In 1982, panic gripped a portion of California's scenic town of Mammoth Lakes. As before the U.S. Geological Survey issued a statement, a story was leaked to the press that a volcano few had ever heard of at the time was about to be placed at a raised alert level. Yet, while the severity of this volcanic unrest was overblown by tabloids, in my opinion, the state was truly only 4 to 6 months away from a volcanic eruption at a point in 1982. This video discusses what exactly occurred, and the three magmatic intrusions which occurred between 1980 and 1990.

Carbon dioxide overexposure symptoms can be found listed within this file:
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Thumbnail Photo Credit: Jennifer Lewicki, U.S. Geological Survey, Public Domain, https://www.usgs.gov/index.php/media/.... This image was cropped, resized, overlaid with text, and then overlaid with GeologyHub made graphics (the image border and the GeologyHub logo).

Note: I am of the opinion that a volcanic eruption was as little as 4 months away from a section of the Long Valley caldera supervolcano had the magmatic intrusion not stalled in the summer of 1982. However, this intrusion did stall, so calling the volcanic eruption close is a subjective term, involving merely GeologyHub's opinion. Others might disagree with this assessment, but I believe that magma going from 8 to 4 kilometers depth is a highly unusual event, even if 90% of magmatic intrusions (like was the case in 1982) fail to ever reach the surface. It is still debated to this day whether the 19811982 intrusion was part of Mammoth Mountain or the Long Valley Caldera, with this video assuming the latter. If an eruption had occurred, GeologyHub is of the opinion that it would have formed a cinder cone in a mildly explosive event, perhaps covering 12 km^2 in a layer of lava. It would not have resulted in a caldera forming event, only a possible VEI 23 eruption. A similar eruption occurred from the Long Valley Caldera 16,000 years ago, producing a basaltic lava flow.
You might be wondering how I can say that the eruption hazard was overblown in 1982. My response is that while an eruption was potentially months away if the magmatic intrusion continued its upward motion, this was still months away from requiring any form of an evacuation. In other words, the tabloids jumped too far ahead of the logical time table progression involving the volcanic unrest in 1982.

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Various licenses used in sections of this video (not the entire video, this video as a whole does not completely fall under one of these licenses) and/or in this video's thumbnail image:
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Sources/Citations:
[1] U.S. Geological Survey
[2] Source of Volcanic Explosivity Index (VEI) methodology and criteria: Newhall, C. G., and Self, S. (1982), The volcanic explosivity index (VEI) an estimate of explosive magnitude for historical volcanism, J. Geophys. Res., 87(C2), 1231–1238, doi:10.1029/JC087iC02p01231. Accessed / Read by    / geologyhub   on Oct 5th, 2022.
[3] Lewicki, J. L., Evans, W. C., MontgomeryBrown, E. K., Mangan, M. T., King, J. C., & Hunt, A. G. (2019). Rate of magma supply beneath Mammoth Mountain, California, based on helium isotopes and CO2 emissions. Geophysical Research Letters, 46, 4636–4644. https://doi.org/10.1029/2019GL082487
[4] Bing Q. Li et al. ,Basal nucleation and the prevalence of ascending swarms in Long Valley caldera.Sci. Adv.7,eabi8368(2021).DOI:10.1126/sciadv.abi8368, CC BY 4.0