Introduction

One of the suitable options for developing countries that does not depend on technology is tourism1,2. Tourism can be a good opportunity to achieve economic development, especially in countries with natural and historical potentials such as Iran3,4. However, several factors can be effective in the attention of international tourists to cities and countries to choose a destination, which includes security, cost, and general culture5,6. One of the important factors that are effective in choosing a tourist destination is the status of public health and urban cleanliness7,8. Therefore, municipal solid waste management, which has a significant effect on the status of urban cleanliness, can lead to the development of the tourism. However, many tourist cities in developing countries face challenges in achieving waste management goals due to technical and economic limitations8. Limitations in waste management infrastructure and implementation programs, especially urban cleaning, are one of the challenges for tourist cities in developing countries8,9, which can lead to a decrease in tourists.

The most important wastes that have an effect on the status of urban cleaning are “litter”, which include wastes that citizens did not dispose of in trash bins or storage containers, but threw them in the urban environment or public places10. Litter composition varies widely and often includes small-sized items9, Common examples include cigarette butts, paper, plastics like bottle caps, facial tissues, bottles, and disposable containers11,12. The density of litter in the urban environment and public places is affected by demographic variables, land-use, infrastructure, and laws13, so the density of litter will have spatial variation8. In this situation, litter was reported as one of the main environmental problems, especially in public environments such as beaches14 and has caused serious visual pollution, which can be a weakness for tourism development8. The small size of some types of litter and their low contrast in the urban environment and public places increase their durability in more density15.

In addition to visual pollution, the leakage of pollutants such as microplastics, heavy metals, organic compounds, and the possibility of microbial contamination in different types of litter is another problem associated with this type of waste9. For example, cigarette butts, which are reported to be one of the most abundant types of litter in the urban environment16,17, contain many pollutants, including heavy metals and toxins, whose leakage into the environment is an environmental and health risk especially by polluting water resources18. Also, littered plastics, especially face masks, which have been widely used by citizens since the Covid-19 pandemic, are now considered a significant source of microplastics19. In addition, items such as facial tissue and health care waste, including condoms, which are reported in the composition of litter, cause the risk of transmitting pathogens20.

Ardakan is one of the ancient cities of Iran, known as a tourist city due to its historical monuments and special architecture. However, economic limitations and waste management infrastructure in this city, changes in the quantity and composition of municipal solid waste in the post-COVID-19 era, citizens’ behavior in waste littering, and lack of access to a long-term plan for municipal solid waste management have caused challenges in urban management of Ardakan. In these situation, urban cleaning as one of the basic measures in municipal solid waste management has an important impact on the goals of tourism development of Ardakan, which is still a subject that needs to be studied.

Previous studies can be categorized into three different groups: first, studies expressing the quantity of pollution, second, studies interpreting the pollution situation qualitatively based on available indexes, and third, review studies on litter. So far, no qualitative study has been conducted on the impact of litter on the urban economy. For example, the impact of litter on tourist cities could be further evaluated. The health and environmental risk associated with litter has been reported in many studies, but the density and interpretation of the situation in tourist cities have not been seriously investigated, which is the innovation of this study. Given the serious differences in the quality of urban cleaning in big cities compared to small cities, the status of litter management in small cities and tourism is a knowledge gap. Therefore, this study, which is an innovation in assessing the status of litter management in small cities and tourism, could be a response to this gap. Therefore, the main question of this study was the status of litter management and pollution levels in small and tourist cities in Iran. The hypothesis of the study was that less access to equipment as well as lower municipal income in small cities in Iran has led to less efficient urban cleaning systems and higher pollution levels. So, the aim of this study was to investigate the density of litter in different land-uses of a tourist city in Iran. Another aim was to interpret the status by a suitable index for classifying the quality of the studied locations. So, this study investigates the inefficiencies in litter management in small Iranian tourist cities, hypothesizing that limited municipal resources and inadequate infrastructure result in unsustainable urban cleanliness levels, thereby impacting tourism development.

