Monday, April 25, 2011

Part 1: Building design to increase physical activity

We all know that we are not getting enough physical activity these days. In fact, 52% of Canadian adults 20 years of age or older are considered inactive, and 88% of children aged 5-19 years don’t meet Canada’s physical activity guidelines. It’s one out of many reasons why the prevalence of overweight and obesity is so high. But physical activity has other health benefits, in addition to staving off obesity and cardiovascular disease, such as reducing stress and improving concentration, promoting correct physical growth in children, and maintaining mobility and independence in the elderly. 

The problem is that it’s just too easy to be physically inactive.  Our society has, for all intents and purposes, engineered physical activity out of the built environment – important, especially when you consider that schools and many jobs require us to be sitting for most of the day to begin with.  Take for instance stair climbing; it is a great means of increasing cardiovascular output, but the need for it has all been eliminated by the design of modern buildings.  Escalators and elevators are easy to access and do the work for us, but are energy guzzlers - elevators account for 3-10% of a building's energy uses. Stairs, our healthy and environmentally friendly benefactor, are difficult to find, often ugly and dark, and sometimes invite anti-social activity. It’s no wonder people don’t use them.

Can we design public buildings then to increase physical activity? This is a burgeoning area of research with evaluation studies still lacking. In the next post, I’ll discuss some recommendations made by the City of New York in their Active Design Guidelines, based on the best available evidence and best practices.  However, I’d like to discuss here point-of-decision prompts as a way to get people to use the stairs instead of escalators and/or elevators – a bit different than design per se but related and still very relevant and interesting.  I was actually pleasantly surprised to see that there was a large enough body of research to warrant a systematic review on the subject.

Motivational sign from Kino Québec (not sure why the guy is blue).  More info is available at: 

This very recent systematic review was published in the Scandinavian Journal of Public Health in 2010 and included 25 studies that examined the role of posters (n = 16), stair-rise banners (n = 5), both (n =4), or posters and floor graphics (n = 1) in helping people decide to take the stairs versus elevators (n = 8) or escalators( n = 18).  The majority of studies were conducted in public transit stations (e.g. train, bus, airport), shopping malls, or office buildings.  All used the interrupted time-series design (before-after where the ‘before’ sample does not necessarily contain the same individuals as the ‘after’ sample).               

Of the 42 comparisons (more than one comparison often conducted in a study), 31 reported modest but significant increases in stair climbing, 10 reported no association, and 1 reported an inverse association. The non-significant results were more likely to be reported by studies examining stairs versus elevators. There were no consistent differences between men and women. Of the significant studies that calculated odds ratios, those in favour of the intervention ranged from 1.05 – 2.93. Results appear promising with perhaps more work to be done to get people to use stairs instead of elevators versus escalators.  

Motivational sign from NYC Active Design Guidelines

There are some important things to keep in mind about this review and the included studies:
  • Follow-up times were fairly short (at most 6 months). Some studies found that stair climbing decreased back to baseline over time (I guess as the novelty wore off)  
  • I’m not certain as to how denominators were calculated at the ‘point-of-decision’. This was not discussed in the review but likely easy to find out by accessing individual articles  
  • Only studies that looked at stair ascent were included. I think descent is equally important  
  • It’s not readily apparent which messages and/or mediums work best 
  • The same authors conducting different studies make up a large proportion of the included studies. This appears to happen in 4 instances and amounts to 16/25 studies.  This increases the likelihood of a bias occurring in one study being replicated in another, and both (or in some cases 6) being included in the review 
  • Finally, as I alluded to earlier, the study designs are methodologically weak. The authors of the review recommend a control-site but comment on the difficulties of making this happen in practice.  In my opinion, stronger designs are more difficult in public transit buildings and malls – but feasible in office buildings (e.g. randomizing buildings and following the same people within each building). 
Point-of-decision prompts look like promising ways to get people to take the stairs (another review came to similar conclusions) but I think that more high quality research is warranted.  Additionally, what if point-of-decision prompts were accompanied by changes in actual building design? You’ll have to read my next post to find out. Stay tuned.

