Metaproteomic analysis of air particulate matter provides information about the properties of bioaerosols in the atmosphere and their influence on climate and public health. In this work, a new method for the extraction and analysis of proteins in airborne particulate matter from quartz microfiber filters was developed. Different protein extraction procedures were tested in order to select the best extraction protocol in terms of protein recovery. The optimized method was tested for extraction of proteins from spores of ubiquitous bacteria species and used for the first time for the metaproteomics characterization of filters from work environment. In particular, ambient aerosol samples were collected in different working environments, i.e. a composting plant, wastewater treatment plant and agricultural holding. One-hundred seventy-nine, 15, 205 and 444 proteins were successfully identified in composting plant, wastewater treatment plant, and agricultural holding, respectively. All identified proteins were mainly originate from fungi, bacteria and plants which is in line with the major categories of primary biological aerosol particles. The paper is the first metaproteomic study applied to bioaereosol samples collected in occupationally relevant environmental sites providing interesting information on the composting, wastewater treatment and feed blending processes. Significance This manuscript describes the metaproteomic analysis of aerosol samples collected in work enviroments. This is a novel use of aereosol samples and is needed as there is no really comprehensive way of analysing aereosol samples from a metaproteomic point of view. This paper could help to advance methods for metaproteomic analysis of bioaersols, specifically by comparing protein extraction protocols and pairing the best performing extraction protocol with a gel-free protein separation procedure applied for the first time for analysis of bioaerosol samples. The obtained data showed as bioaerosol was essentially made of fungi, bacteria and plant proteins, many of which could be associated to possible aerosolisation and could be a major health concern for workers on site and to the populations residing in neighbouring area.