近日，FDA對Valneva Scotland Limited的檢查483缺陷報告中提及氣流流型（氣流可視化或煙霧試驗(yàn)）所用煙霧不當(dāng)?shù)娜毕荩涸摴疚瘁槍υ摕熿F用于潔凈室層流罩的情況，評估煙霧的無菌性、顆粒產(chǎn)生及殘留物可清潔性等因素，如下：
Dynamic smoke studies were performed utilizing smoke from a combustible source, smoke matches. This smoke has not been evaluated by your firm for use in cleanroom hoods for factors such as sterility of smoke, particle generation, and cleanability of residues. In addition, smoke cannot be visualized in all smoke study videos due to blocked camera angles by personnel and manual application of smoke by personnel.
動態(tài)煙霧試驗(yàn)（氣流流型）使用了可燃來源（煙霧棒）產(chǎn)生的煙霧。貴公司未針對該煙霧用于潔凈室層流罩的情況，評估煙霧無菌性、顆粒產(chǎn)生及殘留物可清潔性等因素。此外，由于人員遮擋攝像頭角度以及人工施煙，部分煙霧試驗(yàn)（氣流流型）視頻中無法清晰觀測到煙霧。
氣流流型測試的煙霧要求
Airflow Pattern Testing: There is an increasing expectation that airflow patterns in ISO 5/Grade A through ISO7/Grade B areas be video recorded. Considerations include the selection ofcamera angles, visibility of the smoke against the room background, the useoffiner (thinner) smoke streams to better show stream lines. Video narrative should describe what the viewer sees, with additional pertinent data (perhaps titles) showing date, personnel, air velocity at the filters, etc. Certainaerosols (smoke sources) may be unfit for airflow pattern testing, being eithertoo dense (such as smoke from dry ice and alcohol) or reactive with cleaningagents (titanium smoke sticks leave a catalyst residue that interferes withcertain sterilants). Some of the better smoke sources may require cleaning ofthe room surfaces before the room can be returned to service.
氣流流型測試：對于 ISO 5/ A 級至 ISO 7/ B 級區(qū)域的氣流流型，越來越要求對其進(jìn)行視頻記錄。需要考慮的因素包括攝像機(jī)角度的選擇、煙霧與房間背景的對比度、使用更輕（更薄）的煙霧以更好地顯示氣流流型。應(yīng)有視頻旁白描述所看到的內(nèi)容，并附上相關(guān)數(shù)據(jù)（可能在標(biāo)題），如日期、人員、過濾器處的空氣流速等。某些氣溶膠（煙霧來源）可能不適合用于氣流流型測試，要么過于濃密（例如干冰和酒精產(chǎn)生的煙霧），要么會與清潔劑發(fā)生反應(yīng)（鈦煙棒會留下催化劑殘留物，干擾某些消毒劑）。一些較好的煙霧源可能還需要在房間重新投入使用前對房間表面進(jìn)行清潔。
PDA近期的培訓(xùn)中也提及氣流流型測試（氣流可視化測試或煙霧測試）中的常見誤區(qū)：
Airflow Visualization Studies: A Misunderstood & Underutilized Tool氣流可視化研究：一門被誤解且未充分利用的工具
Smoke Studies are Often Approached as a Rubber Stamp Test. Often Conducted Under the Assumption That They Will Pass Because Other Cleanroom/Barrier System Tests Have Passed:
煙霧試驗(yàn)常被視為 “走過場” 測試，其開展往往基于 “其他潔凈室 / 屏障系統(tǒng)測試已通過，此測試也會通過” 的假設(shè)，例如：
Air Volume and Air Velocity
風(fēng)量和風(fēng)速
Differential Pressure
壓差
Filter Integrity
過濾器完整性
Particle Count
粒子計數(shù)
Heavier Than Air Fogging Systems for Air Flow Visualization (Smoke Studies) do not faithfully (accurately) follow the Actual Air Flow Patterns:
用于氣流可視化（煙霧試驗(yàn)）的霧化系統(tǒng)如重于空氣則無法如實(shí)跟隨實(shí)際氣流流型，存在以下局限：
Do not Identify Dead Spaces
無法識別死空間
Do not identify Eddy Currents
無法識別渦流
Resulting in the acceptance of unsuitable air patterns and aseptic operations being carried out in turbulent or deviant air flow conditions.
導(dǎo)致不合格的氣流模式被接受，無菌操作在湍流或異常氣流條件下進(jìn)行。
Water, CO?, Nitrogen Foggers are Unsuitable.
水、二氧化碳、氮?dú)鉄熿F均不適合用于氣流流型測試。
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