09 December 2015

Air Filtration for Pharmaceutical, Biotech & Hospital Lab Environments

iStock-Ebola Research Laboratory

There are many aspects to consider when maintaining effective air quality and freedom from contamination in Pharmaceutical, Biotech and Hospital Laboratory environments.  Obvious considerations include compliance (or better) with various state and federal standards for air changes, room pressurisation and filtration levels.  Most air filtration systems focus on providing particulate free air (viable and non-viable); however, it is worth considering that there are molecular, non-particulate contaminants that will not be controlled via conventional filtration technology.

If we look broadly at air quality within a facility; internal air quality is equally as important as the quality of air being exhausted from the building.  Both are considerable aspects in worker safety and the wellbeing of workers in and around the facility.

This article will seek to review some of the more significant air quality controls available for Pharmaceutical, Biotech and Hospital Laboratory facilities.

Particulate Contamination: HEPA Filtration

 Most readers will be very familiar with HEPA filtration units of various configurations within the facility.   Generally large units are wall or roof mounted to give the appropriate “face area” that is appropriate to the required air flow for the room.

Unit size is typically driven by two considerations; the required air flow and filter testing access.  A comparatively large surface area is required to achieve an appropriately modest air flow rate through the filter (for effective filtration and reasonable static pressure drops). An incorporated filter access panel is convenient for NATA certification or HEPA integrity testing to assure air quality on a yearly basis.

Airepure Wall mounted HEPA Fascia with Access Panel Decorative CoverInner wall mounted HEPA fascia with access panel (left), and outer decorative fascia (right)

Less visible to the users of the facility are the array of critical items that support these HEPA filtration units. These items include clean ductwork, effective and reliable fan and thermal control units, insect prevention inlet grills and pre-filters to remove larger particulates.  In some cases UV germicidal systems to limit pathogen loads are also utilised.   All of these items must work in a coordinated manner to assure cost effective and reliable delivery of air that is particulate free to acceptable levels.

Particulate Contamination: Isolation and Containment

In a variety of situations specified by AS/NZS 2243.3; BIBO (Bag In/Bag Out) airborne containment systems will be required.   A complete discussion of the requirements for these systems is beyond this article – sufficient to say that the technical manufacturing requirements for these critical items – in terms of dimensions, sealing, welding, air flow rates, filter construction and certification are extremely demanding.

Airepure BIBO Airborne Containment SystemBIBO Airborne Containment System

These containment units inevitably take considerable space within a building – partially for comparatively low air flow rate capacities, and additionally for safe access to the units, which is required for routine testing and regular filter changes.  Workers and users are protected by specific protocols for these BIBO units, which prevent contamination contact for the environment, users, and change out service persons.

Non Particulate Contamination: Molecular Contaminants

Molecular contaminants have significant impacts on the health and wellbeing of the staff and clients in these facilities. Generally unnoticed, unless associated with offensive odours, these contaminants form a very important aspect of the air quality within a facility.

Molecular contaminants can commonly include; acidic gases, bases, condensables (that can condense on clean, cool surfaces), organometallics, and sulphur and nitrogen oxides. Ozone can be an issue in some circumstances as well.

These items can be sourced from outdoor entrainment, scientific or medical devices, fugitive emissions from process equipment, chemical storage areas or laboratories and temporary emissions from construction or repairs.

Significant loads of undesirable chemicals can also be introduced into buildings from heavily used car parks, emergency delivery docks or helipads, which in turn affect the “clean air” systems of these facilities.  The reader will be familiar with the types of airborne chemicals of concern in this area, carbon monoxide and dioxide, sulphur and nitrogen dioxide, reduced sulphur compounds, halogen gases, ozone, and chemicals associated with fine diesel particulates.  In more rural areas, materials associated with fertilisers and insect control measures may also feature on the list.

Table One:  Sources and Contaminants in Outdoor Air 

Source Contaminants Emitted
automotive combustion CO, HBr, HCl, NOx, SO2, SO3, hydrocarbons, organics
cooling towers inorganic chlorides
diesel combustion CO, NOx, many organics
forest fire CO, CO2, HCl
fossil fuel processing H2S, NH3, S, SO2, hydrocarbons, mercaptans, other organics
geothermal processes H2, H2S, SO2
livestock areas CH4, CO2, H2S, NH3
oceans NaCl, chloride ions
plastic manufacture NH3, SO2, alcohols, aldehydes, organics
power generation C, CO, NOx, SO2, hydrocarbons, organics
sewage CO, H2S, H2, NH3, S, aldehydes, mercaptans, organics
C= carbon, CH4=methane, CO= carbon monoxide, CO2= carbon dioxide, H2= hydrogen, HBr= hydrogen bromide, HCl= hydrogen chloride, H2S= hydrogen sulphide, NaCl= sodium chloride, NH3= ammonia, NO= nitrogen oxides, S= sulphur, SO2= sulphur dioxide, SO3= sulphur trioxide

Indoor contaminants are seldom considered, but can be especially relevant in new or recently renovated buildings. The off gassing of building materials and furniture, human activities, cleaning chemicals and test and maintenance materials can introduce significant chemical load to the interior of the building.

