6
Conclusions and Recommendations
To accomplish the objectives of this report, a literature review of the approaches used to combine satellite observations with ground-level monitoring (GLM) measurements of particulate matter with an aerodynamic diameter less than or equal to 2.5 microns (PM2.5) was conducted. The GLM data provided by US Diplomatic Posts and other sources contained in the OpenAQ database were investigated to determine the level of quality assurance and likely uncertainties in the GLM data. Several methods for using satellite aerosol optical depth (AOD) from the publicly available sources to estimate ground-level daily average PM2.5 concentrations within cities were then tested in nine cities in low- and middle-income countries (LMICs) to look for patterns in the performance of the satellite methods with the altitude and location of the city. Based on the results of this work, GLM and satellite data are best thought of as complements to each other. Many GLM networks could be improved by considering satellite data, but all approaches using satellite data improve as the number of high-quality GLM sites is increased. Thus, it is important that LMICs continue to support the establishment of GLM networks to measure air pollutants that cause mortality, notably fine particulate matter (PM2.5), in regions such as Sub-Saharan Africa and other regions with many LMICs before they can take full advantage of satellite data. The GLM data must have adequate quality assurance and quality control and follow standard operating procedures to ensure the data are of sufficient quality to be used to estimate PM2.5 exposures for health studies and to be combined with the satellite estimates. Satellite data may be useful for estimating air quality for countries or large areas based on average estimates. However, for the purpose of protecting human health, LMICs need to prioritize establishment or strengthening of GLM networks where they are lacking or weak. These networks can measure air quality at the level where human activity is typically carried out and where people are exposed to air pollutants, notably PM2.5, that are harmful to health and can cause death. The next section summarizes the conclusions of this report, and the final section provides recommendations for the use of satellite data and the improvement of GLM in LMICs.
43
