No description available.

No description available.

No description available.

No description available.

No description available.

A photoacoustic spectrometer was developed and built for measuring absorption of light by collected particles. Major advantages of the photoacoustic method are that it measures absorption directly, it is insensitive to scattered light, and it is readily used at different wavelengths. To evaluate the performance of the spectrometer, comparisons were made between photoacoustic absorption spectra and spectra calculated with Mie thoery. Pure powders with varied optical properties were used in the comparison, including carbon, hematite, and others. Results were reasonable in both absolute magnitude and spectral shape. Aerosol particles were collected in different environments in southern Arizona under background conditions in the mid-troposphere, and in a moderately polluted city. Results for the two locations, and two size ranges, are compared and contrasted in this thesis. Absolute magnitudes of absorption coefficients, measured at green wavelengths, are used to summarize many important results. Absorption by fine urban aerosol was 6 ± 4 x 10⁻⁷ m⁻¹, and four times larger than absorption by coarse urban aerosol. Normalized photoacoustic absorption spectra for urban aerosol are uniform with wavelength; background aerosol spectra have a relative increase in absorption at near UV wavelengths compared to near IR wavelengths. Urban aerosol absorption can be attributed to carbon particles larger than approximately 0.1 micron. Absorption by hematite (alpha iron oxide) particles in more strongly wavelength dependent than absorption by carbon particles, of the same size. This wavelength dependence is still not great enough to be attributed to hematite alone--although submicron hematite particles may be the dominant absorber in coarse background aerosol. (Abstract shortened with permission of author.)

No description available.

The fibrous aerosol monitor (FAM) was designed to count fibrous particulates as accurately as the standard method, P & CAM 239, now NIOSH 7400. The Hi-Vol (HV) method, a modification of the standard method, was developed to collect fibers over a shorter time interval (i.e., 10-minutes) with the same accuracy as the standard method. The current study sought to compare the HV method with the FAM to assess its validity in measuring airborne asbestos levels and to assess the importance of short-term variation in asbestos levels in determining appropriate respiratory protection. Correlation between the FAM and HV showed a poor linear relationship in all comparison studies. However, there was good correlation between the average of short-term HV samples and long-term time-weighted average (TWA) samples at reported low levels of airborne asbestos. All membrane filter techniques showed strong correlation with each other, but were weakly correlated with the FAM. (Abstract shortened with permission of author.)

Research was initiated to examine the feasibility of removing the majority of 4-PCH from the XSBR latex employed in carpet manufacturing. The reduction of 4-PCH from such latices would lend insight into the control of certain carpet related illnesses.

No description available.