Human health and earth science questions - do they belong here

Question

There's kind of a grey area surrounding the appropriateness of questions on the human health effects of earth science-related processes for this site. Where should the line be drawn?

For example, a recent question was just put on hold that asked about the health effects of vehicle emissions and whether or not these caused cancer (Regarding car exhaust and it's possible carcinogenic effects). But, questions about health effects are routinely asked and answered on the site:

• Water veins underground causing health problems
• Is ground level ozone dangerous to human health when other pollutants are not present, for example, at high altitudes?
• Why do maps of melanoma prevalence correlate negatively with UV index, negatively with ground ozone, and positively with atmospheric ozone levels

I feel like the problem is not as straightforward as it seems at first, partially because human health effects are often used in public policy as a justification for action on climate change, air pollution, extreme weather, etc. and in paper introductions to justify the research conducted. Additionally, much of the research underlying these effects is not biological in nature (is not concerned with the biological mechanisms that cause x to result in health problems), but largely relies on epidemiology and population-based studies that, instead, demonstrate associations between health problems and earth science-related processes or results, and often rely heavily on models and research conducted in the geosciences. If human health is often the why behind earth science research, are we excluding something important or relevant if all questions on this topic are rejected?

Answer 1

I wouldn't say these kind of questions are "routinely" asked here, but as you note there are a few of them. Lets start with the closed question that prompted you to ask this.

The car exhaust question is different than the others in that it does not directly concern earth sciences as I see it. A question related to this that does invoke earth science would be like this or this. These questions wonder how anthropogenic pollution (car exhaust) affects stratospheric ozone and how car pollution compares to other sources of pollution. The closed question, however, is wondering how car exhaust affects humans, particularly cancer causing effects. This shifts the question into a medical or biology realm, as you need an oncologist or someone doing bioinformatic studies on this. You won't find either of those points of expertise on this site and it isn't on-topic here.

Regarding your comparison questions, the melanoma question is borderline and the community seems noncommittal on what do do with it. It took a trip through the close vote queue but the voting was split. I personally feel that that question is a bit outside of our scope, but I don't unilaterally decide things like that, it is up to the community. Questions about UV are on-topic but when we start getting into biological effects and skin cancer I feel that is pushing the boundaries. If the question can be answered solely from a UV/planetary science perspective it is probably OK, but if the answer needs to invoke properties of the population then I feel it should probably be somewhere else rather than here.

The underground river question is OK here since it is a geological thing and the question is about a myth regarding the geology. If it did have to move somewhere else, it would be skeptics. The ozone question is OK because ozone is a well-studied chemical in our atmosphere and atmospheric chemists can readily answer this question (and as you mention this can also be a motivator for study).

The last point may have you asking why ozone->health is on-topic but cars->cancer is not? In my opinion, ozone->health is OK because ozone is not just a pollutant, but a naturally occurring molecule in our atmosphere, and we know a bit about how this molecule affects people. That cars emit this molecule at low-levels just provides more sources for the molecule but does not really change the rest of the problem. On the other hand, car-exhaust->cancer is off-topic because we've removed the planet from the question. This does not depend on the atmosphere (except as a container for pollution) and is really just an interaction between combustion particulates and human biology that does not depend on atmospheric science.

Answer 2

Shouldn't be here.

Whilst it is true that some questions are somewhat relevant and may be motivated by earth sciences, we don't have the expertise here regarding that.