Nocon M, Muller-Riemenschneider F, Nitzschke K, & Willich SN (2010). Increasing physical activity with point-of-choice prompts -- a systematic review Scandinavian Journal of Public Health, 38, 633-38

Wednesday, April 13, 2011

Battle of the bike lanes - in NYC and now Ottawa-Gatineau?

Hat tip to Atif who brought this story to my attention this past November.  Over the last three years the Bloomberg administration has created over 200 miles of bike lanes and passed several bicycle friendly laws. This has been to the detriment of infrastructure supporting car use. To me, this is great news but to others that have a special attachment to their cars, or fear delivery trucks won’t be able to make their morning deliveries, this is terrible news. A similar story is starting to unfold in Ottawa; a ‘not-in-my-backyard’ mentality.

There is a war raging now in New York City – over bike lanes

In NYC, vocal opposition by drivers and elected officials has led to the removal of newly established bike lanes in Brooklyn and on Staten Island – lanes that communities originally wanted after extensive public consultation.  It seems that in the US, if you don’t agree with the government and don’t get your way, then you sue (if you have the means that is). That’s precisely what’s happening in New York City. A bike lane along Prospect Park West, a road forming the boundary between the Prospect Park and the well-to-do neighbourhood of Park Slope, is at the centre of a lawsuit brought on by wealthy, well-connected Brooklyn residents. According to the Times, almost three quarters of Park Slope residents are in favour of the bike lane; however this drops to 50% of residents who live along Prospect Park West, prime real-estate that overlooks the park.

A nice butt shot of me on one of NYC's off-road bike lanes

Opponents have cited many faults by the DOT - erroneous, misleading statistics, lack of transparency and public consultation, sub-par design, reduced room for cars, reduced safety, to name a few.  As reported by the Times, room for the legal complaint to be made stems from a state statute that allows challenges to government actions considered to be arbitrary or unfair. Nowhere do I see these two requirements being met by bike lane opponents. It just seems like a complaint against changing the status quo and making life slightly less convenient.

From an overall perspective, DOT statistics show that bicyclist fatalities and crashes in NYC have decreased almost 19% from 2006 to 2010, with the number of cyclists doubling from 2006-2010, and increasing 13% from 2009-2010. However, I did not come across stats on percentage of mode share (although this is likely premature as I discuss below). For Prospect Park specifically, DOT reports that crashes involving injuries are down 63%, speeding by cars is down from 75% to 20%, and cycling on the sidewalk is down 80%. Area residents and users of the lane also report feeling safer. Opponents, however, feel that the numbers have been deliberately 'fudged'. As reported by TransportationNation, the lawyer of the group filing the lawsuit stated:

“Everyone should be concerned about DOT’s misuse of the data. Everyone. This case is about a government agency wrongfully putting its thumb on the scale by fudging the data and colluding with lobbyists. That is not what ‘public integrity’ means. Some people on both sides of the issue are affluent and have political connections. So, the continuous, one-sided name-calling is hardly appropriate. But, more importantly, it keeps people from focusing on the real issue in the case, which I suspect is the true aim.”

Clearly an independent third party needs to evaluate use and safety of biking infrastructure if these statistics are to be believed. At the same time, new biking infrastructure will take some getting used to (by users and non-users alike) and time to increase awareness in the general NYC community (to increase the number of users), so an in-depth evaluation right away, in my mind, is premature. Additionally, it’s pretty hard to argue with people who think that a bike lane is a terrorist plot. I am truly amazed and saddened by this on-going saga. I mean they are bike lanes after all – meant to reduce congestion and greenhouse gas emissions, and increase safety for all…  

Some debris left in a NYC bike lane; Creative Commons Image  

Foreshadowing for Ottawa-Gatineau?

Certainly, the biking infrastructure in the Ottawa-Gatineau area is not quite as extensive and the proposed plan to create a segregated bike lane on Laurier Street has not generated nearly the level of disaccord; however, it’s there. Interestingly more lanes are planned; the National Capital Commission has quietly announced plans to implement a segregated bike lane on Wellington Street.

The idea of implementing biking infrastructure is to make cycling more enjoyable, safe, and convenient, and driving less convenient – ultimately, to change the commuting mode share.  

