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Why Indoor Chemistry Matters (2022) / Chapter Skim
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Pages 101-126

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From page 101...
... Our understanding of the influence of these ventilation approaches on exposure that results from indoor chemistry is still developing. Ventilation rates are set by building codes that rely on consensus standards, such as ASHRAE Standard 62.1, to achieve "acceptable" indoor air quality.
From page 102...
... The basic reproductive number is the number of new infections resulting from a given BOX 5-2 Human Behavior Building occupants respond to and influence their environment in many ways, sometimes making choices that have more influence than other mitigation efforts. Efforts to control indoor climate by operat ing windows and doors has a substantial effect on outdoor-to-indoor air exchange (Becker et al., 2014; Bekö et al., 2004; Howard-Reed et al., 2002; Iwashita and Akasaka, 1997; Offermann, 2009)
From page 103...
... Extreme pollution events introduce pollution episodically, but residential environments typically rely on occupants to implement mitigation approaches. For example, wildfire smoke occurs sporadically and can have substantial impacts on indoor air qual ity and human exposure to pollutants.
From page 104...
... Particles captured on filter media continue to be exposed to recirculating indoor air and, consequently, can themselves become chemical pollution sources, contributing to odors (Bekö et al., 2004, 2007; Hyttinen et al., 2001; Pasanen et al., 1994; Pejtersen, 1996; Schleibinger and Rüden, 1999) and other adverse effects (Bekö et al., 2004, 2007; Lin and Chen, 2014; Sidheswaran et al., 2013; Siegel, 2016)
From page 105...
... Not only does touching surfaces or ingesting dust lead to chemical exposure but the gas-phase levels of many indoor air pollutants are controlled by partitioning interactions with a much larger quantity of those chemicals on the surfaces (see Chapter 3)
From page 106...
... Surfaces Engineered to Improve Indoor Air Quality As noted in previous chapters, chemicals can deposit, adsorb, absorb, and react with surfaces of building materials, furnishings, and occupants. These phenomena can, in theory, be leveraged, and the materials can be engineered to improve indoor air quality.
From page 107...
... Saturation, re-emission, and reactive chemistry all play roles that require consid eration before passive surfaces are implemented to remove indoor air pollutants. MANAGEMENT THROUGH CHEMICAL TRANSFORMATIONS Chemically modifying air pollutants to transform them into benign species or increase their removal rates is an increasingly used approach to improve indoor air quality.
From page 108...
... , which can undergo a series of reactions resulting in complex products, including peroxides, carbonyls, and carboxylic acids. Hydroxyl radical oxidation is not yet widely used in indoor environments to intentionally degrade VOCs but raises many of the same concerns as ozone, including the potential for production of secondary organic aerosol and other unintended byproducts due to its rapid oxidation chemistry (Friedman and Farmer, 2018; Lee et al., 2006)
From page 109...
... The physical and chemical mechanisms responsible for byproduct formation -- and the health effects of those byproducts in real-world indoor environments -- warrants further study. Ultraviolet Light Photolysis, the decomposition of molecules due to interaction with light, can also be used to control chemical air contaminants and inactivate or kill microorganisms.
From page 110...
... UV light is known to photolyze some compounds, but little real-world testing has been done to identify the extent to which this affects indoor air. Degradation of materials that are exposed to UV-C in HVAC systems has been studied but not the impact of these processes on indoor air quality (Kauffman and Wolf, 2012)
From page 111...
... . While PCO efficiency and byproduct formation have been investigated extensively in controlled laboratory environments, more studies of effectiveness, longevity, and byproducts in real-world indoor environments are needed to understand the potential for subsequent chemical transforma tions.
From page 112...
... For the same reason, air cleaners may be viewed as a more sustainable alterna tive to ventilation for control of indoor contaminants. Despite the attractiveness of filtration and air cleaning, ventilation remains the predominant means of control because of the difficulty of properly specifying air-cleaning systems to achieve overall indoor air quality goals.
From page 113...
... These tests and measurements can help inform a quantitative assessment of thresholds for health effects for relevant compounds. • Developers of air-cleaning technologies need to recognize that many gas-phase mol ecules in indoor air partition with indoor surface reservoirs.
From page 114...
... Indoor Air Cleaning Devices Article 1. Indoor Air Cleaning Devices.
From page 115...
... 2020. Potted plants do not improve indoor air quality: A review and analysis of reported VOC removal efficiencies.
From page 116...
... 1997. The effects of human behavior on natural ventilation rate and indoor air environ ment in summer -- A field study in southern Japan.
From page 117...
... 2019. Prediction of VOC adsorption performance for estimation of service life of activated carbon based filter media for indoor air purification.
From page 118...
... Indoor Air 6(4)
From page 119...
... 2016. Primary and secondary consequences of indoor air cleaners.
From page 120...
... 2011. Can commonly-used fan-driven air cleaning technologies improve indoor air quality?
From page 121...
... Subsequent sections cover the intersection of indoor chemistry and exposure modeling and measurement science for exposure. The chapter concludes with a list of priority research needs identified by the committee.
From page 122...
... , while dermal uptake of volatile organic compounds (VOCs) increases with age (Morrison et al., 2016)
From page 123...
... . Settings, tasks, activities, behaviors, and features and conditions of indoor environments change over time, resulting in indoor environmental exposures that vary both within individuals over time and space and between individuals, even in the same indoor environment.
From page 124...
... households continue to use solid fuels, mostly for space heating, either as a primary or supplemental energy source depending on factors such as access, convenience, cost, and household preferences. A large body of work documents emission rates and factors associated with solid fuel combustion, indoor concentrations of byproducts of incomplete combustion, and exposures and health effects asso ciated with these exposures (Champion, 2017; Noonan et al., 2015; Rogalsky et al., 2014; ­Semmens et al., 2015)
From page 125...
... The reasons why some people are difficult to access or gather informa tion from are likely associated with other socioeconomic and demographic factors that could also be associated with greater likelihood of experiencing elevated or adverse exposures, including in indoor environments, and/or greater susceptibility to the effects of those chemical exposures. Exposure Factors, Behaviors, and Intake Rates Greater insight on the chemical composition of indoor air would be achieved if the scientific community had better data on some indoor activities, including window-opening, cooking, clean ing, and using personal care and leisure products.
From page 126...
... ENVIRONMENTAL HEALTH DISPARITIES AND EXPOSURE VARIABLES Exposure to indoor air pollutants varies across individual households, yet certain exposures affect subsets of the population differently. These differential exposures derive from variables that influence indoor air chemistry.


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