How Does Air Quality Measurement Vary with Elevation?

[Ethan]

I believe this is an AI-written post, but I will answer anyway, as I believe some people may find it useful.

Interestingly, there was recently a discussion about CO2 monitors being influenced by elevation, and I think some people may find that interesting.

CO2 Monitor Readings and Altitude

After this conversation, I wanted to take a bit more of a look at altitude and its impact of carbon dioxide monitors. I recently was in Nha Trang, Vietnam (right on the coast and barely above sea level) and decided to calibrate all of my CO2 monitors there. Today, I moved to Dalat, a city that is 1500 metres above sea level (see images below). [Nha Trang Elevation] [Da Lat Altitude] Instantly, I’ve begun to see massively varied readings between my CO2 monitors, which were, as of yesterda…

However, this question is quite different in that we’re discussing (primarily) PM and the environmental conditions that impact the actual pollutant levels instead of the devices that measure them.

Now, I don’t have any research to back this up at the moment, but I believe that PM levels appear higher (on average) in areas of medium elevation. However, I don’t think this so much depends on elevation as it does geographic features. For example, New Delhi, which is located on the Indo-Gangetic Plain, experiences very severe air pollution due to the fact that pollution gets trapped by the nearby Himalayas. This isn’t necessarily due to the medium elevation (around 210 metres) but rather to the area’s geography.

On the other hand, typically, the places with more coastlines (and, therefore, lower elevation) suffer less from air pollution due to their proximity to the sea and the winds from it. This is shown in AirVisual’s list of the cleanest countries in the world, where we can see that almost all are islands or at least have very significant coastlines in proportion to population - and it’s important to note that most air quality monitors are set up in areas with higher populations.

Of course, there are many other factors at play (development status, population, industry, and many others). Still, even if we look at India alone, we can see that air quality tends to be better in coastal areas - but wind does also have a large impact here.

Therefore, I think that if we look at averages, we can probably say that elevation and air quality are somewhat correlated. At the lowest elevations, air quality is generally better before it deteriorates at medium elevations and then gets better again at higher elevations. Again, however, this is more due to geographical features than elevation itself. As you mentioned, the weather is also very important and plays a big role!