Lol. Once again you made me laugh. Glad I wasn't drinking milk at the time.
Quite the scientific calculations they use to come up with this "index"
This section is based on surveys from visitors of this website. Questions for these surveys are similar to many similar scientific and government surveys.
Each entry in the survey is saved as the number in the range [-2, +2], with -2 having meaning of strongly negative and +2 meaning of strongly positive.
We filter surveys to eliminate potential spam, like people entering a large amount of data which are differentiating from the median value.
To present survey result, we use the scale [0, 100] for values since it is easier to read for users.
To generate a current index (which is always updated) we use data up to 36 months old. We include only cities for which there are at least a certain number of contributors. Our semiannual index is remade twice per year by pushing current index into this historical view.
Most of our data are based on perceptions (opinions) from visitors of this website. For pollution section, we include some relevant data from World Health Organization and other institutions if we find it helpful. Please consult our
Terms of use for details.
Pollution Index is an estimation of the overall pollution in the city. The biggest weight is given to air pollution, than to water pollution/accessibility, two main pollution factors. Small weight is given to other pollution types.
Pollution Exp Scale is using an exponential scale to show very high numbers for very polluted cities, and very low numbers for unpolluted cities. Therefore to calculate formula it uses the exponential function to calculate the index.
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