The particulate matter PM10 has been linked to mortality and morbidity by a variety of epidemiological studies. This research measured concentrations of PM10 in the urban area of Riohacha, Colombia and was evaluated the effect of relative humidity on concentrations of PM10. The instrument used for the study was a nephelometer Dataram 4 (Thermo Electron Corporation). Data were collected for three months in two sites (Desalud and Bienestar) of the urban area of Riohacha. The team worked continuously recording levels every 10 minutes and stored hourly and daily averages. The team located at a height of 4 meters above the ground in open space areas without interference structures. The results of the 28 samples, showed that the average concentration of PM10 was 23.64 µg/m 3 to Desalud sample point and 36.86 µg/m 3 to Bienestar sample point. A weak correlation was found when the relative humidity (RH) was lower than 70%: Rtight = 0.1949 and 0.3860 for sampling points, Desalud and Bienestar respectively, but no significant differences between RH and concentration of PM10 (p = 0.447 for Desalud and p=0.132 for Bienestar). The correlation increased when the RH was higher than 70%. (Rtight= 0.7727 for Desalud and 0.6565 for Bienestar) there significant differences between RH and PM10 for both sampling points (p = 0.000 for Desalud and 0.0032 for Bienestar).