Laser irradiation as a novel alternative to detach intact particulate matter collected on air filters

Abstract

Airborne particulate matter (PM) is collected on specific filters. For subsequent testing, the PM should be detached intact from the filter. Liquid extraction (LE), the standard method to detach PM from air filter surfaces, is challenging and can be tedious. Laser irradiation has been used to characterize PM on filters, but not to detach PM from filters for subsequent testing. A feasibility study was conducted to assess the potential of laser irradiation to detach PM from air filters. Laser-detached PM was deposited on a pre-weighed glass plate. PM detachment and collection were conducted in a single step. PM-coated air filters were subjected to visual inspection, gravimetric assessment of captured PM, and spectroscopic scanning (ATR-FTIR, SEM-EDS, and XRD) before and after laser irradiation. Laser irradiation PM detachment efficiency was up to 78 %. Functional groups, elements, and minerals of PM collected on filter surfaces disappeared or significantly decreased after irradiation, demonstrating detachment, without suffering a change in their nature. No evidence of filter fragments was found in the detached PM. Laser irradiation was i) an easy, ii) rapid, and iii) single step procedure that iv) detached PM, v) didn't detach filter fragments, vi) didn't change PM composition, and vii) is amenable to automation and high throughput. Laser irradiation to detach PM from air filters as an alternative to LE is worthy of further study and development.