Nanofibrous composite polyvinyl alcohol (PVA) nonwovens were prepared by the electrospinning of PVA on polyethylene terephthalate spunbond nonwoven for an air filter media. PVA nanofibers were insolubilized by annealing at 150–170°C for 10 minutes, using citric acid (CA) as a green crosslinking agent. The water stability of PVA nonwovens increased as the amount of CA or annealing temperature was increased. However, there were no significant changes in average fiber diameters, pore sizes, and filtration efficiencies depending on crosslinking conditions. Humidification resulted in the permanent deformation and the reduction of filtration performances. The amount of CA and annealing temperature had significant effects on the resistance to humidity. Composite PVA nonwovens including 12 wt% CA and annealed 160 °C or higher maintained the original filtration performance even after the humidification. Considering the filtration performances and the water- and moisture-resistance, crosslinked composite PVA nonwovens seemed to have the potential for air filtration materials.