Indoor Exposure to Fine Particulate Matter and Practical Mitigation Approaches Proceedings of a Workshop (2022) / Chapter Skim
Currently Skimming:
3 Indoor Sources of Indoor Particulate Matter
3 Indoor Sources of Indoor Particulate Matter
Pages 25-42
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 25... ...
described how secondary aerosols form PM2.5, and Linsey Marr (Virginia Tech) talked about the effect of humidity on the chemistry and biology of indoor air.
|
From page 26... ...
In addition, the volatile fraction of cooking emissions can undergo reactions indoors that may produce particles, and a large fraction of indoor particulate matter from cooking is likely to deposit on indoor surfaces. Some of these emissions may find their way outdoors, where they may undergo atmospheric processing, and the volatile components in particular could form secondary organic aerosols outdoors and impact ambient air quality as well.
|
From page 27... ...
(2020) Figure 1.1 1 https://pubs.acs.org/doi/10.1021/acs.est.0c00740; reprinted with permission from American Chemical Society Publications.
|
From page 28... ...
(2020) Figure S5.1 1 https://pubs.acs.org/doi/10.1021/acs.est.0c00740; reprinted with permission from American Chemical Society Publications.
|
From page 29... ...
Surface deposition can serve as an important sink for indoor particulate matter rich in organic matter. HOMEChem experiments found that although the Thanksgiving Day experiment produced higher airborne particulate matter concentrations than during a normal cooking event, the amount of particles deposited on a piece of glass (which was set up for testing purposes)
|
From page 30... ...
30 Total indoor concentration of SVOCs (gas phase + PM2.5 particle-bound) : FIGURE 3-3 Indoor residential activities enhance semivolatile organic compound (SVOC)
|
From page 31... ...
. However, for someone participating in the Thanksgiving Day experiment "that would be about 50 percent, so half of the particles that they are inhaling would end up in the alveolar system," she said.
|
From page 32... ...
For cooking, effective source control means operating a high-quality, externally vented over-the-stove hood every time cooking activities occur or using a well-positioned, properly selected portable air cleaner. SECONDARY AEROSOL FORMATION OF FINE PARTICULATE MATTER IN THE INDOOR ENVIRONMENT Organic aerosol, explained Michael Waring, comprises hundreds of thousands of types of molecules existing in a state of dynamic equilibrium between the gas and particle phases.
|
From page 33... ...
Lumped product modeling has particular strengths relative to explicit product modeling in that it can account for any arbitrary type of organic aerosol source, both indoor and outdoor; is not limited to secondary organic aerosols; and allows easy computation of bulk aerosol properties such as density or hygroscopicity. After describing the parameters and equations his group uses in its models, Waring explained that this model can yield organic aerosol concentrations based on the volatility of organic mass and oxidation state.
|
From page 34... ...
Another research need is to investigate whether the phase state of organic aerosol influences secondary organic aerosol partitioning and whether equilibrium assumptions about partitioning indoors are valid or secondary organic aerosol formation might be kinetically limited instead. The genesis of this question, said Waring, is modeling showing that most indoor organic aerosols are semisolid rather than liquid or amorphous solid, suggesting that it might be productive to use kinetic partitioning frameworks in models rather than equilibrium partitioning.
|
From page 35... ...
The final research need that Waring identified was to better understand the influence of ozone and hydroxyl-producing technologies, such as ultraviolet lamps and bipolar ionization found in newer ventilation systems, on secondary organic aerosol formation. THE EFFECT OF HUMIDITY ON THE CHEMISTRY AND BIOLOGY OF INDOOR AIR Humidity is not a direct source of indoor particulate matter, but it does affect the chemistry and biology of airborne substances, said Linsey Marr.
|
From page 36... ...
At low relative humidity, the weight of a droplet drops rapidly and solute2 concentrations can rise dramatically. At high relative humidity and slow evaporation, droplets lose far less of their weight and solute concentrations change only slightly (Lin and Marr, 2020)
|
From page 37... ...
Figure 3B; Copyright 2021 American Chemical Society Publications. THE INFLUENCE OF SOURCES OF INDOOR FINE PARTICULATE MATTER ON THE CHARACTERIZATION OF EXPOSURE AND EVALUATION OF HEALTH EFFECTS To start the day's final presentation, Andrea Ferro highlighted a 1996 review paper on indoor particles that summarized studies in what was then a fairly new field (Wallace, 1996)
|
From page 38... ...
The chemical content of indoor PM2.5 is enriched by bioorganic compounds such as squalene, cholesterol, and fatty acids, as well as compounds in chemical additives such as plasticizers, flame retardants, and surfactants. Each of these constituents, said Ferro, partitions between the gas and particle phases in a manner dependent on temperature and relative humidity, as well as chemical transformations including oxidation and acid-based and partitioning reactions.
|
From page 39... ...
Ferro raised the question of whether ambient air quality standards can be used to assess indoor air pollutants. In her opinion, the answer is no given that only some ambient particulate matter makes it indoors.
|
From page 40... ...
A first step is to develop additional knowledge about human activity patterns, determine how personal habits differ with socioeconomic status, culture, and even region of the country, and use that information to inform better experiments to understand realistic exposures. Waring said that for secondary organic aerosols, there are three questions that if answered could start to yield a picture of disparities and secondary aerosol exposure among those who live in underserved or poorer communities: • Are there differences in outdoor concentrations for underserved communities or are they in regions of higher ozone and organic or inorganic particulate matter concentrations, which can infiltrate and potentially drive secondary chemistry?
|
From page 41... ...
Marr noted that she has been collaborating with a colleague on energy savings and building in underserved communities as these two factors pertain to indoor environmental quality. The residents of those communities, she said, are not concerned about ozone, volatile organic compounds, or plasticizers, but are very concerned about mold because they experience major asthma and allergy issues, which are more prominent in underserved communities.
|
From page 42... ...
Chan offered a final question, asking where resources should be spent in schools, given what is known about indoor particulate matter. Waring said that the greatest need in the Philadelphia schools he is familiar with would be adequate ventilation.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.