Method

Study area

This study was conducted in Ardakan city, Iran. Ardakan is located in the central plateau of Iran in Yazd province. This city is an important tourist city in Iran due to its historical monuments and desert nature. The hierarchy of waste management in Ardakan according to the national pattern includes temporary storage, collection, transportation, processing, and final disposal. In recent years, as a result of changes in the consumption pattern as well as social consequences such as the Covid-19 pandemic, the production of solid waste in Iran has changed21. The latest data recorded in the waste management organization of Ardakan Municipality shows that the average per capita production of solid waste in this city is 600 g per day.

Litter management

Litter management in Ardakan city includes urban cleaning service that is done manually using a broom. The activities of sweepers are carried out in the late hours of the night when there is minimal presence of citizens in the urban environment. Waste littering by citizens in Ardakan is common as in other parts of the country. The field survey of the city showed that there are no special containers for the disposal of litter in the city, and only waste storage containers are available to citizens. The number of sweepers in Ardakan includes 100 people, with a total of 800 man-hours spent on sweeping every month.

Studied litter

This study was conducted on litter in Ardakan. Litter included waste that was thrown away by citizens in the urban environment9. Therefore, items like tree branches, fallen leaves and crushed pieces of the sidewalk were not considered10. Based on past experiences, the litter was classified into five general classifications, including cigarette butts, paper and cardboard, plastic, glass, metals, and other types8. Litter such as facial tissue, wood such as ice cream sticks, pieces of cloth, and wastes related to personal protection such as face masks were classified in the category of other types.

Data gathering

This research was done based on field study and visual observation22. As shown in Fig. 1, different areas of the city were divided into three commercial, residential, and recreational land-uses, and from each land-use, some locations were selected for observation. Observation of locations was done in two periods of warm season and cold season. Observations were made on working days in the evening hours (two hours before sunset). The choice of this visit time was made to create a maximum time gap with the urban cleaning process. The studied section of each location includes the distance between two intersections. or at least 500 m long from each street. In this distance, the width of the sidewalk and its side edges, including the water collection channels and the planted space, plus one meter of the street width, were studied for three times. The average of the data was considered as the results of the observation.

Fig. 1
figure 1

Study steps.

Full size image

Status interpretation

Clean Environment Index was used in each of the studied locations. The field study data was applied in Eq. 1 and the clean environment index was calculated for each location. A special coefficient [1 to 2] was determined for each type of litter based on its pollution potential. Based on this, cigarette butts, facial tissue, and masks had the highest coefficient of 2, and plastic waste had a coefficient of 1.5. Other litter including paper and cardboard, wood, glass, and metal had a coefficient of 18. Based on the result of calculating the index in the range of 0–2 to more than 20, the condition of each place was interpreted in one of the five categories including very clean, clean, moderate, dirty, and very dirty23.

$$\:CEI=\frac{\sum\:(\text{W}\text{i}\:\times\:\text{N}\text{i})}{\text{L}\text{e}\text{n}\text{g}\text{h}\text{t}\:\left(\text{m}\right)\times\:\text{W}\text{i}\text{d}\text{t}\text{h}\:\left(\text{m}\right)}\:\times\:K$$
(1)

K is a constant coefficient equal to 20. Wi is a coefficient that is determined according to the explanation above.

Results

Due to the difference in width, the investigated area was different in each location, the details of which are shown in Table 1. Based on this, the investigated area was in the range of 1550m2 to 5200m2, so in total 49800m2 of the urban environment of Ardakan was studied. The number of littered wastes in the warm season ranged from 376 to 2307. The highest number of littered wastes was observed in D3, while the lowest number of littered wastes was found in C3. In total, 19,375 littered wastes were observed in all the studied locations. But in the cold season, the number of littered wastes were in the range of 479 to 1880. The highest number of littered wastes was observed in D4, while the lowest number of littered wastes was observed in P1. In total, 18,608 littered wastes were observed in all the studied locations. Based on this, the number of littered wastes in the warm season was 4.12% more than in the cold season.

