Pollution

How Numbeo calculates the index

Numbeo combines contributor responses about air and water, waste disposal, cleanliness, noise, light, green space and environmental comfort. Its Pollution Index gives particularly strong weight to air quality. CityFit uses that published index from its cached data.

Numbeo owns the source methodology. CityFit stores a snapshot of the published city values; it does not recalculate Numbeo’s underlying surveys or climate model. The source link below explains Numbeo’s calculation in full.

How CityFit uses it

The metric in city profiles stays in Numbeo’s original units. For personalization, CityFit also creates a 0–100 feature using the minimum and maximum across the full city dataset. This feature is reversed so a lower raw value contributes a higher feature score. If every city has the same value, the feature is set to 50.

feature = 100 − 100 × (value − global_min) / (global_max − global_min)

Its base weight is 10% of the practical priority blend. Your slider multiplies that weight, then all active weights are normalized. Practical Fit combines 30% of Numbeo’s Quality of Life Index with 70% of this weighted practical blend, then multiplies the result by 1.75. Setting a metric slider to zero removes its direct priority contribution; the Numbeo baseline still contains its own underlying factors.

Country and region filters select which cities you see. Metric colors continue to use the global scale; percentiles describe a city’s standing across the full dataset and are separate from the raw score.

What the score can tell you

This is a broad perception index, not a live air-quality reading or a measurement of exposure at your address.