I signed this, you should too:

Australian health and transport experts have today called on decision makers to enact urgent measures to support safe walking and cycling and social distancing during the COVID-19 pandemic. Letter here.

The Australian Government has recognised the importance of remaining physically active during the COVID-19 pandemic, and has listed exercise as one of four essential activities. As a result, many Australians have been getting active across the country by walking and cycling, but many areas lack sufficient space required to maintain critical physical separation.

Professor Rebecca Ivers, Head of School, Public Health and Community Medicine at the University of New South Wales has a special interest in health and transport and says,

“Not only do we need Australians to stay active and healthy, we need to consider how they can continue to do this safely during an extended period of physical isolation,

“Keeping active now and as we begin to get back on our feet is hugely important for our mental and physical well-being,

“The continued crowding in popular walking spots could be addressed with simple, temporary changes where we all live,” Prof Ivers said.

Dr Ben Beck, from the School of Public Health and Preventive Medicine at Monash University, has led the call from health and transport experts and is concerned for safety as our paths and cycleways are inadequate to handle the physical activity requirement during this crisis.

“In order to provide safe physical activity and social distancing for adults and children to exercise and move about their neighbourhoods, we need decision makers to enable rapid roll-out of social distancing infrastructure to support walking and cycling.

“We have seen numerous examples across the world of governments introducing reduced speed limits, widened footpaths, emergency cycle lanes and the closure of roads. As yet, we have not seen a similar response in Australia, and we need to act now,” Dr Beck said.

Experts also noted that safe cycling and walking will be imperative in reactivating our economy when social distancing measures are relaxed, enabling people to travel to work and school using transport modes that are both safe and healthy.

Join the conversation on social media under the hashtag #SpaceForHealth.

Media Release:

Are you sick of/from TRB

Every January, at the Washington, DC Convention Center, 15,000 people gather to exchange memes and viruses. I have attended most of the events held over the past 30 years. It seems like I get sick from most of those.

This year, I conducted a Twitter Poll to see if I was alone. The results below

Are you sick of TRB? A poll about the 2020 Washington DC Conference. Did you go this year, or not? And did you get cold or flu symptoms, or not, in the past six weeks?

16.9% TRB, ill
33.1% TRB, not ill
7.7%   Not TRB, ill
42.3% Not TRB, not ill
142 votes · Final results

A low resolution image of the logo of TRB - Transportation Research Board of the National Academies
A low resolution image of the logo of TRB – Transportation Research Board of the National Academies

The evidence from this poll of more than 142 people (coincidentally evenly split between TRB and non-TRB goers) is that you are more than twice as likely to report having gotten sick if you attended TRB (33.8%) than otherwise (15.4%). There were 71 attendees and non-attendees each in the sample, you can decide if that is sufficiently large to draw this conclusion. Obviously correlation is not causation, and there can be other causes:

  • Twitter users are hypochondriacs, easily suggestable and are faking illnesses after this was raised,
  • TRB attendees are world travelers (compared to non-attendees) and may have gotten sick elsewhere as well (which mitigates but does not absolve the Annual Meeting, as TRB is part of world travel they engage greater than the general population)
  • TRB attendees got sick from air and train travel, rather than the conference itself.

Nevertheless, I tend to believe these findings, they align with my priors and have an underlying mechanism. We can validate next year and with other conferences.

If it turns out we had coronavirus all along (for months prior to being aware of it), (people who are not dropping over dead or feeling the need to be hospitalized are not being tested in most of the world, indicating the death rate given the virus is probably much lower than reported, deaths are mostly known (though perhaps some are misclassified), cases are not) this might have been a major vector of transmission.

So in addition to the other known negative externalities of attending conferences, such as the pollution generated, we can add health effects. Do these outweigh the benefits from in-person exchange of knowledge?

The Healthiest vs. Greenest Path: Comparing the Effects of Internal and External Costs of Motor Vehicle Pollution on Route Choice 

On-road emissions, a dominant source of urban air pollution, damage human health. The ‘healthiest path’ and the ‘greenest path’ are proposed as alternative patterns of traffic route assignment to minimize the costs of pollution exposure and emission, respectively. As a proof-of-concept, the framework of a link-based emission cost analysis is built for both internal and external environmental costs and is applied to the road network in the Minneapolis – St. Paul Metropolitan Area based on the EPA MOVES and RLINE models. The healthiest and the greenest paths are skimmed for all work-trip origin-destination pairs and then aggregated into work trip flows to identify the healthier or greener roads in a comparative statics analysis. The estimates show that highways have higher emission concentrations due to higher traffic flow, on which, but that the internal and external emission costs are lower. The emission cost that commuters impose on others greatly exceeds that which they bear. In addition, the greenest path is largely consistent with the traditional shortest path which implies that highways tend to be both greener and shorter (in travel time) for commuters than surface streets. Use of the healthiest path would generate more detours, and higher travel times.
Route choice, Traffic assignment, Shortest path, Pollution, Emissions, Exposure, Intake

“Transit Makes you Short”: On Health Impact Assessment of Transportation and the Built Environment

How the p-value and coefficient changes with observation size
How the p-value and coefficient changes with observation size

Recently published:


This study conducts an in-depth analysis to alert policymakers and practitioners to erroneous results in the positive impacts of transit use on health measures. We explore the correlation of transit use and accessibility by transit and walking with self-reported general health, Body Mass Index (BMI), and height. We develop a series of linear regression and binary logit models. We also depict the coefficient-p-value-sample-size chart, and conduct the effect size analysis to scrutinize the practically significant impacts of transit use and accessibility on health measures. The results indicate transit use and accessibility by transit and walking are significantly associated with general health and BMI. However, they are practically insignificant, and the power of the large sample in our particular case causes the statistically insignificant variable to become significant. At a deeper level, a 1% increase in transit use at the county level diminishes the BMI by only 0.0037% on average. The elasticity of transit use also demonstrates that every 1% increase in transit use would escalate the chance of having excellent or very good general health by 0.0003%. We show there is a thin line between false positive and true negative results. We alert both researchers and practitioners to the dangerous pitfalls deriving from the power of large samples and the weakness of p-values. Building the results on just statistical significance and sign of the parameter of interest is worthless, unless the magnitude of effect size is carefully quantified post analysis.

Causes of Death Are Linked to a Person’s Weight

From the NYT: Causes of Death Are Linked to a Person’s Weight
“Linking, for the first time, causes of death to specific weights, they report that overweight people have a lower death rate because they are much less likely to die from a grab bag of diseases that includes Alzheimer’s and Parkinson’s, infections and lung disease. And that lower risk is not counteracted by increased risks of dying from any other disease, including cancer, diabetes or heart disease.”
So if suburbs cause obesity, and obesity reduces the death rate overall, then suburbs are good and cities bad for public health.