Data from: Using the environmental light field method for measuring biologically relevant light characteristics at the household scale

The increasing prevalence of artificial light at night (ALAN) alters the natural light cycle and has been found to have harmful effects on both human and environmental health. Given its importance as a disease vector, we use Anopheles mosquitoes as a case study. Anopheles mosquitoes, several of which act as malaria vectors, and compare how light characteristics (details of the method followed below) influence key mosquito behaviours differ among regions and houses. We characterise the artificial light environment inside and immediately outside houses in rural settlements (South Africa, Mozambique, and Uganda) as the lighting present in these areas will likely play a role in affecting people’s risk of being infected by vector-borne diseases.  Light measurements The full methods for the environmental light field (ELF) method and analysis are described in Nillson & Smolka (2021), Quantifying biologically essential aspects of environmental light. Journal of The Royal Society Interface 18:rsif.2021.0184, 20210184.   A Nikon D850 camera body and a Sigma 8mm 180° fish eye lens were used in this study. We measured the light characteristics in houses in rural settlements in South Africa, Mozambique, and Uganda. Houses in Venda were measured from May to July 2023 in Mozambique, Mamfene, and Uganda. Each house is classified as an 'environment' in the ELF method. To characterise each environment, images were taken of four 'scenes' within that environment. Scenes were captured by rotating the camera 90° in a clockwise direction between scenes in order to ensure a 360° view of the environment was captured, with overlap between the scenes. Each scene was bracketed, capturing three photographs of each scene, separated by three exposure evaluation settings (3EV). Bracketing is used to increase the dynamic range of the images in the analysis process. In total, 20 houses were measured (Table S2), both inside and outside. Therefore, a total of 480 photographs were taken (20 houses, 2 locations per house, 4 scenes with 3 photographs per scene [2024*3]).   The camera was placed on a tripod at 1 metre above the ground and positioned so that it was level in both the vertical and horizontal planes, using a spirit level mounted on the camera. The camera was placed in the centre of the room for inside measurements, and no further than 2 m outside the houses for outside measurements. The ELF method characterises the entire light environment as detected by the animal eye, and captures a range of potential variation at the different elevation angles in the vertical field of view. Therefore, replication within an environment is not necessary.     Data analysis        To characterise the light environment, the photographs taken were processed in Matlab (The MathWorks Inc., 2022) using the ELF open-source software (Available at: github.com). The ELF analysis software used remaps all images from a circle into an equirectangular format, calculates the image statistics, the mean image of the 360◦ environment, average image statistics, and creates the final plots describing the light characteristics of the environment. All the image statistics calculated include (for each spectral channel, i.e., white, red, green, and blue wavelengths) the mean radiance, radiance standard deviation, median radiance, 2.5th, 25th, 75t,h and 97th percentiles and minimum and maximum radiances for 3◦ elevation angle bins within the 180◦  field of view (Nilsson and Smolka, 2021).      The light environment for each house is described at that specific position for a living organism in a nuanced and meaningful manner (e.g., for a range of biologically relevant wavelengths), reflecting the way animals observe their environment. Radiances are described as photon flux per nm (photons m ^-2s ^-1nm ^-1) for white light and the separate channels (Nilsson and Smolka, 2021). Radiance values are log10 transformed, allowing for comparison over all natural intensities, producing values in a unit called 'lit' (Nilsson and Smolka, 2021).    Note: The picture_start_number in the data file corresponds to the first image of the bracketed sequence for each scene within an environment/house. The three bracketed images of each scene are considered one file in analysis. # Data from: Using the environmental light field method for measuring biologically relevant light characteristics at the household scale Dataset DOI: [10.5061/dryad.15dv41p8c](10.5061/dryad.15dv41p8c) ### Description of the data and file structure **Study sites** The study characterises the artificial light environment inside and immediately outside houses in rural settlements (South Africa, Mozambique and Uganda) as the lighting present in these areas will likely play a role in affecting peoples’ risk of being infected by vector-borne diseases. Given its importance as a disease vector, Anopheline mosquitoes, several of which act as malaria vectors, are used as a case study, and we compare how light characteristics (details of the method followed below) influencing key mosquito behaviours differ among regions and houses. **Light measurements** The full methods for the environmental light field (ELF) method and analysis are described in Nillson & Smolka (2021) Quantifying biologically essential aspects of environmental light. Journal of The Royal Society Interface 18:rsif.2021.0184, 20210184. A Nikon D850 camera body and a Sigma 8mm 180° fish eye lens was used in this study. We measured the light characteristics in houses in rural settlements in South Africa, Mozambique and Uganda. Following the explanation of the methods and objectives of this study, we obtained verbal consent from the owner of each house via a translator. For all images taken, ISO was set to 1600 and the apeture to 3.5. Each house is classified as an 'environment' in the ELF method. To characterise each environment, images were taken of four 'scenes' within that environment. Scenes were captured by rotating the camera 90° in a clockwise direction between scenes in order to ensure a 360° view of the environment was captured, with overlap