One of the main goals of contemporary theoretical physics is to find the quantum theory of gravity. There are various working hypotheses, mostly operating in the regime of high-energy physics well above the reach of particle accelerators. So far, strong experimental or observational evidence to guide the theory is missing. A possible consequence of quantum gravity and quantum spacetime that is often discussed is the vacuum dispersion effect. In this paper, we consider a different line of quantum space phenomenology, the behaviour of microscopic black holes. Even though their exact nature is unknown, some of their features are very model-independent, allowing us to draw conclusions about their role in the current cosmological models.