Recently, increasing attention has been paid to monitoring their levels in the air from the point of view of their influence on human health and the environment. Volatile Organic Compounds (VOC) are reactive carbon-based substances present in the atmosphere, the importance of their study lies as precursors of tropospheric ozone and other photochemical oxidants, mainly hydroxyl radicals (OH), ozone (O3) and nitrate radicals (NO3 .). An atmospheric pollutant generated by VOCs is ozone, which is harmful to humans and plants, as it can cause serious damage to health such as diseases in the respiratory system. Likewise, it should be noted that according to the World Health Organization (WHO) classifies some VOCs as carcinogenic to humans, such as formaldehyde, benzene and 1,3-butadiene. The research focuses its objective on determining the concentrations of VOCs between 2 and 10 carbon atoms that are emitted in rural areas and their contribution as atmospheric precursors, in order to study background levels, especially of longlived species and in this way have a benchmark for a clean atmosphere. This study is descriptive and explanatory, carried out in the Valderejo Natural Park, located in the north of Spain in the community of the Basque Country for the hourly sampling periods of 2003 - 2005 and 2010 - 2012, in agreement with the Technical School Superior of Engineering of the University of the Basque Country (ETSIUPV). The thermal desorption and gas chromatography technique was applied, using a system of equipment called the Perkin Elmer COV Ozone Precursor Analyzer System, among which the TurboMatrix Thermal Desorber for taking air samples, the gas chromatograph with CLARUS 500 GC flame ionization detector (CG-FID) and TotalChrom software for the processing and validation of the data obtained. Among the results, 65 VOCs were identified and quantified, highlighting the most abundant concentrations of light compounds (C2 - C6) and heavy compounds (C6 - C10), obtaining minimums below the detection limit and maximums up to 10 ppbv in rural areas. Between the years of studies, a slight decreasing trend is observed globally (around 1- 2% per year) in the annual mean concentrations of VOCs measured in rural areas.