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CorsIAQ's profile
Dr. Richard Corsi
Dr. Richard Corsi
Dr. Richard Corsi
@CorsIAQ

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Dr. Richard Corsi

@CorsIAQ

Dean of Engineering, University of California, Davis Chair Emeritus, Dept of Civil, Architectural & Environmental Engineering, Univ of Texas at Austin

Davis, CA
corsiaq.com
Joined July 2013

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    1. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      6/ Beware of irrelevant claims made to sound important. In my courses on indoor air quality I often show an advertisement for a personal air purifier that shows a woman holding a baby. It states it can remove particles as small as 200 microns. Well, so does the floor.

      1 reply 11 retweets 50 likes
      Show this thread
    2. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      7/ Beware of “technologies” that are tested in small, poorly ventilated (or non-ventilated chambers) and that show pollutant decay over time. This includes those magic houseplants. In most cases, I could put an old pair of socks in the chamber and get the same result.

      2 replies 4 retweets 44 likes
      Show this thread
    3. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      8/ If one can actually obtain the actual data for these “technologies” (some have been published) and complete a mass balance on the chamber used it will be clear that the Clean Air Delivery Rate (CADR) is often 1,000 times (or more) smaller than a good portable air cleaner.

      1 reply 4 retweets 30 likes
      Show this thread
    4. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      9/ Put another way, you’d need 1,000 of these devices or plants in a room the size of a bedroom to achieve what you can with a single portable air cleaner to remove particles or (with enough activated carbon) ozone and VOCs.

      1 reply 5 retweets 31 likes
      Show this thread
    5. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      10/ There are so many more examples of unproven or proven ineffective (snake oil) sold to those not aware of what to look for – I have outlined an entire chapter in a book on this subject. Not enough time ....

      1 reply 4 retweets 22 likes
      Show this thread
    6. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      11/ Stick to proven technology. During this pandemic aim to remove particles in air of a size of roughly 0.5 (or 1) micron to about 20 microns. A good portable air cleaner with a HEPA filter that has a CADR > 300 ft3/min will make an appreciable dent …

      2 replies 32 retweets 113 likes
      Show this thread
    7. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      12/ in most rooms less than 1,000 ft2 and 8 to 10 ft ceiling height. To get an equivalent increase in air exchange rate, take the CADR, multiply it by 60, and then divide by (floor area x ceiling height)

      1 reply 10 retweets 47 likes
      Show this thread
    8. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      13/ If the CADR = 300 ft3/min X 60 = 18,000 ft3/hr. If floor area is 800 ft2 & ceiling height = 8 ft, volume = 6,400 ft3. 18,000 ft3/hr divided by 6,400 ft3 = 2.8/hr.

      1 reply 9 retweets 40 likes
      Show this thread
    9. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      14/ If the air exchange rate is http://1.4.hr , the portable air cleaner just yielded an effective tripling to 4.2/hr.

      2 replies 7 retweets 28 likes
      Show this thread
    10. Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      15/ Avoid gimmicky add-ons to the portable HEPA filter. You do not need additional ionizers or ozone generation. I am often asked about the activated carbon added to the HEPA filter.

      2 replies 9 retweets 46 likes
      Show this thread
      Dr. Richard Corsi‏ @CorsIAQ 30 Jul 2020

      16/ The activated carbon is harmless, but does little to remove particles & is usually insufficient in mass to remove VOCs/odors. Not needed. Remember, basics! Aim for a portable air cleaner with a HEPA filter & CADR (for smoke) > 300 cfm (see above)

      12:31 AM - 30 Jul 2020
      • 27 Retweets
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      6 replies 27 retweets 129 likes
        1. New conversation
        2. Whitney Pyles‏ @whitpyles 30 Jul 2020
          Replying to @CorsIAQ

          Hi! Public health person here trying to operationalize these types of recs for schools. Appreciate the break down (but I still feel very far from my lane of comfort!). Do you have any brands/models of portable air cleaners that schools might consider?

          2 replies 0 retweets 16 likes
        3. Whitney Pyles‏ @whitpyles 30 Jul 2020
          Replying to @whitpyles @CorsIAQ

          Basically, the starting point is even trying to find CADR specs from the amazon description on a list of thousands of models to consider. It's really too much, even for people used to sorting through a ton of data. A list of brands/models to consider would be an amazing resource

          3 replies 2 retweets 16 likes
        4. Show replies
        1. New conversation
        2. C. Niederstadt, MD, MPH‏ @Niederstadt1 30 Jul 2020
          Replying to @CorsIAQ

          @threadreaderapp unroll please

          1 reply 0 retweets 0 likes
        3. Thread Reader App‏ @threadreaderapp 30 Jul 2020
          Replying to @Niederstadt1

          Bonjour, please find the unroll here: @CorsIAQ: 1/ I have been getting a lot of requests from the media and others to comment on unproven indoor air… https://threadreaderapp.com/thread/1288739082265272320.html … Talk to you soon. 🤖

          0 replies 2 retweets 2 likes
        4. End of conversation
        1. This Tweet is unavailable.
        2. Thread Reader App‏ @threadreaderapp 30 Jul 2020
          Replying to @beccanalia

          Hello, here is your unroll: @CorsIAQ: 1/ I have been getting a lot of requests from the media and others to comment on unproven indoor air… https://threadreaderapp.com/thread/1288739082265272320.html … Have a good day. 🤖

          0 replies 1 retweet 4 likes
        3. End of conversation
        1. Soccer Saber‏ @SoccerSaber 30 Jul 2020
          Replying to @CorsIAQ

          Thank you for this. In your home does the thickness of HVAC filters have any bearing on viruses? Some claim to but seems dubious.

          0 replies 1 retweet 2 likes
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        1. Maria hauschel‏ @HauschelMaria 30 Jul 2020
          Replying to @CorsIAQ

          I’m not a scientist or engineer but this may be one of the coolest and most informative threads I have EVER read. Thank you!

          0 replies 1 retweet 4 likes
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        1. New conversation
        2. Lorraine‏ @Lorraineannear 31 Jul 2020
          Replying to @CorsIAQ

          Does it matter where the air intake and out is?

          1 reply 0 retweets 0 likes
        3. Kim MA, MScE 🚀  💉 💉 💉 😷‏ @stargazer_412 4 Aug 2020
          Replying to @Lorraineannear @CorsIAQ

          The fluid dynamics of airflow on the large scale *might* matter for COVID transmission, as @zeynep 's latest article describes. For a small, portable HEPA filter in your home or office, the intake & outtake grills need to be placed with room around them.

          3 replies 1 retweet 3 likes
        4. Show replies

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