Relationships involving fine particle mass, fine particle sulfur and ozone during episodic periods at sites in and around St. Louis, Mo

The measurements during episodic periods in the St. Louis area in 1975 and 1976 of fine particle sulfur, fine particle mass and ozone are related. Such episodes are concentrated into time periods in the late spring and summer months. During such episodes, particle sulfur is the major constituent of the fine particle mass. The sum of the non-sulfur species in the fine particle mass do not show similar episodic patterns as the fine particle sulfur. Elevated concentrations of fine particle sulfur and of ozone usually occur together within the same episodic time periods. However, the day to day variations in fine particle sulfur and of ozone do differ somewhat within these time periods. Both fine particle sulfur and ozone show the influence of regional scale and local scale atmospheric photochemical processes on their formation during episodic time periods. Regional scale boundary layer processes frequently appear to contribute more to fine particle sulfur concentrations than to ozone formation. Local scale primary emissions also contribute to the ambient fine particle sulfur concentrations at core urban locations.