Health impacts of air pollution accumulate over time. Respiratory issues from long-term exposure to air pollution can result in higher risks of complications from diseases like asthma and COVID-19. Scientists believe that the long-term inhaling hazardous air pollutants included formaldehyde, asbestos, mercury, and others can impair lung function and cause respiratory stress, leading to a higher likelihood of severe illness from COVID-19. Air pollution can come from a number of sources like households, industrial emissions, burning of garbage and waste, construction and demolition, indoor cook stoves, coal plants, passenger vehicles, wildfires, power plants, and other sources. The higher air pollution index levels, the more correlation there is between that pollution and poor COVID-19 health outcomes.

People are using air-polluting cars less during the COVID-19 pandemic, which is contributing to lower levels of air-pollution right now. But past decades of high levels of air pollution still leave people vulnerable to negative health impacts.

A peer-reviewed study published at the end of 2020 estimated that one type of air pollution called particular matter (PM) contributed to about 15% of COVID-19 mortality around the world. PM is a mix of solid and liquid particles, suspended in air. Often it comes from burning fossil fuels from vehicles, fires, and power plants. The study found that over half of COVID-19 deaths attributable to human-made air pollution were related to fossil fuel use. That number was as high as 70-80% in Europe, West Asia, and North America. In general, regions with stricter standards for air quality and lower levels of air pollution (like Australia) had a lower fraction of COVID-19 deaths attributable to air pollution from humans.

The World Bank also released a working paper on the study of long-term air pollution exposure in India, specifically exposure to PM2.5—particulate matter that is super tiny, less than 2.5 microns or micrometers wide, also called fine particulate matter. Fine particulate matter is dangerous because it is small enough to get deep into our lungs and even enter our bloodstream. Long-term exposure to air pollution like PM2.5 can lead to underlying health conditions, like respiratory illness, which can lead to higher risk of death from COVID-19. The study estimated that a 1% increase in long-term exposure to PM2.5 can lead to a 5.7% increase in COVID-19 deaths in India.

There are many other research publications on the links between air pollution and negative health outcomes before, as well as during, the COVID-19 pandemic. Long-term exposure to high levels of air pollution can lead to increased risks of potentially deadly complications from respiratory issues. Public health professionals recommend continuing to protect people from dangerous levels of air pollution during, as well as beyond, the COVID-19 pandemic.

Air pollution, climate change, and human health are closely related. Human activities like burning fossil fuels can lead to human-made air pollution and climate change, with negative impacts on human health.

Additionally, air pollution can impact climate change, and vice versa. Pollutants like particulate matter (PM) can have warming or cooling effects on the climate, and changes in climate can worsen or improve air quality.

The negative health impacts of air pollution are well-documented, including increased risks of respiratory infections, heart disease and lung cancer. Recently, there has been research documenting the negative health impacts of air pollution in terms of increased COVID-19 complications and deaths.

The negative health impacts of climate change are also well-documented. Climate change can affect social and environmental determinants of health (ex. clean air, clean water, food security, shelter security, etc.) as well as lead to increased transmission of infectious diseases and increased risk of conditions like heat stress.