Air ion concentrations in various urban outdoor environments

Characteristics of Atmospheric Small Ions and Their Application to Assessment of Air Quality in a Typical Semi-Arid City of Northwest China

“…The present spatial variation in air ions is consistent with previous results in other cities worldwide obtained by Retalis et al (2009), Pawar et al (2012 and Ling et al (2010). This may be attributed to air pollution and underlying surface conditions in urban and suburban areas.…”

“…The large-to-small ion ratio mirrors transformation rate of small ions into intermediate and large ions to some extent. (Iida et al, 2006;Hirsikko et al, 2007;Ling et al, 2010), small air ions detected in this investigation show lower level. An important reason might be due to the differences in geographic region of different observation locations.…”

“…Most of those existing researches focused on the role of air ions in affecting climate and atmospheric aerosol formation based on large numbers of air ion measurements. Kulmala et al (2004) and Hirsikko et al (2011) gave their own excellent overview of such measurements, respectively, made in different environments such as continental boundary layer , marine boundary layer (Komppula et al, 2007), upper troposphere and lower stratosphere (Lee et al, 2003), Arctic and Antarctic (Virkkula et al, 2007), boreal forests (Vana et al, 2006), coastal regions (Siingh et al, 2005), tropical rural region (Pawar et al, 2010) and various urban outdoor environments (Retalis et al, 2009;Ling et al, 2010). The above studies revealed that the air ions were continuously generated and destroyed by various processes in the atmosphere.…”

Charging State of Aerosols during Particle Formation Events in an Urban Environment and Its Implications for Ion-Induced Nucleation

“…Small ions have a limited lifetime as they are soon lost by recombination or attachment to aerosol particles in the air. Thus, while their concentrations are high in clean environments, in polluted urban environments they may be as low as 200-400 cm -3 (Retalis et al, 2009;Ling et al, 2010;Hirsikko et al, 2011). In stable ambient air with no ion sources, approximately 1 in 3 ultrafine particles carry a charge, the vast majority being a single charge (Hirsikko et al, 2011).…”

Suppression of Cluster Ions during Rapidly Increasing Particle Number Concentration Events in the Environment

“…If the PNC is stable, the CIC will attain a balance value, and this is generally what is observed in the natural environment. While the CIC often exceeds 10 3 cm -3 in clean environments (Hirsikko et al, 2011), it may be as low as 200-400 cm -3 in polluted urban environments Retalis et al, 2009;Ling et al, 2010). Under stable conditions, atmospheric particles attain an equilibrium charge distribution due to bipolar diffusion charging.…”