Earlier this month, I was selected the 2025/26 Herzberg Fellowship awardee by the Department of Chemistry @usask.ca 🎉🎉🎉

Alongside the department’s committee, I would like to thank my supervisor @tfkahan.bsky.social for nominating me for this amazing award and for always supporting me and my career!

A person poses in a stairwell of a brick walled building indoors

Innovators: #USask PhD Candidate Pedro A. F. Souza is investigating some unexpected impacts of using household cleaners on indoor air quality.

Now he is working to help people evaluate their habits and make informed decisions that can help them breathe healthier. news.usask.ca/articles/res...

It was a privilege sharing some aspects of my work with the wider public. I strongly believe that academic research should be accessible and easy to understand for everyone!

Many thanks to my supervisor, Dr. Tara Kahan, and Erin Matthews for making this happen!

The idea was to inform the broader community the fact that cleaning emissions may negatively impact indoor air, especially when cleaning is carried out under illuminated areas, and ways for minimizing exposure.

Young Innovators: U of S student uncovers hidden risk in cleaning products Pedro A. F. Souza is looking to understand how certain cleaning products and conditions compromise our indoor air quality.

This week, I had the pleasure of being featured at the @usask.ca and Saskatoon StarPhoenix Young Innovators series, where I shared a little bit of my research!

thestarphoenix.com/news/local-n...

Mine in this week’s @newyorker.com

Portrait of Marina Vance, a scientist, sitting in a Colorado grassland.

The @nytimes.com Lost Science series continues. Here's my Q&A with a scientist who was studying how wildfire smoke threatens human health when the EPA decided that her research was no longer a funding priority. Gift link: nyti.ms/4jhpw14

Folks - check out this new review, led by the amazing @ericamhartmann.bsky.social: Ten questions concerning indoor dust.

Comic. Confusion matrix showing renditions of different combinations, colored yellow, tan, or gray. [Air: gamma rays Y, neutrons Y, alpha particles G, light Y, sound Y, heat Y, swords Y, toxic dust Y, radio Y, sharks G] [Lead: gamma rays G, neutrons T, alpha particles G, light G, Sound Y, heat Y, swords G, toxic dust T, radio G, sharks G] [Water: gamma rays T, neutrons G, alpha particles G, light T, sound Y, heat Y, swords Y, toxic dust Y, radio G, sharks Y] [Vacuum: gamma rays Y, neutrons Y, alpha particles Y, light Y, sound G, heat T, swords Y, toxic dust Y, radio Y, sharks G] [Oven mitts: gamma rays Y, neutrons Y, alpha particles G, light G, sound T, heat G, swords Y, toxic dust Y, radio Y, sharks Y] [Armor: gamma rays Y, neutrons Y, alpha particles G, light G, sound Y, heat Y, swords G, toxic dust Y, radio G, sharks T] [Biohazard suit: gamma rays Y, neutrons Y, alpha particles G, light G, sound Y, heat Y, swords Y, toxic dust G, radio Y, sharks Y] [Faraday cage: gamma rays Y, neutrons Y, alpha particles Y, light Y, sound Y, heat Y, swords Y, toxic dust Y, radio G, sharks Y] [Shark cage: gamma rays Y, neutrons Y, alpha particles Y, light Y, sound Y, heat Y, swords Y, toxic dust Y, radio Y, sharks G]

Shielding Chart

xkcd.com/3158/

This year, the ozone hole presented an early development, reaching a larger-than-average area mid-September. On #WorldOzoneDay, #CopernicusAtmosphere continues to provide tools for everyone to monitor the health of our planet.

This is great. An EPA activity book for elementary school kids on air cleaning:

www.epa.gov/system/files...

This graphic describes chemical reactions triggered by ultraviolet light from the sun. These reactions include those that break down plastics, aid the production of vitamin D, cause skin burns from the sap and juices of some plants, decompose swimming pool chlorination, and form components of brown smog compounds.

This edition of #PeriodicGraphics highlights how ultraviolet light (UV) from the sun triggers chemical reactions, such as those that break down plastics and aid the production of vitamin D. cen.acs.org/physical-che...

#chemsky 🧪

Postdoctoral Researcher in Atmospheric Chemistry

Are you interested in biosphere-atmosphere interactions, global modeling, and living in Zurich? If so, this postdoc position might be for you! Please share with any interested colleagues: jobs.ethz.ch/job/view/JOP...

Does your bedroom have enough ventilation?

www.tandfonline.com/doi/pdf/10.1...

