Assessment of Nitric Oxide Release In-Vitro via Low-Level Light Irradiation, Equivalent Blue or Red Visible Light Within Daylight

Conflicting evidence exists on whether blue or red light modulate nitric oxide (NO) release within skin cells. This study shows that broad-spectrum blue or red (includ-ing infra-red) light at typical low-level environmental exposures fails to significantly in-crease NO release in skin cell monolayers compared to unexposed controls up to 2 hours post-exposure. We discuss observed discrepancies between our work and recent studies presenting measurable upregulation, noting that significant NO induction typically re-quires high-powered light emitting diode (LED) or lasers used in clinical settings within a specific narrow spectral band. Thus, while our findings show no significant effect, they provide an important counterpoint for public health discussions on visible light exposure at terrestrial levels, particularly low-level exposures.