Surveying Litter as a Citizen Science Chemistry Activity

litter on ground

Easy access to the internet has helped to enable many individuals to gather data to serve a collective purpose. This group data collection approach has been used for a variety of science applications, and can be associated with the terms “citizen science” and “crowdsource.” Oxford Languages defines citizen science as “the collection and analysis of data relating to the natural world by members of the general public, typically as part of a collaborative project with professional scientists” and the related term crowdsource as “obtain (information or input into a particular task or project) by enlisting the services of a large number of people, either paid or unpaid, typically via the internet.”1 A quick web search reveals many websites describing citizen science projects, including SciStarter,2 National Geographic,3 and NASA.4

For three semesters, a survey has been deployed in the Mund-Lagowski Department of Chemistry and Biochemistry at Bradley University asking each student participant to describe and classify items of litter that they find. In the most recent survey, students from local schools were invited to participate. The purpose of the survey is to get students thinking about some of the chemical implications of solid waste and give the students some experience with participating in a citizen science project.

The most recent iteration of the survey was run through Google Forms in April, 2021. The survey instructions and questions are given below, along with some commentary about the questions and some data collected from the survey.

Litter Survey Spring 2021

Instructions: Look at ten pieces of litter that you SEE outside that are bigger than your fingernail (you do not have to pick the litter up, especially in these COVID times) and write down what you have seen on a piece of paper. Then, answer the following questions about the list of litter in this survey.

  • Name (Last, First) [fill in the blank] – This enabled us to assign grades to the participants and to remove multiple submissions from the same person. There were 246 unique respondents.
  • What grade are you in? [multiple choice: K-4, 5-8, 9-12, college, after college] – About 35% of the respondents were college students from three Bradley University courses (General Chemistry 1 lab, Engineering Chemistry, and Introduction to Sustainability). The rest were from a nearby middle school and a nearby junior high school. Ninth grade can either be associated with middle or high school, so this classification might need clarification in the future.
  • What school do you attend? (If you are a Bradley University student give your course code with no space, for example CHM416.) –  As noted above, students from Bradley University and two nearby schools participated.
  • What date did you complete the survey? [fill in the blank] – The survey was left open for several days, and there were still a couple of late submissions.
  • Five-digit zip code location of your survey (Bradley University is 61625) [fill in the blank] – The hope is to eventually look for spatial patterns in litter distributions. Zip codes might have areas that are too large to get clear patterns. Twenty-eight different zip code locations were recorded. Perhaps other descriptors like shopping areas vs. residential areas might be more relevant. 

It was in the first two main questions that the survey encountered a difficulty that needs to be rectified for future use. In these first two questions, the litter items were classified in two different ways. Each litter item was supposed to be classified into one category in each question. Therefore, the sum of the litter items across all categories in that question should have been equal to the total number of litter items. Also, the total number of litter items for the first question should have been equal to the total number of litter items for the second question. This was easily checked by downloading the survey data and checking sums on a spreadsheet. Unfortunately, there were a lot of cases where the sums for the first two questions did NOT match up. Surveys where the question sums were different by more than one were discarded, leaving 113 surveys. This loss of over half of the data collected powerfully illustrates the need to craft careful survey questions. It would have been useful to incorporate a sum check functionality into the survey, e.g., if the data sum for the questions did not match, then some sort of corrective message would pop up asking the respondent to check their work. This might require a survey platform beyond Google Forms. The data described below were drawn from the 113 surveys.

1) Classify each litter item by composition. If a litter item fits in multiple categories, pick the category that best fits. NOTE: The number total from question #1 must match the number total from question #2.  [Each of these categories was multiple choice: 1-10]

  • 113 responses, 1181 items
  • How many total metal-rich items (like cans, metal lids)?  15%
  • How many total carbon-rich items (like plastic, paper, food)?  75%
  • How many total silicon-rich items (like cement, glass, bricks)?  10%

2) Classify each litter item by use. If a litter item fits in multiple categories, pick the category that best fits. NOTE: The number total from question #1 must match the number total from question #2.  [Each of these categories was multiple choice: 1-10]

  • 113 responses, 1185 items
  • beverage items (like plastic bottles, cans, disposable cups, straws)  34%
  • food items (like French fries, apple cores, wrappers, fast food bags)  19%
  • smoking items (like cigarette butts, lighters)  6%
  • cleaning items (like wipes, tissues, cleaning chemical containers)  4%
  • plastic bags/film (like grocery, trash, packaging)  16%
  • medical items (like gloves, masks)  6%
  • construction materials (like wood, nails)  3%
  • transport-related items (like tires, bolts, those little weights they use to balance tires)  1%
  • clothing items (like...clothes)  1%
  • other items  11%

3) Select one carbon-rich litter item for more in-depth analysis, what is that item? [fill in the blank] – A variety of items were selected.

