University of Waterloo Study Predicts One Hundred Million Americans Will Face Chronic Unhealthy Air Exposure by 2100

University of Waterloo research predicts a sevenfold increase in unhealthy air exposure by 2100, impacting 100 million people due to climate change.

By: AXL Media

Published: Apr 1, 2026, 10:11 AM EDT

Source: Information for this report was sourced from University of Waterloo

The Projected Normalization of Atmospheric Health Risks

Environmental shifts driven by climate change are expected to transform poor air quality from a seasonal rarity into a commonplace occurrence across the United States. According to new modeling led by the University of Waterloo, approximately 100 million people will reside in areas where the average air quality during smog season is considered hazardous for sensitive groups by the year 2100. Dr. Rebecca Saari, a professor of civil and environmental engineering, notes that this represents a staggering increase from the 14 million people affected at the turn of the century. For vulnerable populations, the future landscape of atmospheric health could resemble a daily coin flip, with nearly even odds that they will be advised to remain indoors to avoid respiratory distress.

Geographic Concentration of Worsening Smog and Particulates

The study identifies California and the Eastern United States as the regions most susceptible to the dramatic rise in air quality alerts. These areas are projected to experience the highest frequency of poor air days between May and September, the traditional window for smog season. Unlike previous research that may have focused on isolated pollutants, this international study incorporates the combined impact of ozone and fine particulate matter. These two components are the primary drivers of environmental sickness and premature death, making their projected increase a significant concern for regional public health infrastructure and urban planning.

Evaluating the Multiplied Frequency of Public Health Alerts

Current data suggests that the number of air quality alerts issued annually across the country could quadruple as the climate continues to warm. This increase would necessitate a drastic shift in human behavior, as avoiding the associated health risks might require vulnerable individuals to spend an additional 142 days per year indoors by the end of the century. The research team analyzed how these intensifying pollution levels contribute to the overall burden of disease, emphasizing that the sheer frequency of these events will challenge the resilience of communities. This long term trend suggests that the current reliance on temporary alerts may be insufficient as poor air quality becomes a semi-permanent feature of the summer months.