Have You Earned Your Air Pollution Stripes?

Ed Hawkins' Climate Stripes visualization of global heating has quickly become a data visualization classic. Climate Stripes (sometimes known as Warming Stripes) are a visual representation of the long-term increase in global temperatures due to climate change. Ed's striking Climate Stripes visualizations consist of colored vertical stripes, with each stripe representing a single year and the colors indicating the temperature anomaly for each year relative to a baseline period.

Inspired by Climate Stripes Edinburgh University has created Air Quality Stripes visualizations for a number of global cities. Air Quality Stripes use colored stripes to indicate average yearly air pollution levels in cities since 1850. Like Ed Hawkins' Climate Stripes these Air Quality Stripes are effective in providing a simple and easily comprehensible visualization of historical trends in a given dataset.

Each city's Air Quality Stripes can instantly convey the history of air quality in a city. For example, as Edinburgh University notes, the stripes demonstrate "the air in many cities in Europe is much cleaner now than it was 100 years ago." In contrast (as you can see in the screenshots above) the air quality in many Indian cities has become dangerously worse in the 21st Century.

Edinburgh University actually provides four different types of yearly air pollution levels for each city. Despite the effectiveness of the air pollution stripes visualization of the data I actually prefer the more traditional bar graph visualizations of the same data. These bar chart visualizations of yearly PM2.5  concentrations include reference lines to show the WHO Guideline (a target of a concentration of 5 micrograms om PM2.5 per cubic meter) and Edinburgh University's own 'Very Poor Air Quality' level. Alongside the use of color the height of each year's bar provides an additional guide to the average levels of air pollution.