Beach litter monitoring turns scattered debris into comparable evidence. The available measurements show a wide range: the European Union baseline averaged 504 items per 100 meters of coastline in 2015–2016, while a smoothed England series fell to 380 items per 100 meters by September 2021 and remained there through October 2022. Cleanup records also show which everyday products appear most often in large-scale collection work.
Contents
- EU baseline and assessment threshold
- Median abundance across coastal subregions
- Mean abundance and regional variation
- How median and mean differ
- England monitoring trends
- What global cleanup records counted
EU baseline and assessment threshold
The report A European threshold value and assessment method for macro litter on coastlines describes an EU beach-litter baseline for 2015–2016. Its mean abundance was 504 litter items per 100 meters of coastline. The median was much lower, at 133 items per 100 meters. Both figures describe the same baseline period, but they summarize the distribution differently: the mean incorporates every recorded value, while the median identifies the midpoint of the observations.
The lower end of the distribution provides additional context. The 10th percentile was 13 items per 100 meters in 2015–2016. The 20th percentile was 27 items per 100 meters. The threshold selected for EU assessment was 20 litter items per 100 meters, corresponding to the 15th percentile of the 2015–2016 baseline. The threshold was adopted in 2020, so it should be read as an assessment benchmark derived from the earlier baseline, not as a measurement from 2020.
These values are useful when interpreting monitoring results because a single average can conceal a broad spread. A beach count near 20 items per 100 meters sits close to the selected threshold, while a result near the baseline mean of 504 is far above it. The baseline median of 133 also shows why the mean should not be treated as a typical beach without examining the distribution.
Source: A European threshold value and assessment method for macro litter on coastlines (2015–2016 baseline; threshold adopted 2020).
Median abundance across coastal subregions
Median counts varied considerably among European coastal subregions during 2015–2016. The reported values ranged from 26 total items per 100 meters of beach in Germany’s Baltic Sea subregion to 2,134 in France’s Biscay/Iberian subregion.
| Country and coastal subregion | Median items per 100 m |
|---|---|
| Germany — Baltic Sea | 26 |
| Estonia — Baltic Sea | 43 |
| Finland — Baltic Sea | 49 |
| Denmark — Baltic Sea | 66 |
| Belgium — North Sea | 93 |
| Spain — Mediterranean | 120 |
| Spain — Macaronesia | 134 |
| Bulgaria — Black Sea | 174 |
| UK — Celtic Seas | 222 |
| France — Biscay/Iberian | 2,134 |
The Baltic Sea entries illustrate a relatively compact group at the lower end of the supplied median results: Germany recorded 26, Estonia 43, Finland 49, and Denmark 66 items per 100 meters. The Belgium North Sea median was 93 items per 100 meters, while Spain’s Mediterranean and Macaronesia subregions recorded 120 and 134, respectively.
Higher medians were reported elsewhere. Bulgaria’s Black Sea subregion had 174 items per 100 meters. The UK’s Celtic Seas subregion had 222, France’s Celtic Seas had 273, and France’s Mediterranean subregion had 294. Spain’s Biscay/Iberian subregion had a median of 244. The UK’s North Sea subregion had 423, and France’s North Sea subregion had 671.
The largest supplied median was France’s Biscay/Iberian result, at 2,134 total items per 100 meters. It is more than the other listed medians, but the available figures do not explain the local conditions or sampling composition behind that result. It should therefore be retained as a reported subregional value rather than generalized to all French beaches or all Biscay/Iberian beaches.
Source for all median figures: A European threshold value and assessment method for macro litter on coastlines, 2015–2016.
Mean abundance and regional variation
The mean values from the same European report show even stronger differences among subregions. Germany’s Baltic Sea mean was 46 items per 100 meters, while Estonia’s Baltic Sea mean was 45. Ireland’s Celtic Seas mean was 73, Germany’s North Sea mean was 98, and Belgium’s North Sea mean was 118.
Other reported means were 82 items per 100 meters for Denmark’s Baltic Sea subregion, 151 for Spain’s Macaronesia subregion, 178 for Greece’s Ionic/Central Mediterranean subregion, 222 for Bulgaria’s Black Sea subregion, and 242 for Spain’s Mediterranean subregion. France’s Celtic Seas mean was 390, and France’s Mediterranean mean was 394. The UK’s Celtic Seas and North Sea means were 585 and 877, respectively.
