Gas‐phase kinetics, POCPs, and an investigation of the contributions of VOCs to urban ozone production in the UK

Abstract

Ambient concentrations of 22 volatile organic compounds (VOCs) measured at London Marylebone Road (LMR), an urban traffic site, and London Eltham (LE), an urban background site, were analyzed over a period of 23 years to assess the impact of pollution control strategies. A significant decrease in ambient concentration is seen for the majority of VOCs analyzed with total VOC burden decreasing by 76% and 59% for LMR and LE, respectively, across the period studied. This is likely as a result of legislative controls. This analysis was extended to consider the dominant contribution of VOCs to ozone formation at the sites utilizing photochemical ozone creation potential (POCP) values.Similarly, the overall reactivity of the VOC burden at the sites has resulted in a significant decrease of 11% and 7% per year in ozone formation potential (OFP) for LMR and LE, respectively. At LMR, the declines in OFP for VOCs associated with road traffic emissions are all in good agreement at 11%-13% decrease per year. Reasonable agreement is also seen at LE with a decrease of 6%-11% per year in OFP of the VOCs related to traffic sources. VOCs related to non-traffic sources, namely ethane and propane from natural gas leakage, did not see a significant decline over the study period at either site. The variation and composition of the overall VOC burden was compared across three decadal time periods (1997-2000, 2001-2010, 2011-2019) and saw an increase in significance of these pollutants at both sites. At LMR, ethane and propane moved from the fifth and eleventh largest contributors to total VOC burden in 1997-2000 to the first and second largest contributors in 2011-2019. At LE, a similar trend is seen with ethane and propane becoming the first and second largest contributors in the most recent time period, up from second and eighth at the beginning of the dataset. The similarity between these sites suggests such pollutants are not sufficiently controlled under current legislation. The increase in significance of ethane and propane was mirrored in their contribution to ozone generation potential at both sites but ethene continues to dominate in contribution to OFP. At LMR, etheneThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Elucidating the Effects of COVID-19 Lockdowns in the UK on the O3-NOx-VOC Relationship

“…Although alkanes are often emitted from ozone production analyses, due to their comparatively low reactivity as VOCs, they have recently been shown to play a substantial role in tropospheric ozone formation. At the monitoring stations of both London Eltham (LE) and London Marylebone Road (LMR), alkanes accounted for 60% (3 out of 5) of the greatest contributors to ozone production, along with ethene and propene [25]. A study at LMR also suggested the importance of certain alkanes, demonstrating that approximately 75% of the total ozone formation potential (OFP) at this site was accounted for by ethene, propene, m + p-xylene, toluene, isopentane, n-butane, o-xylene and iso-butane [5].…”

“…NO x emission reductions alone are, therefore, not an effective solution for universally reducing pollution levels. Reductions of NO and NO 2 are still important to reduce NO x pollution itself but, at VOC-limited sites, it is more important to reduce emissions of the key VOCs contributing to ozone formation, such as ethene, propene, m + p-xylene, toluene, isopentane, n-butane, o-xylene and iso-butane [5,25,48]. This avoids escalating levels of harmful tropospheric O 3 , which not only has negative health impacts but also contributes to global warming.…”

“…As a result, there is a delicate balance to be achieved when reducing NO x , a common target of air quality-related legislation [17], in order not to inadvertently increase O 3 , which has a range of its own negative impacts [1,12,[18][19][20][21][22][23][24]. This has presented an interesting challenge in design of air quality legislation where either location-specific or dual-pollutant control strategies are likely to be required [9,10,12,25].…”

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“…Despite the continuous development of civilization, increasingly serious environmental degradation problems lead human society into an unprecedented predicament. , Volatile organic compounds (VOCs) are one of the major components of air pollutants and are mainly derived from the combustion of fossil fuels and emissions of vehicles. − Propane (C 3 H 8 ), as a short-chain hydrocarbon, is one of the precursors to near-ground ozone (O 3 ), energetically deteriorating both the ecosystem and human health. − In this context, there is an ongoing requirement for the abatement of C 3 H 8 to contribute to environmental sustainability. Compared with other VOC elimination technologies, catalytic oxidation has aroused a tremendous amount of attention due to its incomparable efficiency at relatively low operating temperatures and eco-friendliness. , The most commonly utilized catalysts in catalytic oxidation are supported noble-mental-based materials. − By far, Pt-based catalysts are one of the most widespread materials and have been studied profoundly because they can satisfy the requirements for VOC elimination at low temperatures. ,− …”

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“…In 2010, the UK published Air Quality Standards Regulations (AQSR) which prompted national PM 2.5 reduction measures, including a specific annual average concentration aim to be met by 2020 [21]. In UK urban areas, the yearly average PM 2.5 concentrations are decreasing over time due to pollution control strategies [22] and ground-level O 3 concentrations were reported to have been increasing over the preceding decade [23][24][25]. However, the current levels of PM 2.5 in urban sites still exceed legislation.…”