Non-methane hydrocarbons in the atmosphere of Mexico City: Results of the 2012 ozone-season campaign

Abstract

With the aim to strengthen the verification capabilities of the local air quality management, the air quality monitoring network of Mexico City has started the monitoring of selected nonmethane hydrocarbons (NMHCs). Previous information on the NMHC characterization had been obtained through individual studies and comprehensive intensive field campaigns, in both cases restricted to sampling periods of short duration. This new initiative will address the NMHC pollution problem during longer monitoring periods and provide robust information to evaluate the effectiveness of new control measures. The article introduces the design of the monitoring network and presents results from the first campaign carried out during the first six months of 2012 covering the ozone-season (Mar-May). Results show reductions during the morning rush hour (6-9 h) in the mixing ratios of light alkanes associated with the consumption and distribution of liquefied petroleum gas and aromatic compounds related with the evaporation of fossil fuels and solvents, in contrast to olefins from vehicular traffic. The increase in mixing ratios of reactive olefins is of relevance to understand the moderate success in the ozone and fine aerosols abatement in recent years in comparison to other criteria pollutants. In the case of

Observed trends in ground-level O<sub>3</sub> in Monterrey, Mexico, during 1993–2014: comparison with Mexico City and Guadalajara

“…New road corridors were designed for improving the intracity transport and the public transport fleet was renewed (ProAire-MCMA, 2001). For industrial sources, the switch from fuel oil to LP gas fuel, relocation of highly polluting industries away from the MCMA, and im- Garzón et al (2015) is consistent with a reduction in light alkane and aromatic levels during the morning rush hour reported by Jaimes-Palomera et al (2016). Continuous measurements of VOCs have been recently introduced by the MCMA government, which precludes an assessment of VOC long-term trends.…”

“…In polluted regions, increased levels of O 3 are prevalent during seasons with stable high-pressure systems and intense photochemical processing of NO x and VOCs (Dentener et al, 2005;Xu et al, 2008) with downward transport from the stratosphere of lesser importance (Wang et al, 2012). By contrast, the main removal processes for tropospheric O 3 are chemical loss and dry deposition (Atkinson, 2000;Jenkin and Clemitshaw, 2000).…”

“…In Mexico, studies of long-term trends in O 3 have focused on the Mexico City metropolitan area (MCMA) (Molina and Molina, 2004;Jaimes et al, 2012;Rodríguez et al, 2016), with reports of a decrease in O 3 annual averages of ca. 33 % during the last 2 decades (Parrish et al, 2011;SEDEMA, 2016a).…”

“…O 3 is a secondary air pollutant formed in the troposphere via the photo-oxidation of CO, methane (CH 4 ), and volatile organic compounds (VOCs) in the presence of NO and NO 2 (NO+NO 2 = NO x ) (Jenkin and Clemitshaw, 2000). The system of O 3 production is not linear and is termed NO x -limited, when O 3 production increases in response to increasing NO x emissions and termed VOC-limited when it responds positively to emissions of VOCs (Monks et al, 2015;Pusede et al, 2015).…”

Non Methane Hydrocarbons variability in Athens during winter-time: The role of traffic and heating

“…NMHCs' oxidation contributes to the formation of secondary organic aerosols (SOA), which in turn affects light scattering, visibility and CCN formation (Tsigaridis and Kanakidou, 2003;Seinfeld and Pandis, 2016 and references therein). They mainly originate from anthropogenic sources such as traffic, solvents' use, residential heating, natural gas use, industrial activity, but also emit from natural sources such as vegetation (Guenther et al, 1995;Barletta et al, 2005;Kansal, 2009;Sauvage et al, 5 2009;Salameh et al, 2015;Baudic et al, 2016b;Jaimes-Palomera et al, 2016). Besides their key role as secondary pollutants precursors, NMHCs are of interest regarding their association with health issues (EEA report, N o 28/2016(EEA report, N o 28/ , 2016.…”