Theoretical Mapping of the Gas-Phase Ozonolysis of α-Pinene: Formation of First-Generation Products under Different Atmospheric Conditions Ozonolysis of α-pinene is a significant and well-established source of atmospheric secondary organic aerosol (SOA), which plays a pivotal role in climate, air quality, and human health. The products of α-pinene ozonolysis measured experimentally are typically characterized by only their molecular formulas, while their structures and formation mechanisms often remain unclear. In this work, we theoretically map the oxidation pathways, structures, and formation time scales of the major first-generation products formed from α-pinene ozonolysis by calculating the H-shift and bond-scission reaction rate coefficients of the peroxy (RO2) and alkoxy (RO) radicals that arise under atmospheric conditions with different RO2 bimolecular reaction rates (kbi): polluted (kbi > 0.2 s–1), moderate (0.2 s–1 > kbi > 0.01 s–1), and pristine (kbi ≈ 0.01 s–1). In polluted environments, almost no RO2 unimolecular reactions are of importance and ozonolysis leads to nitrates and small fragmented products. By contrast, in moderate to pristine atmospheres, C10 highly oxygenated organic molecules (HOMs) with up to 12 oxygen atoms can form from either purely unimolecular or a combination of unimolecular and bimolecular reactions. Our results suggest that explicit chemical mechanisms of α-pinene ozonolysis used ubiquitously in the literature require significant revision in their treatment of unimolecular-isomerization and stereoisomer-specific reactions.

Excited to share our new paper, out today in ACS ES&T Air! Using theory, we map the pathways of α-pinene ozonolysis leading to first-generation products under different atmospheric conditions.

Co-authors: Jing Chen (lead), @atmostaj.bsky.social, and Henrik Kjaergaard.

@uwatmossci.bsky.social
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Wildfire smoke linked to early deaths A recent study estimates that more than 50,000 adults died prematurely in California over 11 years due to exposure to wildfire smoke

Wildfire smoke linked to early deaths: A recent study estimates that more than 50,000 adults died prematurely in California over 11 years due to exposure to wildfire smoke. cen.acs.org/environment/...

Particulate Matter and Total Volatile Organic Compound Emissions Following Surface Cleaning: Comparison of Cleaning Agents and Locations Cleaning activities are essential for maintaining hygiene in indoor environments but can significantly influence indoor air quality (IAQ). We investigated emissions of volatile organic compounds (VOCs...

Ever wonder how cleaning affects #IndoorAirQuality?
Our latest work demonstrates that emissions go beyond the active ingredient, with other compounds contributing to #AirPollution.
This is a very neat story with lots of interesting science, hope you enjoy! #ChemSky

pubs.acs.org/doi/10.1021/...

Exhaled aerosol particles (1-5 um) create a wake behind people walking down hallways. Cool CFD simulations with implications for hospital corridors.

If only this article was out in 2019....

www.sciencedirect.com/science/arti...

RIP Pepe Mujica. He was a true symbol for Latin America!

Among his famous philosophical beliefs, I will forever remember “everything that one purchases, one pays with the spent time to earn the money” and “we are free when we spend time with things that motivate us”.

Do what you love, folks! ♥️

Gas stoves nearly double children’s cancer risk, Stanford study finds Stanford study finds gas stoves emit benzene, nearly doubling cancer risk in children — especially in homes with poor ventilation.

Funny how breathing combustion byproducts causes all kinds of harm.

www.sfchronicle.com/health/artic...

I just heard the disappointing news that a @nationalacademies.org study on far UV to reduce transmission of respiratory infections was canceled.

www.nationalacademies.org/our-work/cli...

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Environmental Health Works (#EHWorks) - YouTube The air we breathe, water we drink, food we eat, and where we live, work, and play are all crucial determinants of our health and the health of our families....

A belated earth day to all! Sharing a channel of short videos discussing the importance of environmental health research and keeping the planet and ourselves healthy: www.youtube.com/playlist?lis...

The role of carbon dioxide in airborne disease transmission: a hidden key to safer indoor spaces The concentration of CO2 in the air directly affects how long a virus remains infectious.

Henry Oswin and I had an article published by
@uk.theconversation.com . In it, we discuss the role of CO2 in airborne disease transmission.

Henry was the PhD student on the project, who has since graduated and is now working with Lidia Morawska down under.

theconversation.com/the-role-of-...

Three men (2 with glasses, all with black hair) stand in a garage, staring in contemplation at computer screens that display science stuff. Photo.

We're getting some garage work done. (Or, at least, that's where we're putting our instruments.)
#IndoorChem

Multiple Researcher / Senior Researcher roles at Blueprint Biosecurity: translate research into plans to prevent future pandemics. Produce publications, provide technical advice to our program teams, and inform our pandemic prevention strategies

blueprintbiosecurity.org/jobs/researc...

They're bad at data analysis because they didn't use a formula with enough superfluous Greek letters

Thanks Dave!

#ACSSpring2025
In the afternoon we have a wonderful set of talks on both indoor and outdoor chemistry. Come hear Sally Ng, @pedroafs.bsky.social, @vbarber.bsky.social, Celine Toubin, @mvermeuel.bsky.social, @sc-k.bsky.social talk about their research after lunch!!

Promo image for the ES&T Air special symposium: "showcasing emerging science in atmospheric chemistry"

#ACSSpring2025 Very excited for our first set of talks tomorrow morning!

We have invited talks by Franz Geiger, @atmosyz.bsky.social, Haofei Zhang, Kevin Wilson, Anthony Carrasquillo, and Marcelo Guzman.

Come here about Atmospheric Multiphase Chemistry in the Marriott Grand Ballroom: Section 2!!

Excited to see so many interesting studies and to connect with awesome people!
Tomorrow, I am presenting my work on how both photo and chemical disinfection can deeply increase radical concentration indoors.
It will be at 2:30 pm at Marriott Hotel Section 2, everyone is invited to attend!!