Observation and Research Progress of Air Negative Oxygen Ion Concentration In China

The recent research progresses, observational methods, spatial and temporal distribution characteristics and influencing factors of air negative oxygen ion concentration in China are reviewed. Most existing research results show that nighttime air negative oxygen ion concentration is higher than that in the daytime, and the diurnal variation characteristics vary greatly depending on the location. Summer experiences the highest concentration of negative oxygen ion, and the concentration in urban areas is lower than that in suburban areas. Ecological environment, vegetation, meteorological condition and air pollutants are the main factors affecting the air negative oxygen ion concentration. It is generally recognized that the air negative oxygen ion concentration is negatively correlated with air temperature and pollutant concentration in the air, and positively correlated with relative humidity. The concentration can also be increased by precipitation and thunder and lightning weather. The study reveals the problems in the monitoring of air negative oxygen ion concentration, such as inconsistent instruments, insufficient data processing methods, and the deficiency of long-term data series. It is suggested to develop unified technical standards, adopt stable monitoring methods to enhance the comparability of research among different regions and to deepen the research.