Monday, March 31, 2014

How Can Statistics Be Used to Link Air Pollution Exposure to Health Impacts?

Classification and regression trees for epidemiologic research: an air pollution example (18 page pdf, Katherine Gass, Mitch Klein,Howard H Chang, W Dana Flanders, Matthew J Strickland, Environmental Health, Mat. 13, 2014)

Today we review a paper that looks at ways that statistical regression trees may be used to improve the estimates of how much “confounding” [mix up (something) with something else so that the individual elements become difficult to distinguish.] goes on when there are multiple air pollutants that may or may not combine and augment each other in producing the health impacts that they collectively cause. The authors used over10 years of daily data for CO, NO2, O3, and PM2.5. Interestingly, they suggest that this same approach may
 be useful in nutrition.
  Aq health statistics  

Key Quotes:

“The end product of a typical C&RT analysis is a dendogram illustrating the paths of dichotomous splits. Every tree starts with a “root node” that contains the observations from which the tree will be grown. The observations are then partitioned into two “child nodes” based on the value of an independent predictor variable… Each child node may be further partitioned, again based on the value of an independent predictor variable. This process continues until a set of partitioning criteria are no longer met, resulting in terminal nodes.. The collection of terminal nodes forms a complete partition of the observations in the root node.”

“The C&RT algorithm we have proposed enables effect estimation through the withholding of a common referent group of days during tree construction. This allows for estimation of joint effects across terminal nodes in relation to the pre-specified reference group. Selecting the referent group a priori ensures that it does not depend on the analysis”

“there may be certain meteorological factors that promote this specific pollutant covariation and influence personal exposure levels, such as relative humidity. These hypotheses lead to several researchable questions…. Does residual confounding or effect measure modification by meteorological factors further explain the relative risks associated with each terminal node?”

“In air pollution epidemiology, while there is currently interest in moving from a single pollutant to a multipollutant framework, the term “multipollutant” is often used broadly and may encompass many different conceptual issues….When the multipollutant interest involves the joint effects of several pollutants, we feel that C&RT, particularly with the modifications mentioned in this paper, is a very appropriate tool.”
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Friday, March 28, 2014

How are Swedish Cities Planning to Adapt to Climatic Change Extremes?

Planning for Climatic Extremes and Variability: A Review of Swedish Municipalities’ Adaptation Responses(27 page pdf, Christine Wamsler and Ebba Brink, Sustainability, Mar. 14, 2014)

Today we focus our attention on Sweden, one of few countries in the world which is on track to become carbon neutral within this decade. The journal article under review looks at how Swedish cities approach the other side of climatic change- adapting to impacts, both natural and anthropogenic, using physical, economic and socio-economic measures. While there is little top-down direction at the national level beyond the provision of tools such as the Klimatanpassningsportalen on the internet to share practices and approaches, within cities top-down is the rule, leaving little for individual initiative but reflecting the local differences among  the cities across Sweden.

local city role impacts

Key Quotes: 

“disaster risk, and consequently disasters, results from an interaction between climatic and non-climatic hazards (H) and conditions of vulnerability (V) …. Climatic hazards include floods, windstorms, droughts, fires, heat and cold waves, sea-level rise (water surges) and landslides …Vulnerability is the degree to which communities or societies are “susceptible to the damaging effects of a hazard”…Risk is thus influenced by both climatic and societal change. “

“adaptive capacity is influenced by six general aspects which can be related to mainstreaming (i.e., the anchoring of adaptation at the institutional level): robust institutional setup, useful knowledge systems, functioning infrastructure, economic resources, access to technology and equity”

 “Physical Measures: Technological and Structural Approaches for Physical Vulnerability Reduction - The majority of the physical measures identified are aimed at hazard and vulnerability reduction to riverine and coastal flooding”

“Environmental Measures: Win-Win and No-Regret Measures for Ecosystem-Based Adaptation - The environmental .. measures identified are principally aimed at managing excess runoff water by (a) directly reducing it where it falls, or (b) delaying its flow to the “traditional” stormwater system”

“Socio-Economic Measures - … Most of these are aimed at preparedness for response, such as the establishment of early warning systems or emergency traffic planning (e.g., keeping cars or trains away from thoroughfares that are exposed to floods)”

 “Sweden has no national adaptation strategy, despite its top-down management of environmental issues in general.. Nevertheless, the national government has certainly influenced today’s risk governance structure.. adaptation in Sweden (and worldwide) needs to move from single physical interventions and technical fixes to institutional change “

“Klimatanpassningsportalen…is a tool developed by the Swedish National Knowledge Centre for Climate Change Adaptation..It provides a great opportunity to address the identified lack of systematization and assessment of current measures and strategies for adaptation and mainstreaming.”

“While at the national level, there seems to be a lack of top-down guidance, at the municipal level top-down approaches are prevalent”
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Wednesday, March 26, 2014

How Dangerous is it to Live Near a Wind Turbine?