Complaints in NYC and in Ottawa have some commonalities

Why do all this for only a select few people? Only the hardiest of hardy cycle all the time and that’s not a lot, especially given our winters. Cycling will never catch on:

Well the point is to encourage MORE people to take their bikes instead of their cars. This will take time for people to switch and for infrastructure to keep up with demand. Biking in winter (as well as in the other three seasons) is possible if it becomes the norm – with dedicated bike lanes that are well-connected and maintained throughout all seasons (a colleague of mine has discussed Finland’s meticulously ploughed bike lanes in winter). 

Bike lanes take away parking spots for paying customers:

This is debatable. Cyclists take up much less space than cars and have easier access to stores and shops (along with public transit users). Thus, bike lanes with bike parking have the capacity to bring in more paying customers; previous estimates in Germany and the UK show that pedestrianised areas can increase the number of shoppers by 20-40%.  And an Australian study determined that each square metre of space allocated to cars contributed just $6/h in shopping expenditures, while each square metre of space allocated to bicycles brought in five times as much ($31/h).

A recent Globe & Mail article also highlighted the problem of traffic congestion and excessive commute times potentially affecting the economic performance of urban centres in Canada. The Toronto Board of Trade’s international city rankings on Prosperity, which measures cities on a number of economic, social and structural indicators, put only two Canadian cities in the top 10 overall (Calgary and Toronto); none cracked the top 12 for transportation. Clearly driving, which has the highest mode share in Canada, is not all that efficient.     

If you want more economic convincing, a writer at the Economist makes a good case for bike lanes (in NYC) ‘from an economic perspective;’ which is definitely worth a read.

Some final thoughts

I think that many people are aware that the design of our residential spaces (at least in North America) is not sustainable. By comparison, we are much more slowly piecing together how our commuting/convenience lifestyle may be at least partially to blame for our growing waistlines and associated chronic diseases. Many people say they would like to do something to change but when it comes down to it, they can’t sacrifice the convenience.  I think we all must be willing to try new things and accept some level of inconvenience if we are to put a halt to both environmental degradation and obesity.  At the same time, we need to measure the impacts of these changes to determine how we can do better, and that public money is spent wisely.  Cyclists need to do their part as well: respect pedestrians, the rules of the road, and not assume that pedestrians or motorists will behave in the right/legal/expected way. Finally, bike lanes are not a be all and end all of sustainable transit – the trick will be balancing the needs of all types of active (e.g. biking, walking, & rollerblading) and public (e.g. rail, tram, bus, etc.) transit modes while making driving less desirable.
WHITEHEAD, T., SIMMONDS, D., & PRESTON, J. (2006). The effect of urban quality improvements on economic activity Journal of Environmental Management, 80 (1), 1-12 DOI: 10.1016/j.jenvman.2005.01.029

Lee, A., & March, A. (2010). Recognising the economic role of bikes: sharing parking in Lygon Street, Carlton Australian Planner, 47 (2), 85-93 DOI: 10.1080/07293681003767785

Monday, April 4, 2011

Is green good for our health?

Is being in a ‘green’ environment good for our health and well-being? Are we starved of this connection with nature? Richard Louv thinks so, author and chairman of the Children and Nature Network.  He has coined the term ‘nature-deficit disorder’ to reflect the psychological, physical and cognitive repercussions of our lack of contact with nature, especially among children in their vulnerable developing years.  Although Mr Louv specifies that this is not a formal diagnosis, I am not in love with the term because I find that it does bring forth this meaning to me. I admit that I haven’t yet read “Last Child in the Woods” (am planning to once the single copy on loan at UO has been brought back finally), but I wanted to investigate the scientific evidence for this idea a little further.  And then discuss, in the grand scheme of things, whether the evidence really matters anyway.

