Apportioning visibility degradation to sources of PM2.5 using positive matrix factorization

Area of Science:

• Atmospheric Science
• Environmental Chemistry
• Air Quality Research

Background:

• California faces significant air quality challenges, particularly in regions with poor air quality.
• Aerosol pollution is a major contributor to reduced visibility and adverse health effects.

Purpose of the Study:

• To conduct intensive aerosol monitoring in two California regions with poor air quality.
• To identify and quantify sources contributing to aerosol extinction and visibility reduction.
• To evaluate different source apportionment techniques for aerosol data.

Main Methods:

• Utilized semicontinuous aerosol monitors and continuous gaseous measurements.
• Integrated speciated aerosol data with Automated Surface Observing System (ASOS) visibility and extinction data.
• Employed positive matrix factorization (PMF) and novel PMF approaches coupled with extinction and modeled water data.

Main Results:

• Fresno winter study identified secondary nitrate and gasoline mobile combustion as high extinction sources.
• Rubidoux summer study highlighted secondary nitrate and ozone-related secondary semi-volatile organic material (SVOM) as major contributors.
• Riverside summer study revealed transported material and relative humidity secondary sources as primary contributors to extinction.

Conclusions:

• A novel PMF approach integrating extinction and modeled water data provided the most robust source apportionment results.
• Aerosol water content plays a crucial role in extinction, especially in coastal and cloudy regions.
• Understanding specific pollution sources is vital for developing effective air quality management strategies.