Projected changes in ultraviolet index and UV doses over the twenty-first century: impacts of ozone and aerosols from CMIP6

This study evaluated the health-related weighted ultraviolet radiation (UVR) due to the total ozone content (TOC) and the aerosol optical depth (AOD) changes. Clear-sky Ultraviolet Index (UVI), daily doses, and exposure times for erythema induction (Dery and Tery) and vitamin D synthesis (DvitD and TvitD) were computed by a radiative transfer estimator. TOC and AOD data were provided by six Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). For projections, we consider four Shared Socioeconomic Pathways scenarios-SSPs (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5)-and two time-slices (near: 2041-2060 and far future: 2081-2100). UVR projections showed pronounced changes for the summer hemispheres in the far future. TOC increases in mid- and high latitudes of the Southern Hemisphere caused decreases in UVR at the summer solstice. However, projections did not indicate sun-safe exposure conditions in South America, Australia, and Southern Africa. On the contrary, exposure around solar noon from 10 to 20 min will still be sufficient to induce erythema in skin type III individuals throughout this century. In southern Argentina and Chile, the UVR insufficiency for vitamin D synthesis at solar noon in skin type III remains the same during this century at the winter solstice. In the Northern Hemisphere, UVI and Dery at the summer solstice should remain high (UVI ≥ 8; Dery ~ 7.0 kJ m-2) in highly populated locations. Above 45 °N, UVR levels cannot be enough to synthesize vitamin D in skin type III during the boreal winter. Our results show that climate change will affect human health through excess or lack of solar UVR availability.

Solar Ultraviolet Radiation Temporal Variability Analysis from 2-Year of Continuous Observation in an Amazonian City of Brazil

Solar ultraviolet radiation (UVR) is a highly energetic component of the solar spectrum that needs to be monitored because of the effects on human health and on the ecosystems. In Brazil, few cities monitor UVR, especially in the Amazon region which is particularly poor in observation. This work is the first to address the short-term (2-year) time variability of UVR in Santarém (2°25′ S, 54°44′ W, 51 m) using ground-based measurements. The irradiance in the wavelength range of 250–400 nm was investigated on different time scales. Furthermore, to understand how the UVR varies without the influence of clouds, the hours corresponding to the clear sky condition were analyzed as well as the hours in all sky conditions. Regarding the averages, there is a slight variation over the year. In all sky and clear sky conditions, the dry season had a higher average than the rainy season, despite the slight difference. Also, both in all-sky and clear-sky conditions the maximums occurred around local solar noon, and reached a maximum of 87 in the dry season under the clear sky condition. Further understanding of the radiative effects of the clouds in UVR time variability is considered essential for future research. This study can serve as a reference for UVR levels in this region where no other ground-based UVR measurements are made.

Multiple sclerosis in Peru: National prevalence study using capture-recapture analysis

BACKGROUND

There is scarce epidemiological data on Multiple Sclerosis (MS) in Latin America. National epidemiological studies are needed to guide the health policy related to MS.

OBJECTIVE

To determine MS national prevalence in Peru and describe clinical and epidemiological characteristics of the disease.

METHODS

We conducted a cross-sectional prevalence study in Peru's four largest regions using two sources. We included adult patients diagnosed with MS by a neurologist using the McDonald criteria. We performed a capture-recapture analysis using the nearly unbiased estimator model, and calculated prevalence as the proportion of the adult Peruvian population in 2016. Additionally, we summarized patients epidemiological and clinical characteristics.

RESULTS

We identified 417 cases: 135 from the first source and 282 from the one. We found a point prevalence of 9.12 cases per 100 000 inhabitants (95% CI: 5.6 - 12.6). The age range was 35 to 45 years-old, and 51.9% were female. The most common type of MS was relapsing-remitting (79.3%) and the most frequent treatment was subcutaneous IFN-1b (40.7%).

CONCLUSION

Peru has a medium MS prevalence compared to other Latin American countries. Lima is the region with the highest number of cases, with similar clinical characteristics to other countries in the region.

