Some rather unscientific responses here
.. let me clear some things up.
the heat generated it's not really healthy i would avoid putting 3 rig(for example) in your room just to heat it
Complete rubbish. It's possible that trace amounts of solvents or chemicals used in the manufacturer of circuit boards will be emitted as the temperature of the component is raised, however these will only ever be trace amounts and will decrease extremely fast over time. Even electric radiators will have the same 'chemical smell' (more from my experience) and recommend you run them at full power for 24 hours in a ventilated place before general use.
Mining equipment has two ratings - electrical consumption and thermal output.
For clarity, let's ignore the electrical consumption and just focus on thermal output (it will usually be close to electrical, depending on the type of mining it may be much less but never more).
If your mining equipment (CPU + GPU + general thermal emissions from motherboard, power regulators etc) outputs 400 Watts thermal - this will be equivalent to an electric or other type of radiator rated at the same energy output (thermal).
The amount of thermal energy radiated from mining hardware does not change based on the temperature of the surrounding air. The temperature of the surrounding air affects how efficiently the heat from the thermal interfaces (i.e. heatsinks) will be transferred to the air the passes over them. The bigger the difference between the air temperature and the heat source temperature, the more efficiently the energy will be transferred (assuming all else is equal). This is why in a cold room air emitted from a PC might seem hotter than a hotter room.
Lastly. something to bear in mind is that most electric heaters are not designed for full power 24/7 operation. They tend to cycle on/off based on internal temperature and any thermostat settings. Mining hardware will continue to output heat at a constant rate irrespective of the temperature of the air around it. Of course, if the air in the surrounding area becomes so hot that it can no longer cool the mining hardware fast enough and the fans can't spin any faster, most equipment will clock lower to prevent damage to components. I'm not sure if this is the case for ASICs as I've never run one but it's certainly the case for CPUs and GPUs.
Hope that helps.
Great post. One point, that any fumes that come out will be filtered by the constant work of the lungs. Of course, a good air filtration could possibly take away any chemicals that may be outputted. As far as cooling the air, not sure how much of a difference this would make, and it's probably been tried, but there are those plastic bottles that juices come in. I wonder if putting water in sealed ones up to about 2 inches, freezing them, and putthing them near a machine would have any affect for a measurable amount of time. If one is a serious miner one could imagine buying a separate freezer and keeping a supply of them going. But there is this for $115:
"The Honeywell 15-Pint Indoor Portable Evaporative Air Cooler provides efficient and inexpensive cooling in areas up to 100 square feet. Standing just over 2-feet tall on durable casters for easy mobility, the Honeywell evaporative cooler is lightweight a.Cools up to 100 square feet.Dehumidifies up to 15 pints of moisture.Cleanses air with carbon air filter.Provides natural air circulation and even distribution of cool air.Small and portable unit for easy mobility.Requires power of only 120 V / 60 Hz, 60 W, and 0.45 A.Air flow up to 150 CFM.Features remote control, LED display, and automatic shutoff timer.Product dimensions: 25.4 by 15 by 9.8 inches (H x W x D).The Honeywell CSO71AE 15-Pint Indoor Portable Evaporative Air Cooler is lightweight and energy-efficient, yet cools areas up to 100 square feet..Efficient Cooling and DehumidifyingThe Honeywell 15-Pint Portable Evaporative Air Cooler provides improved air circulation thanks to its oscillating louvers and three fan speeds, while its honeycomb cooling media offers fast cooling...."
which would of course be counterproductive in cold weather.