1.) Breathalyzers do not directly detect blood alcohol concentration. Instead, they measure the concentration of alcohol in the breath, which is evaporating out of blood processed by the lungs, and infer blood alcohol concentration from the results. One of the reasons Breathalyzer manufacturers recommend waiting 20 minutes from your last drink before blowing into a Breathalyzer is that it is important to only measure alcohol that is coming from the lungs in order to get an accurate indication of blood alcohol content.
2.) The most common form of breathalyzer used is the oxide semiconductor breathalyzer. This works by carrying out a redox reaction of ethyl alcohol to acetic acid and water and measuring the current generated as an indication of how much alcohol is being reacted in the breath.
3.) The oxide semiconductor is an accurate measure of alcohol content in the breath. Legal challenges of breathalyzer results generally instead focus on the more controversial assumptions that the breathalyzer makes:
·That Henry’s law applies
oThis assumes that there are no
interfering volatiles in the bloodstream
oThis assumes that breath temperature is not variable
·That nothing in the body is reacting to create or consume alcohol that can be detected in the breath but that is not in the bloodstream.
oIt has been claimed that acid reflux can cause alcohol to be
generated and detected in the breath in a manner that doesn’t
reflect concentration of alcohol in the blood.
4.) There is little doubt that breathalyzers do not provide a foolproof measure of blood alcohol concentration. However, it is equally incontrovertible that breathalyzer results are used to convict people of DUI. It is also clear that they can provide useful information to would be drivers, often leading to better informed decisions. For a list of five things that cause a false positive breathalyzer reading (it says you're drunk when you're not) and three things that may cause a false negative breathalyzer reading (it says you're sober when your not) be sure to check our blog entry on the Van't Hoff Equation and Breathalyzers.
1.) We scoured the internet looking for objective reviews of consumer and professional breathalyzers. Unfortunately, every review we found was published by a manufacturer or a retailer of breathalyzers. Not exactly an objective source. What we have found is that reputable retailers sell the AlcoMate and AlcoScan line of products. That is why we've chosen these as our primary product line.
2.) We were able to find one review where AlcoHawk and AlcoMate were directly compared by someone other than a breathalyzer retailer. They (Popular Mechanics) concluded that the AlcoMate Prestige (similar to the AlcoMate Premium but without the convenience of pre-calibrated sensor modules) was big, expensive, and very accurate. Unfortunately there was no comparison of the AlcoScan and AlcoMate products, which are more comparable to one another on price.
3.) Breathalyzers, even the very affordable models, can be used in concert with BAC Tables and common sense. If, under controlled conditions, your breathalyzer matches your predicted BAC per BAC tables, then you'll have some confidence in the readings it gives you under less controlled circumstances, such as towards the end of an evening where you haven't necessarily been keeping track of every drink's exact alcohol content.
4.) We advocate using a comfortable margin of error. Even though the FDA certified breathalyzers are accurate to +/- 0.01% BAC, we don't recommend driving at or above 0.05%. In fact, we won't drive until our reading is at or below 0.02%. Keep in mind that, while 0.08% is the legal limit in most states, NHTSA has shown that even at 0.05% your chance of a fatal accident increases eleven-fold.