big Ae/Be clusters. This supports a slightly longer star formation activity for the N160 region ($\sim$10-30 Myr). Both regions are nevertheless quite young compared to the time necessary for carbon dust to be injected in the ISM by the stars and thus participate in the formation of PAHs in the clusters. We finally note that recent studies suggest than the rate of AGB-produced PAHs compared to the rate of PAHs formed in the ISM may also change with metallicity [@Sandstrom2012].\
In conclusion, although the obvious anti-correlation between f$_{PAH}$ and the radiation field favours the destruction of PAHs as a straight forward explanation for the low PAH fraction we observe, the young age of the clusters could be an additional explanation for the absence of PAH in our three H[ii]{} regions.

Star Formation rate
-------------------

Since the total bolometric IR luminosity traces the emission of stellar populations enshrouded in dust cocoons, this quantity is thus very often used to quantify the star formation obscured by dust [@Perez-Gonzalez_2006; @Kennicutt2009]. We first obtain the total IR luminosity map of the complex by integrating the resolved SEDs in a $\nu$-f$_{\nu}$ space:

$$L_{IR} = \int_{8~\mu m}^{1100~\mu m}L_{\nu}~d\nu
\label{eq2}$$

In the SED fitting technique we use, we model the stellar contribution to short wavelengths as a separate component. This contribution is subtracted before performing the integration to only take the thermal emission of dust into account in the calculation. We use the IR-based calibration of @Kennicutt1998 to derive a star formation rate map of the region:

$$\frac{SFR}{M_{\odot}~yr^{-1}}=\frac{L_{FIR}}{5.8 \times 10^9 L_{\odot}}
\label{eq3}$$

@Jones2005 estimated the integrated luminosity of the N159 complex (integration of the SED up to 100[$\mu$m]{} combining [[*Spitzer*]{}]{} and KAO data). They found that the integrated luminosity was consistent with the observed radio emission, assuming that the H[ii]{} region was a cluster with a normal Initial Mass Function (I