Sunlight Exposure Reduces Mortality Risk

April 28, 2021

A brand new research shows that increased exposure to the sun’s rays acts as a simple public health intervention which reduces mortality rates during a pandemic: sunlight exposure and sunnier areas are linked with fewer deaths from covid.

A brand new research shows that increased exposure to the sun’s rays – specifically UVA – acts as a simple public health intervention. Researchers at the University of Edinburgh (Scotland, UK) found that sunlight exposure and sunnier areas are associated with fewer deaths from covid-19.

The study – entitled, “Ultraviolet A radiation and covid‐19 deaths in the USA with replication studies in England and Italy”, peer reviewed and published in the “British Journal of Dermatology” – compared all recorded deaths from covid-19 in the continental US from January 2020 to April 2020 with UV levels for 2,474 US counties for the same time period. Than the analysis was repeated in England and Italy with the same results.

Objective was to investigate the relationship between ambient UVA radiation and covid‐19 deaths. Scottish researchers found that people living in areas with the highest level of exposure to UVA rays – which makes up 95% of the sun’s UV light – had a lower risk of dying from covid-19 compared with those with lower levels.

The researchers took into account factors known to be associated with increased exposure to the virus and risk of death such as age, ethnicity, socioeconomic status, population density, air pollution, temperature and levels of infection in local areas. The observed reduction in risk of death from covid-19 could not be explained by higher levels of vitamin D, the experts said. Only areas, with insufficient levels of UVB to produce significant vitamin D in the body, were included in the study.

One explanation for the lower number of deaths, which the researchers are following up, is that sunlight exposure causes the skin to release nitric oxide. Nitric oxide may reduce the ability of SARS-CoV2 (the cause of covid-19) to replicate.

Previous research from the same group has shown that increased sunlight exposure is linked to improved cardiovascular health, with lower blood pressure and fewer heart attacks.  As heart disease is a known risk factor in dying from covid-19, this could also explain the latest findings.

Authors write: “Understanding factors impacting deaths from covid‐19 is of the highest priority. Seasonal variation in environmental meteorological conditions affects the incidence of many infectious diseases and may also affect covid‐19. Ultraviolet A (UVA) radiation induces release of cutaneous photolabile nitric oxide (NO) impacting the cardiovascular system and metabolic syndrome, both covid‐19 risk factors. Nitric oxide (NO) also inhibits the replication of SARS‐CoV2.”

“The Mortality Risk Ratio (MRR), in the USA, falls by 29% (40% ‐15% (95% CI)) per 100 (KJ/m2) increase in mean daily UVA. We replicate this in independent studies in Italy and England and estimate a pooled decline in MRR of 32% (48%‐12%) per 100 KJ/m2 across the three studies. … Our analysis suggests that higher ambient UVA exposure is associated with lower covid‐19 specific mortality. Further research on the mechanism may indicate novel treatments. Optimised UVA exposure may have population health benefits.”

Lead author Richard Weller, consultant dermatologist and reader at the University of Edinburgh, declared: “There is still so much we don’t understand about covid-19, which has resulted in so many deaths worldwide. These early results open up sunlight exposure as one way of potentially reducing the risk of death.” Co-author Chris Dibben, chair in Health Geography at the University of Edinburgh, added: “The relationship between covid-19 mortality, season and latitude has been quite striking, here we offer an alternative explanation for this phenomenon.”

Full Study “Ultraviolet A Radiation and COVID‐19 Deaths in the USA with replication studies in England and Italy”
University of Edinburgh Release