Linsey Marr

Direct human health risks of increased atmospheric carbon dioxide - Nature Sustainability A review of studies on exposure to elevated CO2 concentrations in air suggests that health damages, such as inflammation or reductions in cognitive abilities, can occur at levels as low as 1,000 ppm.

Results are accumulating that exposure to CO2 has heatlh effects at lower levels than previously thought, but we're not going to drop dead at such levels. @joeallenjoe.bsky.social can better speak to this topic.

www.nature.com/articles/s41...

Influence of Carbon Dioxide and pH on Influenza Virus in Sessile Saliva Droplets Upon exhalation, virus-laden respiratory droplets experience rapid changes in environmental conditions that lead to chemical and physical alterations that can affect virus infectivity. By manipulating...

There has been a lot of interesting research on the pH of respiratory droplets and how it affects flu virus. We looked at large saliva droplets exposed to low and high CO2 and only saw a difference in viability at 80% RH with low CO2. pH changes were small.
pubs.acs.org/doi/10.1021/...

You can check with my former student/postdoc who is the corresponding author about this. There are some calculations about particle deposition in the SI.

Loss of Infectivity of Influenza Virus and SARS-CoV-2 during Aerosol Sampling Our understanding of transmission of influenza virus and other respiratory viruses is limited by the difficulty of detecting infectious viruses in aerosol particles. Most aerosol sampling methods are believed to contribute to virus inactivation, but the magnitude of this sampling artifact is unknown. To investigate this question, we aerosolized influenza A virus (IAV) and SARS-CoV-2 suspended in human saliva into a small chamber (3.7 L). Aerosols settled for 10 min onto either cells or a thin layer of liquid medium that was immediately transferred to cells for plaque assay. Aerosols that deposited directly onto cells led to the formation of 100× more plaque forming units (PFU) compared to aerosols that deposited first into liquid medium. Further experiments ruled out uneven aerosol distribution in the chamber or inefficient virus recovery as causes of this discrepancy. These findings indicate that aerosolized IAV and SARS-CoV-2 lost infectivity by approximately 2 log10 PFU within ∼10 min unless they attached to cells quickly. As natural infection via inhalation occurs by direct deposition of the virus onto cells, we hypothesize that sampling directly onto cells more accurately reflects the potential for exposure to lead to infection.

Our latest paper shows that most aerosol sampling methods may underestimate infectious virus in air. We observed 100x more infectious flu virus and SARS-CoV-2 if it deposited directly on cells (more realistic) rather than in liquid first and then transferred to cells. pubs.acs.org/doi/full/10....

Our results indicate that extended periods spent in poorly ventilated classrooms may be a stronger driver of within-school transmission than individual contact rates.

We found that while close contact contributed to elevated risk (rate ratio 1.16 per doubling daily time, 95%-CI 1.01–1.33), time spent in shared classrooms and poor air quality had larger effects (RR 3.17, 95%-CI 1.96–5.17 and RR 1.90 95%-CI 1.23–2.94) respectively).

Our paper modelling transmission risk in schools is published in Nature Communications. **The relative contribution of close-proximity contacts, shared classroom exposure and indoor air quality to respiratory virus transmission in schools** doi.org/10.1038/s414...

VILLI

Feasibility and Safety of Aerosolized Influenza Virus Challenge in Humans Using Two Modern Delivery Systems This study demonstrates that aerosolized influenza virus can be safely administered to healthy adults using two modern delivery systems. Controlled aerosol

To study influenza infections, we inoculated human participants with aerosolized virus: coarse particles generated by a flow-focusing monodisperse aerosol generator and fine particles generated by a medical nebulizer. academic.oup.com/jid/article-...

Should We All Be ‘House Burping’?

More on house burping: "...lüften is long established in Germany, where many landlords make tenants sign paperwork agreeing to air out their apartments for several minutes daily, if not multiple times per day, since mold removal often falls on the landlord." www.nytimes.com/2026/01/29/r...

‼️a combination of advanced air filtration, ventilation, and purification could cut the average number of infected cases among all students in half‼️

House Burping Sounds Gross But It May Boost Your Wellbeing The centuries-old German practice is trending on TikTok, and for good reason.

