Urban air quality comparison for bus, tram, subway and pedestrian commutes in Barcelona.
Access to detailed comparisons in air quality variations encountered when commuting through a city offers the urban traveller more informed choice on how to minimise personal exposure to inhalable pollutants. In this study we report on an experiment designed to compare atmospheric contaminants inhaled during bus, subway train, tram and walking journeys through the city of Barcelona. Average number concentrations of particles 10-300 nm in size, N, are lowest in the commute using subway trains (N<2.5×10(4) part. cm(-3)), higher during tram travel and suburban walking (2.5×10(4) cm(-3)<N<5.0×10(4) cm(-3)), and highest in diesel bus or walking in the city centre (N>5.0×10(4) cm(-3)), with extreme transient peaks at busy traffic crossings commonly exceeding 1.0×10(5) cm(-3) and accompanied by peaks in Black Carbon and CO. Subway particles are coarser (mode 90 nm) than in buses, trams or outdoors (<70 nm), and concentrations of fine particulate matter (PM2.5) and Black Carbon are lower in the tram when compared to both bus and subway. CO2 levels in public transport reflect passenger numbers, more than tripling from outdoor levels to >1200 ppm in crowded buses and trains. There are also striking differences in inhalable particle chemistry depending on the route chosen, ranging from aluminosiliceous at roadsides and near pavement works, ferruginous with enhanced Mn, Co, Zn, Sr and Ba in the subway environment, and higher levels of Sb and Cu inside the bus. We graphically display such chemical variations using a ternary diagram to emphasise how "air quality" in the city involves a consideration of both physical and chemical parameters, and is not simply a question of measuring particle number or mass.
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain. Electronic address: teresa.moreno@idaea.csic.es.
Teresa
T
Moreno
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Cristina
C
Reche
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Ioar
I
Rivas
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Maria
M
Cruz Minguillón
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Vânia
V
Martins
DICeM-University of Cassino and Southern Lazio, via Di Biasio 43, 03043 Cassino, FR, Italy.
Concepción
C
Vargas
DICeM-University of Cassino and Southern Lazio, via Di Biasio 43, 03043 Cassino, FR, Italy; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Qld, Australia.
Giorgio
G
Buonanno
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Jesus
J
Parga
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Marco
M
Pandolfi
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Mariola
M
Brines
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Marina
M
Ealo
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Ana
A
Sofia Fonseca
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Fulvio
F
Amato
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Garay
G
Sosa
Transports Metropolitans de Barcelona, Santa Eulalia, Av. del Metro s/n, 08902 L'Hospitalet de Llobregat, Barcelona Spain.
Marta
M
Capdevila
Transports Metropolitans de Barcelona, Santa Eulalia, Av. del Metro s/n, 08902 L'Hospitalet de Llobregat, Barcelona Spain.
Eladio
E
de Miguel
Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
Xavier
X
Querol
WPS, C/Major 13, 08870 Sitges, Spain.
Wes
W
Gibbons
D000388:Air / Q000032:analysis / Q000592:standards; D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D019216:Metals, Heavy / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis*; D013030:Spain; D014186:Transportation / Q000592:standards; D014507:Urbanization; D001335:Vehicle Emissions / Q000032:analysis*; D016138:Walking
D000393:Air Pollutants; D019216:Metals, Heavy; D052638:Particulate Matter; D001335:Vehicle Emissions
City transport pollution; Commuting; Exposure; Metalliferous PM(2.5); Ultrafine particles