摘要
超细颗粒物(UFP,空气动力学直径小于或等于100 nm)比粒径更大的细颗粒物(PM_(2.5))和可吸入颗粒物(PM10)具有更大的健康风险.为调查城市中交通微环境内的UFP暴露水平及暴露产生的健康风险,本研究在2023年4~5月,每个观测日的早高峰、非高峰和晚高峰时段(7:00~9:00、12:00~14:00、16:00~18:00),对长三角典型城市南京市5种常见通勤方式(电动车、自行车、公交车、出租车、地铁)下的UFP暴露水平进行了观测,测量指标包括颗粒数量浓度(particle number concentration,PNC)、平均粒径(mean particle size,Diam)和肺沉积表面积(lung deposited surface area,LDSA).结果表明,不同通勤方式之间PNC暴露存在显著差异,其中出租车的PNC水平最高(20513±13425 pt/cm^(3)),其次是公交车(19345±12434 pt/cm^(3)),地铁最低(15533±9945 pt/cm^(3));非高峰时段通勤微环境内PNC水平是高峰时段的1.2倍.气象因素分析显示,温度和相对湿度显著解释了通勤微环境内17.7%~35.8%和17.1%~37.5%的变化.5种通勤微环境中LDSA数值最大为出租车(48.40±27.44μm^(2)/cm^(3)),最小为地铁(37.44±16.68μm^(2)/cm^(3)),相差达到20.6%.在各通勤微环境中,爱根模态占主导地位且具有最高的平均LDSA浓度.
Exposure to traffic-related air pollution poses health risks.Commuters in urban areas are exposed to traffic-related air pollutants at concentrations~3-10 times higher than background levels.Ultrafine particulate matter(UFP),with a diameter of less than 100 nm,is one of the traffic-related pollutants.Due to its small size but large surface area,UFP adsorbs toxic substances and can efficiently reach the deepest parts of the lungs(alveoli),causing a greater health risk than fine particulate matter(PM_(2.5)).Nevertheless,a limited number of studies have investigated UFP exposure in different commuting modes.In this study,we assessed the UFP exposure level in Nanjing,a typical city in the Yangtze River Delta.Real-time measurements of particle number concentration(PNC),mean particle size(Diam),lung deposited surface area(LDSA),temperature(T)and relative humidity(RH)were measured in the microenvironment of taxi,bus,electric vehicle(e-bike),bicycle and subway using a hand-held nanoparticle dosimeter during the morning peak(7:00-9:00),off-peak(12:00-14:00)and evening peak(16:00-18:00)on selected days.During the off-peak hours,the mean PNC of e-bike,bicycle,bus,taxi,and subway commute was 17325±12023,18423±1294,21870±14529,23517±17029,and 18097±12201 pt/cm^(3),which were 101%,114%,123%,123%and 140%of the mean PNC of the morning peak respectively,and 1-1.3 times the mean PNC of the evening peak.The highest UFP concentration is associated with the passing by of diesel trucks and intersections where traffic gathers.Mean PNC levels were highest in semi-enclosed modes(taxi and bus),followed by open modes(bicycle and e-bike),and lowest in closed modes(subway).Analysis of meteorological factors revealed that temperature was positively correlated with PNC within the commuter microenvironment,and relative humidity had a statistically significant negative correlation with PNC.LDSA,an indicator of the hazard associated with the surface area of particles,were observed highest with a mean of 48.40±27.44μm^(2)/cm^(3)in taxi microenvironment which is 1.1-1.3 times higher than the mean LDSA of bus,bicycle,e-bike and subway.The contribution of different particle modes to the LDSA varies considerably.The Aitken mode dominated LDSA within each commuting microenvironment,with the number of particles distributed in the Aitken mode in five commuting modes being 77%-87%of the total and having the highest mean LDSA concentrations(40.1-50.3μm^(2)/cm^(3)).Nucleation mode particles,despite their small proportion,corresponded to a mean LDSA that was only slightly lower than that of the Atiken mode,suggesting that nucleation mode poses a greater health risk than the Atiken mode for an equal number of particles.The lowest mean LDSA concentrations were found in the accumulation mode(18.8-32.4μm^(2)/cm^(3)),and the number of particles in the accumulation mode in the five microenvironments accounted for 2%-9%of the total number of particles.Based on this result,the commuting environment can be improved in the future by increasing green facilities on roads,providing more lanes for public transport,and optimising the energy source of motor vehicle drives.Commuters can reduce the exposure level of semi-enclosed modes by improving the internal ventilation of the compartments(by closing the windows or by simultaneous mechanical ventilation)or by opting for lower-exposure commuting modes,such as the subway,bicycles,or e-bike for shorter commuting distances.
作者
张文静
Dipesh Rupakheti
李晓芳
姬瑜琛
胡建林
Wenjing Zhang;Dipesh Rupakheti;Xiaofang Li;Yuchen Ji;Jianlin Hu(Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,Collaborative Innovation Center of Atmospheric Environment and Equipment Technology,School of Environmental Science and Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,China)
出处
《科学通报》
北大核心
2025年第22期3659-3670,共12页
Chinese Science Bulletin
基金
国家自然科学基金(42007187)资助。
关键词
超细颗粒物
通勤方式
肺沉积表面积
颗粒物暴露
ultrafine particulate matter
commuting modes
lung deposition surface area
particulate matter exposure