Several means were much higher. Denmark’s North Sea subregion had a mean of 1,077 items per 100 meters. Croatia’s Adriatic Sea subregion had 1,686. France’s North Sea subregion had 2,002, while France’s Biscay/Iberian subregion had 2,690. The highest supplied mean was Finland’s Baltic Sea subregion, at 11,414 total items per 100 meters.
That Finland figure is reported alongside a median of 49 items per 100 meters for the same subregion and period. The contrast is substantial: the median indicates the midpoint of the reported observations, while the mean is pulled upward by unusually large values. This is precisely why monitoring summaries are stronger when they provide both measures.
Source for all mean figures: A European threshold value and assessment method for macro litter on coastlines, 2015–2016.
How median and mean differ
The EU baseline gives the clearest overall comparison: 504 items per 100 meters was the mean, compared with a median of 133. The subregional results reinforce the same point. Denmark’s North Sea subregion had a median of 221 but a mean of 1,077. France’s Biscay/Iberian subregion had a median of 2,134 and a mean of 2,690. The supplied values show that a mean can be much higher than a median when a small number of observations have very large counts.
| Comparison | Median | Mean |
|---|---|---|
| EU baseline, 2015–2016 | 133 | 504 |
| Denmark — North Sea, 2015–2016 | 221 | 1,077 |
| France — Biscay/Iberian, 2015–2016 | 2,134 | 2,690 |
| France — Mediterranean, 2015–2016 | 294 | 394 |
| UK — Celtic Seas, 2015–2016 | 222 | 585 |
For coastal conservation, the choice of summary statistic affects the question being answered. A median can describe the central monitoring result without being dominated by extreme counts. A mean reflects the total level across the observations but can rise sharply when some monitored stretches contain exceptional concentrations. Neither number replaces the other, and neither should be transferred from one geography to another without retaining its subregion and measurement period.
England monitoring trends
England’s monitoring series provides a time-based view rather than a single 2015–2016 regional snapshot. The Environmental Indicator Framework Theme C (Seas and Estuaries) reports that an individual England beach survey recorded a maximum of 6,900 litter items per 100 meters in January 2018. Another individual survey recorded a minimum of 0 items per 100 meters in April 2018. These are individual survey results, so they should not be read as national averages.
The smoothed England beach-litter series peaked at 1,280 items per 100 meters in April 2017. It fell to 380 items per 100 meters by September 2021 and stayed at that level through October 2022. The same source reports a statistically significant short-term trend: a decrease of 103.6 litter items per 100 meters per year from 2017 to 2022.
The England figures demonstrate why a monitoring article should identify whether a value is an individual observation or part of a smoothed series. The 6,900-item maximum and the 0-item minimum describe the endpoints of individual surveys recorded in particular months. The 1,280 and 380 values belong to the smoothed series, while the 103.6-item figure describes the estimated annual rate of short-term change over 2017–2022. They are related measurements, but they are not interchangeable.
Source: Environmental Indicator Framework Theme C (Seas and Estuaries), January 2018–October 2022 as specified above.
What global cleanup records counted
The 2024 International Coastal CLEANUP RESULTS report records the items collected by International Coastal Cleanup participants. Food wrappers were the most numerous item in the supplied results, with 1,442,860 recorded in 2024. Plastic beverage bottles followed at 1,284,225, and cigarette butts at 1,227,124.
Other leading categories included 979,400 plastic bottle caps, 523,998 plastic food containers, and 480,371 other plastic bags. Participants also recorded 468,394 plastic grocery bags, 444,485 paper cups and plates, 436,397 plastic cups and plates, and 404,636 foam food containers.
| Item category | Items recorded in 2024 |
|---|---|
| Food wrappers | 1,442,860 |
| Plastic beverage bottles | 1,284,225 |
| Cigarette butts | 1,227,124 |
| Plastic bottle caps | 979,400 |
| Plastic food containers | 523,998 |
| Other plastic bags | 480,371 |
| Plastic grocery bags | 468,394 |
| Paper cups and plates | 444,485 |
| Plastic cups and plates | 436,397 |
| Foam food containers | 404,636 |
These cleanup totals are counts of collected items in 2024, not abundance per 100 meters of beach. They therefore answer a different monitoring question from the European baseline and England series. The value of keeping both types of evidence is that standardized shoreline abundance can track conditions at monitored locations, while cleanup records identify common item categories encountered by participants across the International Coastal Cleanup effort.
Source: 2024 International Coastal CLEANUP RESULTS, 2024.