How do schools maintain student health through regular classroom cleaning?

I’ve been researching the impact of classroom cleanliness on student well-being, especially in terms of reducing allergies and preventing the spread of illness. I’m curious to know what practices schools are currently using to keep classrooms consistently healthy. Do schools rely more on in-house custodial staff, or are they partnering with professional cleaning/janitorial services? Also, has anyone tried eco-friendly or green cleaning methods in schools? I’d love to hear real examples and suggestions from educators who have seen results.