# Lengthening in-flight evaporation time of water droplet in air

How one can increase the in-flight evaporation time of sprayed water droplets in air without changing the thermodynamic conditions of the ambient air ( i.e. RH, T ). For instance mixing water with some chemical additives (non-toxic) that does not change the property of water so much.

1. reduce droplet size: the evaporation rate is proportion to $\frac {1}{D^2}$, where D is droplet diameter.