4C Air

4C Air is an American nanotechnology company based in Sunnyvale, California, founded in 2015 by Stanford University professors Yi Cui and Steven Chu. The company develops and commercializes a patented nanomaterial — marketed under the BreSafe name — that is engineered for air filtration. According to the company, the technology was developed from nanotechnology research at Stanford University and is designed to filter hazardous particles at PM2.5 and below while maintaining low air resistance. 4C Air's business spans several areas of innovation: personal environmental protection, materials and textiles, industrial and consumer filtration, and environmental sustainability. Its best-known consumer-facing product line is the AireTrust Nano Mask, which uses the company's BreSafe nanotechnology. The masks are offered in kids, medium, and large sizes, with bulk packaging options, and are marketed as providing up to 99% filtration efficiency with high breathability. The adult masks are described as KN95 certified, offering greater than 95% protection against 300 nm/0.3 μm particles. Beyond masks, 4C Air is developing nanomaterial applications for textiles and for industrial filtration in sectors such as automotive, aerospace, healthcare, and HVAC. The company positions its technology as a platform — Nanomedia — that can be adapted to many design and filtration contexts. Its stated mission is to improve lives affected by poor air quality by providing safer, cleaner air through nanotechnology products and solutions, citing World Health Organization estimates that nine out of ten people breathe air exceeding acceptable pollution limits. 4C Air operates primarily in the United States but presents its products and technology as globally relevant. The company is privately held and led by CEO Meng Sui. It maintains an e-commerce presence through its website, selling masks directly to consumers and in bulk for businesses.

4C Air was founded in 2015 by Professor Yi Cui and Professor Steven Chu of Stanford University. The company was established to commercialize a new nanomaterial developed through research at Stanford, which the founders identified as ideal for filtration applications. This material became the basis of the company's patented BreSafe nanotechnology. From its base in Sunnyvale, California, 4C Air focused on translating laboratory nanotechnology into practical products. Its early work centered on a nanomaterial that could filter hazardous airborne particles at PM2.5 and below while allowing low air resistance — a combination that distinguishes it from traditional filtration media. The company structured its innovation efforts around four areas: personal environmental protection, materials and textiles, industrial and consumer filtration, and environmental sustainability. The most visible outcome of this work has been the AireTrust Nano Mask line, developed in collaboration with AireTrust using 4C Air's patented BreSafe nanotechnology. The masks are marketed as providing up to 99% filtration efficiency with exceptional breathability, and the adult versions are described as KN95 certified with greater than 95% protection against 300 nm/0.3 μm particles. The product range includes kids, medium, and large sizes, as well as bulk boxes for institutional or business buyers. 4C Air has continued to develop new applications for its nanomedia, aiming to improve personal air quality and to serve industrial filtration needs in automotive, aerospace, healthcare, and HVAC sectors. The company is privately held and led by CEO Meng Sui. Its mission is framed around the global burden of air pollution, citing World Health Organization figures that nine out of ten people breathe air exceeding acceptable pollution limits and that ambient and household air pollution contribute to millions of premature deaths annually.

• 2020

  AireTrust Nano Mask – Large (2020 Version) offered.

• 2015

  4C Air founded by Professor Yi Cui and Professor Steven Chu of Stanford University.

• Development of patented BreSafe nanotechnology for filtration applications.

• Launch of AireTrust Nano Mask line in collaboration with AireTrust.

Developer of patented Stanford-origin nanotechnology for high-efficiency, low-resistance air filtration, spanning consumer masks and industrial filtration applications.

• AireTrust Nano Mask for Kids

  Children's nano mask using BreSafe nanotechnology; priced $20.00–$78.75.

• AireTrust Nano Mask – Medium

  Adult medium nano mask; priced $20.00–$87.50.

• AireTrust Nano Mask – Large (2020 Version)

  Adult large nano mask, 2020 version; priced $20.00–$87.50.

• AireTrust Nano Masks – Kids Size Bulk Box – 300 Face Masks

  Bulk box of 300 kids-size nano masks; priced $1,050.00.

• BreSafe nanotechnology

  Patented nanomaterial for filtration, developed from Stanford University nanotechnology.

• Nanomedia

  Nanotech material platform for textiles and design applications.

1. 14C Air - Innovative Solutions for Clean Air4cair.com
2. 2About Us - 4C Air4cair.com
3. 3Nanotechnology products - Consumers & Businesses - 4C Air4cair.com
4. 4Nanotechnology Masks - 99% Efficiency - Very Breathable - PM 2.54cair.com
5. 54C Air (United States) - Wikidatawikidata.org