Which one to choose? A cost-effectiveness analysis between different technologies of air purifiers

Introduction

CoViD19 pandemic highlighted the importance of air purifiers and, in commercialization, their performance and price influence the choice. Since primary focus concerns only performance in terms of CADR (Clean Air Delivery Rate), this study aims to compare: I) levels of declared air purifications according to different types of air purification technologies; II) price of them to evaluate if, with similar group-mean CADR (within +/- 1 SD), there are significant differences in selling prices.

Methods

A review of several devices was carried out, collecting data in January-April 2022. Four different types of air purifiers were considered, divided into as many groups: those equipped with HEPA filters + UV lamps, only with HEPA filters, only with UV lamps and those using other technologies. We applied Kruskal-Wallis test to evaluate statistical differences among prices normalized by CADR, at significant level of 0.05.

Results

Analysis was carried out on 186 devices: I) 37 had HEPA filters + UV lamps, II) 117 only HEPA filters, III) 11 only UV lamps and IV) 21 other technologies. Eight system had HEPA H11 (95% reduction of particle matter 0.5 μm), 8 had HEPA H12 (99.5%), 70 had HEPA H13 (99.95%), 11 had HEPA H14 (99.995%). The mean normalized costs of each group devices, in Euros/CADR were I) 1.22 (SD 2), II) 1.49 (SD 1.4), III) 7.63 (SD 7.38), IV) 1.22 (SD 0.99), respectively. Statistical comparison of four-group selling prices show significant differences (p < 0.05) due to the devices equipped with only UV lamps.

Conclusions

Comparison between technologies analyzed by mean price normalized to CADR showed significant differences between those that used only UV lamps compared to all the others. This is reasonably due to the fact that the use of only UV lamps requires radiant powers considerably greater than all the others, therefore also higher costs (about 5-6 times). In all cases, the level of disinfection reached, as declared, was always > 95%.

Key messages

• With the same mean price normalized to CADR, the selling price is significanly different only for devices equipped with UV lamps compared to all the others.

• Choice of devices with a certain level of declared air purifications can be directed towards those with HEPA+UV/HEPA/other without the mean price normalized to CADR undergoing significant differences.

Air purifiers, comparison between real and declared surface for use: fake it or make it?

Introduction

Air pollution has been recognized as one of the major risk factors for the global burden of disease. In modern society, most exposure occurs indoors, and air quality may be improved with air purifiers utilizing various cleaning techniques. This analysis aims to evaluate whether recommended room surface in which to use these devices as declared by producers is actually in line with their real effective area of activity.

Methods

A review of devices for the purification of the air was carried out between January-April 2022. Four different types of air purifiers were considered based on the adopted technologies: I) HEPA filters and UV lamps; II) only with HEPA filters; III) only UV lamps and IV) those using other technologies. For each group, based on the CADR (Clean Air Delivery Rate) provided by the producers, the optimal real surface area of the room to use the device was calculated, referring to the standard EN779:2012. This value was compared with the recommended area of the room declared by the producers. Descriptive statistics and Wilcoxon matched pair test used for comparisons. The significance level was set at p < 0.05.

Results

The analysis was carried out on 252 devices; I) 52 had HEPA filters + UV lamps, with a recommended mean room area of 40 m2 (IQR 49.75), II) 142 devices had only HEPA filters with 52.5 m2 (IQR 46.75), III) 27 devices only UV lamps, 40 m2 (IQR 105), IV) 31 devices with other technologies, 54 m2 (IQR 84.2). As required by EN779:2012, the effective area of activity was calculated using CADR x 0.075: the medians of the 4 groups were I) 12 m2 (IQR 16.5), II) 15.83 m2 (IQR 26.4), III) 4.5 m2 (IQR 22.5), IV) 7.5 m2 (IQR 21.53), respectively. Comparing declared and calculated CADR values, all the groups showed significant differences (p < 0.05).

Conclusions

Results show that recommended surfaces derived from CADR declared by producers largely overestimate the real volume of the room that devices can purify, whatever the technology used.

Key messages

• There’s no correspondence between recommended area of room to be sanitized indicated by producers of air purifiers and area that they are actually able to sanitize, which is significantly lower.

• It is necessary to be aware of the difference between data indicated by producers and real data, in order to purchase a device that actually corresponds to dimensional needs of the environment itself.

3.0- Versus 1.5-T MR Cholangiography: A Pilot Study

OBJECTIVE

The purpose of our study was to evaluate quantitative and qualitative image quality of MR cholangiography at a field strength of 3.0 T compared with the standard field strength of 1.5 T.

