Popular science

When it comes to air purifiers, it's important to consider factors such as CADR (clean air delivery rate) and the type of filter used. HEPA (high-efficiency particulate air) filters are a popular option that can capture particles as small as 0.3 microns. Hitekon is a brand that sells air purifiers, among other products. Their air purifiers use HEPA filters and have a CADR of up to 1000 m³/h, indicating that they can effectively purify the air in a large room. It's important to note that while air purifiers can filter out solid particles such as PM2.5, they may have limited effectiveness in removing gases and VOCs (volatile organic compounds). Overall, choosing a reputable brand like Hitekon and selecting an air purifier with a high CADR and HEPA filter can help improve indoor air quality.

Indoor air quality	“Indoor air quality” refers to the quality of the air in a home, school, office, or other building environment.
Importance of Indoor Air Quality	Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations References： [1] U.S. Environmental Protection Agency. 1989. Report to Congress on indoor air quality: Volume 2. EPA/400/1-89/001C. Washington, DC. [2] U.S. Environmental Protection Agency. 1987. The total exposure assessment methodology (TEAM) study: Summary and analysis. EPA/600/6-87/002a. Washington, DC.
	People who are often most susceptible to the adverse effects of pollution (e.g., the very young, older adults, people with cardiovascular or respiratory disease) tend to spend even more time indoors. References： [3] U.S. Environmental Protection Agency. 1997. Exposure factors handbook volume 3: Activity factors. EPA/600/P-95/002Fa. Washington, DC.
	Indoor concentrations of some pollutants have increased in recent decades due to such factors as energy-efficient building construction (when it lacks sufficient mechanical ventilation to ensure adequate air exchange) and increased use of synthetic building materials, furnishings, personal care products, pesticides, and household cleaners.
Pollutants and Sources	Indoor sources (sources within buildings themselves) Combustion sources in indoor settings, including tobacco, wood and coal heating and cooking appliances, and fireplaces, can release harmful combustion byproducts such as carbon monoxide and particulate matter directly into the indoor environment. Cleaning supplies, paints, insecticides, and other commonly used products introduce many different chemicals, including volatile organic compounds, directly into the indoor air. Building materials are also potential sources, whether through degrading materials (e.g., asbestos fibers released from building insulation) or from new materials (e.g., chemical off-gassing from pressed wood products). Other substances in indoor air are of natural origin, such as radon, mold, and pet dander.
Pollutants and Sources	Outdoor sources Outdoor air pollutants can enter buildings through open doors, open windows, ventilation systems, and cracks in structures. Some pollutants come indoors through building foundations. Harmful smoke from chimneys can re-enter homes to pollute the air in the home and neighborhood. In areas with contaminated ground water or soils, volatile chemicals can enter buildings through the same process. Volatile chemicals in water supplies can also enter indoor air when building occupants use the water (e.g., during showering, cooking). when people enter buildings, they can inadvertently bring in soils and dusts on their shoes and clothing from the outdoors, along with pollutants that adhere to those particles.
Main pollutants of different rooms	Living room:A living room is usually a well-used area of a home and may harbor indoor pollutants. It is important to ventilate properly, keep secondhand smoke outside of the house, and vacuum and dust regularly. Pet Dander and Hair Pets can trigger allergy and asthma attacks due to dander and hair. Secondhand Smoke Secondhand smoke from cigarettes, cigars and other tobacco products can trigger asthma and other respiratory illnesses especially in children. Carbon Monoxide Fireplaces and leaking chimneys are sources of carbon monoxide.
	Bathroom:A bathroom is often the dampest area of a home. It is important to ventilate a bathroom during use and dry damp surfaces. Mold Bathrooms are a common source of mold. Humidity from showers can cause moisture problems, which will lead to mold growth. Mold can cause allergic reactions, asthma and other respiratory ailments.
	Bedroom:A bedroom often contains materials that collect dust. It is important to clean bedding and other fabrics, and vacuum regularly. Dust Dust mites can trigger allergy and asthma attacks. Dust mites are everywhere especially on pillows, blankets, carpets, upholstered furniture and stuffed toys.
	Kitchen:A kitchen has appliances that may leak gases, and often contain chemicals for cleaning or removing pests. Pesticides Pesticides used to rid homes of rodents, termites, insects, and other pests, can irritate the eyes, nose, and throat; damage the central nervous system and kidneys; and increase the risk of cancer. Volatile Organic Compounds (VOCs) Common household cleaners, often placed under the kitchen sink, release Volatile Organic Compounds (VOCs), when used and stored Carbon Monoxide The gas stoves vent is sources of carbon monoxide.
	Basement:A basement is a source of air leaks and moisture, and often contains various chemicals. Carbon Monoxide Combustion heating and cooling appliances such as heating, ventilation, and air conditioning units, gasoline-powered heaters, and other appliances are sources of carbon monoxide. Volatile Organic Compounds (VOCs) Paints, resins, paint thinners and chemicals, and other products, will still release Volatile Organic Compounds (VOCs) even while stored properly. Mold Basements can be damp. Install a properly sized dehumidifier to help keep your basement at an appropriate humidity level and reduce the potential for mold. It is important to dry water-damaged areas and items within 24-48 hours to prevent mold growth. Radon Radon is the leading cause of lung cancer among non-smokers in the U.S. It is a naturally occurring radioactive gas that can enter a home through cracks and openings in floors and walls that are in contact with the ground.
Effects on Human Health	The link between some common indoor air pollutants (e.g., radon, particle pollution, carbon monoxide, Legionella bacterium) and health effects Radon is a known human carcinogen and is the second leading cause of lung cancer [references：U.S. Environmental Protection Agency. 2003. EPA assessment of risks from radon in homes. EPA/402/R-03/003. Washington, DC.////////National Research Council. 1999. Health effects of exposure to indoor radon: biological effects of ionizing radiation (BEIR), report VI. Washington, DC: National Academies Press.] Carbon monoxide is toxic, and short-term exposure to elevated carbon monoxide levels in indoor settings can be lethal [source:Raub, J.A., M. Mathieu-Nolf, N.B. Hampson, and S.R. Thom. 2000. Carbon monoxide poisoning—a public health perspective. Toxicology 145:1-14.] Episodes of Legionnaires' disease, a form of pneumonia caused by exposure to the Legionella bacterium, have been associated with buildings with poorly maintained air conditioning or heating systems [source:Allan, T., et al. 2001. Outbreak of Legionnaires' disease among automotive plant workers—Ohio, 2001. MMWR 50(18):357-359.//////Fields, B.S., R.F. Benson, and R.E. Besser. 2002. Legionella and Legionnaires' disease: 25 years of investigation. Clin. Microbiol. Rev. 15(3):506-526.] Numerous indoor air pollutants—dust mites, mold, pet dander, environmental tobacco smoke, cockroach allergens, particulate matter, and others—are “asthma triggers,” meaning that some asthmatics might experience asthma attacks following exposure [source:Institute of Medicine. 2000. Clearing the air: Asthma and indoor air exposures. Washington, DC: National Academies Press.]
How to decrease the pollutants and improve indoor air?	The most effective ways to improve your indoor air are to reduce or remove the sources of pollutants and to ventilate with clean outdoor air. In addition, research shows that filtration can be an effective supplement to source control and ventilation. Using a portable air cleaners and furnace or HVAC filters can help to improve indoor air quality.