Source apportionment of PM 2.5 chemically speciated mass and particle number concentrations in New York City

The major sources of fine particulate matter (PM2.5) in New York City (NYC) were apportioned by applying positive matrix factorization (PMF) to two different sets of particle characteristics: mass concentrations using chemical speciation data and particle number concentrations (PNC) using number size distribution, continuously monitored gases, and PM2.5 data. Post-processing was applied to the PMF results to: (i) match with meteorological data, (ii) use wind data to detect the likely locations of the local sources, and (iii) use concentration weighted trajectory models to assess the strength of potential regional/transboundary sources. Nine sources of PM2.5 mass were apportioned and identified as: secondary ammonium sulfate, secondary ammonium nitrate, road traffic exhaust, crustal dust, fresh sea-salt, aged sea-salt, biomass burning, residual oil/domestic heating and zinc. The sources of PNC were investigated using hourly average number concentrations in six size bins, gaseous air pollutants, mass concentrations of PM2.5, particulate sulfate, OC, and EC. These data were divided into 3 periods indicative of different seasonal conditions. Five sources were resolved for each period: secondary particles, road traffic, NYC background pollution (traffic and oil heating largely in Manhattan), nucleation and O3-rich aerosol. Although traffic does not account for large amounts of PM2.5 mass, it was the main source of particles advected from heavily trafficked zones. The use of residual oil had limited impacts on PM2.5 mass but dominates PNC in cold periods

Analysis of major air pollutants and submicron particles in New York City and Long Island

A year-long sampling campaign of major air pollutants and submicron particle number size distributions was conducted at two sites taken as representative of city-wide air quality in New York City and Long Island, respectively. A number of species were quantified with hourly time resolution, including particle number concentrations in 6 size ranges (20-30 nm, 30-50 nm, 50-70 nm, 70-100 nm, 100-200 nm, and >200 nm), nitrogen oxides, sulfur dioxide, ozone, carbon monoxide, methane, non-methane hydrocarbons, PM2.5 mass concentration and some PM major components (sulfate, organic and elemental carbon). Hourly concentrations of primary and secondary organic carbon were estimated using the EC tracer method. Data were matched with weather parameters and air parcel back-trajectories. A series of tools were thus applied to: (i) study the seasonal, weekly, diurnal cycles of pollutants; (ii) investigate the relationships amongst pollutants through correlation and lagged correlation analyses; (iii) depict the role of atmospheric photochemical processes; (iv) examine the location of the potential sources by mean of conditional bivariate probability function analysis and (v) investigate the role of regional transport of air masses to the concentrations of analyzed species. Results indicate that concentrations of NOx, SO2, CO, non-methane hydrocarbons, primary OC and EC are predominantly determined by local sources, but are also affected by regional transports of polluted air masses. On the contrary, the transport of continental polluted air masses has a main effect in raising the concentrations of secondary PM2.5 (sulfate and secondary organic carbon). By providing direct information on the concentrations and trends of key pollutants and submicron particle number concentrations, this study finally enables some general considerations about air quality status and atmospheric processes over the New York City metropolitan area. (C) 2016 Elsevier Ltd. All rights reserved

Source Apportionment of PM2.5 in New York City: Chemical Speciated Mass Concentration vs. Particle Number Concentration

Epidemiologic studies have amply demonstrated that exposure to elevated mass concentrations of airborne particulate matter pollution is associated with many adverse health effects. In U.S., air quality standards are regulated under the National Ambient Air Quality Standards (NAAQS), which set the limit values to be fulfilled across the U.S. for mass concentrations of both PM10 and PM2.5. However, recent population-based studies have reported that even exposure to low mass concentrations may increase acute and chronic effects and mortality. It is estimated that current (2009-2011) levels of PM2.5 still cause annually more than 2,000 deaths, 4,800 emergency department visits for asthma, and 1,500 hospitalizations for respiratory and cardiovascular disease in NYC. This study investigates the main sources of PM2.5 in NYC through the application of receptor models for two particulate metrics: mass concentration and particle number concentration (PNC). The most probable sources of PM2.5 mass concentration were identified and apportioned using the positive matrix factorization (PMF) model on chemically speciated samples analyzed for major inorganic ions, organic (OC) and elemental (EC) carbon and elements. The sources of PNC were investigated by applying PMF to hourly measurements of multiple variables including number concentrations resolved over six bins (20-30 nm, 30-50 nm, 50-70 nm, 70-100 nm, 100-200 nm, 200 nm to 2.5 μm), gaseous air pollutants and mass concentrations of PM2.5 and particulate sulfate, OC, and EC. Subsequently, post-processing methods were applied to help interpret the results including: (i) the comparison of sources identified with composition and particle number concentrations; (ii) relationships with weather parameters; (iii) the use of wind data through the polar analysis to detect the location of the most probable local sources, and (iv) the use of meteorology-based hybrid methods for extracting further information on the strength of potential external sources

Source Apportionment of PM2.5 in New York City: Chemical Speciated Mass Concentration vs. Particle Number Concentration

Epidemiologic studies have amply demonstrated that exposure to elevated mass concentrations of airborne particulate matter pollution is associated with many adverse health effects. In U.S., air quality standards are regulated under the National Ambient Air Quality Standards (NAAQS), which set the limit values to be fulfilled across the U.S. for mass concentrations of both PM10 and PM2.5. However, recent population-based studies have reported that even exposure to low mass concentrations may increase acute and chronic effects and mortality. It is estimated that current (2009-2011) levels of PM2.5 still cause annually more than 2,000 deaths, 4,800 emergency department visits for asthma, and 1,500 hospitalizations for respiratory and cardiovascular disease in NYC. This study investigates the main sources of PM2.5 in NYC through the application of receptor models for two particulate metrics: mass concentration and particle number concentration (PNC). The most probable sources of PM2.5 mass concentration were identified and apportioned using the positive matrix factorization (PMF) model on chemically speciated samples analyzed for major inorganic ions, organic (OC) and elemental (EC) carbon and elements. The sources of PNC were investigated by applying PMF to hourly measurements of multiple variables including number concentrations resolved over six bins (20-30 nm, 30-50 nm, 50-70 nm, 70-100 nm, 100-200 nm, 200 nm to 2.5 μm), gaseous air pollutants and mass concentrations of PM2.5 and particulate sulfate, OC, and EC. Subsequently, post-processing methods were applied to help interpret the results including: (i) the comparison of sources identified with composition and particle number concentrations; (ii) relationships with weather parameters; (iii) the use of wind data through the polar analysis to detect the location of the most probable local sources, and (iv) the use of meteorology-based hybrid methods for extracting further information on the strength of potential external sources