  As Covid-19 remains a cause of concern, especially due to its mutations,
wearing masks correctly and efficiently remains a priority in order to limit
the spread of the disease. In this paper we present a wearable smart-mask
prototype using concepts from Internet of Things, Control Theory and
Distributed Ledger Technologies. Its purpose is to encourage people to comply
with social distancing norms, through the use of incentives. The smart mask is
designed to monitor Carbon Dioxide and Total Volatile Organic Compounds
concentrations. The detected data is appended to a DAG-based DLT, named the
IOTA Tangle. The IOTA Tangle ensures that the data is secure and immutable and
acts as a communication backbone for the incentive mechanism. A
hardware-in-the-loop simulation, based on indoor positioning, is developed to
validate the effectiveness of the designed prototype.
