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Air pollution control and mitigation
Published in Abhishek Tiwary, Ian Williams, Air Pollution, 2018
As shown in Chapter 7, indoor air pollution control is vital for both residential and industrial applications: the former mainly to alleviate pollution exposure for health reasons and the latter to maintain high standards of precision manufacturing and/or cross-contamination of products with microscopic airborne pollutants. Specifically, clean room standards have been developed as benchmark for controlling indoor air pollution for industrial applications. Pollutant removal efficiency is usually determined in controlled laboratory environments, which may not be realised in practice. However, the existing data make it difficult to extract information such as clean air delivery rate (CADR; defined as the product of the single-pass removal efficiency and volumetric airflow rate through the cleaning device), which represents a common benchmark for comparing the performance of different air-cleaning technologies. To compare and select suitable indoor air-cleaning devices, a labelling system accounting for characteristics such as CADR, energy consumption, volume, harmful by-products, and life span is recommended. The majority of focus in indoor air pollution control is laid on removal of particulates (both inorganic and bioaerosols), NOx and CO.
Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2
Published in Aerosol Science and Technology, 2021
J. Curtius, M. Granzin, J. Schrod
For a relative humidity far below 100% droplets emitted during speaking will lose a large fraction of their water content rapidly and much smaller droplet cores will remain (e.g., Mikhailov et al. 2004). Droplet cores with sizes below about 10 µm will remain airborne for minutes to hours and these particles are transported in a room by thermal convection, turbulence and other air movements. Therefore, the particles are distributed throughout a classroom within minutes and they can accumulate in a closed room over hours. Mobile air purifiers offer the possibility to reduce the aerosol load in closed rooms substantially (Offermann et al. 1985; Shaughnessy and Sextro 2006). If the air in a closed room is drawn continuously through a filter, the risk of an infection from respirable aerosols will likely be reduced (Offermann et al. 1985; Miller-Leiden et al. 1996). The Clean Air Delivery Rate (CADR) is used as a metric to characterize the efficacy of air purifiers (Küpper et al. 2019; Shaughnessy and Sextro 2006). It is given as the product of the device’s particle removal efficiency η and the volumetric flow rate through the device. It can also be calculated by subtracting the natural particle decay rate knat in a room from the decay rate measured with the air purifier in operation kpurifier and multiplying by the volume of the room Vroom (Küpper et al. 2019):
COVID-19 aerosol transmission modeling in support of company HVAC guideline
Published in Journal of Occupational and Environmental Hygiene, 2022
Ty J. Oberlin, Cheryl K. DuBois, Mike Sheppard, Jodi D. Quam, Amanda J. Kramer, Perry W. Logan, Michael J. Murphy
Step 3. Gather room dimensions to calculate total room volume. Measure and calculate, or, alternatively, obtain from facilities’ engineering or building drawings, the ventilation rate (ACH) of each space. If air purifiers are used in a space, record the number of continuously run air purifiers and the clean air delivery rate (CADR) rating or volume of air in cubic feet per minute (CFM) provided by each air purifier.