Table 1 Studied location data.
Full size table

The density of littered wastes was varied in different locations and in different seasons. The density of littered wastes in each of the studied locations is shown in Fig. 2. Based on this, the highest density of litter was observed in P3 and the lowest density was observed in C3. Also, the average density of litter in the studied land-uses in the warm season and in the cold season is shown in Fig. 3. The results showed that the average density of litter in commercial, residential, diverse, and recreational land-uses was 0.339 items/m2, 0.447 items/m2, 0.363 items/m2, and 0.546 items/m2, respectively.

Fig. 2
figure 2

Density of littered wastes in studied locations.

Full size image
Fig. 3
figure 3

Average density of littered wastes in studied land-uses.

Full size image

The results of the analysis of the composition of littered waste in the warm season showed that cigarette butts had the largest share in the composition, which was equal to 54.62%. After cigarette butts, paper receipts, candy wrap, plastic, and facial tissue had the largest ratio by 10.80%, 5.49%, 5.31%, and 4.30%, respectively (Fig. 4). Also, the results of the analysis of the composition of littered waste in the cold season showed that cigarette butts had the largest share in the composition, which was equal to 55.11%. After cigarette butts, paper receipts, candy wrap, and facial tissue had the largest share ratios by 12.63%, 6.23%, and 4.88%, respectively (Fig. 4).

Fig. 4
figure 4

Composition of littered wastes in studied city.

Full size image

The results showed that in the warm season, the clean environment index ranged from 6.83 to 34.15 (Fig. 5). On average, the index in all the studied locations was equal to 19.55, which indicated the dirty status. Based on this, 16.6% of the studied locations were in moderate status, 58.3% in dirty status, and 40% in extremely dirty status. Also, in the cold season, the clean environment index calculated by 10.43 to 25.56. On average, the index was equal to 18.63 in all the studied locations, which indicated the dirty status. So, 67% of the studied locations were in dirty status, and 33% in extremely dirty status. However, as shown in Fig. 6, the clean environment index in the warm season for commercial, residential, diverse, and recreational land-uses is 16.54, 22.59, 19.36, and 19.75, respectively. and in the cold season for commercial, residential, diverse, and recreational land-uses, it was 18.54, 19.17, 21.33, and 14/44, respectively.

Fig. 5
figure 5

Calculated clean environment index in studied locations.

Full size image
Fig. 6
figure 6

Calculated clean environment index in studied land-uses.

Full size image

Discussion

The quantity of litter was different in the studied locations and land-uses. In addition, the composition of littered wastes was different in the studied locations and land-uses. Therefore, urban land-use is effective in the quantity and composition of litter8. As the results showed, cigarette butts had the highest ratio in littered wastes and its range was more than 50% in all locations. After cigarette waste, paper and cardboard category and plastic waste category had the largest ratio in litter composition. In this situation, the question must be answered that whether the problem of litter in the urban environment exists only in Ardakan, or is this problem reported in other cities of the country and even in other countries? Therefore, it is necessary to compare the results of other studies with the results of the present study. In previous studies in the country, it was reported that urban environment and public areas such as beaches are polluted by littered wastes24,25. Also, some studies in other countries are available (Table 2), which were mostly conducted litter in public environments, including beaches25. For example, the study of litter in one of the largest cities in Argentina showed the pollution of the urban environment by all kinds of littered waste26. The study that was conducted in Mardel Plata, by investigating four urban areas, reported the existence of 20,336 litter, of which cigarette butts, paper and plastic consist the largest number of litter by 33, 31, and 22%, respectively26. In another study, a total of 38,368 littered wastes were counted, in Qazvin, Iran, of which 25,837 were cigarette butts27. In our work, a total of 19,375 littered wastes were observed in the warm season and 18,608 in the cold season. Cigarette butts were 10,587 in the warm season and 10,255 in the cold season. This result was consistent with the results reported in Mardel Plata, Argentina and also in Qazvin, Iran. Commercial, residential, recreational, and industrial land-uses were contained 26.33%, 12.75%, 23.92%, and 39.92% of total littered waste in Mardel Plata, Argentina, respectively26,27. But in Ardakan, this ratio for commercial, residential, diverse, and recreational land-uses was 26.1%, 25.9%, 32.7%, and 15.1% respectively. Also, in Qazvin, Iran, commercial, residential, administrative and recreational land-uses were contained 48.11%, 5.28%, 0.68%, and 22.66% of total littered waste, respectively27.

