If I read this paper right, viruses on surfaces/aerosols decay exponentially (so no specific "life-time") and they determined the half-lives here. Start with more particles and you reach the detection threshold later.
To figure out when all viral particles are inactive you'd have to know how many particles you'd typically start with. I doubt that the amount of particles they spread on the surfaces is typical of what an infected person would spread.
If I read this paper right, viruses on surfaces/aerosols decay exponentially (so no specific "life-time") and they determined the half-lives here. Start with more particles and you reach the detection threshold later.
To figure out when all viral particles are inactive you'd have to know how many particles you'd typically start with. I doubt that the amount of particles they spread on the surfaces is typical of what an infected person would spread.