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22 August 2026 Inhalation Inhalation: Thank you both for your thoughtful reflections on the early days of manufacturing the NGI. Again, our congratulations to the entire NGI team—the NGI Consortium, MSP Corporation and the many dedicated machinists and assemblers who continue to play their critical role—on the 25th anniversary of shipping NGI serial number one. References Design and calibration 1. Marple, V. A., D. L. Roberts, F. J. Romay, N. C. Miller, K. G. Truman, M. Van Oort, B. Olsson, M. J. Holroyd, J. P. Mitchell, D. Hochrainer. Next Gener- ation Pharmaceutical Impactor, Part I: Design. Jour- nal of Aerosol Medicine, 16(3), 283-299 (2003); doi 10.1089/089426803769017659. 2. Marple, V. A., B. A. Olson, K. Santhanakrishnan, J. P. Mitchell, S. Murray, B. Hudson-Curtis. Next Generation Pharmaceutical Impactor, Part II: Cal- ibration. Journal of Aerosol Medicine, 16(3), 301- 324 (2003); doi 10.1089/089426803769017668. 3. Marple, V. A., B. A. Olson, K. Santhanakrishnan, D. L. Roberts, J. P. Mitchell, B. L. Hudson-Curtis. Next Generation Pharmaceutical Impactor: A New Impactor for Pharmaceutical Inhaler Testing, Part III: Extension of Archival Calibration to 15 L/min. Journal of Aerosol Medicine, 17(4), 335-343 (2004); https://doi.org/10.1089/jam.2004.17.335. European Pharmaceutical Aerosol Group reports of early experience with the NGI 4. Asking, L., S. Nichols, Next Generation Pharma- ceutical Impactor (NGI)–EPAG Collaborative Study. e Aerosol Society, Drug Delivery to the Lungs 14, London, UK, December 11-12, 2003, pages 33-36. 5. Nichols, S., D. Russell-Graham, Comparative Efficiency of the Use of the Next Generation Impac- tor Compared to the Andersen Cascade Impactor when Used with Dry Powder Inhalers. e Aerosol Society, Drug Delivery to the Lungs 18, Edinburgh, UK, December 12-14, 2007, pages 120-123. Daryl L. Roberts, PhD, President, Applied Particle Principles, LLC, 17347 Westham Estates Court, Hamil- ton, VA, 20158, US, Tel.: +1 612 845-3293, droberts@ particleprinciples.com, www.particleprinciples.com Jolyon P. Mitchell, PhD, President, Jolyon Mitchell Inhaler Consulting Services, Inc., London, Ontario, Canada. Tel.: +1 519 472-5364, mitchelljolyon@ gmail.com thin layer of a nonionic surfactant (sold commercially as Brij 35) and other methods. Inhalation: What would each of you do differently in constructing the NGI if you were to do it again? Daryl: From the outset, I would make all the parts, except the bottom frame, out of 316 stainless steel (316SS). We spent too much time with nickel coat- ing and precision issues related to it and with cor- rosion of 304 stainless steel. ere's no material like 316SS; it has reasonable machining costs and high mechanical and chemical stability. Jolyon: On reflection, I would have addressed the corrosion resistance issue earlier, through my contacts in EPAG. I had experience using ACIs machined from 100% 316SS in the 1980s, when those impac- tors were available commercially only in aluminum. So I was aware of the need to optimize corrosion resistance. In the end, after corrosion issues with the nickel-coated Micro Orifice Collector (MOC) had become apparent, it took up to serial number 640 for MSP to make the change successfully to 100% 316SS (as discussed in the first republished article). Members of the NGI Consortium As recognized during the development and early user experiences with the NGI, "considerable technical input was obtained from representa- tives from all the sponsoring companies and their technical staffs; their input is gratefully acknowl- edged." [1] e Consortium representatives and their affiliated companies were: Lars Asking (AstraZeneca R&D Lund) Jeremy Clarke (Vectura, Ltd.) Tön Forch (Pharmachemie) Beatrix Fyrnys (Asta Medica—later Sofotec GmbH) David Ganderton (Coordinated Drug Development, Ltd.) Bernie Greenspan (Dura Pharmaceuticals) Dieter Hochrainer (Boehringer Ingelheim Pharma KG) Mike Holroyd (Norton Healthcare—later IVAX Pharmaceuticals) Hans Keegstra (Pharmachemie) Jari Kovalainen (Orion Pharma) Terhi Mattila (Orion Pharma) Paul Miller (Pfizer) Jolyon Mitchell (Trudell Medical International) Steve Nichols (Aventis Pharma) Bo Olsson (AstraZeneca R&D Lund) Dilraj Singh (Novartis Pharma AG) Keith Truman (GlaxoSmithKline) Mike Van Oort (GlaxoSmithKline) Dave Warren (3M Healthcare, Ltd.) Bruce Wyka (Schering-Plough Research Institute)