between the scenes. Each scene is bracketed, capturing three photographs of each scene, separated by three exposure evaluation settings (3EV). Bracketing is used to increase the dynamic range of the images in the analysis process. In total, 20 houses were measured (Table S2), both inside and outside. Therefore, a total of 480 photographs were taken (20 houses, 2 locations per house, 4 scenes with 3 photographs per scene [20*2*4*3]). The camera was placed on a tripod at 1 metre above the ground and positioned so that it was level in both the vertical and horizontal planes, using a spirit level mounted on the camera. The camera was placed in the center of the room for inside measurements, and no further than 2 m outside houses for outside measurements. The ELF method characterises the entire light environment, and captures a range of potential variation at the different elevation angles in the vertical field of view. Therefore, replication within an environment is not necessary. **Data analysis** ``` To characterise the light environment, the photographs taken were processed in Matlab (The MathWorks Inc., 2022) using the ELF open-source software (Available at: github.com). ``` The ELF analysis software used to remaps all images from a circle into an equirectangular format, calculates the image statistics, the mean image of the 360◦ environment, average image statistics and creates the final plots describing the light characteristics of the environment. All the image statistics calculated include (for each spectral channel i.e. white, red, green and blue wavelengths) the mean radiance, radiance standard deviation, median radiance, 2.5th, 25th, 75th and 97th percentiles and minimum and maximum radiances for 3◦ elevation angle bins within the 180◦ field of view (Nilsson and Smolka, 2021). The light environment for each house is described at that specific position for a living organism in a nuanced and meaningful manner (e.g. for a range of biologically relevant wavelengths), reflecting the way animals observe their environment. Radiances are described as photon flux per nm (photons m-2s-1nm-1) for white light and the separate channels (Nilsson and Smolka, 2021). Radiance values are log10 transformed, allowing comparison over all natural intensities, producing values in a unit called 'lit' (Nilsson and Smolka, 2021). ### Files #### File: Mamfene_ELFdata.xlsx Description: Data file for the Mamfene region, containing the ELF raw output values for inside and outside each house. #### File: Metadata_file_vanZyl_et_al_Using_the_environmental_light_field_method_for_measuring_biologically_relevant_light_characteristics_at_the_household_scale.csv Description: Metadata file with the following for each house sampled: date, location, description of weather conditions, the unique site code assigned to houses in this study, sky quality meter (SQM) and lux-meter readings, light types present, and notes describing what room of the house was used. In the metadata file we have changed the location data to 2 decimal places as an adjustment to protect privacy. #### File: Mozambique_ELFdata.xlsx Description: Data file for the Mozambique region, containing the ELF raw output values for inside and outside each house. #### File:Uganda_ELFdata.xlsx Description: Data file for the Uganda region, containing the ELF raw output values for inside and outside each house. #### File: Venda_ELFdata.xlsx Description: Data file for the Venda region, containing the ELF raw output values for inside and outside each house. ### Variables #### Metadata file * date Description: The date on which the measurements were taken. * region Description: The study region in which the houses fall. * village Description: The name of the village in which the houses fall. * house_code Description: The unique house code assigned to each house in this study, consisting of a region code and the number of the house in the region. V = Venda, Mo = Mozambique, M = Mamfene, U = Uganda.The unique house codes used in the dataset are arbitrary identifiers and do not contain or convey any information regarding the physical addresses of the houses. * inside/outside Description: The location of the measurements, either inside or outside the house. * unique_site_code Description: The unique site code is a combination of the arbitrary house code assigned and the location of the measurement, following the format: HouseCode_Inside/Outside. * latitude Description: The latitude coordinate of the house in decimal degrees. * longitude Description: The longitude coordinate of the house in decimal degrees. * SQM Description: Sky quality meter (SQM) reading outside the house. * lux Description: Lux meter reading (lux) at the position of the camera used for the ELF method. * weather Description: A description of the weather conditions at the time of measurements as this my influence the light conditions detected by the ELF method. * light_types_present Description: The light type(s) present i.e., light-emitting diode (LED) lights, LED spotlights, compact fluorescent lights (CFL), and incandescent lights. * notes Description: Room type measured inside houses. #### ELFdata files ##### Variables for row 1 to 5 * channel Description: The spectral channel (i.e., red, green, blue and white light wavelengths) for which the summary statistics of the entire field of view are specified. * mean Description: The average spectral photon radiance described as photon flux per nm (log10 (photons m−2 s−1 nm−1)) (i.e., in the unit lit). * std Description: One standard deviation (std) of the mean spectral photon radiance (lit). * median Description: The median spectral photon radiance in the entire field of view (lit). * 25th percentile Description: The 25th percentile of spectral photon radiance across the entire field of view (lit). * 75th percentile Description: The 75th percentile of spectral photon radiance across the entire field of view (lit). * min Description: The minimum spectral photon radiance across the entire field of view (lit). * max Description: The maximum spectral photon radiance across the entire field of view (lit). * 2.5th percentile Description: The 2.5th percentile of spectral photon radiance across