A monitoring study conducted on young adults (20-24-years old) from the Madrid region (Spain) revealed a lower iron (Fe) status in this demographic, particularly in women. Given the potential adverse effects of suboptimal iron status on academic performance, we monitored iron status in adolescents through analyzing it in hair. This approach could be advantageous because it is not affected by rapid fluctuations due to dietary intake, which can complicate the interpretation of iron status assessments based on other biological samples. Scalp hair was collected from 97 adolescents (13- to 16-years-old; 68 girls) living in Alcalá de Henares (Madrid). Fe was monitored by ICP-MS (LoD=1.148 µg/g). Contrarily to the results observed in young adults, Fe hair concentrations did show sex dependency, being significantly higher in female adolescents [p-value=0.000057; median and ranges; all in µg/g: 5.524 (3.167-13.262) vs. 4.464 (2.666-6.173)]. The observed effect of sex might be reflective of the endocrine system, which usually becomes active earlier in females with the onset of adolescence. Thus, the levels of Fe did not show statistical differences according to the four areas of residency (p-value=0.370) distributed in relation to Alcalá’s environmental characteristics: 5.230 (green spaces), 5.197 (urban), 5.522 (traffic), and 6.225 (industrial). The levels of Fe were similar to those detected in young adults (5.157 vs. 5.054) but were much lower than those detected in individuals 11-15-years-old (14.8; all in µg/g) living in the Madrid region. Previous studies have documented a decline in iron in hair with age, which could explain our observations. Although our results have shown a similar trend in relation to the effects of age and sex reported in the literature, they might highlight a lower Fe status in Alcalá’s adolescent population, which should be further investigated to increase public health interventions to enhance the status of iron in the population monitored.