I'm not a chemist, but I feel that this might be a good place to ask this question:
I keep a full (unopened) bottle of windshield washer fluid in my trunk for reserve, as many people probably do. The fluid contains methanol (methyl alcohol), about 30% of the total weight. Methanol is highly toxic if swallowed or inhaled.
Just recently it was a warm spring day with sun shining all day. The interior of the car and the trunk must have gotten really hot. When I got home from work (at night, it was a lot cooler then), I opened the trunk to find a puddle of blue liquid in there – the cap of the washer fluid bottle had somehow popped open, but there was still a protecting seal that had remained in place. The seal does not let any liquid out, so it was a mystery how this puddle had formed inside the trunk.
I suspect that the explanation is in the boiling point of methanol being fairly low (about 150 degrees) and even with it not boiling, it still vaporizes at a fast rate when it gets hot. So apparently methanol started to vaporize inside the bottle and found its way out through a tiny leak in the seal. This has probably happened over the course of several hours. I estimate that about 10 oz of the contents of the bottle got out. If most of it is methanol, it’s a lethal dose if inhaled in a small compartment such as the trunk, or the entire car.
10 oz of methanol weighs a little over 200 grams. The trunk has volume of about 1 cubic meter. The concentration would thus be 200g/m^3. This is a) highly flammable, b) highly toxic – a couple of breaths and you are severely poisoned (the threshold level for immediate life threatening danger is a concentrate of about 10g/m^3).
Anyone else find this a bit worrying? Or is my reasoning really wrong here? Even though I did not directly breathe in the fumes in the trunk, I still drove the car for a couple of hours, and the fumes are likely to spread inside the cabin as well. Also, methanol odor is very weak at low concentrations, so even if you don’t smell it, breathing it in over a long period of time can have serious long term effects.