Decay of airborne contamination and ventilation effectiveness of cleanrooms

This article reports an investigation into the ability of the air supply in non-unidirectional cleanrooms to aid recovery from episodes of airborne contamination, and minimise airborne contamination at important locations. The ISO 14644-3 (2005) recovery test, which measures the rate of decay of test particles, was assessed and a reinterpretation of the test results suggested. This allowed air change effectiveness indexes to be calculated and used to evaluate the ventilation effectiveness of the cleanroom’s air supply. Air change effectiveness indexes were measured in various designs of cleanrooms, and reasons for deviations in the value of the indexes investigated

The application of the ventilation equations to cleanrooms - Part 2: Decay of contamination

This article is the second of a three-part series that investigates the application of the ventilation equations to designing and testing cleanrooms. This part is concerned with the decay equation. The recovery test, described in ISO 14644-3 (2005) is discussed, and improvements recommended. The application of the decay equation to the ‘clean up’ requirement given in the EU GGMP (2008) is also discussed. Finally, a method is considered that calculates the time needed for airborne contamination in cleanroom areas to decay to acceptable concentrations

Dispersion of microbes from floors when walking in ventilated rooms

The redispersion factor of microbe-carrying particles, which is the ratio of the concentration of floor-derived microbes in room air to those on a floor surface, was determined, as was the percentage of floor-derived microbes in room air. These relationships were shown to vary according to conditions in the room. Equations were derived that allow these relationships to be calculated for a variety of room conditions, including air supply rates, levels of personnel activity, and the effect of gravitational deposition on microbe-carrying particles.<p></p> The redispersion factor in ventilated rooms, such as cleanrooms and operating rooms, when the floor surface concentration was measured by nutrient agar contact dishes, was found to vary from about 1.5 x 10-4 to 7.4 x 10-6, and the percentage of floor-derived microbes in room air from about 0.004% to 10.5%. In a typical cleanroom, the redispersion factor is likely to be about 1.0 x 10-4, and the percentage of floor-derived microbes, 0.7. In a typical operating room, the redispersion factor is likely to be about 5.2 x 10-6 and the percentage of floor-derived microbes, 2.<p></p&gt

Calculation of air supply rates and concentrations of airborne contamination in non-UDAF cleanrooms

This article reviews a series of scientific articles written by the authors, where the following topics were investigated in relation to non-unidirectional airflow cleanrooms. (1) The air supply rate required to obtain a specified concentration of airborne contamination. (2) The calculation of concentrations of airborne contaminants in different ventilation and dispersion of contamination situations. (3) The decay of airborne contamination (a) during the ‘clean up’ test described in Annex 1 of the EU Guidelines to Good Manufacturing Practice (2008); (b) during the recovery rate test described in Annex B12 of ISO 14644-3 (2005); (c) associated with clean areas, such as airlocks, to reduce airborne contamination before a door into a cleanroom is opened. Worked examples are provided to demonstrate the calculation methods to provide solutions to the above topics

Rheology of the gel formed in the California Mastitis Test

The California Mastitis Test has previously been adapted for use in an inline, cow-side sensor and relies on the fact that the viscosity of the gel formed during the test is proportional to the somatic cell concentration. In this paper, the use of capillary and rotational viscometry was compared in light of the expected rheology of the gel formed during the test. It was found that the gel is non-Newtonian, but the initial phase of viscosity increase was not due to shear dependence, but rather due to the gelation reaction. The maximum apparent viscosity of the gel was shear dependent while the time it took to reach the maximum was not truly shear dependent, but was rather dependent on the degree of mixing during gelation. This was confirmed by introducing a delay time prior to viscosity measurement, in both capillary and rotational viscometry. It was found that by mixing the reagent and infected milk, then delaying viscosity measurement for 30 s, shortened the time it took to reach maximum viscosity by more than 60 s. The maximum apparent viscosity, however, was unaffected. It was found that capillary viscometry worked well to correlate relative viscosity with somatic cell count, but that it was sensitive to the reagent concentration. It can therefore be deduced that the rheology of the gel is complicated not only by it being non-Newtonian, but also by the strong dependence on test conditions. These make designing a successful sensor much more challenging

Cost-effectiveness of granulocyte colony-stimulating factor prophylaxis for febrile neutropenia in patients with non-Hodgkin's lymphoma in the United Kingdom (UK)

Introduction: We report a cost-effectiveness evaluation of granulocyte colony-stimulating factors (G-CSFs) for prevention of febrile neutropenia (FN) following chemotherapy for non-Hodgkin’s lymphoma (NHL) in the United Kingdom (UK). Methods: A mathematical model was constructed simulating the experience of patients with NHL undergoing chemotherapy. Three strategies were modelled: primary prophylaxis (G-CSFs administered in all cycles); secondary prophylaxis (G-CSFs administered in all cycles following an FN event), and no G-CSF prophylaxis. Three G-CSFs were considered: filgrastim; lenograstim and pegfilgrastim. Costs were taken from UK databases and utility values from published sources with the base case analysis using list prices for G-CSFs and a willingness to pay (WTP) threshold of £20,000 per QALY gained. A systematic review provided data on G-CSF efficacy. Probabilistic sensitivity analyses examined the effects of uncertainty in model parameters. Results: In the base-case analysis the most cost-effective strategy was primary prophylaxis with pegfilgrastim for a patient with baseline FN risk greater than 22%, secondary prophylaxis with pegfilgrastim for baseline FN risk 8-22%, and no G-CSFs for baseline FN risk less than 8%. Using a WTP threshold of £30,000, primary prophylaxis with pegfilgrastim was cost-effective for baseline FN risks greater than 16%. In all analyses, pegfilgrastim dominated filgrastim and lenograstim. Sensitivity analyses demonstrated that higher WTP threshold, younger age, or reduced G-CSF prices result in G-CSF prophylaxis being cost-effective at lower baseline FN risk levels. Conclusions: Pegfilgrastim was the most cost-effective G-CSF. The most cost-effective strategy (primary or secondary prophylaxis) was dependent on underlying FN risk level, patient age, and G-CSF price

