The ozone sensor is made of two platinum electrodes immersed in potassium iodide solutions of different concentrations contained in separate cathode and anode chambers. The chambers are linked with an ion bridge, which when the ozone in the air enters the cathode half of the sensor, produces a small electron flow. This small electrical current that is produced is proportional to the amount of ozone present. Three different instruments are measuring aerosol particles and concentrations. The nephelometer measures the scattering part of the extinction coefficient due to particles.
First air is pulled into the instrument through a filter which removes all the aerosol particles.
Scattered light intensity is measured and this is recorded as the background. Then ambient air is then introduced into the instrument and the intensity of the scattered light is measured again. Simple subtraction then yields the contribution due to aersols. Particle sizes measured range from 0.1 to 1.0 micrometers. The condensation nuclei are typically 0.001 to 0.1 micrometers in radius.