English: Modern wind energy plant in rural sce...
English: Modern wind energy plant in rural scenery. Français : Une éolienne moderne dans un paysage rural. (Photo credit: Wikipedia)
Measuring electromagnetic fields (EMF) around wind turbines in Canada: is there a human health concern?(8 page pdf, Lindsay C McCallum, Melissa L Whitfield Aslund, Loren D Knopper, Glenn M Ferguson and Christopher A Ollson, Environmental Health, Feb. 15 ,2014) 

Also discussed here: Electromagnetic fields and public health - Exposure to extremely low frequency fields(Backgrounder, World Health Organization, June 2007) 

Today we review the first objective research into health hazards near wind turbines n Canada, based on extensive measurements of electromagnetic fields (EMF) near a wind farm in southwestern Ontario. Despite popular fears about the potential dangers, results indicate that the EMF near a wind turbine (3-4 mG) is much less than from a microwave oven (300 mG) or a electric shaver (600mG) and therefore does not constitute a significant health threat which is backed up by statements form the World Health Organization and Health Canada. Even the fields below high voltage (500 kV) power lines, another target of public health concerns, are small (16-46 mG) by comparison. This finding is important in dismissing arguments against windpower which could be a major replacement for carbon-powered electricity sources which play a large role in high air pollution levels. 

magnetic field  

Key Quotes: 

“this study is the first to provide quantitative measurements of EMF around wind turbines in Canada.” 

“The results suggest that there is nothing unique to wind farms with respect to EMF exposure; in fact, magnetic field levels in the vicinity of wind turbines were lower than those produced by many common household electrical devices and were well below any existing regulatory guidelines with respect to human health” 

“the WHO has stated (based on approximately 25,000 articles published over the past 30 years) that the evidence related to childhood leukemia is not strong enough to be considered causal” 

“there are no accepted biophysical mechanisms that would suggest that low-level exposures are involved in cancer development.” (WHO, 2007) 

“human exposure to EMF from wind turbines is negligible in comparison to common household exposures. For example, typical magnetic field levels associated with common household appliances reported by the NIEHS at six inches from the source, include 40 mG for a refrigerator, 50 mG for a ceiling fan, 100 mG for a dishwasher, 300 mG for a microwave, 600 mG for an electric shaver and 700 mG for a hairdryer” 

“Health Canada does not consider that any precautionary measures are needed regarding daily exposures to EMFs at ELFs. There is no conclusive evidence of any harm caused by exposures at levels found in Canadian homes and schools, including those located just outside the boundaries of power line corridors”
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Monday, March 24, 2014

Marketing the Environment

Amanda Little
Amanda Little (Photo credit: ChimpLearnGood)
Want everyone else to buy into environmentalism? Never say “Earth” ( Heather Smith, Grist, Mar. 12, 2014)

Also discussed here: No, we’re not “environmentalists.” It’s more complicated than that

Key Quotes: 

 “People working in the nonprofit world sometimes have trouble adopting a marketing mindset....But in the end, the goal is for people to ‘buy’ our ideas — ideas for a better world.”” 

“If you look at the budgets of environmental groups, only teeny tiny portions are spent on communications. And if you remove the portions spent on building membership and fundraising, it’s even less….foundations that support environmental groups don’t tend to value communications, either.” 

“in communications, only simplicity works. Our side doesn’t like simplicity because they view it as manipulative or not capturing the truth. Without simplicity, people don’t remember anything.”

 “too much of the public thinks that environmentalists are people who care about the environment and not about people. So the environment has become a thing apart.” 

“we think because we’ve said something, know something, or done something, that everybody else knows it. We don’t realize the bubble we live in. It’s only when you’ve said something so many times that you’re utterly and completely sick of it that someone has even heard it.”
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Friday, March 21, 2014

How Dangerous is Traffic-Related Air Pollution to Your Health?

Traffic Related Air Pollution and the Right Ventricle: The Multi-Ethnic Study of Atherosclerosis(Abstract, Peter J Leary, Joel D Kaufman, R Graham Barr, David A Bluemke, Cynthia L Curl, Catherine L Hough, Joao A Lima, Adam A Szpiro, Victor C Van Hee, and Steven M Kawut, American Journal of Respiratory and Critical Care Medicine, Mar. 7, 2014)

 Also discussed here: Traffic-related air pollution associated with changes in right ventricular structure, function(Science Daily, Mar. 7, 2014)

And here: A New Study Shows How Fossil Fuel Pollution Damages The Heart(Jeff Spross, ThinkProgress, Mar. 7, 2014)

Today we review research into the health impacts of traffic-related air pollution on the heart, specifically the right ventricle which has not been studied as much as the left. Results indicate exposure to nitrogen dioxide- one of the main hazardous pollutants from vehicle emissions (along with particulate matter from diesel vehicles) causes the right ventricle to expand and this is linked to heart attacks and cardiovascular death.


Key Quotes:

 “increased exposure to nitrogen dioxide went along with a roughly 5 percent increase in the mass of the heart’s right ventricle, as well as changes in the blood flow through the ventricle.”

“Although the link between traffic-related air pollution and left ventricular hypertrophy, heart failure, and cardiovascular death is established, the effects of traffic-related air pollution on the right ventricle have not been well studied…Greater right ventricular mass is also associated with increased risk for heart failure and cardiovascular death.”

“Using estimated exposure to outdoor oxides of nitrogen at the homes of participants over the year preceding MRI, the authors found that increased exposure to nitrogen dioxide was associated with an approximately 1.0 g (5 percent) increase in right ventricular mass and a 4.1 mL (3%) increase in right ventricular end-diastolic volume.”

“The morphologic changes in the right ventricle of the heart that we found with increased exposure to nitrogen dioxide add to the body of evidence supporting a connection between traffic-related air pollution and cardiovascular disease,”
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