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Monitoring and Detection Equipment for Terrorist Agents
Published in Robert A. Burke, Counter-Terrorism for Emergency Responders, 2017
Particle filters are assigned a value called the minimum efficiency reporting value (MERV) rating. Higher MERV ratings reflect more efficient and effective filters. For example, an MERV-13 filter captures less than 75% of particles between the size of 0.3 and 1.0 μm, whereas an MERV-16 filter captures greater than 95% of particles within that range.21 The NYPD recommends that owners of high-tier buildings incorporate solid particle filters with high MERV ratings. In particular, high-tier buildings should use multiple MERV-16 filters, at least one MERV-17 filter, or a high-efficiency particulate air (HEPA) filter.23 MERV-17 filters and HEPA filters are 99.97% effective at removing the particulate matter greater than 0.3 μm in size, including biological agents such as B. anthracis. However, hazardous particles less than 0.3 μm in size are likely to pass through the recommended filters.
Retail Design in a Post-Pandemic World
Published in AnnaMarie Bliss, Dak Kopec, Architectural Factors for Infection and Disease Control, 2023
Layout and Systems: Escutcheon and belt barriers at entrance and checkout areas to organize queues were the quintessential organizing feature. Mannequins and elaborate window displays were replaced by sobering messages of courage and solidarity. For stores that remain closed, the storefront windows were either covered with elaborate brand messages or handmade signs signaling the open/close status and shopping protocol. Sanitizer, disinfectant wipes, and mask stations were placed at the entrance. Merchandise floors were distanced to reduce contact. Clothing trials and returns increase spread of infections, and so does the return of merchandise. Many clothing stores closed their fitting rooms and trials during the pandemic. Returns, if allowed, followed quarantine protocols, and to accommodate quarantine of merchandise, fitting rooms were converted to temporary quarantine/storage facilities. Bring-your-own-bag grocery stores, checkout areas at stores, and carts are other germ-friendly processes that increase infections. Grocery stores prohibited the use of personal bags for shopping and encouraged shoppers to bag their groceries. Checkout areas at stores switched to cashier-less checkout via digital apps. Wipe stations were placed close to cart intake and exit areas. Amazon is popularizing the dash-cart/smart-cart technology that will enable customers to leave the store without entering the checkout line. Increased air filtration by upgrading HVAC filters to MERV 13 (or the highest MERV rating a building’s ventilation system can accommodate) and placing portable air cleaners in high-occupancy areas, such as a mall, grocery, or department store, were implemented.
Summer Air-Conditioning Systems/Saving Natural Resources
Published in Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo, Energy Conservation Guidebook, 2020
Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo
Currently filtration is used to remove dust from air handling systems. However, these filters are very coarse by nature and do not block the smaller particles related to mold and allergens. Other types of filtration such as HEPA (high efficiency particulate absorbing) that are capable of removing over 99.9% of the particulate matter from the air are added to heating and air conditioning systems to improve IAQ. In addition to a HEPA filter, other air-handling-equipment filters can be fitted which have a minimum efficiency reporting value or MERV rating. MERV ratings are from 1 to 16 and reflect the filter’s ability to remove particles. A low MERV number indicates a fairly coarse filter, and a filter with a MERV rating of 14 might be used in a hospital where airborne bacteria are a concern. Because a MERV rating is an industry standard, it is an effective method to use when evaluating filters from different manufacturers. In addition to filtration, UV (ultraviolet) lighting can be used to inhibit airborne biological hazards. UV systems can be installed in plenums, air handlers or ductwork for disinfection. By passing harmful germs past the UV light source, the DNA of the germ is destroyed. This technology has been proven effective in the treatment of viruses, molds, spores, fungi, and bacteria. As with many IAQ technologies, filtration and UV lamps have costs that increase as IAQ increases. In filtration, filters with higher MERV ratings cost more and restrict airflow, thereby decreasing efficiency. In UV light treatment, in addition to the initial cost of installation, the UV lamps have a relatively short life, sometimes as brief as one year.
Filtration efficiency of woven metal fiber filter for aerosol generated by plasma torch metal cutting
Published in Aerosol Science and Technology, 2023
Min-Ho Lee, Hee Kwon Ku, Hyunjin Boo, Jonghyeon Kim, Geundong Song, Deokhee Lee, Kaphyun Yoo, Byung Gi Park
The MERV rating was used to evaluate the performance of the metal filters on particle removal in size range of 0.3 to 10 µm. Table 2 shows the results of composite average particle size efficiency under certification test and actual metal cutting environment test. In MERV testing, the particle removal efficiency is estimated in three sub-groups: the coarsest particles in group E3 (3.0 to 10.0 µm), the finest in group E1 (0.3 to 1.0 µm), and the intermediate in group E2 (1.0 to 3.0 µm). The higher MERV rating means that a filter has better capability to remove particulate matter having a size of 0.3 to 10 µm. The accredited certification test was carried out with a 0.3-micron mono-disperse dioctylphthalate (DOP) aerosol according to ASHRAE Standard 52.2 methodology. Type I filter was certified the MERV rating 7, while Type II filter was certified the MERV rating 10.
Characterizing the performance of a do-it-yourself (DIY) box fan air filter
Published in Aerosol Science and Technology, 2022
Rachael Dal Porto, Monet N. Kunz, Theresa Pistochini, Richard L. Corsi, Christopher D. Cappa
A recently proposed, easy-to-construct, and low-cost alternative air filter constructed from MERV-13 filters and a box fan provides an opportunity for more people to access filter-based air cleaners in an affordable manner. This do-it-yourself (DIY) air filter, known as the “Corsi-Rosenthal Box” (hereafter, CR Box), is finding use in classrooms and other indoor environments across the U.S. through a grassroots movement driven by social media and the accessibility of the materials (Emanuel 2021). Although MERV-13 filters have a lower intrinsic filtration efficiency than HEPA filters, in-room air filtration using MERV-13 filters will still lead to a reduction in particle concentrations. While some work on airflow optimization in the CR Box has been done (Elfstrom 2021) and some initial characterization exists (Srikrishna 2021; Wieingartner, Rüggeberg and Wipf 2021), no systematic evaluation of the performance yet exists. Given the adoption of the CR Box in classrooms and other indoor environments, such evaluation is critical.
Integrating IAQ control strategies to reduce the risk of asymptomatic SARS CoV-2 infections in classrooms and open plan offices
Published in Science and Technology for the Built Environment, 2020
Air cleaning strategies involve applying air filtration or purification in the outdoor supply, recirculated or mixed air duct, locally in a room or a cubical, and at personal level (e.g., properly worn masks). To be effective, high efficiency filters and sufficient airflow through them are necessary. At the building level, high efficiency particulate (HEPA) filters in the recirculated or mixed air duct can reduce the cross contamination between rooms and increase the total clean air delivery rate (outdoor plus filtered air) for diluting the virus concentration in the ventilated space. HEPA filters have a minimum efficiency of 99.97% for 0.3 to 10 µm particles. MERV 14 or higher rating filters have a minimum efficiency of 75% − 84% for 0.3 − 1.0 µm, and 90% or greater for 1.0 − 3.0 µm particles. Assuming that 80% of the air is recirculated, use of MERV 14 or HEPA filters to treat the recirculated air can further dilute the pollutant concentration by a factor of 4 or 5, respectively. The benefit of having the filters on the recirculated air reduces as the percent of outdoor air increases as expected. The updated ASHRAE Position Document on Infectious Aerosols (ASHRAE 2020) recommends the use of ventilation in combination with air filtration to reduce the risk of infection.