Clean Air Overview

Clean Air Overview What is clean air? A space where particle concentration in the air is controlled to the levels appropriate for working on contamination-sensitive activities Where is clean air products used? Micro-electronics / Semiconductors Optical manufacturing Nuclear & Aerospace Pharmaceuticals Life sciences & laboratory Food processing Security (Anthrax mail)

Clean Air Devices • Cleanrooms - Fan Filter Units • Laminar Flow cabinets • Class I, Class II and Class III Biohazard Safety cabinets

Clean Air Standards ISO 14644.1 Federal Standard 209E (obsolete) British Standard BS 5295 German Standard VDI 2083 French Standard AFNOR X44101 Australian Standard AS 1386 Japanese Standard JIS B9920 Korean Standard KS27030.1

Particle Definitions Definition of particle by ISO 14644:1999 solid or liquid object between 0.1 to 5 micron Particle size measurement: Discrete Particle Counter Particle concentration: number of individual particles per unit volume of air Particle size distribution: cumulative distribution of particle concentration with respect to particle size

Particle Size Comparison

HEPA & ULPA Filter HEPA: High Efficiency Particulate Air ULPA: Ultra Low Penetration Air Important definitions: - Modern “American-convention” HEPA: 99.99% at 0.3 microns (at Most Penetrating Particle Size) - Modern “American-convention” ULPA: 99.999% at 0.12 microns (at Most Penetrating Particle Size) Note: The “classical” definition of HEPA filter is 99.97% at 0.3 microns, but nowadays all BSC and LF in US use 99.99% at 0.3 µm

HEPA & ULPA Filter at Most Penetrating Particle Size

HEPA/ULPA Capability Removes a broad range of airborne contaminants: • Fine dust • Smoke • Bacteria (typical size: 500 to 0.3 micron) • Soot • Pollen • Radioactive particles • Impurity ion -> can affect Integrated Circuit speed

Filter Construction HEPA / ULPA filter construction: - Media pack of pleated borosillicate glass fibers - Pack is glued into a frame - Frame is gasketed to form final assembly

Separator VS Separatorless Filters

Separator VS Separatorless Filters Modern minipleat separatorless: • Compact size -> Contains more pleat per cm • Increase usable area -> more dust holding -> more life • Lower airflow resistance -> lower energy consumption • Galvanized Steel frame->lighter,no swelling in moist conditions • Eliminates media damage by alum. Separator • Handle some harsh environment that may attack alum. separator Conventional aluminium separator construction: • Larger size -> Less pleat per cm -> shorter life • Higher airflow resistance -> higher blower power • Wood cardboard frame -> heavier, moist problem • Possible media damage -> dangerous !

Filtration Principle Larger particles have too much inertia and hence deviate from the air stream (which normally curves around the filter fiber) thus impacts on the filter fiber

Filtration Principle Medium sized particles follow the air stream however have a diameter larger than the distance between the air stream and filter fiber and are hence intercepted

Filtration Principle Sub-micron sized particles vibrate with Brownian motion due to bombardment by air molecules. When a particle contacts the fiber, it is retained. More significant effect for smaller particles

Laminar Flow Cabinets

Definition of laminar / unidirectional flow: Air flow straight, parallel pass in enclosed space Principle of laminar flow cabinet: Sterilize air though filter and blow it across work surface as a particle-free laminar air stream Typical laminar air flow velocity: 0.3 - 0.5m/s Purpose of a laminar flow cabinet: Product protection only (does not protect operator)

Purpose of LF Cabinets Sample applications of LF Cabinets: - Pharmaceutical: sterile production of drugs - Semiconductor: protect sensitive chip from dust Creating economical super-clean mini environment: Place a Class 10 or Class 100 LF cabinet in a Class 1000 clean room to obtain a Class 1 mini-environment Effectiveness of LF cabinet: Room: 35 million/ft3 Inside LF cabinet: 35/ft3

Horizontal vs Vertical LF

• Risk of spillage on filter

• No risk of spillage

• Large object -> blocking • Safer from blocking • Blow air on face

• No blow air on face

• Easier to put sensitive

• Difficult to protect

Large Object: Blocking

Major problem with Horizontal Laminar Flow: Blocking: room air being induced due to large object in airstream

The Need for Biosafety The need for biosafety - High risk of laboratory-acquired infections - First documented in the US in the 1940s Purpose for BSC - Operator protection by inflow (not in LF) - Product protection (like LF ; only BSC Class 2 and 3, but not Class 1)

Containment & Safety Containment principles - Primary containment (safety equipment) - Secondary containment (facility design) Standard microbiological practices Principle of selecting which class of BSC - Only operator or operator & product protection - Degree of operator protection (Biosafety level)

Primary Containment • All manipulations inside Biohazard Safety Cabinets • Clothing:wrap-around gowns, scrub suit, or coverall • Gloves: infectious materials / contaminated equipment • Frequent changing of gloves and hand wash • If manipulations can not be done inside BSC: - Personal protective equipment (respirator, face, shield) - Physical containment devices (centrifuge cup)

