Street cleanliness in Basel is measured using a cleanliness index that ranges from 0 to 5, with values below 3 considered poor, between 3 and 4 moderate, and above 4 good. The Grand Council has set a target of achieving a city-wide cleanliness index of at least 4.5, meaning that most street sections should be rated as good or better. This threshold serves as a benchmark for evaluating whether the city’s cleaning efforts are meeting public expectations.

In the most recent month, August 2026, a total of 4,744 street sections were monitored, producing 123,461 individual measurements. The cleanliness index across these measurements ranged from a minimum of 3.4 to a maximum of 5.0, with an average of 4.74. About 89.2 percent of all measurements exceeded the required threshold of 4.5, while 10.8 percent fell below it. This indicates that the large majority of street sections are currently meeting or surpassing the city’s cleanliness target, though a notable minority still falls short.

The top five and bottom five streets and districts in terms of cleanliness are not listed in the provided data, but the description indicates that such rankings exist and are based on average cleanliness index values. Average cleanliness is only one possible metric for ranking districts, and the order may change when using alternative indicators, such as the percentage of measurements exceeding the 4.5 threshold. Tables 1 and 2, referenced in the original analysis, would contain the full details for these rankings.

Comparing the first available month, January 2024, with August 2026 shows a clear improvement over time. In January 2024, 67.8 percent of measurements exceeded the 4.5 threshold, and 98.8 percent were rated as good (4.0 or better). By August 2026, the share above the threshold had risen to 89.2 percent, and the share rated as good or better reached 99.7 percent. This upward trend suggests that street cleanliness in Basel has improved substantially over the observed period, with both the threshold exceedance rate and the proportion of good ratings increasing.