The Child and Nature Network has been busily compiling together the evidence base for nature and health.  While it is important for an advocacy group to do this, I find it somewhat biased from my perspective as an epidemiologist – where are the studies that examined these types of relationships but didn’t find anything? So like any good epidemiologist would do, I set out to look for some systematic reviews and meta-analyses.    
Without much looking I came across a recent systematic review that sought to examine studies that compared health outcomes in natural and synthetic environments, usually over a short duration. Twenty-five studies were included, with most being cross-over or controlled trials; although seven were randomized controlled trials. The most common outcomes were scores on various self-reported emotions. This is somewhat problematic in that respondents often can guess what is being studied (especially if it’s a non-randomized cross-over study) and will sometimes adjust their responses. More robust study designs (such as RCTs or at least randomizing order of exposure to each of the environments) can help to mitigate this bias. Other common outcomes included physiological measures such as cardiovascular functioning (blood pressure or pulse), and hormone levels (salivary or urinary cortisol, amylase, and adrenaline). Less common outcomes included immune function, physical activity, motor performance, cerebral brain activity, engagement, memory recall, and sleeping hours. There were too few of these to conduct a meta-analysis so I won’t discuss them further – you can get more info here.

The meta-analysis revealed (see Table 1 above) a possible benefit of natural versus synthetic environments for energy, anxiety, anger, fatigue and sadness. No benefit was seen for more objective measures like blood pressure and cortisol levels. There was a benefit reported for attention before effect sizes were adjusted for baseline levels. Because only 3 out of the 5 attention studies had baseline measures, this may have reduced statistical power, as the effect size decreased only slightly but the confidence interval increased.

Important points to keep in mind:  

·         Most of the included studies were experimental in design and included college students, adult males, or physically active adults – so the overall finding of the meta-analysis is not generalizable to the overall population, or to children 
·         Outcomes were examined over a very short duration. Some beneficial effects may take longer to manifest and/or require repeated or prolonged exposure to the natural environment
·         We’re not sure what exactly in the natural environment is responsible for these beneficial effects. Does this matter?
·         I am a little concerned with regard to the small number of studies, as well as study quality (this was not formally assessed). We may find a different association with a larger number of high quality studies

What does this all mean then? Over the short-term natural environments may reduce negative emotions and improve energy levels but they don’t appear to improve some cardiovascular and endocrine measures of health. Of course, I have to add the requisite last line: ‘more studies of high quality are needed,’ to make any definitive conclusions.         

Now from my own expertise and knowledge, I know that there have been more and more studies conducted to determine how the residential environment influences physical activity and/or obesity. This is a difficult area of research – perhaps why results have been mixed and effect sizes often small in comparison to the effects of individual and family characteristics. As I discussed in a previous post, some of these studies have found a positive association between the availability/amount of green space and the physical activity and obesity levels of area residents (in both adults and children). For the most part however, these have been cross-sectional associations, and overall, findings are not consistent from study to study. Putting this aside, we’re not even sure if it’s the greenery itself or simply the open space that invites people to be more physically active. Certainly greenery adds to the aesthetics and quality of the built environment, and aesthetics, as a general theme, has been previously associated with physical activity and obesity (see my previous post). Who knows though, we’d have to ask people why.       

In summary, the evidence of nature and health isn’t hugely convincing but not dismissive either – it’s there in some form. What we don’t know is whether it’s simply being active and away from our gadgets that helps the most – perhaps it’s not necessarily the ‘nature’ itself. Whether it’s the chicken or the egg doesn’t really matter to me and probably will never be totally discernible. As a society we are much more sedentary then in days gone by, and so it follows, less connected to nature. Green spaces can recycle the harmful outputs of urban living and add to the quality of our living spaces. To me, these two concepts go hand in hand. Paraphrasing a remark made by the artist Robert Bateman that was reiterated by Mr. Louv: if we don’t know about nature, we will be less likely to care for it and do something to preserve it. This is especially important among our children who will be the ones left to take care of the planet. Getting outside gets us physically active and connected to nature. So even though the evidence may not be sound, there is no harm in advancing this issue – it can only improve the quality of our spaces and help to sustain the world for future generations. Perhaps what is needed now are well conducted intervention studies to determine how green spaces can best be designed to maximize health, well-being, and sustainability benefits.

Bowler DE, Buyung-Ali LM, Knight TM, & Pullin AS (2010). A systematic review of evidence for the added benefits to health of exposure to natural environments. BMC public health, 10 PMID: 20684754