Ground-level ozone following astrophysical ionizing radiation events: an additional biological hazard?

TL;DR

This study investigates whether ozone produced in the lower atmosphere after astrophysical ionizing radiation events poses a biological hazard, concluding that the ozone levels are too small to be significant.

Contribution

It provides the first assessment of lower atmospheric ozone production following ionizing radiation events using atmospheric chemistry modeling.

Findings

Lower atmospheric ozone levels are too small to threaten biosphere

Results can be extended to supernovae and solar proton events

Ozone depletion remains the primary concern for biological impact

Abstract

Astrophysical ionizing radiation events such as supernovae, gamma-ray bursts, and solar proton events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in solar UV radiation at Earth's surface and in the upper levels of the ocean. Other work has also considered the potential impact of nitric acid rainout, concluding that no significant threat is likely. Not yet studied to-date is the potential impact of ozone produced in the lower atmosphere following an ionizing radiation event. Ozone is a known irritant to organisms on land and in water and therefore may be a significant additional hazard. Using previously completed atmospheric chemistry modeling we have examined the amount of ozone produced in the lower atmosphere for the case of a gamma-ray burst and find that the values are too small to pose a significant additional threat to the biosphere. These results may be extended to other ionizing radiation events, including supernovae and extreme solar proton events.