4) What realistic hazards might be associated with the item (is it poisonous, is it flammable, does it clog sewer lines, does it choke animals)? [fill in the blank] – A variety of answers were given many based on the suggestions (e.g., choking animals)

5) What is your best estimate of the material from which that item is made (for example, many water bottles are made from polyethylene terephthalate, paper is made from cellulose)? [fill in the blank] – A variety of answers were given, some based on the suggestions (e.g., polyethylene terephthalate) but some answers were broad, like plastic or rubber

6) What was the likely source of the carbon in the material? [multiple choice]

  • 113 responses
  • fossil fuels (like gas, oil, coal) 62%
  • biomass (like plants and animals) 38%

- It would be interesting to know if the relative amounts of fossil fuel derived litter and biomass derived litter held true for all of the carbon-rich litter items.

7) What elements (if any) might be present in the material besides carbon and hydrogen?  [fill in the blank] – A variety of answers were given, with various metal and nonmetal elements, or sometimes answers like “none” (no other elements), but some answers were not elements, like fibers or carbonate.

8) Could the litter item be [Each of these categories was multiple choice yes or no]

  • 113 responses
  • reused for the same purpose? 70% yes, 30% no   
  • used for a different purpose? 73% yes, 27% no
  • recycled?  77% yes, 23% no
  • burned as fuel?  43% yes, 57% no

9) How long in units of years is an item like the one you chose projected to persist in the environment? [fill in the blank] – A variety of answers were given. This information would be difficult to check, and this question might not be used in the future.

10) What is a "green" (less polluting, less hazardous) item that could have been used instead of the litter item that you chose? [fill in the blank] - A variety of answers were given, and most of these described green alternatives.

- end of survey -


Although many of the survey responses were varied, a few points are worth more emphasis.

  • Three-quarters of the litter was classified as carbon-rich.
  • Over half of the litter was classified as being related to food and drink.
  • Over 60% of the carbon-rich litter items selected for closer scrutiny were classified as being derived from fossil fuels.
  • 70-80 % of the carbon-rich litter items selected for closer scrutiny were classified as reusable or recyclable, but less than half were classified as being able to be burned for fuel.
  • Most of the carbon-rich litter items selected for closer scrutiny were thought to be replaceable by a less polluting or less hazardous item.
  • The survey instrument must be refined to make the questions as simple to answer as possible, with built-in check methods to make sure that participants are answering questions in ways that produce useful data.

The plan is to continue to refine, reissue, and perhaps expand the survey in the future. A sufficiently robust survey would enable the tracking of litter distributions spatially and temporally. It is regretful that the survey was not developed before the COVID-19 pandemic, so that the increase in number (and hopefully the eventual decline in number) of face masks on the ground could be tracked. Another relatively recent litter distribution change to track could be the number of vaping-related litter items. Questions that could be asked of students in the future would be for them to formulate additional questions for the survey, in order for them to engage more in the process of designing citizen science activities. Larger litter surveys and studies continue to be run, including the Marine Debris Tracker project2 and the Keep America Beautiful 2020 “Litter in America” study.5 Smaller, more informal surveys such as the one described in this post could provide a stepping stone for students to appreciate, and hopefully contribute to, citizen science.

If you would like a copy of the survey file or have questions, comments or suggestions, please feel free to comment below or contact Dean Campbell at Bradley University.

Safety: The survey is designed for participants to collect data without needing to physically collect the litter itself. Although this author is a strong supporter of litter cleanup, there are some times health hazards associated with some litter items. Drug paraphernalia like nitrous oxide canisters, health-related litter like surgical masks, and sharps like broken glass are just a few items to watch out for. Some sort of trash grabbing device is highly recommended for actually picking up litter.

Acknowledgements: This work was supported by Bradley University and the Mund-Lagowski Department of Chemistry and Biochemistry with additional support from the Illinois Heartland Section of the American Chemical Society and the Illinois Space Grant Consortium. Thanks to all who took the survey and who helped to deploy the survey, and thanks especially to Driffin Don and Zaman Shah for assistance with the data analysis.  


  1. Oxford University Press. Oxford Languages. (accessed May, 2021).
  2. Dautant, A. To Fight Plastic Pollution, These Researchers Want Your Pictures of Beach Trash. (accessed May, 2021).
  3. National Geographic. Citizen Science Projects. (accessed May, 2021).
  4. NASA Science. Citizen Science. (accessed May, 2021).


General Safety

For Laboratory Work: Please refer to the ACS .  

For Demonstrations: Please refer to the ACS Division of Chemical Education .

Other Safety resources

: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies



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Comments 1

Sharon Flowe | Tue, 07/27/2021 - 13:49

I am very interested in doing this with my high school students.   How do I get started?