Dust enables low-mass stars to form from low-metallicity gas by inducing fragmentation of clouds via the cooling by its thermal emission .
Dust may , however , be evacuated from star-forming clouds due to radiation force from massive stars .
We here study the condition for the dust evacuation by comparing the dust evacuation time with the time of cloud destruction due to either expansion of H ii regions or supernovae .
The cloud destruction time has weak dependence on the cloud radius , while the dust evacuation time becomes shorter for a cloud with the smaller radius .
The dust evacuation thus occurs in compact star-forming clouds whose column density is N _ { H } \simeq 10 ^ { 24 } -10 ^ { 26 } ~ { } { cm ^ { -2 } } .
The critical halo mass above which the dust evacuation occurs becomes lower for higher formation redshift , e.g. , \sim 10 ^ { 9 } ~ { } M _ { \odot } at redshift z \sim 3 and \sim 10 ^ { 7 } ~ { } M _ { \odot } at z \sim 9 .
In addition , metallicity of the gas should be less than \sim 10 ^ { -2 } ~ { } Z _ { \odot } .
Otherwise the dust attenuation reduces the radiation force significantly .
From the dust-evacuated gas , massive stars are likely to form even with metallicity above \sim 10 ^ { -5 } ~ { } Z _ { \odot } , the critical value for low-mass star formation due to the dust cooling .
This can explain the dearth of ultra-metal poor stars with the metallicity lower than \sim 10 ^ { -4 } ~ { } Z _ { \odot } .