Agricultural workers are exposed to both heat stress and ultraviolet (UV) radiation due to spending significant amount of time outdoors. Worker exposure data is important in determining worker risk to related illnesses and the appropriate preventive and control measures to reduce such risk. The most accurate worker exposure data is obtained from actual worksite measurements using instrumentation-based exposure assessment methods, but may not always be readily available for certain worksites, such as agricultural settings, due to lack of financial resources to procure appropriate instruments and/or hire trained personnel. Risk information from mobile apps is more readily available for timely advice on risk management that is crucial in preventing severe acute illnesses and deaths, but its reliability is unknown. The purpose of this study is to determine the reliability of the OSHA-NIOSH Heat Safety Tool and the EPA UV Index mobile apps in providing accurate risk information to prevent heat- and UV-related illnesses among agricultural workers in eastern North Carolina. The findings of this study will serve as baseline information on the usefulness of mobile apps as exposure assessment methods in providing cheaper, readily available and reliable data for the protection of agricultural workers and other similar outdoor workers against heat stress and solar UV exposure.