June 19, 2023 – Stepping into the house, the first thing you notice is the air: the purity and odorlessness of it. There’s no rush of a sneeze from your allergies that bothered you earlier that morning. You soon find the cause of this reprieve: three portable air purifiers that Olivia Raya, customer service team lead of the air purifier company Rabbit Air, has used for years in her home.

In close to 2 decades, Rabbit Air has launched two tabletop air purifiers and a model customers can hang, camouflaged by an image of your favorite painting or photograph. The devices cost from $370 to $750 for ones that can purify a group office space or apartment. 

“We are at the awareness now of how air quality is vital to our survival,” Raya said. 

Air purifiers spiked consumer interest post-pandemic as people sought cleaner air that lowered respiratory distress that added to complications from illnesses such as COVID-19.

The need to maintain air quality hit hard once again recently as eerie orange smog and acrid smells shrouded parts of the country, spreading from wildfires in Canada. Levels of smog veiled many skylines across the U.S. and greeted millions of people with air quality warnings. 

Consumer groups and government agencies are responding. The popular website Consumer Tested Reviews released its latest recommendations for a variety of consumer air purifiers in June. In April, the Environmental Protection Agency published its guidance for air cleaners and HVAC filters to clear away airborne pollutants and contaminants. 

The guidance tells manufacturers to use the clean air delivery rate (CADR) system for the purifier’s performance. Also, high-efficiency particulate air (HEPA) filters, the ability to filter smoke, and the purifier’s ability to remove particles are strongly recommended for portable air cleaners. 

The CDC then updated its guidance on ventilations in buildings in May, raising the minimum filter recommendation. Maintaining that level requires replacing filters as manufacturers recommend. 

A Concern About Clean Air

Karrie Chan and her husband Edwin Cheung launched Rabbit Air in 2004 out of concern about the air their child breathes. Starting out in their garage, the co-founders worked to improve the quality through user feedback.

 According to Raya, the original niche market included people with allergies, exotic bird collectors, and later expanded to cigarette and cigar smokers. The Rabbit Air purifiers also found their way to woodworkers and painters. 

Raya said in addition to the “wellness crowd,” Rabbit Air also saw customers from nail salons, doctor’s offices, and schools near freeways looking for ways to reduce pollutants that may later bring on asthma in children. 

“You can tell it’s working because there’s a lot – I even see pieces of my hair,” she said. 

Do-it-yourselfers can look for plans online. From the oceanside in San Diego comes the Corsi-Rosenthal (C-R) air filtration box, a build-your-own air filtration unit that costs around $70 for materials. Kimberly Prather, PhD, a professor in the Department of Chemistry and Biochemistry at the University of California San Diego, presented the invention to the White House Office of Science and Technology Policy in 2022. 

“I always say we can choose our water and we can choose our food. But we can’t choose our air. So, we have got to clean our air” Prather said. 

The C-R box has four walls of MERV-13 filters, a standard box fan on top, and relies on tape to hold the purifier together. A cardboard box top with a circular opening allows the air to get pulled in through the fan, pushed through the filters, and released as purified air. Last year, Prather held an initiative to build 250 C-R boxes as part of the air filtration work at UCSD. 

According to the CDC, do-it-yourself air filters such as the C-R box, if well-constructed, can reduce viral particles as well as wildfire smoke indoors. The crucial factor is to prevent air leakage from the C-R box with duct tape.

In an average classroom, Prather said that the C-R box clears 90% of particles out of the air in 5 to 10 minutes. During the pandemic, many people started building C-R boxes on their own using the blueprint from cleanaircrew.org with their innovative and creative spins on the fans and exterior decorations. 

Opening the window and using air purifiers are two ways to improve indoor air quality, but Prather recognizes that for those living in areas with lots of traffic or bad air conditions, a good air purifier might be the only alternative. 

“I would just say do both if you can. If you can’t, you still have the layers – the key is layers of protection,” she said. 

The C-R box, when the fan is running at a low level, makes no sound at all. At a high level, it sounds like a regular fan at high speed and can filter the air more quickly. 

“The thing I like about the filters is also the reason I have them in my house, which is because you can put them everywhere and they are taking the air out right there,” Prather said. 

Prather is gathering data on the performance of C-R boxes in schools and care facilities, and she’s collecting stories on their impact from users. She said having good air quality will improve student thinking skills and help especially those living in areas with low air quality. 

Local government agencies, such as the California Air Resources Board, maintain high standards for certifying air purifiers. Both Rabbit Air and the Corsi-Rosenthal box have passed the requirements.

Since 2020, the board has added electronic air cleaners to the same regulations required for commercial portable indoor air cleaning devices. 

Pat Wong, PhD, who manages the board’s Buildings and Indoor Environments Section, said in recent years, more companies are applying for certification. In 2022 alone, he said, the agency certified 2,805 air cleaners, almost three times the total from 2020. 

The certification includes two tests: electronic safety and ozone removal. An electronic safety test ensures the safety of the purifier to prevent a fire. The ozone test measures the emission concentration to ensure it is below 50 parts per billion. 

Even though the Air Resources Board does not test how well the purifiers otherwise perform, Wong said the best recommendation for consumers is to choose a purifier that has the recommended filters. 

“Our biggest advice is making sure it [the air purifier] has a filter and make sure it has the correct room size,” he said. “So, it doesn’t really matter if you’re in a classroom, your home, or your business.”