Abstract
ABSTRACTUrban ambient aerosols have been of much concern in recent decades due to their effects upon both atmospheric processes and human health. This study aimed to apportion the sources of submicron particles measured at an urban background area in London and to identify which sources are most responsible for particles deposited in the human lung. Particle number size distributions (PNSD) measured by a Scanning Mobility Particle Sizer (TSI, USA), covering the size range of 16.5–604 nm at the London North Kensington background sampling site during 2012 were used in a Positive Matrix Factorization (PMF) model to apportion to six dominant sources of particles. These included local traffic emissions (26.6% by number), aged traffic emissions (29.9%), urban accumulation mode (28.3%), nucleation (6.5%), inorganic secondary aerosol (1.7%) and mixed secondary aerosol (6.9%). Based on the ICRP model, the total deposition efficiencies of submicron particles for the aforementioned sources in the human respiratory tract were 0.57, 0.41, 0.24, 0.62, 0.24 and 0.24, respectively. In terms of source apportionment of particles deposited in the lung, traffic emissions represent the main source of particles deposited by number in both the regional and total lung, accounting for 59 to 71% of total deposited particles, followed by regional accumulation mode (17%) and nucleation (10%) particles. Secondary aerosols only account for 5.1% of total deposited particles by number, but they represent the main source of particles deposited in the lung expressed as surface area (44.6%) and volume (72.3%) of total deposition. The urban accumulation mode contributes 27.3% and 17.3% of total deposited particles by surface area and volume, while traffic emissions contribute 26.6% and 9.7%, respectively. Nucleation contributes only 1.6% and 0.7% of total deposited particles by surface area and volume.
Highlights
Particles in urban ambient air are released from various anthropogenic activities such as combustion of fuels and from secondary sources such as atmospheric nucleation (Ogulei et al, 2007)
Particle number size distributions (PNSD) measured by a Scanning Mobility Particle Sizer (TSI, USA), covering the size range of 16.5–604 nm at the London North Kensington background sampling site during 2012 were used in a Positive Matrix Factorization (PMF) model to apportion to six dominant sources of particles
The majority of particle number was in the ultrafine region (Dp ≤ 100 nm) which represented 81.4% of total number concentration, whereas accumulation mode particles only accounted for 18.6% of total particle number, but presented 90.5% of total particle volume
Summary
Particles in urban ambient air are released from various anthropogenic activities such as combustion of fuels and from secondary sources such as atmospheric nucleation (Ogulei et al, 2007). Exposure to ambient aerosols is consistently associated in numerous scientific studies with adverse health effects (Pope and Dockery, 2006) Very small particles such as ultrafine particles (Dp < 100 nm) are able to penetrate deep into the respiratory tract (e.g., reaching the pulmonary epithelium), causing serious health problems such as respiratory morbidity and mortality (Donaldson et al., 1998). Different types of sources generate particles with different size distributions, chemical composition and concentration characteristics (Lighty et al, 2000). This results in particles from different sources behaving differently during the process of inhalation, showing different penetration through the respiratory tract and depositing with different efficiency in different regions of the lungs. A detailed identification of the most relevant sources of atmospheric particles and the association between a particle source and lung deposition could play a vital role for risk assessment of air pollution in epidemiological studies, and for policymakers to introduce optimal legislation for air quality control
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
