MedWorm.com provides a medical RSS filtering service. Over 5000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Cathryn's blog' source. Sat, 16 Aug 2008 14:40:24 +0100 http://www.cathryntonne.com/?p=16 Clearly exposure to air pollution remains a public health problem for the developed world. For pollutants such as particles, there is no threshold below which exposure is no longer harmful. That means even in cities with relatively low ambient levels, further reductions in exposure will still lead to health benefits. Despite the clouds of diesel exhaust I always seem to walk through on my way to work, compared to other global cities, London is faring quite well. One of the points I was most struck by while at ISEE in Mexico City earlier this month was not just how high the ambient concentrations are in many developing countries, but how shockingly little monitoring data are available in many places. I’m not sure I’m ready to pack my bags and head to central Africa, but filling in the paucity of data on exposures in the developing world is the first step in quantifying the burden of mortality and morbidity attributable to air pollution and getting on with the work of reducing exposures. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=886165 Thu, 20 Sep 2007 07:24:53 +0100 886165 http://www.cathryntonne.com/?p=15 WHO recently published country-by-country estimates of population health impacts attributable to environmental exposures. Having recently done my first health impact assessment which was for London - a city for which there is generally very good data, I’ve become increasingly interested in the methods used to make these large scale international comparisons of the burden of disease. The first part of the project used comparative risk assessment methods to estimate deaths and disability-adjusted life years (DALYs) attributable to three exposures: water, sanitation and hygiene; indoor air pollution; and outdoor air pollution in urban areas. Outdoor air pollution estimates were based on population weighted averages of PM10 from monitoring sites (where available). They estimated the burden due to outdoor air pollution that could be avoided by reducing PM10 levels to the WHO air quality guideline rather than for PM10 in its entirety. The second part, which considered additional exposures such as lead, climate change, and occupational factors, was based on the methods used in the WHO ‘Preventing disease through healthy environments’: a combination of comparative risk assessment and expert judgement. A fascinating effort, needless to say, and one that is continuously evolving. However, given the enormous uncertainties and data limitations involved, I remain undecided about what the currently available estimates really can tell us. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=791253 Fri, 10 Aug 2007 11:14:49 +0100 791253 http://www.cathryntonne.com/?p=14 Unfortunately the odds of a congestion charging scheme, similar to that of London, being implemented in NYC just got longer. Last week the NY state senate, whose approval is required to implement the program, shelved the plan. The proposed pilot scheme was quite similar to London’s in spirit: drivers would be charged daily $8 for cars and $21 for trucks to travel below 86th St during working hours, Monday through Friday. Revenue generated through the scheme would be dedicated to transportation investment. The pilot program was one of the transportation initiatives proposed as part of PlanNYC 2030, a long-term sustainability plan for the city. Fingers crossed that the plan can be salvaged or that a similarly aggressive traffic management scheme in an American city will finally emerge. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=757722 Wed, 25 Jul 2007 17:15:02 +0100 757722 http://www.cathryntonne.com/?p=13 Defra just published the Air Quality Strategy for England, Scotland, Wales and N. Ireland on 17 July. Giving it a read helped me understand some of the differences between air pollution regulation in the UK compared to the US. The opportunity to learn more about air pollution regulation in the EU in general, and the UK in particular, was one of the things I was most looking forward to in doing a postdoc in London. I found the new air quality objectives for PM2.5 especially interesting. Rather than focus on hotspots, or locations with concentrations in exceedence of a standard, they have adopted an ‘exposure reduction’ approach. This approach has many advantages in that it 1) more fully appreciates there is no recognized safe level of exposure to PM2.5 2) creates a driver to reduce concentrations everywhere rather than just in hotspots 3) potentially maximizes public health benefits for the general population and 4) more explicitly deals with the equity issues involved in air pollution control strategies. For more details on the latter, see Levy et al. EHP 2007. