Abstract
Negative air ions (NAIs) are a natural component of air and have a positive impact on the health of urban residents. Few studies have focused on the relationship between NAI concentration (NAIC) in the urban atmosphere and environmental factors, such as meteorological factors and air pollutants. Therefore, we established observation points in Zhongshan Park in downtown Shanghai, China, and continuously measured and recorded changes in NAIC for one year. We also monitored nine meteorological factors and six atmospheric pollutants. Through correlation analysis and multiple linear regression analysis, the key factors influencing NAIC were screened, and the effects of those factors on NAIC were explored using the random forest algorithm. The results show that NAIC is most sensitive to humidity, followed by radiation and temperature, and finally to PM2.5. Humidity is the most critical factor, primarily because it directly affects the formation of NAIs from both the environment and vegetation. Furthermore, our results reveal that the mechanisms through which NAIC is influenced by the same factor varies seasonally. We analyzed the relationship between NAIC in an urban atmosphere and environmental factors by using big data, which is a new method for studying the relationships between NAIs and environmental factors. Our results indicate potential explanations for the mechanisms underlying NAI response to various environmental factors.
Highlights
Negative air ions (NAIs) are gaseous molecules and light ions that are electronegative [1]; they are known as “vitamins and auxins” in air [2]
We found that temperature and humidity were significant influencing factors on NAI concentration (NAIC) in all seasons except autumn
The influence of various factors on NAIC differed by season, and their synergistic mechanisms were relatively complicated
Summary
Negative air ions (NAIs) are gaseous molecules and light ions that are electronegative [1]; they are known as “vitamins and auxins” in air [2]. One study shows that the environmental factors that affect NAIC are mainly divided into two types: meteorological factors and air pollutants [15,16]. Most related studies have been conducted in mountain forests or ecological protection zones with extremely high NAIC [18,20,21]; few have been conducted in urban environments, especially central urban areas of large cities. Such studies have yielded no useful recommendations for improving air quality in the living environments of urban residents. What are the correlations between NAIC and the main environmental factors? What are the main factors affecting NAIC?
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