Environment Persistent Free Radicals: Long-Lived Particles

Reactive Oxygen Species (ROS)-Mediated Antibacterial Oxidative Therapies: Available Methods to Generate ROS and a Novel Option Proposal

“…EPFRs are persistent because of the protection by the particles containing them and the presence of transition metals, thus having lifetimes exceptionally longer (from days to years) than other free radicals. These surface-bound radicals are found in contaminated soil, tar balls, and cigarette smoke, and primarily form during thermal processes such as pyrolysis and combustion of organic materials, waste incineration and photoactivation [295]. In fact, the byproducts from these processes, such as phenols and aromatic polycyclic hydrocarbons provide a breeding ground for EPFR generation.…”

“…In fact, EPFRs are also found in the matrix of ultrafine and airborne fine particulate matter (PM), which is emitted into the environment by both natural and anthropogenic processes, including coal combustion emissions (16.8%), vehicular emission (32.1%), industrial processes (11.7%), dust storm (27.2%), and nitrates (3.4%). PM is a mixture of organic, inorganic species, solid and liquid components of metals which have the tendency to form radicals with or without the sunlight photoactivation [295,296]. The environmental factors affecting the EPFRs' formation, lifetime and abundance such as precursors, temperature, light irradiation, presence of metals, temperature, pH, humidity, thermal processing time, and oxygen [297].…”

“…EPFRs can produce reactive oxygen species, including hydroxyl radicals, which induce oxidative stress in living organisms, posing adverse environmental and human health effects. The atmospheric oxygen is the only sink for stable free radicals converting them into not particles and/or metal stabilized molecular species thus decaying [295]. The EPFRs decay in atmosphere depends on reaction of EPFRs with molecular oxygen.…”

“…Anyway, recent research has also explored their potential for degrading organic environmental contaminants. By activating hydrogen peroxide or persulfate EPFRs produce ROS species such as superoxide, singlet oxygen, or OH−, thus inducing the degradation of environmental organic pollutants [295]. Collectively, although EPFRs are longlived environmental pollutants, harmful to environment and living beings, their capacity of activating ROS generation, if properly controlled, can make them a wide range tool to environment remediation.…”