Digitally measuring solar ultraviolet radiation in outdoor workers: A study protocol for establishing the use of electronic personal dosimeters in Portugal

**Background:** Skin cancer, particularly keratinocyte carcinomas (KC), is a major public and occupational health issue, with an estimated 7.7 million new cases worldwide in 2017. Solar ultraviolet radiation (UVR) is classified as a Group 1 carcinogen by the IARC. Outdoor workers are at increased risk, with a meta-analysis reporting a 60% increased risk of non-melanoma skin cancer (RR: 1.60; 95% CI: 1.21–2.11) and a 142% increased risk for squamous cell carcinoma (RR: 2.42; 95% CI: 1.66–3.53). The International Commission on Non-Ionizing Radiation Protection (ICNIRP) defines an acceptable daily exposure of 1.0 to 1.33 Standard Erythema Dose (SED). This protocol aims to measure occupational solar UVR doses in outdoor workers in Lisbon using personal electronic dosimeters integrated with a digital platform, to raise awareness and inform prevention strategies.

**Methods:** This prospective observational study will be conducted in Lisbon, Portugal, from April to October 2023. The target population includes 174 gardeners, 27 masons, and 88 gravediggers from the municipality of Lisbon. A sample of 210 outdoor workers will be invited to participate. Thirty workers (10 per occupation) will wear the GENESIS-UV personal electronic dosimeter for 1 month each, with dosimeters rotating among workers over the 7-month period. The dosimeter (X-2012-10, Gigahertz, Germany) measures UV irradiance in UVA and UVB/C bands and is worn on the upper left arm during working hours (typically 9:00 a.m. to 5:00 p.m.). Data are uploaded weekly via a tablet and processed to calculate daily and monthly averages (W/m²) and cumulative erythemal doses (J/m²), converted to SED (1 SED = 100 J/m²). A training session will be provided before dosimeter use. Dermatological screening will be performed by expert dermatologists using digital dermoscopy, ultrasound, and in vivo confocal microscopy to assess skin cancers, pre-neoplastic lesions, nevi count, and photoaging. A digital health platform (METHIS) will provide private dashboard visualization of UVR exposure data for workers and supervisors. Environmental UVR data from nearby weather stations (IPMA) and CAMS/IFS models will be collected for correlation. Descriptive statistics will characterize the sample by socio-demographic variables, and mean SED/day with standard error will be reported per occupation.

**Key Results:** As a study protocol, no results are reported. The expected outcomes include occupational solar UVR doses expressed in SED per day for each occupation over 7 months. The authors anticipate that doses will exceed the threshold of 1 to 1.33 SED/day due to Lisbon's latitude and the nature of the occupations. Data from 70 months of measurement per occupational group (gardeners, masons, gravediggers) will be available. The dermatological screening will map acute and chronic skin effects of chronic occupational solar UVR exposure.

**Clinical Implications:** This study will provide the first comprehensive occupational UV-related skin cancer risk assessment for outdoor workers in Portugal, combining direct UVR dosimetry with dermatological screening. The real-time data and digital platform can enhance risk communication and behavior change, supporting primary, secondary, and tertiary prevention. Results are expected to inform the design of tailored prevention campaigns and policies for occupational skin cancer, potentially reducing under-reporting and improving worker safety. The approach may also be extended to evaluate ocular diseases (e.g., cataracts, ocular melanoma) and the beneficial effects of UVR on vitamin D synthesis.