In today’s installment of Map Monday, I wanted to focus on air pollution as mapped by Hsu et al and The Atlantic. Go to this link to see the full interactive map, which details air pollution by country and city. Below, I have copied in a global snapshot with some perhaps unsurprising shades of pollution severity, including China and India in dark hues.

Over the past year, you have probably seen numerous news stories detailing Beijing’s and other Chinese cities’ attempts to grapple with air pollution, as well as those pointing out that New Delhi actually has worse air pollution than Beijing. In fact, according to the World Health Organization (WHO), 13 of the 20 dirtiest cities in the world are in India. In both countries, some blame has been put on food vendors cooking in open-air and others have pointed to emissions from industrial pollution, but certainly the power and road transport sectors are significantly contributing towards air pollution; but what are those shares exactly?

The short answer is: it’s hard to measure without proper monitoring. This is a global problem with wide-ranging local effects. However, there has been some good progress in analyzing these issues recently. Here are some of the headline findings:

These items together paint a grim picture, but they also highlight the substantial work now going into data collection and analysis: important steps towards combating air pollution.

However, I’d be interested in hearing what you find surprising from the map above? Check out the time series function, and toggle between cities and countries and you might come up with some unanticipated results. For example, have a look at Norway versus Oslo in 2012, and you’ll see what I’m getting at.