The group is very excited to see our first publication using low-cost sensors. The sensor – we assembled ourselves – represents a collective efforts of three undergrad student/research associates (Ryan, Ariel, and Wayne), and two graduate students (Rowshon and Timothy) over the past three years. The sensor sends real-time data of PM, CO₂, temperature, and RH to ThingSpeak, an online data platform for storage and analysis. In this paper, just published online by RSC Environmental Science: Atmospheres (LINK), we deployed 35 sensors in school-run residences in a Canadian university for four months. Despite the number of students who live on campus, there is surprisingly little information about indoor air quality in such kind of residences. Low-cost sensors were a great fit to this purpose, for its low cost, quietness, and the ability to provide real-time yet personalized air quality information. We identified humidifier use and cooking as the two main sources of indoor PM_2.5. Ventilation and outdoor sources also affected indoor air quality. Our study also highlighted challenges of air quality management during extremely cold periods.

This project was funded by University of Alberta’s Campus Sustainability Grant.

Congratulations to Shuang Wu’s new publication on Royal Society of Chemistry Environmental Science: Processes & Impacts (Link)! In this work, we explored third-hand exposure of common flavourings used in novel nicotine delivery systems, including e-cigarettes and hookah tobacco. Third-hand exposure refers to the exposure to chemicals initially released to the surrounding environment (e.g., indoors). Such exposure pathways have not been carefully studied for e-cigarettes but are highly dependent on chemical partitioning of chemicals of interests. Shuang and Erica performed careful measurement and modeling for carbonyl flavourings commonly used in e-cigarettes. We have also performed a fundamental analysis on the hydrolysis equilibrium coefficients of these carbonyls, which governs their chemical partitioning. Our study shows that many of these flavouring compounds can likely present between indoor air and organic indoor films, and the fraction of which is highly dependent on temperature and the reservoir size. These results show that third-hand exposure for harmful flavourings is likely important and should be studied in depth in the future.

We hosted a lab tour for a number of special guests this morning, including Bill Flanagan (president of U of A), Aminah Robinson Fayek (Vice President – Research and Innovation), among others. Group members, Sohaib, Shuang, Max, and Tania, each enjoyed an opportunity to directly showcase their research projects. They totally nailed it!

We are very proud of Timothy’s work, titled “Impact of glycol-based solvents on indoor air quality—Artificial fog and exposure pathways of formaldehyde and various carbonyls”, just published in Indoor Air (Link). A big congratulations to Timothy, Tolu, and Chester, who contributed to this work. Artificial fogs are commonly used in the entertainment and theatric industries to create special visual effects. Artificial fogs are made by heating a ‘fog juice’, which contain triethylene glycol and water. Although the risk of glycol inhalation has been implied, there has been no systematic study on how artificial fogs can affect indoor air. In our work, we monitored the particles arising from a fog machine, as well as the chemicals present in those particles. Surprisingly, we found a high concentration of carbonyls, including formaldehyde, from the fog juice. We hypothesized that autooxidation of triethylene glycol during storage is likely the source. This study presents a significant implication to stage actors, workers in the entertainment industry, and consumers of artificial fogs.

Congratulations to Vikram for his recent publication on ACS Earch and Space Chemistry “Evolution of Brown Carbon Aerosols during Atmospheric Long-Range Transport in the South Asian Outflow and Himalayan Cryosphere” (LINK)! Compiling field observations over the past 15 years, we have shown that the photochemical evolution of Brown Carbon – light-absorbing organic compounds – appears to be slower in the atmosphere over the Himalayas than in South Asian Outflow. We hypothesized that the cold and dry atmosphere over the Himalayas may be making the aerosol more viscous, delaying its photochemistry. This paper raises the possibility that The Himalaya cryosphere, which is among the most sensitive to climate change, may be slowing down the decay of light-absorbing species due to its inherent environment.

We are super excited about Shuang’s paper just published online on Environmental Science & Technology! (LINK) Microbial volatile organic compounds (MVOCs) are responsible for malodors and certain health issues related to indoor air. Henry’s law constants, and partitioning coefficients in general, governs the behavior and exposure pathway of organic pollutants. The Henry’s law constants of many MVOCs were either unknown or unreliable. In this paper, Shuang developed a reliable method to determine Henry’s law constants of key MVOCs. In collaboration with Dr. Chen Wang at SUSTech (LINK), we have also input Shuang’s results into a 2D chemical partitioning plot to simulate behavior of these MVOCs in the indoor environment.

Check out our newest publication, led by Tania, on Journal of Physical Chemistry A (LINK). We found that the presence of olefins (C=C double bonds) can compromise the accuracy of iodometry. Iodometry is a technique used widely in a number of fields to quantify peroxide contents. It’s been known that olefins may react with the molecular iodine intermediate generated in the process of iodometry. Using detailed laboratory measurements and a kinetic box model, our study for the first time studied this matrix effect systematically. We found that this matrix effect is negligible for outdoor aerosol, but can be significant for indoor materials, as well as edible oils.

Dried cow dung is widely burned as solid fuel in developing part of the world. However, the chemicals arising from this type of fuel are extremely poorly understood. In our new contribution lead by Max, we surveyed across a number of key chemical properties of emissions from cow dung burning. These include the light absorption of particles, emission factor of levoglucosan (tracer for biomass burning), an other detailed chemical feature monitored by LC-MS. The major conclusion from our work is that the levoglucosan emission factor from cow dung is much less than that from wood burning. There was also a substantially larger organic nitrogen pool in the cow dung emission than wood burning emissions.

Link to the paper:

https://pubs.acs.org/doi/10.1021/acsearthspacechem.1c00268

Jessica successfully defended her MSc thesis on Jan 28, 2021.

Congratulations! You are the first to complete a graduate degree in the Zhao group.

Our Humidifier paper has got some media attention and was highlighted by Global News, and CTV News! We are happy that our research can be directly translated into knowledge of the general public.