# Vans sampling the air on the interstate? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 3, 2013, 7:00pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760 "2013-04-03T19:00:15Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Mama\_Zappa](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@Mama\_Zappa](https://boards.straightdope.com/u/Mama_Zappa)\ **Post date:** [April 3, 2013, 7:00pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/1 "2013-04-03T19:00:15Z")
A few times lately, I’ve been entering or exiting an interstate, and have seen a white van (standard small van, larger than a minivan), with signs by it that say “Surveying”. In small letters somewhere on the van there’s something like “department of environmental testing”. A while back, someone told me that there are often mobile testing sites on ramps, that can send you a ticket if your car is putting out too many pollutants. Then of course I started noticing those vans. They may well have been there all along but I just ignored them, I suppose. I’ve also seen some web references suggesting that this is part of traffic monitoring - i.e. if general patterns are too heavy, this will pick that up (because of the air quality) and the data will be be used for… something. So: anyone know what the real purpose of such vans might be? Are they doing it to catch emissions-testing failures? Can they really send you a ticket in the mail? (This is in Virginia, for what it’s worth, but I’d imagine other areas have this as well). ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [April 3, 2013, 7:09pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/2 "2013-04-03T19:09:00Z")
It could be that they are establishing background pollutant levels along roads and off-ramps and such. I used such data as an intern for a county environmental monitoring agency in the mid-90s. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [April 3, 2013, 7:32pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/3 "2013-04-03T19:32:13Z")
Considering that actual emissions testing stations still have to fit a hose to your exhaust pipe of your car which is standing still in a mostly-enclosed garage, I’d say there’s no way that anyone could check individual vehicle emissions by driving a van around. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [April 3, 2013, 8:44pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/4 "2013-04-03T20:44:02Z")
This is happening in many states. But not with a van parked by the road. It’s done with photographic devices by the road. The take a photo of a passing car’s license plate, and also take an infrared and/or UV photo of the air behind the passing car. This photo is analyzed to detect emissions from the car. If too high, you get a ticket in the mail. [ROADSIDE EMISSIONS & REMOTE SMOG TEST CHECKPOINTS](http://www.smogtips.com/remote_sensing.cfm) Google roadside emissions detectors to find many more articles. ETA: Okay, just read that article more closely. You get a warning letter, not a ticket. ---
**Author:** ![JerrySTL](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@JerrySTL](https://boards.straightdope.com/u/JerrySTL)\ **Post date:** [April 3, 2013, 9:39pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/5 "2013-04-03T21:39:11Z")
> [@Ferret\_Herder](#): > > Considering that actual emissions testing stations still have to fit a hose to your exhaust pipe of your car which is standing still in a mostly-enclosed garage, I’d say there’s no way that anyone could check individual vehicle emissions by driving a van around. Missouri use to do it around metropolitan areas such as St. Louis. That was years ago and not all that effective. Now they just test cars newer than 1996 by hooking up a computer to the ODBII port on the car. Basically if your Check Engine Soon (CEL) or Service Engine Soon light is on, you’re going to fail. In fact there’s a few things that won’t trip the light and my still cause a failure. This has replaced the old tail pipe checks. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [April 3, 2013, 9:50pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/6 "2013-04-03T21:50:45Z")
I will admit that I just took our (now-sold) 1999 car in for testing and didn’t confirm that they still hooked up a hose to the tailpipe, since I was sitting in the booth and not paying any attention. For all I know they could have tested by flying paper airplanes through the exhaust stream. 😃 ---
**Author:** ![60wag](https://avatars.discourse-cdn.com/v4/letter/6/7ba0ec/32.png) [@60wag](https://boards.straightdope.com/u/60wag)\ **Post date:** [April 3, 2013, 9:53pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/7 "2013-04-03T21:53:18Z")
We have the test vans in the Denver metro area. If you drive by the vans enough times and produce clean enough exhaust, they waive the requirement to bring you car in for the biannual dynomometer test - so yes, they can attach air sampling data to a specific vehicle that drives by the mobile test station. the van is parked when it is doing the air sampling. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [April 3, 2013, 10:12pm UTC](https://boards.straightdope.com/t/vans-sampling-the-air-on-the-interstate/654760/8 "2013-04-03T22:12:04Z")
Well, color me impressed… though with how infrequently we do any driving outside of a couple suburbs (and a few out-of-state roadtrips a year), I don’t think we’ll ever get randomly tested if they do that in Illinois.