Instrument for measuring airborne particulate matter

Abstract

An apparatus for measuring the optical absorption of airborne matter or other light absorbing species in a sample airflow. The apparatus comprises a flow path through a fibrous filter to collect light absorbing species in the sampled air. The filtered airflow may subsequently pass through a second filter, used for reference measurements. At least one light source impinges in the filter generating one or two optical signals to determine the light absorption of particulate matter or other species in the sampled airflow. The apparatus includes at least one auxiliary sensor in the sample flow path to monitor an environmental factor, such as temperature. During a training period, a mathematical model of the apparatus' environmental sensitivity is derived. Using the mathematical model and measurements from the auxiliary sensor, optical signals are compensated in real time to increase the precision and accuracy of light absorption measurements recorded under fluctuating environmental conditions.

Description

BACKGROUND OF THE INVENTION[0001]The present application relates to an instrument and method for determining the optical absorption of matter, including black carbon, in the atmosphere.[0002]Black carbon (BC), or soot, is a primary light-absorbing component of particulate matter generated by biomass and fossil fuel combustion. BC is extremely harmful to both human health and the environment. It has been estimated that airborne particulate matter, including BC, kills an estimated 4 million people per year worldwide. In addition, BC is the second largest contributor to global warming after carbon dioxide. In order to assess BC's impact on climate and human populations, it is necessary to measure both the geographical and vertical distribution of BC in the atmosphere on a large scale.[0003]In the past, an instrument known as an Aethalometer has been employed to measure the concentration of optically absorbing (“black”) suspended particulates in a gas. Such airborne particulate matter (...

AI Technical Summary

Benefits of technology

[0014]In addition, the detector of the present application is designed with a short unobstructed path for the flow of sampled air. This flow path allows for greater airflow rates to be pumped through the instrument, requiring less power and, consequently, leading to an increase in the effective sensitivity to BC concentrations.

[0028]A further object of the present application is to provide an aerosol black carbon detector that is symmetrically arranged to allow reversal of a sample air path to reduce maintenance.

Problems solved by technology

BC is extremely harmful to both human health and the environment.

Current Aethalometers or BC instruments are usually large bench-top units and are quite expensive to acquire.

Furthermore, current BC instruments are not designed to be deployed outdoors and, thus, perform poorly in fluctuating ambient conditions.

Images