Blog

The National Institute for Occupational Safety and Health (NIOSH) is a government-funded organisation that certifies workers' safety and health. This is a section of the Center for Disease Control and Prevention (CDC) in the United States. This agency is primarily concerned with the safety and health of workers in the construction of safe and healthy workplaces.

To receive adequate NIOSH approval for face masks, each producer had to go through a series of trials and tests, as well as preserve the masks' quality at all costs. The approval process is broken down into several parts, which we'll go over in detail below:

1. Airflow Resistance test:

• Before each test in accordance with the additional valve leakage test, resistance to airflow will be measured in the tight-fitting respiratory inlet covering of a complete particulate respirator set on a test fixture with air flowing at a continuous rate of 85.22 litres per minute.
• Resistance of a complete tight-fitting powered air-purifying particulate respirator system will be measured with the blower off if the manufacturer indicates that the respirator should not be doffed in the event of a blower failure.
• The maximum allowable resistance (measured in mm water-column height) requirements for air-purifying particulate respirators are as follows:

2.Exhalation Valve Leakage Test:

• Dry exhalation valves and valve seats will be subjected to a suction of 25 mm water-column height while in a normal operating position.
•  Leakage between the valve and valve seat must not exceed 30 mL per minutes

3. Filter efficiency level determination Test ( non-powered series- N, R, & P)

• Twenty filters of each non-powered air-purifying particulate respirator model will be tested for filter efficiency against:
• A solid sodium chloride particulate aerosol as per this section, if N-series certification is requested by the applicant.
• A dioctyl phthalate (DOP) or equivalent liquid particulate aerosol as per this section, if R-series or P-series certification is requested by the applicant.
• Filters including holders and gaskets, when separable, will be tested for filter efficiency level, as mounted on a test fixture in the manner as used on the respirator.
• Prior to filter efficiency testing of 20 N-series filters, the 20 to be tested will be taken out of their packaging and placed in an environment of 85 ± 5 percent relative humidity at 38 ± 2.5 °C for 25 ±1 hours. Following the pre-conditioning, filters will be sealed in a gas-tight container and tested within 10 hours.
• When the filters do not have separable holders and gaskets, the exhalation valves will be blocked so as to ensure that leakage, if present, is not included in the filter efficiency level evaluation.
• For non-powered air-purifying particulate respirators with a single filter, filters will be tested at a continuous airflow rate of 85 ± 4 liters per minute. Where filters are to be used in pairs, the test-aerosol airflow rate will be 42.5 ± 2 liters per minute through each filter.

Filter efficiency test aerosols:

• When testing N-series filters, a sodium chloride or equivalent solid aerosol at 25 ± 5 °C and relative humidity of 30 ± 10 percent that has been neutralized to the Boltzmann equilibrium state will be used. Each filter will be challenged with a concentration not exceeding 200 mg/m3.
• When testing R-series and P-series filters, a neat cold-nebulized dioctyl phthalate (DOP) or equivalent aerosol at 25 ± 5 °C that has been neutralized to the Boltzmann equilibrium state will be used. Each filter will be challenged with a concentration not exceeding 200 mg/m3.
• The test will continue until minimum efficiency is achieved or until an aerosol mass of at least 200 ± 5 mg has contacted the filter. For P-series filters, if the filter efficiency is decreasing when the 200 ± 5 mg challenge point is reached, the test will be continued until there is no further decrease in efficiency.
• The sodium chloride test aerosol will have a particle size distribution with count median diameter of 0.075 ± 0.020 µm and a standard geometric deviation not exceeding 1.86 at the specified test conditions as determined with a scanning mobility particle sizer or equivalent. The DOP aerosol will have a particle size distribution with count median diameter of 0.185 ± 0.020 µm and a standard geometric deviation not exceeding 1.60 at the specified test conditions as determined with a scanning mobility particle sizer or equivalent.
• The efficiency of the filter will be monitored and recorded throughout the test period by a suitable forward-light-scattering photometer or equivalent instrumentation.
• (i) The minimum efficiency for each of the 20 filters will be determined and recorded and must be equal to or greater than the filter efficiency criterion listed for each level as follows:

4. Breath Response Test (PAPR classes HE and PAPR100)

• Resistance to airflow will be measured with a breathing machine as.
•  Minimum inhalation resistance must be greater than zero mm of water-column height.
• Maximum exhalation resistance must be less than 89 mm of water-column height.

This process of approval takes around 3-4 months. In case, during testing, NIOSH has any questions for the manufacturer or regarding the deposited masks, they may allot a reasonable time to the manufacturer to answer the questions. Each manufacturer is also required to undergo field and onsite audits. If NIOSH finds any discrepancy, they can ask to either stop the selling of masks or do the necessary corrections if any.

All these regulations, tests for obtaining the certification may seem complex and time taking, but it is meant to ensure the safety of men, women and children. For this reason NIOSH certification for masks holds good value and trust among the people.