We investigate KI or NaI fluorescent emission in circumstellar shells to study their ionization and mass-loss rates. First-time KI detections around the mira-type stars W Hya and R Hya are presented. Together with the previously analysed cases of α Ori, α Her and ο Cet (Mauron and Caux
1992A&A...265..711M) and other observations, this gives an extended sample of 10 envelopes which includes µ Cep, CE Tau, β Peg, ρ Per and g Her. A few non-detections are also considered. In order to compare observed with expected values of KI intensities, the ionization model of Glassgold and Huggins (
1986ApJ...306..605G) is used, and the relevant parameters such as distance d, mass-loss rate {dot}(M), gas temperature, fractional electron abundance x
e and stellar photoionizing rates G_⊕ _have to be known. Using data found in the literature, we estimate these parameters in detail for each case. The values of x
e are obtained with a hypothesized simple rule based on the circumstellar abundance of molecules and grains which could lock electron donors, giving either x
e∼3x10
–4 or ∼2x10
–5. The G_⊕ _values depend on the rare ultraviolet spectrophotometric data available for red giants. The kinetic temperature was assumed to be 30K at the probed impact parameters r
obs∼0.5 to 5x10
16cm. Despite real uncertainties, the predicted KI intensities with our best estimates of the parameters are in very reasonable agreement with observations in 8 cases in 10. The largest discrepancy concerns the red supergiant µ Cep (M2Ia): our KI data suggest that, similar to α Ori, CO and dust are incompletely formed; for this object we favor {dot}(M)=5x10
–6M
☉/yr. The wind of β Peg is the second case for which a larger mass-loss and/or a larger x
e than primarily believed is suggested, but confirming observations are needed. Finally there is no indication that K or Na might be depleted in silicate grains.