the entire field of view (lit). * 97.5th percentile Description: The 97.5th percentile of spectral photon radiance across the entire field of view (lit). ##### Variables for row 6 to 66 * elevation Description: Elevation angle within the 180° vertical field of view. Spectral photon radiances are calculated for 3° elevation angle bins within the 180° vertical field of view. * mean R Description: The average spectral photon radiance for red (R) light wavelengths described as photon flux per nm (log10 (photons m−2 s−1 nm−1)) (i.e., in the unit lit). * mean G Description: The average spectral photon radiance for green (G) light wavelengths described as photon flux per nm (log10 (photons m−2 s−1 nm−1)) (i.e., in the unit lit). * mean B Description: The average spectral photon radiance for blue (B) light wavelengths described as photon flux per nm (log10 (photons m−2 s−1 nm−1)) (i.e., in the unit lit). * mean W Description: The average spectral photon radiance for white (W) light wavelengths described as photon flux per nm (log10 (photons m−2 s−1 nm−1)) (i.e., in the unit lit). * std R Description: One standard deviation (std) of the mean spectral photon radiance (lit) of red (R) light. * std G Description: One standard deviation (std) of the mean spectral photon radiance (lit) of green (G) light. * std B Description: One standard deviation (std) of the mean spectral photon radiance (lit) of blue (B) light. * std W Description: One standard deviation (std) of the mean spectral photon radiance (lit) of white (W) light. * median R Description: The median spectral photon radiance of red (R) light (lit) at the specified elevation angle. * median G Description: The median spectral photon radiance of green (G) light (lit) at the specified elevation angle. * median B Description: The median spectral photon radiance of blue (B) light (lit) at the specified elevation angle. * median W Description: The median spectral photon radiance of white (W) light (lit) at the specified elevation angle. * 25th perc R Description: The 25th percentile of spectral photon radiance in the red (R) spectral channel at the specified elevation angle (lit). * 25th perc G Description: The 25th percentile of spectral photon radiance in the green (G) spectral channel at the specified elevation angle (lit). * 25th perc B Description: The 25th percentile of spectral photon radiance in the blue (B) spectral channel at the specified elevation angle (lit). * 25th perc W Description: The 25th percentile of spectral photon radiance in the white (W) spectral channel at the specified elevation angle (lit). * 75th perc R Description: The 75th percentile of spectral photon radiance in the red (R) spectral channel at the specified elevation angle (lit). * 75th perc G Description: The 75th percentile of spectral photon radiance in the green (G) spectral channel at the specified elevation angle (lit). * 75th perc B Description: The 75th percentile of spectral photon radiance in the blue (B) spectral channel at the specified elevation angle (lit). * 75th perc W Description: The 75th percentile of spectral photon radiance in the white (W) spectral channel at the specified elevation angle (lit). * min R Description: The minimum spectral photon radiance in the red (R) spectral channel (lit). * min G Description: The minimum spectral photon radiance in the green (G) spectral channel (lit). * min B Description: The minimum spectral photon radiance in the blue (B) spectral channel (lit). * min W Description: The minimum spectral photon radiance in the white (W) spectral channel (lit). * max R Description: The maximum spectral photon radiance in the red (R) spectral channel (lit). * max G Description: The maximum spectral photon radiance in the green (G) spectral channel (lit). * max B Description: The maximum spectral photon radiance in the blue (B) spectral channel (lit). * max W Description: The maximum spectral photon radiance in the white (W) spectral channel (lit). * 2,5th perc R Description: The 2.5th percentile of spectral photon radiance in the red (R) spectral channel (lit). * 2,5th perc G Description: The 2.5th percentile of spectral photon radiance in the green (G) spectral channel (lit). * 2,5th perc B Description: The 2.5th percentile of spectral photon radiance in the blue (B) spectral channel (lit). * 2,5th perc W Description: The 2.5th percentile of spectral photon radiance in the white (W) spectral channel (lit). * 97,5th perc R Description: The 97.5th percentile of spectral photon radiance in the red (R) spectral channel (lit). * 97,5th perc G Description: The 97.5th percentile of spectral photon radiance in the green (G) spectral channel (lit). * 97,5th perc B Description: The 97.5th percentile of spectral photon radiance in the blue (B) spectral channel (lit). * 97,5th perc W Description: The 97.5th percentile of spectral photon radiance in the white (W) spectral channel (lit). ### Code/software NA - This study made use of the ELF open-source software (Available at: [github.com](github.com)) described by Nilsson, D.-E., and J. Smolka. 2021. Quantifying biologically essential aspects of environmental light. Journal of The Royal Society Interface 18:rsif.2021.0184, 20210184. ### Access information Other publicly accessible locations of the data: \* None Data was derived from the following sources: \* None - Primary data ## Human subjects data For this project, participants received a clear explanation of the study methods and objectives. Verbal informed consent was obtained via a translator prior to any data collection. In the regions in which we conducted the research, including South Africa, verbal consent is standard practice and fully compliant with both institutional and regional ethical guidelines. This procedure is routine and permitted under the approved ethical framework governing the study. Regarding de-identification and minimization of re-identification risk, the GPS device used in the field has an accuracy of approximately 10 meters. In a village setting, this level of precision does not allow for the identification of specific households. In the metadata file, we have changed the location data to 2 decimal places as an adjustment to protect privacy.