The purification and ventilation of the fresh air system is an effective way to deal with the common indoor harmful substances.
The three elements of healthy housing are: energy-saving peripheral protection structure, comfortable temperature and humidity control, healthy and efficient full heat recovery ventilation. Among them, the outer protective structure must have a thick insulation layer, sunshade outside and high air tightness; the temperature and humidity control must be flexible air conditioning instead of strong air conditioning, no sense of blowing indoors and low indoor noise; the high-efficiency full heat recovery ventilation must have high heat recovery efficiency, eliminate secondary pollution and purify indoor air.
The harmful gases in the air are formaldehyde, ammonia, radon, VOC, stone radiant, chloroform and other harmful gases, such as ethanol and benzene. The sources include building decoration, paint, plywood, particleboard, foam filler, interior wall coating, plastic veneer and so on.
The main pollutant affecting the air quality of the city is the inhalable particulate matter. The effective treatment method can use the purifier and ventilation equipment. The purifier and fresh air purification system have obvious effects on the treatment of pollen, PM2.5, bacterial virus, formaldehyde, carbon dioxide and even peculiar smell.
The functions of ventilation include purification, replacement and dilution.
|Hazardous substances||Unit||GB||WHO AQGs||Treatment|
|PM2.5||g/m3||35（24 hour average）||25（24 hour average）||purifier、Purification and ventilation|
|O3||g/m3||160（1 hour average）||200（1 hour average）||Purification and ventilation|
|g/m3||50（24 hour average）||20（24 hour average）||Purification and ventilation|
|NO2||g/m3||120（1 hour average）||200（1 hour average）||Purification and ventilation|
|CO2||ppm||1000（24 hour average）||1000（24 hour average）||Purification and ventilation|
|Total bacteria||cfu/m3||2500||700（Risk of infection）||purifier、Purification and ventilation|
The first is purification.
In the fresh air system, a filter screen is added at the air inlet to purify the air. The high-efficiency filter screen effectively filters PM2.5 particles, bacteria and viruses, including aerosols.
The second effect is displacement.
Reasonable layout of fresh air and air return, reasonable design of positive pressure area and negative pressure area. Replace harmful substances in the room by ventilation. Reasonable design of ventilation, effective control of the concentration of harmful substances, to ensure quality air. According to the 24-hour carbon dioxide average < = 1000 > = 30m3 / h / person. The outdoor CO2 concentration in big cities is about 450ppm, and it is recommended to select products with air volume of > = 45m3 / h / person.
The third effect is dilution.
Bacteria and viruses in the air can only infect people when they reach a certain concentration. Dilute the concentration of harmful substances, bacteria and viruses in the room by delivering fresh air. Aerosols are tiny liquid particles floating in the air. According to the experience of SARS in 2003, it is safe for the fresh air to reach 10000 times of the patient's exhaled air! Exhaled air volume: 0.5l/time, 15 breaths per minute, exhaled air volume: 0.5x15x60/1000 = 0.45m3/h. Safe fresh air volume: 0.45x10000 = 4500m3 / h.
Therefore, it can be concluded that it is difficult for residential ventilation to achieve such a large dilution air volume. The probability is very low. If there is any infected person in the family, they must be isolated and disinfected. The effect is affected by the outdoor wind. If the patient must be far away from the outdoor air is safe.