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When satellites help keep us healthy

Earth observation satellites (EO) are used to gather essential information about climate and environmental conditions that can affect the health of Canadians.

Published in spring , Earth Observation, Public Health and One Health is the product of a collaboration by the Public Health Agency of Canada and the Canadian Space Agency, with contributions from international experts.

Various examples demonstrate how EO images are used to study factors that can influence conditions likely to cause public health problems.

Lyme disease

According to scientists, because of the warming climate, the spread of ticks and the risk of contracting Lyme disease will increase in Canada. Of course, ticks are not visible from space, but it is possible to observe and assess the effects of climate change on their habitat using satellite images.

Black-legged ticks carry bacteria that causes Lyme disease. They are currently found in North America, Europe and Asia. Since they spread this disease, monitoring the areas where they can survive and become established is a matter of public health.

For the last 15 years, researchers at the Public Health Agency of Canada (PHAC) have been producing tick exposure risk maps. Satellite data provide information about ground temperature and tick habitat that PHAC researchers need to create maps of geographic tick distribution in Canada.

Researchers have observed that ticks are moving northward due to global warming. Satellites regularly scan remote regions as well as densely populated ones; with the data they collect on tick habitat conditions, researchers can follow the spread of ticks. PHAC experts can then inform the public on the risk of Lyme disease exposure, particularly in wooded areas.

Exposure risk map of black-legged ticks, carriers of Lyme disease, in central and eastern Canada in . (Credit: Public Health Agency of Canada)

Malaria

The last 20 years have brought a great deal of progress in the public health sphere, reducing the risk of contracting malaria, which is transmitted by mosquitoes.

Satellite EO has helped fight the spread of this disease. Satellites collect data on environmental factors that can impact malaria transmission cycles and at-risk populations.

Scientists can use these data to analyze significant relationships between the climate and malaria, as well as detailed images to assess the effects of agriculture, city expansion, reduced forest cover and water resource management on the spread of the disease.

Recent satellite missions, including the RADARSAT Constellation Mission, have supported the improvement of observations and more frequent collection of high-resolution images of areas where the presence of malaria-carrying mosquitoes is a risk. These areas are characterized by a microclimate, with specific soil and vegetation. By making it possible to identify these areas, EO data can indicate the potential presence of mosquitoes.

Public health authorities and EO specialists produce reliable risk maps using satellite data. These tools are widely accessible, and municipalities, for example, use them to inform the public about high-risk areas.

COVID-19

Throughout the COVID-19 pandemic and duration of stringent public health measures the capabilities of EO satellites became a reliable asset to assess rapid environmental and socio-economic changes and impacts. Remote sensing instruments provided an uninterrupted and reliable stream of geospatial data and information for monitoring activities, or inactivities, at local as well as regional, countrywide and international levels. Their major advantage is that they can provide repeat-images for change detection all over the globe; and because images from the same sensor can be directly compared to each other. EO and public health practitioners applied it in innovative ways, for example monitoring air quality and providing data where civilian authorities need support to target vulnerable populations and estimate population density and mobility.

Several important lessons have been learned over the course of the pandemic by national and international agencies alike. EO can deliver fast and detailed geospatial information about air quality that can improve the understanding of respiratory pandemics like COVID-19 and assist in forecasting severity of symptoms in those infected. EO can help generate actionable knowledge and public information regarding the dynamics of the pandemic. Over the next few years research concerning EO data collection and curatorial services will be essential for providing evidence-based data and know-how for decision makers in the public health Community of Practice to plan for future pandemic response and recovery phases.

Air pollution illness

Considered to be one of the greatest global health risks, air pollution is the world's leading environmental cause of premature death.

According to the World Health Organization, nine of ten people on the planet breathe air containing high levels of pollutants. Residents of densely populated areas are at higher risk of being exposed to air pollution; it is highly concentrated in these areas, and there is not enough green space to mitigate it.

Long-term exposure to polluted air can lead to shorter life expectancy, respiratory tract infections, chronic obstructive pulmonary disease, cerebrovascular events, heart attacks and even lung cancer.

Satellite EO is used to:

Satellites help experts identify air pollution sources, determine how pollutants move through regions, countries and continents, and monitor and study air quality uninterrupted (or nearly so).

Forecasters provide the public with daily air quality maps based on satellite data and models. Information on where and when air pollution becomes a danger to public health is now an important part of weather forecasts and reports.

The value of satellite heat maps, local air quality indicators and forecasting services is particularly evident when it comes to detecting and monitoring seasonal forest fires. These fires have serious consequences, particularly for the livelihood of many Canadians. What's more, the smoke from forest fires often impacts people hundreds and even thousands of kilometres away. The WildFireSat mission, which is currently in development, will strengthen Canada's capacity to monitor forest fires in the country as of .

Satellite image of an area in the Northwest Territories with the clear presence of smoke from forest fires. (Credits: NASA Earth Observatory, Laurent Dauphin, Landsat data from the U.S. Geological Survey and MODIS data from EOSDIS LANCE and GIBS/Worldview, NASA)

Whether it is being used to inform the public about the risk of Lyme disease exposure, collect data on environmental or climate factors that can impact malaria transmission cycles, or identify air pollution sources, Earth observation via satellite has become an invaluable tool for helping us protect our health.

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