Abstract. Potential Aerosol Mass (PAM) can be defined as the maximum aerosol mass that the oxidation of precursor gases produces. In the measurement, all precursor gases are rapidly oxidized with extreme amounts of oxidants to low volatility compounds, resulting in the aerosol formation. Oxidation occurs in a small, simple, flow-through chamber that has a short residence time and is irradiated with ultraviolet light. The amount of the oxidants ozone (O 3 ), hydroxyl (OH), and hydroperoxyl (HO 2 ) were measured directly and can be controlled by varying the UV light and the relative humidity. Maximum values were 40 ppmv for O 3 500 pptv for OH, and 4 ppbv for HO 2 . The oxidant amounts are 100 to 1000 times troposphere values, but the ratios OH/O 3 and HO 2 /OH are similar to troposphere values. The aerosol production mechanism and the aerosol mass yield were studied for several controlling variables, such as temperature, relative humidity, oxidant concentration, presence of nitrogen oxides (NO x ), precursor gas composition and amount, and the presence of acidic seed aerosol. The measured secondary organic aerosol (SOA) yield of several natural and anthropogenic volatile organic compounds and a mixture of hydrocarbons in the PAM chamber were similar to those obtained in large, batch-style environmental chambers. This PAM method is being developed for measuring potential aerosol mass in the atmosphere, but is also useful for examining SOA processes in the laboratory and in environmental chambers.

Abstract. Potential Aerosol Mass (PAM) can be defined as the maximum aerosol mass that the oxidation of precursor gases produces. In the measurement, all precursor gases are rapidly oxidized with extreme amounts of oxidants to low volatility compounds, resulting in the aerosol formation. Oxidation occurs in a small, simple, flow-through chamber that has a short residence time and is irradiated with ultraviolet light. The amount of the oxidants ozone (O3), hydroxyl (OH), and hydroperoxyl (HO2) were measured directly and can be controlled by varying the UV light and the relative humidity. Maximum values were 40 ppmv for O3, 500 pptv for OH, and 4 ppbv for HO2. The oxidant amounts are 100 to 1000 times troposphere values, but the ratios OH/O3 and HO2/OH are similar to troposphere values. The aerosol production mechanism and the aerosol mass yield were studied for several controlling variables, such as temperature, relative humidity, oxidant concentration, presence of nitrogen oxides (NOx), precursor gas composition and amount, and the presence of acidic seed aerosol. The measured secondary organic aerosol (SOA) yield of several natural and anthropogenic volatile organic compounds and a mixture of hydrocarbons in the PAM chamber were similar to those obtained in large, batch-style environmental chambers. This PAM method is being developed for measuring potential aerosol mass in the atmosphere, but is also useful for examining SOA processes in the laboratory and in environmental chambers.

Since the advent of cosmetic aerosols in metal cans, corrosion has taken its place as a major problem in the formulation of these products. Much corrosion information can be gathered by electrochemical measurement that cannot be obtained in any other way. This article, which deals with these modern systems, is an abridged version of a paper presented to the Society of Comestic Chemists, May 1959, in New York.