It's fair to say that I'm confident they work. I've tried them myself. I know that they will detect alcohol. However, developing standards for instruments or devices that test environment is very different from developing a standard for testing blood alcohol by way of a direct analysis of a person's breath.
I am currently involved in a committee that is setting standards for alcohol interlock devices, and the number of considerations when you are looking at something outside of a laboratory and not testing an individual directly makes for a much greater challenge. For example, I dare say that everyone on this committee drives a different car. The dissemination of alcohol molecules through different sizes of cars will be different. Most of these devices actually are.... They suggest that they can be used ambiently, but there's a greater suggestion that they actually are placed directly in front of the individual to get a breath sample, albeit without a mouthpiece and without breathing directly into them.
I know there have been suggestions that they be held six inches in front. With regard to one of the ones I have with me, their suggestion is two inches. That's a lot closer than six inches. It depends on the manufacturer. They all make it very clear that the further away you are, the less likely you are to get a result that is reliable.