"House burping" is trending. Open your windows for a few minutes each day to ventilate the house, like a full-body cleanse for your indoor air. Pollutants from cooking and product use build up indoors, so it's good to flush if outdoor air quality is good.

www.outsideonline.com/health/welln...

FOLiAR

E.P.A. to Stop Considering Lives Saved When Setting Rules on Air Pollution

Whaaat?! The EPA's cost-benefit analysis of air pollution regulations can only consider costs to businesses but not health benefits?! This is nonsense.

GIFT ARTICLE: www.nytimes.com/2026/01/12/c...

Here's an easy way to select a minimum clean air delivery rate (CADR) when you're shopping for a portable air cleaner (filter).

For example, if my room is 15 ft x 12 ft = 180 sq ft, then I'd want a CADR of at least 120 CFM (cubic feet per minute).

Evaluating modes of influenza transmission (EMIT-2): Insights from lack of transmission in a controlled transmission trial with naturally infected donors Author summary Human-to-human influenza virus transmission under controlled conditions could provide insights leading to better control of epidemics and pandemics. However, a previous study using labo...

Results from @donmilton.bsky.social's flu study now published. No transmission from naturally infected donors to recipients, possibly due to insufficient virus emitted by donors, low susceptibility of recipients, and rapid air mixing of breath plumes.

dx.plos.org/10.1371/jour...

Why flu seems to be everywhere — even if ‘super flu’ is not a thing Welcome to the winter of subclade K.

Repeating to correct an error:
There's no such thing as super #flu. But there is a doozy of a flu season underway right now. Here's what you need to know about subclade K, the #H3N2 variant making so many people sick. (Earlier I said H5N1. This is not that!!!) www.statnews.com/2026/01/06/f...

Drones detect deadly virus in Arctic whales' breath Whale breath collected by drones is giving clues to the health of wild humpbacks and other whales.

Here's a story about detection of cetacean morbillivirus, in the same genus as measles virus, in whales' blowhole breath. I'm contemplating what we can learn by exploring transmission between animals. HT Julian Tang

bbc.com/news/article...

COULOIR, given the other foreign-language words that are allowed

Thanks for speaking up about this to put a story, impact, and face to the cuts that are happening.

What a loss that @marinavance.bsky.social's EPA-funded research on wildfire smoke in homes has been canceled! I remain a proud academic mom. She did her PhD on exposure to engineered nanoparticles @virginiatech.bsky.social, right as my lab was shifting to study viruses in the air.

Heart Attacks, Lung Conditions Jumped After Los Angeles Wildfires Mysterious illnesses also rose after the fires, according to a new study that reviewed emergency-department visits.

Gift article about LA wildfires: "Visits to the emergency department rose 46% for heart attacks and 24% for pneumonia and other pulmonary illnesses compared with earlier years, the researchers reported."

www.wsj.com/health/healt...

Agree with this. I have been contemplating TikTok for a while to reach people. I need my kids to show me. I may assign my class to make TikToks about air quality, as a starting point.

We are excited to invite abstract submissions for talks and posters for the 2026 Ecology and Evolution of Infectious Diseases meeting at Virginia Tech (June 2-4). Abstract submissions should be made by February 3, 2026 for consideration, using the google form here: cpe.vt.edu/eeid2026/abs...

1. Looks like we're into #flu season, folks. A 🧵
#CDC reports that for the week ending 12/6, 3.2% of medical visits were for flu-like illnesses. The baseline — ie the point where flu season is considered to have started — is 3.1%.
This timing is pretty normal, coming after the mixing at Thanksgiving

Fascinating outlook on similarities in aerosolization of microbes from the ocean surface and respiratory tract fluid by Dommer @rommieamaro.bsky.social @kprather.bsky.social

Six-week study of 67 students in four classes, 1047 saliva samples ->
"Prolonged exposure in shared, poorly ventilated spaces, which potentially includes several infectious sources, drives respiratory virus transmission more than close contact."
www.nature.com/articles/s41...
HT: Emily Martin

DECADAL

Thanks for tackling this important question! I agree with your suggestion that experimental variability may explain differences in results between labs. I like your recommendations. Seemingly insignificant differences in water and gas-phase composition could matter.

Free access to the final version of "Ten questions concerning indoor dust" for the next 50 days at authors.elsevier.com/c/1m7oK1HudN...

@ericamhartmann.bsky.social