Zinc concentrations in hobby rocket exhaust aerosols were measured by ICP-MS to be approximately 300 mg/g, revealing that hobby rocket motors emit particulate matter highly enriched in zinc. Zinc is a commonly used indicator species in receptor models for atmospheric particulate matter and is assumed to be emitted only by well-established point sources and mobile sources. The potential impact of the ephemeral particle-bound zinc from hobby rockets on atmospheric particulate zinc concentrations was estimated using a Gaussian puff model. The results from the model were compared to 24-hour averaged particulate zinc concentration data collected in three US urban centers. Potential impacts several kilometers downwind of the rocket launch site were found to be significant. Clearly the impact of ephemeral and unregistered emissions such as those from hobby rockets needs to be considered when using zinc in source apportionment models.