Optical Aerosol Spectrometer (OAS) and dry aerosol generator (DAG) for COVID-related research

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During the COVID-19 pandemic, most authorities have focused on reducing the contact and droplet transmission of SARS-CoV-2 (coronavirus) by recommending handwashing, surface sanitizing and 2-m physical distancing with little attention to the potential for airborne transmission of SARS-CoV-2. However, recent US Centers for Disease Control (CDC) and ASHRAE statements show the urgency of this RTI grant and our COVID-research to quantify and reduce airborne pathogen transfer in HVAC systems. ASHRAE: “Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning [HVAC] systems, can reduce airborne exposures.” CDC: “There are several well-documented examples in which SARS-CoV-2 appears to have been transmitted over long distances or times.” The proposed optical aerosol spectrometer (OAS) and dry aerosol generator (DAG) will allow us to generate aerosols and measure the key parameters affecting airborne transmission (i.e., the size, concentration and movement of aerosol particles). While the exact viral dose that is required to infect a person with COIVD-19 is unknown, humans infected with influenza generate around 2,000 infectious aerosol droplets per hour and even more during coughing, sneezing and singing. The distance that these aerosols can travel depends on their size and the ambient air velocity. While the coronavirus alone (0.1 µm) may remain airborne for days, exhaled aerosols containing body fluids and the coronavirus are expected to be 1 to 5 µm and may remain airborne for hours (e.g., 3 µm particle will settle at a rate of 1 m/h and natural indoor air currents could transport the aerosol nearly 100 m). The COVID-19 pandemic has increased public awareness of the importance of indoor air quality (IAQ) in buildings. Canadians spend over 90% of their time indoors and intake 15,000 L (17 kg) of air a day, which is much higher than our daily intake of food (~2 kg) and water (~2 L). Bottled water has mandated labels to indicate contents and purity, while the air we breathe is assumed to be clean. Clearly, the large volumes of air we breathe can impact our health and well-being with or without a pandemic. Therefore, while this RTI grant focuses on research related to the COVID-19 pandemic and pandemic operation of HVAC systems, the research will have long-term impacts for buildings under normal operation. The 20 HQP trained with the optical aerosol spectrometer (OAS) and dry aerosol generator (DAG) purchased with this RTI grant will develop solutions for HVAC systems that improve IAQ and reduce infectious disease transmission during pandemic and normal operation. During their careers, the HQP trained using the OAS and nebulizers will be well positioned to lead the implementation of these and other solutions in Canadian buildings and thus improve the health and well-being of Canadians.