Table 2 Results of assessing the status of litter in the public environment in some studies.
Full size table

The study of a coastal city in the south of the Caspian Sea showed that the density of litter was different in different uses and there was a significant difference between the coastal environment and the urban environment, this study reported that cigarette butts and paper consist 45% and 17% of the composition of litter, respectively8, which was consistent with the results of our work. Although most studies investigated all types of litter, some studies focused on one type of litter. Cigarette butt is the most important litter that was investigated independently in most studies. The study conducted in Berlin, Germany showed that the density of littered cigarette butts was 1 number/m2 to 42 number/m2 (on average, 5 number/m2 in the studied environment)18. In another study in Madrid, Spain, it was reported that the density of littered cigarette butts in the urban environment was not the same as its higher in commercial centers and around urban transportation stations28. In addition to the studies conducted in urban environments, some studies have investigated the density and composition of littered wastes in other environments, which have comparable results with the present study. For example, Moriwaki et al. 2009. reported that 220 litter per kilometer of roads in one month. Cigarette butt was most abundant litter on the studied roads, so an average 150 number/kilometer29.

Land-use is one of the most important factors in the litter quantity due to its direct effect on the population density. Although in tourist cities, the importance of some parts of the city, such as cultural environments, shopping centers, downtown areas, historical sites, and similar locations, is greater due to the presence of tourists, but in small tourist cities in Iran, where the residential part is also attractive in terms of architecture and local accommodations for tourists, residential land-use is also important. In commercial and diverse land-uses where the presence of citizens is more due to the increase probability of waste littering behavior, the density of littered waste was higher30. In fact, waste littering is a common behavior by some citizens, so in crowded places, high traffic hours, busy days, and recreational places during holidays, according to the increase in the presence of citizens, the littering behavior and as a result, the density of litter be more31. The difference in the efficiency of the urban cleaning system in different places and also in different cities can be one of the factors of the difference in litter density reported in different studies22. Although the absence of urban cleaning systems in places such as beaches has been reported as one of the main factors of the presence of littered wastes, however, the same quality of the urban cleaning system in different land-uses of a city has caused the effect of this factor to be estimated as insignificant30. Points such as ATMs, supermarkets and stalls, urban transport stations, and intersections are known as high potential points8. Increase of high potential points in a location leads to increase of littering behavior and the density of littered waste27. Commonly, there are more high potential points in commercial and diverse land-uses, which is one of the important factors of increasing the density of littered wastes in these land-uses compared to other parts of the city23. Also, installing more waste containers or trash bin at certain intervals in the urban environment can be effective in reducing waste littering by citizens by creating a suitable option for correct disposal18. The direct impact of citizens’ behavior in littering waste causes the behavioral factor to be emphasized as the most important factor in the concentration of littered wastes9. In fact, the behavior of citizens, which is affected by their knowledge and attitude in proper waste management, is known as critical factor in reducing the density of litter in the urban environment32.