Table Two: Contaminants Emitted from Internal Sources

Source Contaminants
cleaning products ammonia, alkanes, alkenes, aromatics, turpenes
combustion sources CO, NOx, formaldehyde, polycyclic aromatic hydrocarbons, respirable particles
damp/wet areas bacteria, insects, mould
furnishings, pressed wood products benzene, chlorinated hydrocarbons, formaldehyde, VOCs
personnel aromatics, alcohols, aldehydes, ketones, organic acids
sterilization processes ethylene oxide, chlorine, chlorine dioxide, formaldehyde, hydrogen peroxide, and ozone
tobacco smoke benzenes, CO, formaldehyde, NOx, PAHs, respirable particles, VOC’s

Particulate Contamination Example: IVF Laboratory Environment

By way of example, we can consider the impact of airborne chemical contamination on IVF clinical environments. Success rates have been linked to aspects of chemical air quality in the clinical environment.

Examples of the sources and chemicals that may impact on these IVF environments are tabulated below.

Table Three:  Example Source List for Makeup Air to an IVF Lab

Source Related Contaminants
automotive exhaust CO, HBr, HCl, NOx, SO2, SO3, hydrocarbons, organics
cooling towers NACl, HCl, Cl-ions
diesel exhaust CO, NOx, many organics
helicopter pad similar to automotive & diesel exhaust described in Table One

A control strategy for these items includes both conventional particulate removal and chemical absorption by dry media materials housed in filters or scrubbing units.

In general terms, chemically contaminated air is passed through beds of dry media particles at a predetermined rate and residence time. Designed and implemented correctly, these filter beds are able to remove more than 99% of many common contaminants.

Figure 1 Purafil Side Access System & ComponentsThe process of chemisorption, absorbtion and reaction that are employed are complex but well understood. Materials are readily available and consistent in terms of quality and performance. The media have extremely high surfaces area, similar to activated carbon, however, base materials like activated alumina and impregnates like permanganate may be used to provide superior retention and binding capacity of contaminants.

Figure 1: (A) Modular side access chemical filtration system; (B) drawing describing components.

In the context of an IVF lab, a typical air flow layout is shown in the figure below.

Figure 2: Diagram of setups used to control airborne molecular contaminants at an IVF Lab. (A) scrubbing outside air, (B) scrubbing mixed supply air, (C) scrubbing recirculated air from the space, and (D) scrubbing internally recirculated air.

Figure 2 IVF Lab Airflow Setup

Air is purified at several potential points.  Supply air from outside sources can be polished at point A, mixed recirculated air may be dealt with at point B or C; and additionally, air within the chamber can be improved with free standing recirculation units at point D. While the design and location of these scrubbers are relatively routine; once the air flow, contaminant make-up and levels are known, the sealing of the room and relative room pressurisation can make or break these systems. Thus a comprehensive evaluation of the site will yield the best results in the long run.

The consumption of the dry filter media is directly driven by the contamination load – the more contamination – the more material that will be used. Generally an aim of the system design will be to give one year of life between change-out of filter media. However, real life application can only be determined in practice. Sampling of the media is possible, for exhaustion testing – so that the remaining media life can be calculated. The media essentially works at 100% of the nominal efficiency until exhaustion, then this efficiency plummets to zero.

In most cases, the media is general waste, which makes it relatively easy and inexpensive to dispose of. When used in radio-nucleotide or particularly hazardous environments, testing before disposal will need to be done.

The range of uses in clinical environments for this chemical scrubbing material is extensive.  Examples include odour control for insulin production, ammonia scrubbing for research animal enclosures and removal of fugitive emissions for sterilization units.   There are literally solutions for any chemical material that can be safely absorbed and recirculated.

Conclusions

There are several layers of air filtration and purification that can be used together to assure high quality air in hospital, clinical and pharmaceutical/ biotech environments. A systematic approach to these techniques, including an assessment of what contaminants are present and their levels, is the starting point for successful remediation. All of these critical air services, do require space and service access for effective performance and any compromise in those parameters will incur both cost and performance penalties for the end users.

Written by Dr Allan Heckenberg (PhD), BDM, Airepure Australia and Shannon Roger (B.Ed), Marketing Coordinator, Airepure Australia, for The Australian Hospital Engineer Journal, Vol 38, No 4, December 2015.  See attached published article, containing all relevant references.

About the Author

Allan Heckenberg Airepure

Written for AHE Journal by
Dr. Allan Heckenberg (PhD)
& Shannon Roger (B.Ed)
Airepure Australia
1300 886 353
info@airepure.com.au

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