Paper Reviewed
Monsé, C/. Jettkant, B., Schramm, B.K.H., Broding, H.C., Knappe, M., Michl, M., Hoffmeyer, F., Sucher, K., Brüning, T. and Bünger, J. 2019. Effects of exposure to carbon dioxide in potash miners. Advances in Experimental Medicine and Biology - Neuroscience and Respiration 42: 1-10.

Are there any significant direct health threats from rising atmospheric carbon dioxide?

Although many have made this claim, it has failed to withstand the scrutiny of scientific inquiry, evidenced by the recent works of Liu et al. (2017) and Rodeheffer et al. (2018). And now, a new paper adds another nail in the coffin of this ridiculous assertion.

The authors of the new study are Monsé et al. (2019) and they have published their work in the journal Advances in Experimental Medicine and Biology -- Neuroscience and Respiration. As their contribution to this topic, the ten German researchers investigated the physiological effects of long-term exposure to elevated CO2 in miners who had experienced repeated exposure to high CO2 levels on a regular basis.

In all, 93 miners were examined for the study. Each worked in the potash mines of the Werra-Fulda district in Hesse, Thuringia and Saxony-Anhalt in Germany for a minimum of two years. Each of the miners underwent medical examinations directly before and after underground shifts that subjected them to CO2 levels ranging from near-ambient to 15,000 ppm. Specific examinations included testing of thoracic and abdominal organs, laboratory analyses of blood, urine and lung function. Because of a varying CO2 exposure range from ambient to 15,000 ppm (as determined by monitoring the concentration around each miner), the authors categorized the CO2 exposure levels into one of three ranges: less than 1,000 ppm, 1,000 to 5,000 ppm and 5,000 to 15,000 ppm.

Results of the medical examinations, in the words of the authors, "failed to reveal any signs of acute and chronic health hazard of potash mining related to [elevated levels of CO2 in] the workplace." More specifically, they report that "there were no pathological alterations or short-term adverse effects of CO2 exposure" on blood gas content, adding that "all measured values remained within reference values." Additionally, they found "no evidence of any appreciable influence on lung function of CO2 exposure in potash miners, nor any pulmonary impairment comparing pre/post work shift conditions regardless of the [CO2] exposure severity."

And so, as the air's CO2 content continues to rise, it is extremely unlikely that there will be any negative direct health effects on humans, especially since the CO2 values measured in the study go far beyond the limit of ~1500 ppm that scientists think is possible if society utilized all of the currently-known fossil fuel reserves on the planet.

References
Liu, W., Zhong, W. and Wargocki, P. 2017. Performance, acute health symptoms and physiological responses during exposure to high air temperature and carbon dioxide concentration. Building and Environment 114: 96-105.

Rodeheffer, C.D., Chabal, S., Clarke, J.M. and Fothergill, D.M. 2018. Acute exposure to low-to-moderate carbon dioxide levels and submariner decision making. Aerospace Medicine and Human Performance 89: 520-525.