1/ With COVID-19 on the rise (again). Remember, the SARS-CoV-2 virus is transported by respiratory aerosols. INHALATION of aerosols is the dominant transmission pathway. Many of us have not wavered on this fact since early in the pandemic. It's about inhalation dose, folks.
2/ Since the dominant pathway is INHALATION of virus-laden respiratory aerosols, then reducing inhalation dose of these particles or inactivating viruses in the particles is the answer to reducing infection (pre- or unvaccinated & even vaccinated breakthroughs).
3/ Science & engineering gave us all of the tools we need to drive this pandemic into the ground. Vaccinations are a gift handed to us on a silver platter. The rest is not rocket science. The rest should be common sense.
4/ For 1,000th time since early spring 2020... To significantly reduce inhalation dose of virus-laden particles or SARS-CoV-2 in those particles: Universal good mask wearing & increased ventilation + improved filtration (HVAC and/or portable HEPA) &/or upper-room UV disinfection.
5/ These are the tools, folks. Vaccinate. Mask up. Ventilate. Filter. Disinfect (the air!). Proven technologies/approaches that reduce inhalation dose. Don't flirt w/ the unproven.
6/ #COVIDisAirborne means that #COVID-19 is an airborne infectious disease transmitted by INHALATION of viable SARS-CoV-2 viruses. The key is vaccination and lowering inhalation dose.
2/ This paper offers a platform that is somewhat more mechanistic than traditional risk estimates for airborne infectious disease. It includes ability to include aerosol size distributions & emissions from infected individuals + particle fate mechanisms indoors.
3/ Insertion of control options (increasing ventilation, masks, filtration) in single zone systems can be employed. The model predicts particle deposition in the respiratory system of receptors & converts these to total volume of particle deposition.
1/ Indoor Air Quality in Schools
Some slides from a presentation on indoor air quality in schools a decade ago. It contains reference to what I thought were important/insightful papers at the time. A lot more slides than shown here. Will post at corsiaq.com
1/ Don't be fooled by some air cleaning companies that claim their device is highly efficient. When claims are made about removing 95% or 99% of particles from air, this nearly always refers to % of particles removed THAT FLOW THROUGH THE DEVICE (single pass removal efficiency).
2/ A device can be 99.5% efficient & highly INEFFECTIVE if it has little flow moving through it. The product of fractional removal efficiency (max = 1.0) & volumetric flow rate (e.g. cubic feet per minute) is the important parameter (& known as CADR or Clean Air Delivery Rate).
3/ Example - Company for device 1 claims it removes 99.5% of particles from air (fractional single-pass removal efficiency = 0.995), but the device moves only 30 cfm of air (CADR = 0.995 x 30 cfm = 30 cfm).
1/ Inhalation Dose
It's been about inhalation dose from day 1. We have not kept our eye on the ball. Critical pre-vaccination. Critical post-vaccination. Been writing & speaking about this for nearly 20 mos. Reducing inhalation dose is a must. Come on folks, just do it!
2/ Reducing Inhalation dose using layered interventions is still important, whether unvaccinated or vaccinated (breakthrough cases), in close contact (near field) or far field in the same indoor space, in a car or classroom, in a restaurant or apartment, young or old.
3/ Inhalation dose associated with virus laden aerosol particles is defined by the same variables (whether close contact or far field ---- don't bicker about one or the other - I've previously tweeted about this):
2/ My message will be clear. Stay safe. Stay focused. Learn the fundamental principles and tools of your trade as you will be able to use these to change society for the better and to help heal the planet.
3/ While you are in college, take advantage of being on such a great campus. Join student groups & get to know faculty and staff. Ask for help when you need it. We are a community and are here for each other.
1/ As a follow-up to my earlier email ....
First, the concentrations of ozone needed to disinfect indoor surfaces is significant and approach or exceed the IDLH (Immediately Dangerous to Life or Health) level. So, use of ozone should be done w/ great care, if done at all.
2/ Ozone (O3) is a moderate oxidant. It reacts with almost all indoor materials, some more than others, as well as oils that we add to or unknowingly leave behind (e.g., skin oils) on those surfaces.
3/ These reactions can (over time), lead to material degradation, e.g., brittleness of rubber seals, leaching of lead from lead-based paints, and even increased susceptibility of some materials to mold growth (research done in collaboration w/ @KerryKinney14@ut_caee ).