WEST HILLS, LOS ANGELES (KABC) -- As heavy haze and smoke continues to fill the air above areas affected by California's wildfires, many are concerned about the unhealthy air quality.Stores all over Southern California are seeing an increase in air purifier purchases.Rosalyn Sokoler had to evacuate her home in Bell Canyon. She's one of thousands of people shopping for items to help clear the air."My husband went back in," Sokoler said. "He said the house is still standing, so we got lucky, but it's full of ash and smoke."The top item people are looking for right now are air purifiers. Most warehouse stores near the fire damaged areas are completely out of stock."We completely sold out of air purifers, air masks, everything," Ryan Novacek, an assistant manager at Lowe's Home Improvement, said.Lowe's Home Improvement in West Hills is one of the few stores able to get more air purifiers shipped in."We're trying to meet the needs," Novacek said. "We know there are a lot of displaced customers, and we're working to meet the needs of that as they go back into their homes."Dignity Health Pulmonologist Dr. Eli Hendel said air purifiers come in an active and passive form.Purifiers that ionize the air and trap charged particles may be beneficial, but Hendel said the problem with those is that they can accumulate ozone, which is not healthy for breathing.Hendel said the most important thing to look for are the words "HEPA filter."Avoid purifiers that say "HEPA-like" or "HEPA-type.""The U.S. Department of Energy certifies HEPA filters that can filter 99.7 percent of all particles greater than three microns or more," Hendel said.The other important thing to look for is how big of an area it can clean."In some cases, it's preferable to buy two smaller units than one unit and have it in two separate rooms, one of them being the bedroom, especially for children," Hendel said.Air purifiers are on Sokoler's shopping list because she knows she has a lot of work ahead."It's going to be a process, but I was one of the lucky ones," Sokoler said. "My house is still there."