Berkeley has been having it's coldest/rainiest weather of the year during the last week. Really heavy rain last weekend. Unlike most of the year where everyone can leave their windows open because the weather is almost always sunny and 70.

They may have had a deadly amount of CO/particulates from their laser cutter in their apt but their ventilation kept them alive. Closing their windows during last week's rain/cold spells could have been deadly. Also there is a possibility of particulate buildup in vents that could have been released if they turned on their heat in an enclosed apartment.

CO leaves you with diminished capability to bind o2, breathing in a small enclosed apt leads to a buildup of CO2. This tragedy could be a combination of CO and CO2 inhalation.