Ozone precursors and boundary layer meteorology before and during a severe ozone episode in Mexico city.

Volatile organic compounds (VOCs) data in conjunction with other inorganic pollutants, surface meteorological data and continuous measurement of the Planetary Boundary Layer height (PBLH) at an urban site in Mexico City were performed from 6 to 18 March 2016. Positive Matrix Factorization (PMF) identified four emission source factors of VOCs along with equivalent black carbon (eBC), gaseous pollutants (CO, NO, NO, SO, NH) and ions (Na, Mg, Ca, NO, NH): (1) secondary aerosol precursors, (2) evaporation and non-LPG fuel combustion, (3) geogenic source and (4) vehicle exhaust. Propylene Equivalent and Maximum Incremental Reactivity (MIR) methods identified isoprene and ethylene as the highest oxidant and O forming species.

A global observational analysis to understand changes in air quality during exceptionally low anthropogenic emission conditions.

This global study, which has been coordinated by the World Meteorological Organization Global Atmospheric Watch (WMO/GAW) programme, aims to understand the behaviour of key air pollutant species during the COVID-19 pandemic period of exceptionally low emissions across the globe. We investigated the effects of the differences in both emissions and regional and local meteorology in 2020 compared with the period 2015-2019. By adopting a globally consistent approach, this comprehensive observational analysis focuses on changes in air quality in and around cities across the globe for the following air pollutants PM, PM, PMC (coarse fraction of PM), NO, SO, NOx, CO, O and the total gaseous oxidant (OX = NO + O) during the pre-lockdown, partial lockdown, full lockdown and two relaxation periods spanning from January to September 2020.

Ultraviolet Radiation Environment of a Tropical Megacity in Transition: Mexico City 2000-2019.

Tropical regions experience naturally high levels of UV radiation, but urban pollution can reduce these levels substantially. We analyzed 20 years of measurements of the UV index (UVI) at several ground-level locations in the Mexico City Metropolitan Area and compared these data with the UVI values derived from the satellite observations of ozone and clouds (but not local pollution). The ground-based measurements were systematically lower than the satellite-based estimates by ca.

Historical trends of metals concentration in PM collected in the Mexico City metropolitan area between 2004 and 2014.

In this work, we report metals concentrations in 80 PM samples collected at four sites in the Mexico City Metropolitan Area (MCMA): Tlalnepantla (NE), Xalostoc (NE), Merced (C), and Pedregal (S), during the dry/cold season (October to January) for the 2004-2014 period. Mean PM mass concentration (66.1 µg m) significantly exceeds the annual mean air quality guidelines recommended by the World Health Organization.

Spatial and temporal distribution of metals in PM during 2013: assessment of wind patterns to the impacts of geogenic and anthropogenic sources.

The Mexico City Metropolitan Area (MCMA) was the object of a chemical elemental characterization (Ti, V, Cr, Mn, Co, Ni, Cu, Mo, Ag, Cd, Sb, Pb, La, Sm, Ce, and Eu) of PM collected during 2013 and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Sampling campaigns were carried out at five locations simultaneously-northwest, northeast, center, southwest, and southeast-during dry-warm season (April), rainy season (August), and dry-cold season (November). By means of enrichment factor (EF) and principal component analysis (PCA), it was possible to attribute the analyzed elements to geogenic and anthropogenic sources, as well as to identify a group of elements with mixed provenance sources.

Estimating particle exposure in the Mexico City metropolitan area.

Study Question: We examined whether methods for measuring exposure to airborne particles less than 10 microm in aerodynamic diameter (PM10) in the Mexico City metropolitan area give different estimates of PM10 levels, and the nature of these differences, and developed a model for estimating missing PM10 data for one measurement method.

Methods: Government PM10 measurements using two different technologies at five sites (the Sierra-Anderson PM10 High-Volume Air Sampler System, Hi-Vol) (every sixth day) and the Rupprecht and Patashnik Tapered Element Oscillating Microbalance (TEOM) monitor (daily), as well as Harvard Impactor (HI) data collected for research purposes from one monitoring station were matched by day and monitoring site, then compared visually and with basic descriptive statistics. We fit linear regression models with airport visual range measurements, meteorological data, and information on other air pollutants to predict the Hi-Vol measured PM10 levels for those days when direct measurements were not available.