The half-life of the α-decaying nucleus 221Fr was determined in different environments, that is, embedded in
Si at 4 K, and embedded in Au at 4 K and about 20 mK. No differences in half-life for these different conditions
were observed within 0.1%. Furthermore, we quote a value for the absolute half-life of 221Fr of t1/2 = 286.1(10) s
that is of comparable precision to the most precise value available in the literature.