[Avodah] Hevel and bor

[Shoshana L. Boublil]

> From: Micha Berger <micha at aishdas.org>
> Subject: [Avodah] Hevel and bor

> My father (CC-ed, kindly use "reply to all) asked me to ask the chevrah:
>
> According to the gemara, eg BK 50b-51a, a bor that is 10 tefachim deep
> or more contains hevel which is dangerous to breathe. And even if it's
> less than 10 tefachim, the air is still injurious.

10 tefachim, is at least 2 feet deep.

> My father was surprised that he couldn't find any rishonim or acharonim
> who compare this to the experimental data. Not whether to dismiss it or
> explain how it works -- no one seems to think it's intriguing and worth
> discussion?!

Here is a general one:

http://www.msha.gov/KIDS/ABANDON/UNDER.HTM

Bad Air (Lack of Oxygen or the Presence of Deadly Gases)
The normal atmosphere we breathe is composed of several gases. Oxygen, an 
important part of normal atmosphere, is the only gas that will support life. 
Mine atmosphere or mine air maybe contaminated with gases that are poisonous 
and may displace the necessary oxygen to support life.

Minerals and decaying timbers use up oxygen. Carbon dioxide is given off by 
decaying timbers. Some gases are also released from rocks and decaying 
vegetable matter. In active mines, it is necessary to keep fresh air coming 
in from the outside to ventilate the places where miners are working. When 
mines are deserted, air no longer may be circulating or air passages maybe 
completely blocked by fallen rock or timber. In many abandoned mines, no 
fresh air is present below the surface. Persons have lost their lives even 
in shallow pits and wells because of bad air. Some abandoned mines also 
contain explosive gases which are easily ignited.

OTOH, the discussion of Hevel (or Havla) is part of a discourse given by Rav 
Nechemia Goldberg on the question of stopping the breathing machine for a 
dying patient to save anther ill patient:

http://www.medethics.org.il/articles/ASSIA/Emek2/183.asp

This is a copy of a collection of articles from Assia. It is in Hebrew, and 
worth studying.

>From reading the article, "Havla" appears to be Carbon Monoxide (poisoning) 
or Carbon Dioxide.  This actually matches what I saw in the quote I copied 
earlier in this post.

The articles contains Mareh Mekomot in the Rambam that discuss Havla and its 
dangers.

Shoshana L. Boublil