Effectiveness and cost-effectiveness of an awareness campaign for colorectal cancer: a mathematical modeling study

Background A campaign to increase the awareness of the signs and symptoms of colorectal cancer (CRC) and encourage self-presentation to a GP was piloted in two regions of England in 2011. Short-term data from the pilot evaluation on campaign cost and changes in GP attendances/referrals, CRC incidence, and CRC screening uptake were available. The objective was to estimate the effectiveness and cost-effectiveness of a CRC awareness campaign by using a mathematical model which extrapolates short-term outcomes to predict long-term impacts on cancer mortality, quality-adjusted life-years (QALYs), and costs. Methods A mathematical model representing England (aged 30+) for a lifetime horizon was developed. Long-term changes to cancer incidence, cancer stage distribution, cancer mortality, and QALYs were estimated. Costs were estimated incorporating costs associated with delivering the campaign, additional GP attendances, and changes in CRC treatment. Results Data from the pilot campaign suggested that the awareness campaign caused a 1-month 10 % increase in presentation rates. Based on this, the model predicted the campaign to cost £5.5 million, prevent 66 CRC deaths and gain 404 QALYs. The incremental cost-effectiveness ratio compared to “no campaign” was £13,496 per QALY. Results were sensitive to the magnitude and duration of the increase in presentation rates and to disease stage. Conclusions The effectiveness and cost-effectiveness of a cancer awareness campaign can be estimated based on short-term data. Such predictions will aid policy makers in prioritizing between cancer control strategies. Future cost-effectiveness studies would benefit from campaign evaluations reporting as follows: data completeness, duration of impact, impact on emergency presentations, and comparison with non-intervention regions

Cost-effectiveness of granulocyte colony-stimulating factor prophylaxis for febrile neutropenia in patients with non-Hodgkin's lymphoma in the United Kingdom (UK)

Introduction: We report a cost-effectiveness evaluation of granulocyte colony-stimulating factors (G-CSFs) for prevention of febrile neutropenia (FN) following chemotherapy for non-Hodgkin’s lymphoma (NHL) in the United Kingdom (UK). Methods: A mathematical model was constructed simulating the experience of patients with NHL undergoing chemotherapy. Three strategies were modelled: primary prophylaxis (G-CSFs administered in all cycles); secondary prophylaxis (G-CSFs administered in all cycles following an FN event), and no G-CSF prophylaxis. Three G-CSFs were considered: filgrastim; lenograstim and pegfilgrastim. Costs were taken from UK databases and utility values from published sources with the base case analysis using list prices for G-CSFs and a willingness to pay (WTP) threshold of £20,000 per QALY gained. A systematic review provided data on G-CSF efficacy. Probabilistic sensitivity analyses examined the effects of uncertainty in model parameters. Results: In the base-case analysis the most cost-effective strategy was primary prophylaxis with pegfilgrastim for a patient with baseline FN risk greater than 22%, secondary prophylaxis with pegfilgrastim for baseline FN risk 8-22%, and no G-CSFs for baseline FN risk less than 8%. Using a WTP threshold of £30,000, primary prophylaxis with pegfilgrastim was cost-effective for baseline FN risks greater than 16%. In all analyses, pegfilgrastim dominated filgrastim and lenograstim. Sensitivity analyses demonstrated that higher WTP threshold, younger age, or reduced G-CSF prices result in G-CSF prophylaxis being cost-effective at lower baseline FN risk levels. Conclusions: Pegfilgrastim was the most cost-effective G-CSF. The most cost-effective strategy (primary or secondary prophylaxis) was dependent on underlying FN risk level, patient age, and G-CSF price

Ventilation effectiveness in cleanrooms and its relation to decay rate, recovery rate, and air change rate

Non-unidirectional airflow cleanrooms are supplied with filtered air to minimise the contamination of a product or process by airborne contamination. The effectiveness of the ventilation system in providing the required type of airflow in the cleanroom that will minimise airborne contamination can be assessed by measuring ventilation effectiveness indexes. This article provides information on what ventilation effectiveness indexes are suitable for cleanrooms, and how they can be obtained by test methods in common use in cleanrooms. Three methods of measuring ventilation effectiveness are discussed, namely, the Contamination Removal Effectiveness (CRE) index, the Air Change Effectiveness (ACE) index and the Performance Index (PI), and it was considered that the ACE index and PI were the most suitable for use in cleanrooms. The decay rate and recovery rate of airborne contamination in relation to the air change rate in non-unidirectional cleanrooms is also considered, and it is demonstrated that when measured at the same location, the three rates are identical. Also considered is the measurement of these rates in cleanrooms and how they can be used to obtain the ACE index

A Comparative Analysis of the Major Religions in Japan and Korea During the Colonial Period

To understand why the Christian gospel has success amid one culture, while seeming to fail in similar, neighboring cultures, one must look to additional factors than those often cited by missionary sources. Some of these factors would include the socio -political and religious context of each of those cultures in question, in addition to the prior encounters with Christianity and the reactions to the gospel by the receiving cultures. To illustrate this need, this paper analyzes the contexts of Japan and Korea during the period of Japanese expansion and wartime (1894 – 1945), and looks specifically at what was happening in the other major religions present at the time (Confucianism, Buddhism, and Shintoism), which would include their responses to the Christian missionary presence