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=742503 Wed, 18 Jul 2007 14:43:02 +0100 742503 http://www.cathryntonne.com/?p=12 Approximately half of the world population now live in urban areas. In 1950, 30% did. The implications of this growth for transportation, air quality, and public and open space are addressed, in part, in the Global Cities exhibit now on at the Tate Modern. The exhibit uses statistics, images, videos, etc to compare the experience of ten different cities, one of which is London. If anything the exhibit reminded me that, in comparison to other world cities, London has a relatively small, stable population and rather low population density. Nonetheless, London seems almost hopelessly complex and dynamic when trying to understand how the ever-shifting traffic patterns; traffic interventions large (e.g. congestion charge) and small (e.g. creating a bus lane); and flow of commuters in and out of the city influence population exposure to traffic related air pollution. Though London has relatively good data compared to other cities, the composite these data create is still only a crude picture of how many people spend how much time where. The exhibit was certainly thought provoking, though I was hoping for a bit more in the way of design solutions for problems unique to these urban environments. That said I’m left wondering how the efficacy of any potential design solutions could ever be assessed. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=721198 Mon, 09 Jul 2007 13:21:12 +0100 721198 http://www.cathryntonne.com/?p=11 Yes, it’s been rather quiet at cathryntonne.com. I didn’t think anyone was reading and I got a bit discouraged. While back in Boston for the Society for Epidemiologic Research conference, which was very interesting by the way, a few friends encouraged me to give it another try. So here goes. Quite a few exciting things have happened in London in the interim. We’ve had the westerly extension of the congestion charge. This includes more than twice the area of the original boundary (21 km2) as well as a much larger residential population, and is covered by more ambient air pollution monitors. These are all very helpful for the purposes of eventually assessing potential air pollution and health impacts of the scheme. And of course, there was the announcement in May of plans to implement the Low Emission Zone in February 2008. While the congestion charge was designed to address traffic congestion alone, the LEZ specifically targets vehicle emissions and air quality. It also will cover all of Greater London. London is quite an exciting place to be at the moment if you’re interested in strategies to improve the urban environment in general and traffic related air pollution in particular. These various policies, in part, force people to consider the impacts of their transportation choices and become more comfortable with the idea that using roads and emitting pollution aren’t free. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=708696 Mon, 02 Jul 2007 10:21:15 +0100 708696 http://www.cathryntonne.com/?p=9 Earlier this week, I had the opportunity to share a bit of my research on the air pollution related health impacts of the Congestion Charge at the House of Commons. It was through a reception held as part of National Science and Engineering week designed as an opportunity for early-stage researchers to interact with their MPs. Despite my visit to his surgery which is just around the corner from my flat and a call to his assistant, George Galloway, my MP failed to make an appearance. I would have been interested to hear his thoughts on the equity issues related to the Congestion Charge since the costs of transportation seem to be a key issue for the Respect Party. Though there was a smattering of other epidemiologists, the session presented work from all of the sciences which I found to be rather refreshing; everything from how to make windmills run more efficiently to how to reconstruct diet of historical populations from bone remains. I was pleasantly surprised to learn that the public can observe the proceedings in either House whenever they are sitting. I took my seat in the Stranger’s Gallery of the House of Lords after handing over my bag and swearing that I wouldn’t interrupt the session and then managed to see a finance bill get passed uncontested (maybe not surprising at 9pm on a Monday night). (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504388 Thu, 22 Mar 2007 11:15:55 +0100 504388 http://www.cathryntonne.com/?p=8 I’ve had the good fortune to recently visit both the Alexander Fleming Museum and the Deutsches Hygiene Museum, making January a stellar month for exploring the treasure trove of public health history at hand. With time to spare between meetings at the Imperial College St. Mary’s campus, I wandered into the Fleming Museum and was greeted by a most enthusiastic retired nurse. Happy to have an epidemiologist passing through the door and a bacteriologist on his way out, she gave me