Conventional nail polish contains large amounts (typically around 70%) of chemical solvents such as toluene, acetates and alcohol. When nail polish is applied to nails, these solvents evaporate into the air, generating toxic chemical fumes; the well known and VERY offensive "chemical smell". This is why many people find it hard to breathe when using conventional nail polish: you are surrounding yourself with heavily polluted air, inhaling toluene, acetates etc.; chemical solvents.
In Suncoat water-based nail polish, all the chemical solvents are replaced by water. The major ingredient is water, not chemical solvents! So when Suncoat water-based nail polish is being applied, it is only water that evaporates to the air, not toxic chemical fumes.