MATERIALS AND METHODS

A standardized MR cholangiography sequence protocol was used for 15 healthy male volunteers (mean age +/- SD, 32.4 +/- 4.3 years) who underwent both 1.5- and 3.0-T MRI within 2 hr in an alternating fashion. Dedicated circular polarized torso coils (1.5 and 3.0 T) were used. The sequence protocol included breath-hold single-slice rapid acquisition with relaxation enhancement (slice thickness, 50 mm; orientation, coronal and +/- 20 degrees oblique coronal); breath-hold multislice HASTE (slice thickness, 3 mm; coronal only); and a non-breath-hold, respiratory-triggered 3D turbo spin-echo (TSE) T2-weighted sequence (slice thickness, 1 mm; 60 slices per slab; coronal only). Maximum intensity projections were generated from each multislice data set. Bile duct (common bile duct, right posterior segmental branch, and left hepatic duct) to periductal tissue contrast-to-noise ratios were compared at 1.5 and 3.0 T. Qualitative image analysis was performed by three independent reviewers. Qualitative analysis included delineation of the extra- and intrahepatic biliary anatomy, with specific attention given to the presence (or absence) of cystic or intrahepatic ductal variants, using a 4-point confidence scale. Statistical analysis consisted of the paired Student's t test and the signed rank test.

RESULTS

Contrast-to-noise ratios between the bile duct and the periductal tissue were higher at 3.0 T in all three locations (common bile duct, right posterior segmental branch, and left hepatic duct). In each magnet class, the 3D TSE sequence offered the best contrast-to-noise ratio and qualitative analysis. Superiority of the 3D TSE sequence was statistically significant in all analyses. Five of the 15 volunteers had intrahepatic biliary variants that were detected with a higher level of confidence (p < 0.01) on the 3.0-T system than on the 1.5-T system.

CONCLUSION

Compared with MR cholangiography at 1.5 T, MR cholangiography at 3.0 T offers improved contrast-to-noise ratio and a higher level of confidence for depicting intrahepatic variants.

Total respiratory support from swine lungs in primate recipients

The use of nonhuman lung donors, such as swine, has the potential to provide an unlimited supply of organs. However, hyperacute rejection has prevented pulmonary xenotransplantation.

OBJECTIVE

Our aim was to test the hypothesis that immunodepletion by pretransplantation swine lung perfusion will prevent hyperacute swine-to-primate pulmonary xenograft rejection and allow for a functional swine pulmonary xenograft.

METHODS

Seven baboons underwent left pneumonectomy followed by orthotopic transplantation of the swine left lung. Four baboons received immunodepletion by perfusion with swine lungs before transplantation, and three received no treatment before transplantation.

RESULTS

After transplantation, pulmonary xenografts from immunodepleted baboons had a low pulmonary vascular resistance and a high pulmonary blood flow compared with control animals, which had a high pulmonary vascular resistance and a low pulmonary blood flow. After 60 minutes of reperfusion, three of four immunodepleted animals also tolerated complete occlusion of the right pulmonary artery, with the baboon relying completely on the swine pulmonary xenograft for respiratory function for 11 hours. Pathologic analysis of peripheral lung biopsy specimens taken from control lungs displayed alveolar disruption and hemorrhage within small vessels, whereas swine lungs transplanted into immunodepleted baboons displayed little histologic evidence of injury. Furthermore, pulmonary xenografts transplanted into immunodepleted baboons demonstrated excellent respiratory function and adequate hemodynamics during occlusion of the right pulmonary artery.

CONCLUSION

Hyperacute pulmonary xenograft rejection can be prevented by pretransplantation swine lung perfusion. Swine pulmonary xenografts can provide complete respiratory support in primates when rejection is prevented.

The role of natural anti-Gal alpha 1-3Gal antibodies in hyperacute rejection of pig-to-baboon cardiac xenotransplants

Xenoreactive natural antibodies in humans and higher primates are directed predominantly at Gal alpha 1-3Gal. These antibodies are thought to initiate hyperacute rejection of porcine organ xenografts. The contribution of anti-Gal alpha 1-3Gal antibodies to the xenoractive natural antibody repertoire and to the initiation of hyperacute rejection was tested in a pig-to-baboon cardiac xenograft model. Anti-Gal alpha 1-3Gal antibodies were depleted from baboons by extracorporeal absorption of anti-Gal alpha 1-3Gal antibodies from plasma using columns with a matrix bearing Gal alpha 1-3Galb1-4GlcNAc. Specific removal of anti-Gal alpha 1-3Gal antibodies was achieved prior to transplantation as demonstrated by immunoassay. Porcine hearts were then transplanted into these baboons and the outcome of the transplants was analysed. Immunofluorescence revealed little deposition of baboon antibodies in the grafts. The porcine hearts did not undergo hyperacute rejection even though complement activity was approximately 90% of baseline at the time of transplantation. These findings demonstrate that anti-Gal alpha 1-3Gal antibodies constitute a major fraction of xenoreactive natural antibodies in primate blood and that these antibodies contribute significantly to the pathogenesis of hyperacute xenograft rejection.