a private tour of Fleming’s laboratory which hasn’t been touched since his discovery of penicillin in 1928. The lab was rather drafty and looked as though it could use a good cleaning, but these otherwise undesirable conditions were the very same that led to his petri dish getting contaminated with mold and where the story essgentially starts. We visited the Deutsches Hygiene Museum on a recent trip to Dresden. The fantastic design of the building is well worth the trip in its own right. Unfortunately, much of the building was destroyed in 1945, but has been largely restored to its former glory. The permanent exhibits were broad in scope with sort of a ‘museum of man’ theme, but included some superb examples of early tools to visualize the human body. Not only did this include the museum’s famous transparent man (below), but also an absolutely ancient X-ray machine used by a GP in E. Germany until about 15 years ago. Alongside, they presented a cast of his mangled hands after a lifetime of exposure. Arguably, the most interesting exhibit was the temporary Deadly Medicine. I thought its treatment of the eugenics movement under the Nazis in general, as well as the museum’s active role in supporting the Nazi’s racial hygiene programs in particular, was very well done. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504389 Fri, 26 Jan 2007 16:08:22 +0100 504389 http://www.cathryntonne.com/?p=7 Though I’m enjoying the challenge, I’m also acutely aware that assessing the air pollution related health impacts of the CCS is going to be hard. The project is what can be considered an accountability study; that is, one that tries to evaluate the impact of a specific regulation on public health. Accountability studies are hard to do for a number of reasons. Firstly, many steps come between the introduction of a policy and the human health response. Air pollution regulations typically focus on reducing emissions, or in this case, reducing traffic (and traffic emissions indirectly). But does this reduction in emissions result in a reduction in ambient concentrations? Does it actually lead to a reduction in the air pollution people are exposed to? A reduction in emissions would have to propagate through a complex chain before we could expect to see an impact on human health. Not to mention, the further challenges posed by evaluating impacts on non-specific health outcomes (e.g. cardiovascular disease) that are associated with air pollution exposures but are also influenced by a host of other factors. Then there is the potential for time trends in the health outcomes or traffic emissions for reasons unrelated to the policy that can muddle the picture. Also, it can be unclear how long you have to wait after the policy is introduced before you can expect to see a change in health outcomes? Despite the challenges, it’s a study that is definitely worth doing. It can potentially give more direct information about the effectiveness of a given policy than would be available through other more indirect approaches like risk assessment. In the end, we’ll have the best understanding of the utility of such traffic management programs as public health interventions by looking at the question using a number of different, complimentary approaches. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504390 Mon, 15 Jan 2007 14:19:33 +0100 504390 http://www.cathryntonne.com/?p=6 Of course London is a fantastic city, but you may still be wondering how I ended up here. In 2003, the Mayor of London introduced the Congestion Charge Scheme (CCS), a traffic-pricing programme by which drivers travelling in to the city centre are charged £8 per day to travel within a designated zone between working hours. The revenue generated through the scheme is then directed towards expanding London’s transport facilities. The introduction of the CCS presents something of a natural experiment for studying the impacts of reduced traffic related air polluiton on morbiditiy and mortality. This, among others reasons, is why I’ve come to London. I’m here on a post-doctoral research fellowship for the next two years to asses the health impacts of the CCS. (Not an easy task!) It’s a great opportunity to work with a diverse group of researchers at King’s College, London School of Hygiene and Tropical Medicine, and St. George’s Medical School. As urban centres worldwide face growing congestion problems, they are increasingly looking towards traffic pricing schemes similar to the CCS. Our hope is that this work will provide a bit of useful insight into the potential of these strategies as public health interventions. