中国城市环境中空气负离子研究进展

Research progress on negative air ions in urban environment in China

空气负离子被誉为"空气维生素和生长素",其浓度被列为衡量空气质量好坏的一个重要指标,对于城市空气质量的改善意义重大。综述了中国城市环境空气负离子研究方面的主要进展,对空气离子产生的机理机制、观测方法、时空特征、评价指标体系以及关键影响因子及其相互之间的关系等方面进行深入和系统的阐述。其中重点阐述了空气负离子与不同自然环境和建筑环境的关系。国内外主要研究结果表明,(1)不同环境场所下空气负离子浓度差别很大,呈现出由城市中心到郊区再到乡村逐渐增大的趋势。(2)空气负离子浓度的年变化和日变化均存在明显差异。(3)水体对空气负离子浓度影响较大,动态水的空气负离子浓度大于静态水,以瀑布为最大。同时离水体的距离越近,周边的空气负离子浓度越高。(4)空气负离子与风的关系最为密切,有风时空气负离子浓度高于无风时,且风速与空气中负离子浓度成正相关。其他因素如温湿度、天气状况、植物绿化、建筑材料以及建筑高度等都能影响空气负离子浓度的高低,从而影响城市环境的空气清新度,其中有研究者发现空气负离子能够降低空气中颗粒物的浓度,并与PM2.5的关系最大。这些研究为综合地指导和评价城市环境空气质量提供科学依据和设计思路。因此笔者结合中国城市化的进程,进一步提出了更多的想法:(1)在控制性详细规划的层面上,与城市设计和城市绿地系统等研究结合起来,开展周期性的空气负离子浓度实证研究。(2)尝试建立空气负离子浓度与城市住区通风关系的评估方法,为城市住区空气清新度与通风关系的评估做应用性基础研究。

Negative air ion is regarded as “Air Vitamin and Auxin”, and its concentration has been proved to be an important assessment index in air quality, and takes an significant role in improving urban air. The paper reviewed the study of negative air ion in urban environment in major developments, and elaborated the negative air ion generation mechanism, observation methods, spatiotemporal characteristic, assessment index system, key impact factors and their relationships thoroughly and systematically. Next, the author focuses on the negative air ion relationship with the natural environment and the built environment. The main results of domestic and foreign research show that： （1） Negative air ion concentration varies widely in different environments, and increasing from the country center to the suburban to the village. （2） Annual and diurnal of negative air ion concentration changes are significantly different. （3）Water is greater impact on negative air ion concentration, negative air ion concentration of dynamic water is higher than static water, especially for the waterfall reach the max value. At the same time, the nearer to the water, the higher the negative air ion concentration will be gotten. （4）Negative air ion is most close to the wind, and negative air ion concentration the wind is higher than without wind, and wind speed with negative air ion concentration have a positive correlation. Other factors such as temperature and humidity, weather conditions, plant green, building materials and building height can also affect the level of the negative air ion concentration, thus affecting the air cleanliness degree of the urban environment. Researchers found that negative air ion can reduce the concentration of airborne particles, and has relationship with PM2.5. These studies provide a scientific basis for the comprehensive guidance and evaluation of the built environment air quality and design ideas. With the process of urbanization in China, the author advises the further more ideas： （1） At the level of regulatory detailed planning, the author suggest studying the negative air ion concentration with urban design and urban green space system, and carrying out periodic negative air ion concentration empirical research. （2）Try to establish assessment method of the negative air ion concentration with the urban residential ventilation, in order to do basic research on air cleanliness degree and ventilation of urban residential.