Thanks, Marcus, for asking whether our study only plans to focus on commuters. The answer is yes: we do plan to focus on commuters. Specifically, we will ask study participants to carry our gear for ~24 hour periods bracketing 5 morning commutes over a 2-week period. We chose this focus for several reasons:
- In addition to measuring air pollution exposures, we will be measuring cardiovascular responses to those exposures (specifically blood pressure and heart rate variability). Since time of day affects blood pressure, we want rides that occur at approximately the same time for each subject.
- We know from a number of sources that there’s a lot of day-to-day variability in air pollution levels in NYC. This fact is important for the statistical design of our study: we will compare cardiovascular parameters for a given rider on high- vs low-pollution days. There’s also a lot of variation across places (e.g., the west side bike path vs. 6th Ave). By limiting our study to commuters, we will minimize the spatial variation across rides (assuming that most folks take more-or-less the same route each time they commute). This will limit the possibility that the spatial variation cancels out the temporal variation.
- Framing the study in terms of commuting allows us to make comparisons with other commuting modes (see, e.g., this study that colleagues at Columbia are carrying out).
We probably could have designed the study around other biking activities, but commuting seemed to fit our hypotheses best.
We are also collaborating with WNYC to develop some cool tools that folks can use to explore air pollution exposures on rides of all types. Sign up here (if you haven’t already) to be considered for the main study, and to receive updates on these new tools.