I know that when a human body burns, it smells… bad. I worked on a wrecker service and we got calls from time to time on car fires. We usually got there just before the remains were removed. My firefighter friends tell me of the victims of house fires.
So… when someone is cremated, how does the crematorium handle this issue? Special chemicals to hide/kill the smell? Special ventilation? Is it so hot that the smell doesn’t have time to develop?
What’s the Straight Dope?
The trick is high heat (760° to 1150°C) and good chamber/chimney design. The gases do not go directly up the chimney, but cycle round over the burners to give the gases a chance to reburn. There may even be a secondary afterburn chamber. This gets rid of most of the burned meat volatiles. The chimney will also probably have a cooler, scrubber and filter (to meet environmental requirements). Waste heat may be recycled to heat the crematorium. What goes out the chimneys is warm CO[sub]2[/sub] and H[sub]2[/sub]O.
Si
In India where many cremations take place in public small pieces of sandalwood are often added to the pyre. The use of sandalwood carries some symbolic meaning as well but I imagine that it also helps to improve the smell.
The number of family home funerals is increasing due to a lot of factors but it looks like back yard cremation might NOT be an option until far in the future! 
If you could and would opt for such a thing (can you get THAT much heat from charcoal?) how long would it take for the smell to go away? I guess if there is a HUGH pyre the rising gases would carry the smell up, up and away from those in attendance and dissipate in the upper air?
I’ve never burned a carcass, so I have no idea. However, if I was going for a home cremation I would try for a wick effect. Takes longer to destroy the body, but it pretty effective at reducing it to almost nothing. Pretty smoky, though.
Recently, a hindu man won a battle in the UK to have an “open-air” cremation - however, this is not a fire in a field. The eventual facility must be enclosed and comply with environmental and pollution regulations. I prefer woodland burial myself.
Si
Why would human meat smell this bad ? Is it that different to animal (pork, beef) as grilled on a bbq ?
I don’t think that it smells particularly bad. I’ve witnessed a lot of open-air hindu cremations and have never noticed that it smells bad. Just burnt wood and charred meat. Kinda bbq-ey - I suppose that some people are uncomfortable with connecting that particular smell with the knowledge that it stems from a human body and not a badly burnt roast.
This.
I was there when my father was cremated. There was no meaty smell.
There isn’t any additional smell (meaning as opposed to cooking meat, which has been prepared) from the internal organs, hair, etc.?
Can’t say that I’ve noticed. There probably is, but together with every other smelly thing that litters the cremation grounds in Varanasi, for instance, it hasn’t been enough to make an impression. The only smells I distinctly remember are burnt wood and charred/burnt meat. Lots of smoke.