Measuring lethality in reduced expected heartbeats

No, chaosmage is just a very active hummingbird. Hitting keys on the keyboard takes work when you only weigh 10 grams.

(1800 heartbeats in 80 seconds is 1500 beats per minute, as opposed to the human average of around 80 beats per minute)

This comment made me notice a flaw in measuring lifespan in heartbeats: inducing tachycardia would increase the number of heartbeats you experience (unless it decreases your actual lifespan by more than that).

Associating cigarettes with time might help me in reverse. Cigarettes disgust me. My self-image strongly states that I am a person who doesn't do stupid things like smoke cigarettes. Would I smoke a pack of cigarettes per day? Hell no! Would I smoke three packs per day? That would be suicide.

But I do waste time. 80 seconds per cigarette works out to 30 minutes per pack. If I thought of wasting 30 minutes the same way I think of smoking a pack of cigarettes, I would waste a lot less time.

I can't visualise 1800 heartbeats,

On reading this in the Recent Comments sidebar, I thought “1 heartbeat = 1 second, 1800 seconds = half an hour” in less time than it takes me to tell left from right.

This is another thing that just came to my mind: You have to distuingish between how the survivor's distribution of lifetime looks like, as stated in your example with driving. Some die very young, but most live. With smoking however you can reasonably say that they reduce their lifespan proportionally, in addition to some risk to die very young. I know of no good way to visualise this.

It does assume linearity but not irreversibly.

You can calculate conditional probabilities based on chances of quitting and not quitting cigarettes in the future.

Linearity is a more interesting issue. There the model of cancer being caused by a single mutation. In that model a single cigarette has a certain chance of creating a single mutation. If you deeply believe in that model you can justify linearity to some extend.

In reality cancer however seems more complicated. But it's hard to calculate the micromorts of a single cigarette. We don't have a good theory for doing so.

It similar to other regulation of substances that harm us. We can measure in a lab how much of a substance you need to give rats to kill 50% of them. It's plausible that a 1/1000 of that substance can still do harm to the rats but we have no clear way of finding out.

We just have models that try to use the existing data to produce risk estimates that are as good as possible. Then we use those estimates to make policy. The models are best we have at the moment so they seem to be better than nothing.