Why did roasting of copper(II) sulfate pentahydrate hurt my nose? I want to use copper(II) sulfate as rocket propellant additive in hope that it will alter the flame colour. Because water is not welcome in rocket fuel, I decided to dehydrate the crystals.

First I tried stainless steel mess tin, but that produced some smoke warning me that it's reacting. So I switched to aluminium mess tin, that one didn't smoke.

But still some fumes, presumably steam was produced. I continued roasting. Almost at the end, I noticed that my nose hurts in the inside a little.

I suppose copper sulfate has got in there. Do you think I risked badly, or is it just weak irritation? How can I avoid it next time, apart of using fumehood?
Roasting of copper(II) sulfate at elevated temperatures generates sulfur trioxide, which would hurt your nose.  

$$\begin{align}
\ce{$\underset{\text{(blue)}}{\ce{CuSO4.5H2O}}$ &amp;-&gt;[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][100\ \mathrm{^\circ C}] CuSO4.H2O + 4H2O}\\[6pt]
\ce{CuSO4.H2O &amp;-&gt;[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][\gt\ 200\ \mathrm{^\circ C}] $\underset{\text{(white)}}{\ce{CuSO4}}$ + H2O}\\[6pt]
\ce{CuSO4 &amp;-&gt;[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][] CuO + SO3}
\end{align}$$