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Comment by IanCal | Hacker News Reader

Well, there are a few reasons here.

1. Installing a permanent sensor means ensuring some power source

2. Any kind of planning / permissions needed to sort it out

3. They're fixed

The first two simply aren't problems if you whack them on a car. No approval needed, no lengthy agreements about the look & impact of placing them around.

Three is really important. While the same money spent on fixed sensors gives greater time resolution, it'll give worse spatial resolution. Is it worth sticking a permanent sensor down to find out that actually the pollution levels never get high enough to be a problem? How many side-roads will get covered?

> This doesn't seem very useful

A huge amount of spatially dense readings across cities? That doesn't seem like it might be useful to you?

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How often does a google car go past a location? I always assumed it was less than once a year based on how often they update street view where I live.

Plus, you have no idea what time of day the car will be passing through a location.

So you can't compare the data points over time - they're not taken the same time of day. And I'm not sure if you can even compare different regions - your data may tell you that one part of the city has cleaner air than another, but it's only because one part of the city was measured in the morning and another part of the city in the afternoon.

It's unlikely that this would be the last step in climate data collection---it feels more like pilot program, ironing out the practical issues with attaching such a sensor alongside a suite of existing sensors in the form-factor of a car.

... which might be very clever of Google, since they have a self-driving car program right around the corner that would promise to put O(10,000) of their cars on the road, driving continuously in densely-populated cities. Don't mistake the short game for the long game. ;)

> Plus, you have no idea what time of day the car will be passing through a location.

I don't, but I assume google does.

> So you can't compare the data points over time - they're not taken the same time of day

Not in a simple way, no. But to say it doesn't provide useful information seems odd when the article says

> Independent scientific analysis confirmed that the mobile sensor system worked for collecting street-by-street data, and could improve upon the regional network of sensors operated by the Environmental Protection Agency.

How do you read that quote as a positive thing? The first half merely says it was successful in collecting data and the second half uses weasel words "could improve".

I've worked on projects in the past where we collected a ton of data like this, gave it to some poor graduate student or post-doc to do a bunch of data wanking with it, only to produce throw-away papers in bad journals because even. Though it was a huge amount of data it wasn't good data.

Lots of people buy and install home weather systems, and hook up their data feeds to Weather Underground (or what have you). I'm not a climatologist/meteorologist, but my understanding is that personal weather stations provide a serious bump in data volume. Perhaps the future of pollution data looks something like that? Add a few pollution sensors to a personal weather station? Market a stand-alone pollution sensor with "health" justifications?

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