Particulate Air Pollution from Bushfires: Human Exposure and Possible Health Effects

Abstract

Toxicological studies have implicated trace metals adsorbed onto airborne particles as possible contributors to respiratory and/or cardiovascular inflammation. In particular, the water-soluble metal content is considered to be a harmful component of airborne particulate matter. In this work, the trace metal characteristics of airborne particulate matter, PM2.5, collected in Singapore from February to March 2005 were investigated with specific reference to their bioavailability. PM2.5 mass concentrations varied between 20.9 mug/m3 and 46.3 microg/m3 with an average mass of 32.8 microg/m3. During the sampling period, there were several bushfires in Singapore that contributed to sporadic increases in the particulate air pollution, accompanied by an acrid smell and asthma-related allergies. The aerosol samples were subjected to analysis of trace elements for determining their total concentrations as well as their water soluble fractions. Our results showed an increase in concentration of several water-soluble trace metals during bushfires compared to their urban background levels in Singapore. In order to measure the human exposure to particulate air pollution, the daily respiratory uptake (DRU) of several trace metals was calculated and compared between haze and nonhaze periods. The DRU values were significantly higher for several metals, including Zn, Cu, and Fe, during bushfires. Electron paramagnetic resonance (EPR) measurements showed that the particulate samples collected during bush fires generate more toxic hydroxyl radicals (OH.) than those in the background air, due to the presence of more soluble iron ions.

Wildfire smoke exposure and human health: Significant gaps in research for a growing public health issue

“…In real-world scenarios, particulate collected during wildfire events has more oxidative potential than ambient urban particulate due to the presence of more polar organic compounds (Verma et al, 2009). This is consistent with studies suggesting that particles from bushfire and forest fires may generate more free radicals and more oxidative stress in the lung than urban ambient particulate from the same region (Karthikeyan et al, 2006; Williams et al, 2013). …”

Cluster analysis of inorganic elements in particulate matter in the air environment of an equatorial urban coastal location

“…It was also stated by Santamaria et al [7] that inorganic elements in urban areas are significantly higher than their natural concentrations due to human activities, leading to the realisation that air quality standards based on total suspended solids (PM 10 , PM 2.5 ) alone are not sufficient. It has also been postulated that human health may deteriorate because of PM 10 from biomass burning containing redox-active metals such as Fe due to the reactive nature of the radicals produced [9,10].…”

Low dose inflammatory potential of silica particles in human-derived THP-1 macrophage cell culture studies – Mechanism and effects of particle size and iron

“…Transition metals such as iron are a common component of ambient particulate matter from various sources (street [11–15], street dust [16], automobiles [17–21], brush fire [22,23], coal combustion [24,25] and subway [26–28]). and contribute to the biologic effects of particles with different chemical properties [27, 29–33].…”