Previous studies have associated ambient particulate chemical constituents with adverse cardiopulmonary health effects. However, specific pollution sources behind the cardiopulmonary health effects of ambient particles are uncertain. We examined the cardiopulmonary health effects of fine particles (PM2.5) from different pollution sources in Beijing, China, among a panel of 40 healthy university students. Study subjects were repeatedly examined for a series of cardiopulmonary health indicators during three 2-month-long study periods (suburban period, urban period 1, and urban period 2) in 2010-2011 before and after relocating from a suburban campus to an urban campus with changing air pollution levels and contents. Daily ambient PM2.5 mass samples were collected over the study and measured for 29 chemical constituents in the laboratory. Source appointment for ambient PM2.5 was performed using Positive Matrix Factorization, and mixed-effects models were used to estimate the cardiopulmonary effects associated with source-specific PM2.5 concentrations. Seven PM2.5 sources were identified as traffic emissions (12.0%), coal combustion (22.0%), secondary sulfate/nitrate (30.2%), metallurgical emission (0.4%), dust/soil (12.4%), industry (6.9%), and secondary organic aerosol (9.9%). Ambient PM2.5 in the suburban campus had larger contributions from secondary sulfate/nitrate (41.8% vs. 22.9%-26.0%) and metallurgical emission (0.7% vs. 0.3%) as compared to that in the urban campus), whereas PM2.5 in the urban campus had larger contributions from traffic emissions (13.0%-16.3% vs. 5.1%), coal combustion (21.0%-30.7% vs. 10.7%), and secondary organic aerosol (9.7%-12.0% vs. 8.7%) as compared to that in the suburban campus. Potential key sources were identified for PM2.5 effects on inflammatory biomarkers (secondary sulfate/nitrate and dust/soil), blood pressure (coal combustion and metallurgical emission), and pulmonary function (dust/soil and industry). Analyses using another source appointment tool Unmix yielded a similar pattern of source contributions and associated health effects. In conclusion, ambient PM2.5 in Beijing suburban and urban areas has two distinct patterns of source contributions, and PM2.5 from different sources may play important roles on different aspects of PM2.5-related cardiopulmonary health effects.

Background: Elevated blood pressure (BP) has been associated with particulate matter (PM) air pollution, but associations with PM chemical constituents are still uncertain.Objectives: We investigated associations of BP with various chemical constituents of fine PM (PM2.5) during 460 repeated visits among a panel of 39 university students.Methods: Resting BP was measured using standardized methods before and after the university students relocated from a suburban campus to an urban campus with different air pollution contents in Beijing, China. Air pollution data were obtained from central monitors close to student residences. We used mixed-effects models to estimate associations of various PM2.5 constituents with systolic BP (SBP), diastolic BP (DBP), and pulse pressure.Results: An interquartile range increase of 51.2 μg/m3 in PM2.5 was associated with a 1.08-mmHg (95% CI: 0.17, 1.99) increase in SBP and a 0.96-mmHg (95% CI: 0.31, 1.61) increase in DBP on the following day. A subset of PM2.5 constituents, including carbonaceous fractions (organic carbon and elemental carbon), ions (chloride and fluoride), and metals/metalloid elements (nickel, zinc, magnesium, lead, and arsenic), were found to have robust positive associations with different BP variables, though robust negative associations of manganese, chromium, and molybdenum with SBP or DBP also were observed.Conclusions: Our results support relationships between specific PM2.5 constituents and BP. These findings have potential implications for the development of pollution abatement strategies that maximize public health benefits.

[1] Beijing aerosols are scrutinized as a case study for atmospheric interactions in a complex multisource situation. For the first time, fine (<2 mm) and coarse (>2 mm) aerosols were continuously collected during a time period (20 months) long enough to capture seasonal trends of sources and interactions. Weekly samples were obtained from January 2003 to August 2004 downtown and during 9 months at two periurban sites. Aerosol samples were chemically characterized (black carbon (BC), organic carbon (OC), and major ions) and dust was obtained from mass closure. Concentration data were smoothed and boundary layer height (BLH) corrected in order to better identify sources and processes. All yearlong, the coarse aerosol is dominated by dust (75%) whereas the fine mode is dominated (46%) by carbonaceous particles. Photochemistry is an intense driving force for secondary aerosol formation including secondary organic aerosol (SOA). Dust particles present a reactive surface for secondary aerosol formation from the intense anthropogenic pool of acidic gaseous precursors (SO 2 , HNO 3 , and volatile organic compounds (VOCs)). These interactions favor the formation of a very significant coarse fraction for SO 4 , NO 3 , and POM, a feature almost never encountered in developed countries. Surprisingly too is the presence of fine NH 4 NO 3 in summer. A new result is also that the winter ''heating season'' appears at present of minor importance with, however, a significant component from domestic heating as traced by BC/OC. In the future, traffic is likely to dominate downtown anthropogenic emissions. Year-to-year variability in meteorological conditions is likely to influence inputs from arid regions and from regional industrial and biomass burning sources.

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