we can notice
that a 5% difference in percentage of reuse results in 22 Kg CO2
equivalents of global warming potential (around 20% of GWP) in
Fig. 3, which showcases the importance of reuse option. It is a wellknown
fact that the more reuse of shopping bags, lesser will be the
environmental impact. However the magnitude of importance
needs to be revealed, which will portray the real scenario to the
consumers of shopping bags. Even 1% of more reuse of shopping
bags will make a world of difference in terms of environmental
impact, which has to be unveiled to public, if one wants them to be
educated in terms of environmental improvement. If we expect the
Percentage Plastic bags Paper bags Non-woven bags Woven bags
China HK India China HK India China HK India China HK India
Recycle 21% 22% 18% 31% 25% 25% 22% 25% 21% 20% 23% 27%
Reuse 46% 42% 55% 42% 38% 28% 78% 69% 55% 80% 75% 73%
Sent to landfill 33% 36% 27% 27% 37% 47% 0% 6% 24% 0% 2% 0%
2500
2000
1500
1000
500
0
Plastic Bags Paper Bags Non-woven bags Woven Bags
GWP (KgCo2-eq.) in 20 Years
GWP (KgCo2-eq.) in 100 Years
GWP (KgCo2-eq.) in 500 Years
Fig. 1. Carbon footprint results without usage and disposal options in China and Hong
Kong (Results rounded-off).

350
300
250
200
150
100
50
0
Plastic Bags Paper Bags Non-woven bags Woven Bags
GWP (KgCo2-eq.) in 20 Years
GWP (KgCo2-eq.) in 100 Years
GWP (KgCo2-eq.) in 500 Years
Fig. 2. Carbon footprint results without usage and disposal options in India (Results
rounded-off).
Woven bags
Non-woven bags
Paper bags
Plastic bags
0 500 1000 1500 2000
GWP(KgCo2-eq.) in 100 Years
Baseline study China HK
Fig. 3. Carbon footprint results with usage and disposal options in China and Hong
Kong (Results rounded-off).
Woven bags
Non-woven
bags
Paper bags
Plastic bags
0 50 100 150 200 250
GWP(KgCo2-eq.) in 100 Years
Baseline study India
Fig. 4. Carbon footprint results with usage and disposal options in India (Results
rounded-off).
public to appreciate the environmental education in terms of their
contribution to reduce environmental impact, they should be
aware of the real values of environmental impact. Based on the
above results and discussions, one important point to be noted here
is, if any product is not reused till the end of its life, the concerns
about environmental impact are huge. On the other hand if any
product is not recycled and sent to landfill more, the eco-impact
S.S. Muthu et al. / Atmospheric Environment 45 (2011) 469e475 473
Fig. 5. Recycling System in China (Shenzhen City).
Fig. 6. Recycling System in Hong Kong (Hung Hom Area).
concerns are more acute than the manufacturing and usage state,
which can be understood from the results of this research work. So,
usage and disposal of shopping bags assumes greater significance
in minimizing the carbon footprint.
If policies of these governments have been reconsidered and
recycling systems are encouraged and if they are in their appropriate
places, percentage of recycling options will be increased and
it is beyond anybody’s doubt that the impact of global climatic
change will come down enormously. Though governmental policies
to promote recycling can be seen all around the globe, still
they need to be up to the mark; thereby every individual goes for
it. As far as China and Hong Kong is concerned, recycling systems
can be seen in major areas, some photos taken in China
Fig. 7. Recycling Bins from an apartment in HK.

474
(Shenzhen) and Hong Kong (Hung Hom) are presented in Figs.5
and 6. Also in order to support government’s activities, individuals
also need to take some initiative to promote recycling activity.
One typical example is the initiative taken by residents of an
apartment in Hong Kong to promote recycling options, which can
be seen from Figs.7 and 8. Such activities should be initiated and
continued by all individuals.
The emphasis on interpretation phase of this analysis is not on
concluding which one is much better. Actually the conclusion needs
to be drawn on how to reduce the impacts caused by carbon
footprint by all variety of shopping bags. One of the possible ways to
decipher this is by means of finding ways to reduce, reuse and
recycle. In fact, many retail stores have started utilizing this
philosophy of reducing, recycling and reusing the grocery bags.
Building up public awareness and motivation to reduce, reuse and
recycle all these bags will definitely help to resolve the environmental
problems to a greater magnitude.
4. Conclusions
This research article encompasses the study of carbon footprint
of different types of shopping bags in both cradle to gate and cradle
to grave stages in China, Hong Kong and India. Among different
phases of a product’s life cycle, disposal phase assumes greater
significance as far as the environmental impact on carbon footprint
is concerned. The peculiar part of this phase is that end-of-life
scenarios are mostly decided by consumer behaviour and governmental
policies. In this research paper, an exploratory study was
performed to analyse the impact of various shopping bags on
carbon footprint by using secondary data for LCI to manufacturing
phase. In this stage, reusable bags such as non-woven bags made
out of polypropylene followed by woven cotton bags seem to be
environmental friendly compared to the conventional plastic and
paper bags for the functional unit assumed for this comparative
study. As far as the end-of-life phase is concerned, it lies mostly in
the hands of the public. Also it is vitally important to use real values
rather than assumptions, which can be obtained only from the
actual users. Hence the inputs from public opinion were employed
to deduce the values for end-of-life scenarios. In the first stage of
LCA modelling without disposal options, according to the LCI data
S.S. Muthu et al. / Atmospheric Environment 45 (2011) 469e475
Fig. 8. Recycling Bins for used clothes recycling from an apartment in Hong Kong.
and the software used for this study, which also has certain
hypothesis and assumptions, non-woven bags made out of polypropylene
are found to be better in terms of carbon footprint
compared to its counterparts. However this stage of conclusion
depends solely upon the secondary data and the LCA software
employed for the study. Public opinion was used to model the usage
and disposal values of LCA, where the GWP values of all bags were
less in all cases.
It was found in all of the cases under study that the more the
option of reuse is chosen, the lower the environmental impact. In
one of the cases in this study, it was found that even a 5% increase in
reuse option selected, around 20% of carbon footprint will be saved.
Hence, the key here is that consumers must reuse the bags till they
can be discarded. Once they decide to discard, the other best option
would to be sending the bag to recycling rather than disposing it off
to landfill.
The production process of the various shopping bags considered
in this study is a long chain and the amount of carbon footprint of
the same could be different in today’s scenario when compared to
the results presented in this study, derived from second-hand data
sources. It should also be noted that the number of times each type
of bag can be reused and potential of each type of bag to be recycled
with their consequent environmental implications also would be
different from each other.
The consumers’ behaviour and governmental policies are pivotal
in terms of encouraging people to go for reusable bags and promote
more recycling systems to scale down the environmental impacts
made by any type of shopping bag. We have only one planet to live it
is imperative for every one of us to take care of the same. We must
unite as one human family in new understanding and care for this
wonderful nest in the stars: Planet Earth, our home.
Acknowledgements
The authors are grateful to The Hong Kong Polytechnic University
for providing funding support to this research through project
RP7Q and to all the respondents to the survey conducted in China,
India and Hong Kong. The authors are also thankful to Dr. Xuemei
Ding, Laili Wang and Weibang Chen, of Donghua University,
Shanghai, China for their help in conducting the survey in China.

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