Analytical challenges and opportunities for indoor air chemistry field

Delphine Farmer. Anal. Chem. , Just Accepted Manuscript. DOI: 10.1021/acs.analchem.9b00277. Publication Date (Web): February 21, 2019. Copyright © 20...
0 downloads 0 Views 319KB Size
Subscriber access provided by WEBSTER UNIV

Feature

Analytical challenges and opportunities for indoor air chemistry field studies Delphine Farmer Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.9b00277 • Publication Date (Web): 21 Feb 2019 Downloaded from http://pubs.acs.org on February 25, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Analytical Chemistry

Analytical Challenges And Opportunities For Indoor Air Chemistry Field Studies Delphine K. Farmer Department of Chemistry, Colorado State University, Fort Collins, CO 80523 [email protected] SUMMARY Despite the vast time humans spend indoors, indoor air is far less well chemically characterized than the outdoor atmosphere. Advanced instrumentation for measurement of reactive trace gases, particles and surfaces is enabling a renaissance in indoor chemistry; this article highlights the challenges and opportunities for analytical chemistry in the built environment. INTRODUCTION Indoor air chemistry is an emerging field focused on the composition and chemical evolution of air in buildings, including surface-air exchange, multiphase chemistry and gas phase chemistry.1-4 We spend 90% of our lives indoors, where we breathe air that, while influenced by outdoor air, is quite different in composition and driving chemical processes from traditional outdoor atmospheric chemistry. Indoor air is a growing topic of interest for public health, but measuring the air composition of the built environment provides an intriguing set of challenges for analytical instrumentation. Indoor chemists avoid many pitfalls experienced in outdoor atmospheric chemistry (e.g. varying temperature and relative humidity; aircraft measurement requirements of tolerance to vibration and pressure fluctuations), but face other challenges. Indoor air is the result of infiltration of outdoor air; rapid ventilation; indoor sources (e.g. emissions from surfaces and events, such as cooking or cleaning, as well as human and animal occupants); chemical reactions in the gas, particle and surface phases; and deposition processes. Concentrations of oxidants and photon fluxes are lower indoors, but organic compounds are often higher.5-6 The scope of organic molecules detected in the indoor environment is staggering.7 Variable air exchange rates coupled to large emission sources and high surface area-to-volume ratios mean that the concentrations of gases and particles can change rapidly, on the order of seconds to minutes for orders of magnitude concentration changes!8-9 The timescales for oxidation chemistry are radically different indoors from out: where OH is considered important to the lifetime of atmospheric toluene, the resulting ~2 day lifetime is negligible given typical air exchange rates in American homes (0.5-1 hr-1), meaning that the volume of air within a house is ‘turned over’ or replaced in 1-2 hours. Dry deposition to surfaces is an important loss mechanism indoors, but wet deposition (removal by precipitation) is not. Indoor air includes many of the compounds breathed outdoors - mostly N2, Ar, and O2, but also trace gases and particles. Particles, often referred to as aerosols, are liquids or solids suspended in the air. Particles range in size from ~10-9 m (1 nm), where they are arguably clusters of gases rather than defined solids or liquids, to ~10-4 m (100 μm) for mineral dust and biological matter such as skin flakes. Both size and chemical composition of particles influences human health, with ultrafine (