The impact of α-pinene on urban smog formation: an outdoor smog chamber study

Kamens, Richard M.; Jeffries, Harvey E.; Gery, M.W.; Wiener, Russel W.; Sexton, Kenneth G.; Howe, G.B.

doi:10.1016/0004-6981(81)90097-4

Cited by 31 publications

(10 citation statements)

References 6 publications

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“…UNC’s atmospheric chemistry groups use environmental irradiation chambers (smog chambers) to study the dynamics of the chemical and physical processes that occur naturally in the atmosphere (Jeffries et al, 1976; Kamens et al, 1981; Jeffries et al, 1985; Sexton et al, 2004; Doyle et al, 2007). The chambers allow complex atmospheres to be generated repeatedly in a controlled environment, but still aged in a more-realistic manner than has previously been available to toxicologists.…”

Section: Methodsmentioning

confidence: 99%

“…Volatile organic compounds (VOCs) are constantly shifting between the gas and particle phases of ambient air and at the same time can be modified by chemical reactions in each phase. Partitioning theory has evolved over decades, and has more recently been coupled to atmospheric chemistry models in an attempt to capture and characterize these interactions in a quantitative way (Kamens et al, 1981; Pankow et al, 1997; Kamens and Jaoui, 2001; Lee et al, 2004; Donahue et al, 2006; Hu and Ka- mens, 2007). What has remained uncharacterised to this point is if – and how – these interactions affect the actual toxicity of each phase.…”

Section: Introductionmentioning

confidence: 99%

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Gaseous VOCs rapidly modify particulate matter and its biological effects – Part 1: Simple VOCs and model PM

Ebersviller

Lichtveld²,

Sexton³

et al. 2012

Preprint

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This is the first of a three-part study designed to demonstrate dynamic entanglements among gaseous organic compounds (VOC), particulate matter (PM), and their subsequent potential biological effects. We study these entanglements in increasingly complex VOC and PM mixtures in urban-like conditions in a large outdoor chamber. To the traditional chemical and physical characterizations of gas and PM, we added new measurements of gas-only- and PM-only-biological effects, using cultured human lung cells as model indicators. These biological effects are assessed here as increases in cellular damage or expressed irritation (i.e., cellular toxic effects) from cells exposed to chamber air relative to cells exposed to clean air. The exposure systems permit gas-only- or PM-only-exposures from the same air stream containing both gases and PM in equilibria, i.e., there are no extractive operations prior to cell exposure. Our simple experiments in this part of the study were designed to eliminate many competing atmospheric processes to reduce ambiguity in our results. Simple volatile and semi-volatile organic gases that have inherent cellular toxic properties were tested individually for biological effect in the dark (at constant humidity). Airborne mixtures were then created with each compound and PM that has no inherent cellular toxic properties for another cellular exposure. Acrolein and p-tolualdehyde were used as model VOCs and mineral oil aerosol (MOA) was selected as a surrogate for organic-containing PM. MOA is appropriately complex in composition to represent ambient PM, and it exhibits no inherent cellular toxic effects and thus did not contribute any biological detrimental effects on its own. Chemical measurements, combined with the responses of our biological exposures, clearly demonstrate that gas-phase pollutants can modify the composition of PM (and its resulting detrimental effects on lung cells) – even if the gas-phase pollutants are not considered likely to partition to the condensed phase: the VOC-modified-PM showed significantly more damage and inflammation to lung cells than did the original PM. Because gases and PM are transported and deposited differently within the atmosphere and the lungs, these results have significant consequences. For example, current US policies for research and regulation of PM do not recognize this “effect modification” phenomena (NAS, 2004). These results present an unambiguous demonstration that – even in these simple mixtures – physical and thermal interactions alone can cause a modification of the distribution of species among the phases of airborne pollution mixtures and can result in a non-toxic phase becoming toxic due to atmospheric thermal processes only. Subsequent work extends the simple results reported here to systems with photochemical transformations of complex urban mixtures and to systems with diesel exhaust produced by different fuels.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gaseous VOCs rapidly modify particulate matter and its biological effects – Part 1: Simple VOCs and model PM