Preliminary evidence for seasonality of Covid-19 due to ultraviolet radiation

The Covid-19 pandemic has spread across the world during early 2020, with unforeseen consequences. Beyond social measures and biomedical research, it is important to assess the seasonality of the epidemic to inform strategies, with limited available data in the short period of time between the March equinox and the June solstice. While the effect of multiple factors is being investigated, little attention has been paid to ultraviolet (UV) radiation, a key parameter of seasonal forcing. We review the effects of UV radiation, proposing it as a potential element of seasonality, and provide evidence from the current literature and scant, yet revealing, observations. Explicit consideration should be given to UV radiation for the seasonality of Covid-19 at high latitudes and altitudes, based on the SARS and MERS epidemics and coronavirus diseases, and not just the ‘warmer days’ of summer.

Physiological responses of maca (Lepidium meyenii Walp.) plants to UV radiation in its high-altitude mountain ecosystem

Ultraviolet (UV) radiation is a small fraction of the solar spectrum, which acts as a key environmental modulator of plant function affecting metabolic regulation and growth. Plant species endemic to the Andes are well adapted to the harsh features of high-altitude climate, including high UV radiation. Maca (Lepidium meyenii Walpers) is a member of Brassicaceae family native to the central Andes of Peru, which grows between 3500 and 4500 m of altitude, where only highland grasses and few hardy bushes can survive. Even though maca has been the focus of recent researches, mainly due to its nutraceutical properties, knowledge regarding its adaptation mechanisms to these particular natural environmental conditions is scarce. In this study, we manipulated solar UV radiation by using UV-transmitting (Control) or blocking (UV-block) filters under field conditions (4138 m above the sea level) in order to understand the impact of UV on morphological and physiological parameters of maca crops over a complete growing season. Compared to the UV-blocking filter, under control condition a significant increase of hypocotyl weight was observed during the vegetative phase together with a marked leaf turnover. Although parameters conferring photosynthetic performance were not altered by UV, carbohydrate allocation between above and underground organs was affected. Control condition did not influence the content of secondary metabolites such as glucosinolates and phenolic compounds in hypocotyls, while some differences were observed in the rosettes. These differences were mainly related to leaf turnover and the protection of new young leaves in control plants. Altogether, the data suggest that maca plants respond to strong UV radiation at high altitudes by a coordinated remobilization and relocation of metabolites between source and sink organs via a possible UV signaling pathway.

A Semiempirical Approach to the Determination of Daily Erythemal Doses

The maintenance of ground-based instruments to measure the incidence of ultraviolet radiation (UVR) from the Sun demands strict and well-developed procedures. A piece of equipment can be out of service for a couple of weeks or months for calibration, repair or even the improvement of the facilities where it has been set up. However, the replacement of an instrument in such circumstances can be logistically and financially prohibitive. On the other hand, the lack of data can jeopardize a long-term experiment. In this study, we introduce a semiempirical approach to the determination of the theoretical daily erythemal dose (DED_t ) for periods of instrumental absence in a tropical site. The approach is based on 5 years of ground-based measurements of daily erythemal dose (DED) linearly correlated with parameters of total ozone column (TOC) and reflectivity (R_PC ) from the Ozone Monitoring Instrument (OMI) and the cosine of solar zenith angle at noon (SZA_n ). Seventeen months of missing ground-based data were replaced with DED_t , leading to a complete 5-year series of data. The lowest and the highest values of typical DED were 2411 ± 322 J m^-2 (1σ) (winter) and 5263 ± 997 J m^-2 (summer). The monthly integrated erythemal dose (mED) varied from 59 kJ m^-2 (winter) to 162 kJ m^-2 (summer). Both of them depended mainly on cos(SZA_n ) and R_PC . The 12-month integrated erythemal dose (12-ED) ranged from 1350 kJ m^-2 to 1546 kJ m^-2 , but it can depend significantly on other atmospheric parameter (maybe aerosols) not explicitly considered here.

The geospatial relationship of pterygium and senile cataract with ambient solar ultraviolet in tropical Ecuador

The distribution of modelled surface ultraviolet for Ecuador, South America was determined by satellite observation and compared to national pterygium (WHO ICD H11) and senile cataract (WHO ICD H25) incidence.