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504391 Tue, 02 Jan 2007 13:58:33 +0100 504391 http://www.cathryntonne.com/?p=5 Epidemiology is a blunt instrument, indeed. Particularly in the case of environmental epidemiology where we seem particularly bedevilled by poor measures of what individuals are exposed to as they go about their daily lives. Stepping outside of my usual routine to attend the IAPSC meeting in Birmingham last week made me appreciate even more just how problematic exposure assessment in air pollution epidemiology can be. After working with modeled air pollution exposures for the past few years, having measured concentrations seems like a luxury: so much more concrete and reliable. But as presented at the meeting, even ambient measurements can be highly dependent on the instruments used, etc. For more details about the meeting and issues surrounding PM10 measurements check out Green and Maggs. At some point, the discussion turned to emissions inventories and how the emissions factors we rely on in emission-dispersion exposure models can vary by tens of percents from year to year (for inadequately explained reasons). Given the uncertainties factoring into the measurements let alone modeled exposure, I’m amazed that epidemiology analyses at the end of this chain have managed to see anything other than a null association. Reflecting on this over the past week has been simultaneously discouraging and affirming about the utility of air pollution epidemiology. Regardless, it continues to be fascinating. And yes, the meeting roughly coincided with the anniversary of the 1952 London Fog. Some excellent images of such pea soupers can be seen in the Clean Air Act talk; and here for other thoughtful commentary on the impact of the London Fog on air pollution regulation in the UK and elsewhere. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504392 Thu, 14 Dec 2006 10:26:38 +0100 504392 http://www.cathryntonne.com/?p=4 One of my least favourite activities as an epidemiologist are the obligatory power/sample size calculations, and yet I seem to spend so much time doing them. Invariably, I end up questioning whether the calculations are really all that informative. Firstly, it’s usually a struggle to find software or online applications that do sample size calculations for the types of study designs or models I use (e.g. random effects). Secondly, most approaches are unrealistic in that they don’t account for the extent of correlation between exposure and other covariates or measurement error. Then of course, there is the frustration involved in getting different results from different sample size calculators for the exact same inputs. Despite such tribulations, I have come across a few gems in the past week. One was particularly useful for calculating sample size for a difference in incidence rates. The other was a great help for higher order crossover designs, including washout periods, etc. Both are programs that you actually download with enough documentation to help make your way through the black box. I’ve come to appreciate the importance of having the software actually on your computer after relying on a web based application for a project last year. When I went back to revisit my calculations, the site had been taken down, inducing a few moments of panic. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504393 Sun, 10 Dec 2006 19:52:38 +0100 504393 http://www.cathryntonne.com/?p=3 Bear with me; needless to say this is something of an experiment for me. In fact, I had to be cajoled by parties who will remain unnamed to give blogging a go. Now that I’ve opened up to the idea, I’m optimistic about having a single forum by which I can let people know what I’ve been working on since my arrival in the UK. -ERG- Yes, it’s a strange and wonderful beast and very different from my previous work environments. The Environmental Research Group – it’s part academic research group, part company with mostly public sector clients housed within King’s College, University of London. Everyone here is thinking about air pollution in some fashion, only each comes from a completely different background (toxicologists, biochemists, modellers, monitoring gurus). And for a few weeks now, they’ve had me, the lone epidemiologist. In many respects, I’ve found it to be the best of both worlds in that people and projects are well managed but it’s still within an academic environment. I was beginning to think the two were mutually exclusive. Our office is in the Franklin-Wilkins building near Waterloo station. It was initially used as a military hospital during WWI. Apparently there used to be tunnels from Waterloo to the hospital in order to transport injured soldiers from the field directly to the hospital without demoralizing civilian onlookers. It’s also rumoured to have housed secret service outposts while it was the Office of the Government Chemist (yes, if you can believe it, England also has a National Statistician). The first professional school of nursing founded by none other than Florence Nightingale is just down the street. So loads of rich public health history to take in in my new environs. (Source: Cathryn's blog) Cathryn's blog blogs http://www.medworm.com/rss/comments.php?id=504394 Sat, 04 Nov 2006 12:07:15 +0100 504394