Effect of spring grass fires on indoor air quality in air-conditioned office building

Abstract

Open biomass burning (OBB) is a significant air pollution source, but it is still not clear to what extent OBB events affect indoor air quality [1]. Outdoor and indoor measurements of submicron particulate matter (PM1) were conducted on 25–29 April (2019) in the capital city Vilnius (Lithuania). Fires from neighbouring countries (Belarus, Ukraine and Russia) and in the vicinity of Vilnius broke out during the measurement campaign. The temporal evolution and transport of OBB plume were investigated by combining the air mass backward trajectory analysis and fire satellite observation (MODIS) database. Measurements of the PM1 chemical composition in real-time were performed using an aerosol chemical speciation monitor (ACSM) and an aethalometer. Organic matter was the clearly dominant component, accounting for >70%, in both indoor and outdoor PM1. The air filtering system of the office building removed approximately up to 55% of PM1. Despite a significantly lower PM1 pollution level in the office, highly acidic indoor PM1 could have harmful effects on the human health. Source apportionment of particulate carbonaceous matter revealed a significant importance of OBB-related particles (average 56%) to indoor air.