Thread by @rafaerts

Is living in a green environment good for your health?

Read my PhD thesis in a Twitter thread🧵
“𝑮𝒓𝒆𝒆𝒏 𝒔𝒑𝒂𝒄𝒆 𝒂𝒏𝒅 𝒃𝒊𝒐𝒅𝒊𝒗𝒆𝒓𝒔𝒊𝒕𝒚 𝒊𝒏 𝒓𝒆𝒍𝒂𝒕𝒊𝒐𝒏 𝒕𝒐 𝒉𝒆𝒂𝒍𝒕𝒉” 🌳⚕️ (in Belgium 🇧🇪)

#phdchat #ThesisThread [1/n]

Earlier research shows that green environments often have:
-less air pollution🏭
-less traffic and noise 🚔
-less heat🔥
-more birds, flowers, butterflies… 🐦🌻🦋

and green areas may engage people to walk or interact.

All this may benefit health [2/n]

To measure how green an environment is, these earlier studies have often used "NDVI".

NDVI is an index derived from satellite images, that tells you… how ‘green’ an area is [3/n]

NDVI is easy to obtain for large areas and with sufficient detail (high resolution) 👍

But a manicured football pitch 🏈 and a forest 🌳 may have the same level of greenness on NDVI maps
( 🟢= 🟢) [4/n]

But the species composition and structure of a football field (🌱) and a forest (🌳) differ widely.

Therefore also the ecosystem services they provide (such as cooling the environment ❄️) differ, and importantly, also the potential human health benefits will differ! [5/n]

Therefore, I set out to find other sources of information to determine the amount and quality of green space near the place where people live 🏡🧐

and then I linked this information to indicators of human health 👩‍⚕️[6/n]

First I used CORINE land cover data.

This map has information on the size and distribution of 32 land cover classes in Belgium such as forest, arable land, pastures, etc. [7/n]

We then compared the amount of forest 🌳in residential areas to sales of heart medication💟.

We found that:
-less heart medication was sold in greener environments
-the socio-economic background was a stronger predictor of health [8/n]

The problem with the CORINE map is that the map is not very detailed.

Parks and woodlands smaller than 0.5km x 0.5 km (almost all green areas in cities!) are not classified as green but are ‘lost’ in urban land cover.

➡️We needed something more detailed 🔎 [9/n]

Thus enters the Green Map.

This detailed map of Flanders tells you, for every square meter, whether it is high green (>3m) 🟩, low green 🟢, agriculture 🟨, or not green ⬜️ [10/n]

We compared the amount of green near the house of tree pollen allergy patients with the levels of stress they experienced during the tree pollen season 🤧

We found that:
-stress was lower when there was more green
-distress was higher when birch trees were present
[11/n]

The problem with the Green Map is that it the map is only available for Flanders, and I was looking for patterns across Belgium.

Thus enters another map: the topographic map of Belgium 🗺️ [12/n]

We compared the amount of different green space types to:

- sales of medication for asthma (for children) 🚸
- sales of medication for mood disorders such as depression and anxiety (for adults) 💊[13/n]

We found that there were fewer medication sales for mood disorders when there were more:

-forests 🌳
-low green areas 🍀
-grasslands 🌱
-gardens 🏡

or in short, a better mood where there was less built-up area [14/n]

But we also found that there were more medication sales for asthma when there were more:

-grasslands 🌱
-gardens 🏡

(and we found no evidence for a beneficial effect of forests!) [15/n]

Thus, in this thesis, we showed that living in green areas is often good for health, but health effects:

-depend on the type of green
-may differ between specific groups (allergy patients, children…)

And we should not solely rely on simple indicators of greenness! [16/n]

The way forward?

Even more detailed measurements of green space!

@dengkai_chi identified all trees in Brussels using laser sensor data 🛩️

Together we showed that living near large trees results in lower medication sales for mood disorders and heart disease) @EHPonline [17/n]

And we looked inside private gardens too 🧐

We found that gardeners were more active in gardens with higher biodiversity values 🍀🐞🪲🦔, and this was then related to lower depression scores during the COVID-19 pandemic. [18/n]

This PhD research was hosted by @sciensano and @CMK_Uhasselt & supported by @belspo with several partners including @KU_Leuven @dForNatLan @M3BIORES @UNamur @meteobenl and @AirAllergy.

You can find OA versions of my publications here
🔓📄⬇️
lirias.kuleuven.be/cv?Username=u0… [19/n]

And oh yes. This is in fact my second PhD 👨‍🎓

I also studied how African wild olive trees can regenerate in Ethiopia (research funded by @VLIRUOS).

Read why I did a second PhD in the story by @VirginiaGewin on double doctorates in @Nature

@threadreaderapp Please unroll and thank you very much!

✍️The residential green space and distress work was presented at the 2019 @ISEEORG conference in Utrecht, NL. The positive feedback on my Pecha Kucha presentation based on emojis triggered me to keep using emoji throughout my PhD and in all my publication graphical abstracts.