The clean environment index showed the qualitative difference between the studied locations. The parameters that affect the results of calculating this index include the density of litter and the coefficient. Therefore, the sensitivity of the index to a higher coefficient causes cigarette butts, facial tissue, and plastic to have a greater impact on the pollution status of the studied environments. Also, the types of litter that had a higher ratio in the composition of the littered wastes also had a higher impact on the results of calculating the index. The difference between this index and the density was in the coefficient derived from the risk potential of each type of litter23. One of the most important observed litter in the studied city was cigarette butt. The impact of this waste was significant in the density and also the clean environment index. Due to the function of the cigarette filter in trapping cigarette smoke pollutants, the cigarette butt has many types of pollutants33, which causes applied coefficient equal 2 in formula to calculate the clean environment index23. Therefore, the increase in the number of littered cigarette butts in the environment, as observed in this study, will cause a significant increase in the clean environment index8. In addition to cigarette butts, the impact of sanitary waste such as facial tissue and face masks is higher than other types of littered wastes due to the possibility of infectious risk in the urban environment27. In this study, the impact of littered sanitary waste was more than other types of waste, but due to the lower density compared to littered cigarette butts, this type of litter was not important in the clean environment index as cigarette butts. Therefore, the effective factors in the index include the quantity of each type of littered wastes and also the weight coefficient defined for them27. So, the effect of cigarette butts, paper, sanitary waste, and plastic on the clean environment index was more than other types of litter in Ardakan.

While other indexes, including the Clean Coast Index, Environmental Status, Waste Accumulation Index, and Waste Accumulation Rate, are also available in interpreting the status caused by litter27, the Clean Environment Index has characteristics that can be considered as a comparative advantage of this index. The most important advantage of the Clean Environment Index over the other mentioned indexes is that it considering the risk potential of each type of litter, which is defined in the interpretation of the pollution status by applying a coefficient32, while other indexes interpret the status solely based on the density of litter8. Therefore, the results of this study can provide a more accurate assessment of the environmental pollution status than other studies that used other indexes. However, one of the limitations of these indexes in assessing environmental pollution is the failure to consider the risk of exposure to other pollutants, including street dust, because scientific evidence of exposure to pollutants, including heavy metals, resulting from inhalation of street dust has been reported34.

The importance of this study at the international level could be in expanding data to compare the situation in different cities and understanding the impact of behavioral factors and local management on the composition and density of litter. According to the results of the study and investigation of the reasons for the observed situation, the following can be suggested to improve the situation and reduce the level of pollution:

Educating citizens to improve waste disposal behavior.

Installing special bins for some types of litter such as cigarette butts.

Using appropriate equipment to increase the efficiency of the urban cleaning system, especially in low-access points.

Developing the necessary laws to deal with waste littering, especially cigarette butts.

The following can also be suggested for future studies:

Study of the leakage of pollutants such as heavy metals and microplastics from litter into the urban environment.

Assessment of health and carcinogenic risks associated with exposure to pollutants leaked from litter in the urban environment and public area such as beaches.

Assessment of environmental conditions affecting the risk potential from litter in the urban environment.

Conclusion

The status of litter management in a historical tourist city in Iran was studied. This study was an innovation in assessing the status of litter management in small and tourist towns, which included the hypothesis of higher pollution than in big cities due to differences in the quality of urban cleaning. The results showed that the number of litter in the studied city in a length of 500 m ranged from 376 to 2156, and the calculated density was in the range of 0.23 number/m2 to 0.953 number/m2. The composition of littered wastes included tobacco waste, plastic, paper, metals, glass, and other types of litter, so that the average ratio of cigarette butts, plastic, and paper in the total litter composition was 55.11%, 4.9%, and 13.9%, respectively. The average of the clean environment index in commercial, residential, diverse, and recreational land-uses was 16.54, 22.59, 19.36, and 19.75, respectively. In addition to environmental and health risks, these conditions have economic consequences due to the negative impact on tourism. It can be concluded that the urban cleaning system is inefficient and citizens do not behave in the desired manner in waste disposal. This situation has been the worst pollution level reported in studies in Iranian cities. Considering the importance of public cleanliness in the criteria for tourist destinations selection, the management of littered wastes should be planned. The development of litter management infrastructure is needed to reduce the density of litter and change the behavior of citizens to prevent waste littering is necessary. Also, improving the efficiency of urban cleaning service and using mechanical tools should be considered. Finally, estimating the economic consequences of littered waste on the tourism market in small cities, as well as assessment of the associated health and environmental risks, could be considered for future studies.