A: No. The performance of an air purifier is not determined by the number of filters it uses. The decisive factor is whether the filters can remove the target pollutants from the air. To remove different pollutants, the air purifier should use different combinations of filters that have various filtering functions, or use a multi-functional composite filter that can remove both formaldehyde and particulates. If you stack two filters of the same function together, they can only increase air resistance, reduce clean air output volume and eventually lead to lower purification efficiency and higher energy consumption.

A: No. The thickness of the filter does not determine its filtration efficiency. A well-functioning filter should have a combination of such features as good filtration efficiency, low resistance, high dust-capturing capacity, and craftsmanship. Too thick a filter will only increase air resistance, noise level and energy consumption.

A: All exhalation valves are not air-tight, but they are tested and meet the basic requirements according to the authoritative standards (such as China GB2626-2006).

After applying the respirator, the air pressure within the respirator will be lower than that outside when you inhale, thereby forcing the valve to close automatically.

The airtightness of an exhalation valve is an essential indicator of the performance of the respirator. It should go through rigorous testing by instrumental devices as well as user’s fitting tests which are based on national standards for product certification and testing. The qualified products will, therefore, provide adequate respiratory protection.