The Research On The Diurnal Distribution Of UVA And UVB Exposure Intensity With Time And Solar Elevation Angles In The Interior Of The Living Room

Objective:Visual disorders and age-related eye diseases seriously affect the economic level and life quality on people.It is universially known that cataract is one of the most severe public health problems globally,especially in developing countries.Meanwhile,it cannot be ignored that ultraviolet（UV）exposure has become an important environmental exposure factor.Due to the elderly and children being the high-risk population on cataract and most of them spending more time indoor,most importantly,we believe that the exposure patterns to age-related cataract is the“long-term,low-dose,and continuous”exposure.All these lead us to explore the UVA and UVB exposure indoor.In this study,we describe the general diurnal distribution between UV and time and solar elevation angles.It may provide a theoretical basis for age-related cataract exposure patterns and may further completely simulate the human UV exposure patterns all day.Methods:Thisstudy was conducted in the city of Sanya on Hainan island（18.4°N,109.7°E,at an altitude of about 18m,China）and the city of Lhasa in Tibet autonomous region（29.7°N,91.14°E,at an altitude of 3650m,China）using three rotating manikins.Experiments were performed only on clear or slightly cloudy days.Final data set was obtained on May 16^th and 20^th,2015 in Sanya,and May 19^th and24^th,2016 in Lhasa.Indoor measurements were carried out in the living rooms which only has one windows in them.For monitoring UV exposure density indoor,the model is divided into four categories based on the different displaying status:facing to the open window,back to the open window,facing to the closed window,and back to the closed window.These four states were then respectively recorded in the Excel.The maximum exposure area,building orientation and the exposure state of the model could be found by describing the diurnal distributions od UVA,UVB and time and solar elevation angles.Compared with UVA and UVB density outdoor,we can obtain the variation between indoor and outdoor on UV exposure density.Results:In Sanyaand Lhasa,the air quality during monitoring periods were pretty good.The corresponding mean of AQI were 30 and 78,meanwhile,the average temperature is 29℃and 15℃,respectively.The diurnal distribution curves of ambient and ocular UVA and UVB intensity in these two regions were consistent with previous studies.The ambient curves were“bell shape”and the ocular curves were“bimodal distribution”.The exposure intensity of ocular UVA and UVB indoor whose model is facing to the open window is higher than the corresponding ambient intensity when controlled the other confounding factors.In the east and west interior,the diurnal distribution curves of ocular UVA and UVB intensity when models facing to the open window were approximately“linear”.While in the south and north living rooms,the curves were“bimodal distribution”.When investigating the effects of different model displaying states on the intensity of ocular UVA and UVB,we found that the ocular UVA intensity was almost zero when the models back to the windows.Whether switching off the window has also played a certain role on the reduction of the ocular UVA and UVB intensity.In north and south living rooms in Sanya,the closed window might have almost 50%reduction;and for UVB intensity,the maximum radiation intensity can be reduced by about 96%even the model facing to the windows.However,even if the model back to the windows,the reduction on the ocular UVB intensity when open the window is far worse than the closed window.When we discussed the exposure intensity of ocular UVA and UVB in different areas,we found that the ocular UVA and UVB intensity indoor in Lhasa was higher than those in Sanya except in the south orientation at the same monitoring time point.When we explored the maximum orientation for ocular UVA and UVB intensity indoor,we found that the east orientation has the peak intensity in Sanya and Lhasa.To investigate the difference between model ocular UVA and UVB intensity indoor and outdoor,we found that the eastward ratio of maximal exposure intensity of UVA and UVB to ambient intensity was the largest in Sanya area,which was 48%and 33%respectively,followed by west direction.And the largest proportion in Lhasa area was west direction.The maximal exposure intensity ratio of UVA and UVB was 89%and50%respectively,followed by eastward.Conclusion:The maximum of ambient and ocular UVA and UVB intensity occurred at the models facing to the open window.With the movement of sun,the room orientation corresponding to the maximum exposure intensity of UVA and UVB was eastward,followed by westward,southward and northward.The exposure intensity rules of UVA was consistent with UVB.The exposure intensity of model ocular UVA and UVB in the east and west room was influenced by the ambient surroundings.