What are the differences between a water air purifier and a HEPA air purifier, and which one is more effective in improving indoor air quality?

A water air purifier uses water to trap particles and pollutants, while a HEPA air purifier uses a filter to capture particles as small as 0.3 microns. HEPA air purifiers are generally more effective in improving indoor air quality as they can capture smaller particles and allergens compared to water air purifiers.