High-performance filtration plays a crucial role in many labs and beyond. As discussed in “The Basics of HEPA Filters”, high-efficiency particulate air (HEPA) filters started keeping lab air cleaner in the 1950s. That application continues, and part two of this series explores the applications of HEPA filters in lab environments and even homes. This article looks more closely at the protection provided to personnel.
Although the average consumer might not think about HEPA filters in their household, they can be found in an increasing number of consumer products. According to Air Filtration and the Use of HEPA Filters in Biological Safety Cabinets from NuAire (Plymouth, MN): “Air cleanliness is a trend in the home consumer product market due to increased awareness of health problems caused by allergens.” In these cases, the filter might capture a range of allergens, from dust and mold to pet dander and pollen.
Most homeowners are familiar with filters in an HVAC system. Many of these filters consist of pleated material that is a disposable mat of fiberglass, but these only capture 5–10% of submicron particles. As the NuAire document points out: “A healthy human body can filter out particles as small as the 3¬5 micron size via the respiratory system [but] it is exposure to smaller sub¬ micron particulate matter that can present health risks in humans.”
Fortunately, there are additional elements that can be utilized to increase the air purifying potential of an HVAC filter system. Adding electrostatic-charge filtering to a pleated material can remove 20–60% of submicron particles, but that’s with monthly or even weekly maintenance. To really get filtering that improves health, an HVAC system can use a HEPA filter. As noted by NuAire, “HEPA filters are 99.97% efficient at the 0.3 micron particle size and are therefore very effective on sub¬micron particles.” However, not all HVAC systems can accommodate such a filter.
Manufacturers of consumer products also add HEPA filters to other devices, such as vacuum cleaners. This can purify the air that the vacuum handles but is significantly less than an HVAC system.
In a lab, HEPA filters can also be used in HVAC systems. Additionally, a HEPA filter is often incorporated in biological safety cabinets and fume hoods.
Assessing safety
The level of filtration required really depends on the application. In most consumer uses, a HEPA filter makes life easier, more like makes breathing easier, but it’s not crucial. In biological or clinical labs, filtration provides key protection to personnel.
For example, “Biosafety in Microbiological and Biomedical Laboratories”, produced by the U.S. Centers for Disease Control and Prevention (CDC), notes: “From the earliest laboratory-acquired typhoid infections to the hazards posed by bioterrorism, antibiotic-resistant bacteria and rapidly mutating viruses, threats to worker safety have stimulated the development and refinement of workstations in which infectious microorganisms could be safely handled.”
Keeping personnel safe takes multiple technologies. As the CDC document points out: “HEPA filters are effective at trapping particulates and thus infectious agents but do not capture volatile chemicals or gases.” So, a HEPA filter alone is not enough for complete protection.
A HEPA filter must be changed as needed and an entire biological enclosure tested on a routine schedule. Only then can the safety of personnel be maintained at the highest level.