Is the air pollution health research community prepared to support a multipollutant air quality management framework?

Ambient air pollution is always encountered as a complex mixture, but past regulatory and research strategies largely focused on single pollutants, pollutant classes, and sources one-at-a-time. There is a trend toward managing air quality in a progressively "multipollutant" manner, with the idealized goal of controlling as many air contaminants as possible in an integrated manner to achieve the greatest total reduction of adverse health and environmental impacts. This commentary considers the current ability of the environmental air pollution exposure and health research communities to provide evidence to inform the development of multipollutant air quality management strategies and assess their effectiveness. The commentary is not a literature review, but a summary of key issues and information gaps, strategies for filling the gaps, and realistic expectations for progress that could be made during the next decade. The greatest need is for researchers and sponsors to address air quality health impacts from a truly multipollutant perspective, and the most limiting current information gap is knowledge of personal exposures of different subpopulations, considering activities and microenvironments. Emphasis is needed on clarifying the roles of a broader range of pollutants and their combinations in a more forward-looking manner; that is not driven by current regulatory structures. Although advances in research tools and outcome data will enhance progress, the greater need is to direct existing capabilities toward strategies aimed at placing into proper context the contributions of multiple pollutants and their combinations to the health burdens, and the relative contributions of pollutants and other factors influencing the same outcomes. The authors conclude that the research community has very limited ability to advise multipollutant air quality management and assess its effectiveness at this time, but that considerable progress can be made in a decade, even at current funding levels, if resources and incentives are shifted appropriately.

Relations between PM10 composition and cell toxicity: a multivariate and graphical approach.

Previous studies have used particle mass and size as metrics to link airborne particles with deleterious health effects. Recent evidence suggests that particle composition can play an important role in PM-toxicity; however, little is known about the specific participation of components (individually or acting in groups) present in such a complex mixture that accounts for toxicity. This work explores relationships among PM(10) components in order to identify their covariant structure and how they vary in three sites in Mexico City. Relationships between PM(10) with cell toxicity and geographical location were also explored. PM(10) was analyzed for elemental composition, organic and elemental carbon, endotoxins and the induction of inhibition of cell proliferation, IL-6, TNFalpha and p53. PM(10) variables were evaluated with principal component analysis and one-way ANOVA. The inhibition of cell proliferation, IL-6 and TNFalpha were evaluated with factorial ANOVA and p53 with the Welch test. The results indicate that there is heterogeneity in particle mass, composition and toxicity in samples collected at different sites. Multivariate analysis identified three major groups: (1) S/K/Ca/Ti/Mn/Fe/Zn/Pb; (2) Cl/Cr/Ni/Cu; and (3) endotoxins, organic and elemental carbon. Groups 1 and 3 showed significant differences among sites. Factorial ANOVA modeling indicated that cell proliferation was affected by PM concentration; TNFalpha and IL-6 by the interaction of concentration and site, and p53 was different by site. Radial plots suggest the existence of complex interactions between components, resulting in characteristic patterns of toxicity by site. We conclude that interactions of PM(10) components determine specific cellular outcomes.

Do associations between airborne particles and daily mortality in Mexico City differ by measurement method, region, or modeling strategy?

We evaluated whether associations between PM10 and daily mortality in Mexico City differ by the PM10 measurement device or by regional differences in particle composition. Additionally, we reanalyzed previously collected data in light of recent insights about flaws in commonly used time series analysis techniques. We examined daily associations between mortality and four indicators of ambient PM10 using Poisson regression, controlling for temperature and time trends with cubic natural splines. Associations were calculated for five subregions corresponding to five monitoring sites and pooled for the entire metropolitan area. PM10 was measured with three methods: Tapered Element Oscillating Microbalance (TEOM), Sierra-Anderson High Volume (Hi-Vol) and Harvard Impactor (HI), the latter only at one site. In addition, predicted values of daily PM10 were developed using the Hi-Vol measurements, which were taken every sixth day, and weather, visibility and other pollutant data. We assigned deaths to the exposure from the monitor nearest to their residence. We also re-evaluated the HI PM2.5 and mortality association in southwest Mexico City, which was estimated previously using nonparametric statistical models. Slight decreases in effect estimates were observed (a 1.45% increase (95% CI: 0.09%, 2.83%) in total mortality per 10 microg/m(3) increment of PM2.5 at lag 0) compared to a 1.68% change (95% CI: 0.45%, 2.93%) using the previously employed nonparametric approach. Using data pooled over all the regions, PM10 measured by the TEOM and the predicted PM10 values showed little association with mortality at any of the lags examined. The pooled estimates for Hi-Vol PM10 (using one sixth of the data) were positive across all lags examined and significant for lags 3 and 5. No consistent patterns of differing associations were seen across regions that would correspond with particle toxicity or composition. Particulate air pollution, measured with gravimetric methods, is associated with daily mortality and presents a risk to health in Mexico City. The reanalysis suggests that previous research is robust to statistical method and likely to yield the same overall conclusions about the short-term effects of airborne particles on mortality.

Población, recursos y medio ambiente en México / Population, resources and environment in Mexico

En el presente trabajo se analizan las complejas relaciones que existen, en el caso concreto de México, entre población y medio ambiente. Para ello se echa mano de datos cuantitativos que provienen de instituciones gubernamentales y no gubernamentales y de las apreciaciones de un grupo de individuos con experiencia en el análisis de problemas ambientales. El estudio está organizado en capítulos que tratan diversos aspectos del tema. El primer capítulo delínea la problemática planteada por las relaciones entre población, medio ambiente y desarrollo, para lo cual se toma como marco de referencia al mundo en su totalidad. El segundo capítulo ofrece un perfil de la realidad demográfica de México, impresindible para poder establecer más adelante las interrelaciones con el medio ambiente y el desarrollo. En el capítulo tres se abordan, de manera regionalizada, las interrelaciones entre dos recursos naturales de gran importancia, el suelo y el agua, y la población. Los capítulos cuatro y cinco se refieren a las interrelaciones entre los procesos de industrialización y urbanización con el medio ambiente y los recursos naturales. Se hace especial referencia al desarrollo de la industria petrolera, por su importancia en la historia contemporánea de México. El capítulo seis es un análisis breve de las repercusiones que los cambios en el medio ambiente han tenido en la salud de la población. El siete es una síntesis de lo que se ha señalado a lo largo del libro. Finalmente, el capítulo ocho presenta algunas reflexiones que señalan las opciones para el futuro y las dificultades que se encuentran si se pretenden realizar acciones que modifiquen la realidad actual, mejoren la situación y eviten la aparición de nuevos problemas ambientales y poblacionales