Ebersviller

Lichtveld²,

Sexton³

et al. 2012

Preprint

View full text Add to dashboard Cite

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“…Most organic emissions are highly reduced, [1,2] and all organics oxidise by complex oxidation pathways in the Earth's atmosphere. [3][4][5][6] Oxidation would convert all reduced carbon in the atmosphere into CO 2 , given time. Consequently, to first order, the concentration of any given constituent (C i ) will be in a pseudo-steadystate at long enough timescales; given a production rate P i and a first-order lifetime t i , the pseudo steady-state concentration C i ss will be:…”

Section: Introductionmentioning

confidence: 99%

Why do organic aerosols exist? Understanding aerosol lifetimes using the two-dimensional volatility basis set

et al. 2013

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Environmental context. Fine particles (aerosols) containing organic compounds are central players in two important environmental issues: aerosol-climate effects and human health effects (including mortality). Although organics constitute half or more of the total fine-particle mass, their chemistry is extremely complex; of critical importance is ongoing oxidation chemistry in both the gas phase and the particle phase. Here we present a method for representing that oxidation chemistry when the actual composition of the organics is not known and show that relatively slow oxidant uptake to particles plays a key role in the very existence of organic aerosols.Abstract. Organic aerosols play a critical role in atmospheric chemistry, human health and climate. Their behaviour is complex. They consist of thousands of organic molecules in a rich, possibly highly viscous mixture that may or may not be in phase equilibrium with organic vapours. Because the aerosol is a mixture, compounds from all sources interact and thus influence each other. Finally, most ambient organic aerosols are highly oxidised, so the molecules are secondary products formed from primary emissions by oxidation chemistry and possibly non-oxidative association reactions in multiple phases, including gas-phase oxidation, aqueous oxidation, condensed (organic) phase reactions and heterogeneous interactions of all these phases. In spite of this complexity, we can make a strong existential statement about organic aerosol: They exist throughout the troposphere because heterogeneous oxidation by OH radicals is more than an order of magnitude slower than comparable gas-phase oxidation.

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“…Intercomparison of formaldehyde measurement in chambers [94] 1991 Better formaldehyde predictions by photochemical mechanisms [95] Experiments with biogenic hydrocarbons 1981 The impact of a-pinene on urban smog formation: an outdoor chamber study [96] Photolysis rates in chambers 1991 Light transmission into Teflon bags and chambers [97] Chemical mechanisms in air quality models 1981 Effects of chemistry and meteorology on ozone control calculations using simple trajectory models and the EKMA procedure [98] 1983 Comments on the rationale and need to consider an alternative to EKMA [99] 1987 Technical discussion related to the choice of photolytic rates for carbon bond mechanisms in OZIPM4/EKMA [100] 1988…”

Section: Experiments To Test Photochemical Modelsmentioning

confidence: 99%

Early history and rationale for outdoor chamber work at the University of North Carolina

2013

Self Cite

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Environmental context. Imagine in 1968 having to tell the largest cities in the US that they would have to spend billions of dollars to reduce human exposure to a gas in their air that no one emitted and that no one knew for sure how it came to be there. This history recalls how scientists and policy makers met this challenge so that by 1985 effective programs were in place.Abstract. The University of North Carolina (UNC) outdoor chamber facility was established in 1972. The chamber produces reliable and interpretable results using ambient sunlight, temperature and weather, providing an effective physical model system for learning about atmospheric chemistry. This article recounts the 40-year history of the chamber facility, from the early days in understanding ozone-precursor relationship to the latest in studying gas and particulate toxicities on human lung cells. PrefaceLike other models, histories are subject to generalisations, distortions and deletions depending upon who is creating the history. We are sure that this history suffers from these operations. Please forgive us in advance if our recollections and mental constructs are somewhat at odds with your own. Perhaps we can have a 'conversation' about this sometime.

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The impact of α-pinene on urban smog formation: an outdoor smog chamber study

Cited by 31 publications

References 6 publications

Gaseous VOCs rapidly modify particulate matter and its biological effects – Part 1: Simple VOCs and model PM

Gaseous VOCs rapidly modify particulate matter and its biological effects – Part 1: Simple VOCs and model PM

Why do organic aerosols exist? Understanding aerosol lifetimes using the two-dimensional volatility basis set

Early history and rationale for outdoor chamber work at the University of North Carolina

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