Secondary Containment (1) Example: Biosafety Level 3 Lab: • Access to lab is separated from general traffic flow • Access is restricted - two self closing lockable door • All windows are closed and sealed • Interior surfaces (walls, floor, ceiling): - Easy for cleaning and decontamination - Smooth, impermeable to liquids & chemicals in lab - Seams and openings must be sealed - Floor: monolithic and slip-resistant

Secondary Containment (2) • Bench top: resist moderate heat & chemicals • Chairs: non-fabric material-> easy decontamination • • • • •

Waste decon: autoclave, chemical treat, incineration Ducted exhaust air ventilation - HEPA filtered Exhaust: away from occupied area and air intakes Directional room airflow:clean to contaminated area Audible alarm for HVAC failure

• Hands-free sink for hand washing - near exit door • Eyewash station • Personnel shower

Standard Microbiological Practice • Access to lab limited by lab director during experimt • Wash hand: - Handling hazardous materials - Change glove, exit from lab • No eating, drinking, smoking, handling contact lens • Contact lens --> wear goggles / face shield • No mouth pipetting --> use mechanical pipet • Safe handling of sharp objects • Minimize aerosol generation • Work surfaces decon per day or after spill • Waste decon inside lab | outside with leakproof cont • Insect & rodent control program

Biosafety Level 3 Germs (Air-borne) Virus Venezuelan equine encephalomyelitis Rift Valley fever Chikungunya Yellow fever Japanese encephalitis Louping ill West Nile Lymphocytic choriomeningitis Orungo Piry Wesselsbron Mucambo Oropouche Germiston Bhanja Hantaan

Cases (lab death) 150 (1 death) 47 (1 death) 39 38 (8 deaths) 22 22 18 15 13 13 13 10 7 6 6 6

Biosafety Level 4 Germs (air-borne) According to US CDC in Atlanta: Virus

Cases (lab death) Junin 21 (1 death) Marburg 25 (5 deaths) Russian Spring-Summer 8 Congo-Crimean hemorrhagic 8 (1 death) Omsk hemorrhagic fever 5 Lassa 2 (1 death) Machupo 1 (1 death) Ebola 1 Sabia 3 (1 death)

Summary of Biosafety Levels

1 2 3 4

Lethality Medium Cure Ex Safe Liquid Yes B.Subtilis Some Liquid Some HIV Serious Airborne Some TBC Extreme Airborne None Ebola

Class I Biological Safety Cabinet  Only operator protection (no product protection).  Used for Biosafety level I, II, III Germs  Inflow away from operator.  HEPA filtered exhaust to environment.  Current trend: Switch to Class II

Class 2 Biological Safety Cabinet • Both operator and product protection • Biosafety level 1, 2, 3 • Inflow away from operator • HEPA filtered exhaust to environment • HEPA filtered laminar downflow • Volatile Toxic Chemical in cell culture: biological & chemical -> need ducting

Airstream® Class II Airflow

Class 3 Biological Safety Cabinet • • • • • • • • •

Used for Biosafety level 1, 2, 3, 4 germs Offers both product and operator protection Gas leak tight 1x10-5 cc/sec leak rate Internal operations -> attached glove Material transfer -> 2 doors pass box Negative air pressure > 0.5 “WC (120 Pa) Supply is HEPA filtered Double exhaust HEPA filter in series or: Single exhaust HEPA and an incinerator

Class III: Double Exhaust HEPA

Using the Biological Safety Cabinet (1) - Do not obstruct the front or back air grilles - Work as far in to the cabinet as possible - Minimize arm movement; make slow movements to avoid disrupting cabinet airflow - When removing arms from cabinet be sure to surface decontaminate first, and move arms out slowly of the cabinet (in direction perpendicular to plane of work zone opening)

Using the Biological Safety Cabinet (2) - Work from “clean to dirty” - Biohazard collection bags should be placed inside the cabinet instead of outside

Using the Biological Safety Cabinet (3) - Use absorbent pads on the work surface where appropriate to minimize splatter and aerosol generation in case of a spillage - Surface decontaminate before removing potentially contaminated items from the interior - Put air turbulence generating equipment such as centrifuge, blender, or sonicator in the back 1/3 of the cabinet

Using the Biological Safety Cabinet (4) - Clean materials should be at least 150mm away from aerosol generating objects to minimize the chance for cross contamination - Hold lids / covers above dishes / sample plates in order to prevent impingement of downward air - Do not use a gas flame whenever possible as it interferes with airflow

Shutting down the Biological Safety Cabinet Note: operate the cabinet continuously whenever possible to maximize protection - Surface decontaminate all items - Seal biohazard bags if used - Surface decontaminate the cabinet inner side walls, back wall, work surface, drain pan and the inner side of the sliding sash / hinged window with 70% IPA or other agents - Allow work zone air to purge - Close sash and when available activate UV lamp for 1 hour (using timer)