Short-term effects of ultrafine particles on daily mortality by primary vehicle exhaust versus secondary origin in three Spanish cities

• Published in: Environment international Vol. 111; pp. 144 - 151
• Main Authors: Tobías, Aurelio, Rivas, Ioar, Reche, Cristina, Alastuey, Andrés, Rodríguez, Sergio, Fernández-Camacho, Rocío, Sánchez de la Campa, Ana M., de la Rosa, Jesús, Sunyer, Jordi, Querol, Xavier
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01-02-2018; Elsevier
• Subjects: Adolescent; Adult; Aerosols; Aged; Aged, 80 and over; Air Pollutants - adverse effects; Air Pollutants - analysis; Air Pollution - adverse effects; Air Pollution - analysis; Black carbon; Child; Child, Preschool; Cities; Environmental Monitoring; Humans; Infant; Infant, Newborn; Middle Aged; Mortality; Particle Size; Particulate Matter - adverse effects; Particulate Matter - analysis; Secondary emissions; Spain - epidemiology; Time series; Ultrafine particles; Vehicle Emissions - analysis; Vehicle Emissions - toxicity; Vehicle exhaust; Young Adult; Ultrafine particles; Vehicle exhaust; Black carbon; Mortality; Time series; Secondary emissions
• ISSN: 0160-4120; 1873-6750
• DOI: 10.1016/j.envint.2017.11.015

Evidence on the short-term effects of ultrafine particles (with diameter<100nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution.
We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N). The first component accounts for aerosol constituents emitted by vehicle exhaust (N1) and the second for the photochemical new particle formation enhancements (N2). We applied city-specific Poisson regression models, adjusting for long-term trends, temperature and population dynamics.
Mean BC levels were higher in Barcelona and Tenerife (1.8 and 1.2μg·m−3, respectively) than in Huelva (0.8μg·m−3). While mean UFP concentrations were similar in the three cities, from which N1 was 40% in Barcelona, 46% in Santa Cruz de Tenerife, and 27% in Huelva. We observed an association with N1 and daily mortality in Barcelona, by increasing approximately 1.5% between lags 0 and 2, per an interquartile increase (IQR) of 3277cm−3, but not with N2. A similar pattern was found in Santa Cruz de Tenerife, although none of the associations were significant. Conversely, in the industrial city of Huelva mortality was associated with N2 at lag 0, by increasing 3.9% per an IQR of 12,032·cm−3.
The pattern and origin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account.
•Association between segregated components of UFP (N1 and N2) and daily mortality•BC is a better parameter to evaluate health effects of particulate vehicle exhaust emissions.•Pattern and origin of UFP determines its short-term effect on daily mortality.