Within the phagosome, two superoxide anions (O2.-) can react with each other and two H+ molecules to form oxygen and hydrogen peroxide (H2O2)(Root RK & Metcalf JA 1977; Fridovich I 1978; Johnston RB Jr et al. 1975; Rada B & Leto TL 2008; Winterbourn CC & Kettle AJ 2013). This dismutation of superoxide can occur spontaneously and is faster at lower pH. Unlike superoxide anion, which is short-lived and local in its effect, hydrogen peroxide is longer-lasting and membrane-permeable, so it can diffuse away from the site of production. H2O2 can react with a limited range of biocompounds, but the derivatives of H2O2 such as hydroxyl radical are far more reactive.