On this blog, started in 2021, I plan to occasionally post some updates. Having recently moved from Cape Town to Medellín, I might be looking at the differences between these cities, or report on some of the delights or challenges of moving to a new country.

Air quality in Medellín: a scoping exercise

In our quest to locate a suitable place in Medellín where air pollution levels are within reasonable levels, it seems like a good idea to obtain data. This made me dive deeper into the topic of air quality measurement. Turns out, there is quite a lot to it!

First of all, let's have a look at some guidelines around air pollution. Particulate matter is our main concern. The WHO Air quality guideline values for particulate matter are as follows:

Fine particulate matter (PM2.5)

  • 10 μg/m3 annual mean
  • 25 μg/m3 24-hour mean

Coarse particulate matter (PM10)

  • 20 μg/m3 annual mean
  • 50 μg/m3 24-hour mean

The "Un Mejor Aire" website from the Metropolitan Area of …

Traffic intensity in Medellín

Air quality is a concern in Medellín - and in the wider Metropolitan Area of the Aburrá Valley. High concentrations of particulate matter (PM10 and PM2.5) are a chief concern, but so are the levels of nitrogen oxides (NOx), sulfur oxides (SOx), and ozone (O3). The main cause, as usual, is human activity. Fossil fuel combustion is the primary driver of most of these emissions.

Having experienced poor air quality in our first week in Medellín, we decided that air quality should be one of the factors taken into account when deciding where to live. The question is: how to do this? After an initial scoping exercise of existing literature and data, it seems that fine-grained (neighborhood-level) insights are …

iNaturalist and the great delights of nature photography

About 3 years ago, I started participating on iNaturalist. iNaturalist is an online platform where you can upload biodiversity observations. From plants to birds, and from insects to lichens - anything goes! Observations are mainly uploaded in the form of photos, but you can also upload them in other formats (such as sound recordings).

After uploading an observation, the system will suggest a species name, based on how well it can detect what is being observed. You can select what you think it is - however broad ("Bird") or specific ("Southern Double-collared Sunbird") you can be. Once your observation is recorded, other people on the website will help to confirm (or adjust) this classification. There are a lot of people …

The surprising diversity of the Klein Karoo

We recently visited the Klein Karoo. I had never realized this area is quite a bit different from the Great Karoo. Hereby, a short introduction into this captivating area. Most info comes from the very handy book, Plants of the Klein Karoo (Vlok & Schutte-Vlok, 2010)

With almost plant 3,200 species, a fascinating geology, and 19 different major habitat types the Klein Karoo is "the most complex and species rich arid area of the world". More than 400 plant species are endemic to the Klein Karoo. The area measures approximately 23,500 km2, most of which is situated in South Africa's Western Cape province, and a small area spilling into the Eastern Cape province. The area is shaped largely like …