HEPA technology is used in portable air purifiers as it removes common airborne allergens. There are two types of ionic air purifiers, the fanless and fan base ionizers. Oreck air purifiers are made in China. It is distinguished from air purifiers, which use disposable filters to remove dust. Drawbacks to UV light water purifiers include turbidity. Ozone production is typical for air ionizing purifiers. Air ionisers are used in air purifiers to remove particles from air. Electrostatic precipitators operate on the same principle as home "Ionic" air purifiers. Some commercial air purifiers are designed to generate negative ions. In the U.S., air purifiers emitting low levels of ozone have been sold. The noise levels for most purifiers are low compared to many other home appliances. About 80% of its revenues are from its reverse osmosis purifiers. Electrospray is used in some air purifiers. Lima has built billboards which serve as air purifiers. Their product Aquaguard purifiers are most selling water purifiers in India.