Riverside County experienced the most bad air days in the last 20 years, totaling 3,090 days. The breakdown comprises 1,979 days that were unhealthy for sensitive groups, 943 days as unhealthy, 144 days as very unhealthy, and 24 days as hazardous. This results in an average of about 155 bad air days per year. (Source: HealthNews Report 2024)
San Bernardino County has officially claimed the title of the most polluted county in the United States over the last two decades, according to an extensive analysis of Environmental Protection Agency data conducted by Healthnews. With a staggering 3,020 bad air days recorded between 2003 and 2023, San Bernardino faces the harsh reality of consistently unhealthy air quality. The breakdown of these figures is alarming: over the 20-year period, 1,602 days were deemed unhealthy for sensitive groups, 1,126 days were classified as unhealthy, 291 days were categorized as very unhealthy, and one day was marked as hazardous. On average, residents endured 151 days each year where the air posed significant health risks.
While Riverside County experienced more total days of poor air quality, ranking second with 3,090 bad air days over the same period, San Bernardino still tops the list due to the severity of its pollution. Riverside’s 1,979 days deemed unhealthy for sensitive groups and 943 unhealthy days were overshadowed by San Bernardino’s higher number of days in the more dangerous “very unhealthy” and “hazardous” categories. Riverside, despite having more total days of pollution, averaged 155 bad air days per year—four more than San Bernardino—but San Bernardino’s heavier pollution tipped the scales.
The Inland Empire, which includes both San Bernardino and Riverside counties, has long struggled with deteriorating air quality. Experts point to several key factors driving this trend. First, natural air currents from the densely populated Los Angeles area carry pollutants eastward, trapping them in the Inland Empire’s mountain-ringed basin. This topographical feature acts like a bowl, allowing pollutants to accumulate and linger, worsening the air quality for local residents.
The region’s rapidly growing logistics and warehousing industries have also contributed heavily to the air pollution crisis. As of December 2022, the logistics sector employed 284,000 people in the Inland Empire, making it the second-largest employer in the area. The constant flow of diesel trucks and freight trains transporting goods in and out of these massive distribution hubs has led to increased emissions of harmful pollutants, compounding the problem.
The public health implications of these pollution levels are severe. Long-term exposure to such consistently poor air quality has been linked to increased mortality rates, higher incidences of lung cancer, and a spike in cardiopulmonary diseases. Residents of San Bernardino and Riverside counties are particularly vulnerable, as the sustained exposure to these harmful pollutants has significantly reduced life expectancy and heightened the risk of chronic health issues.
While local governments and environmental agencies have introduced regulations and initiatives to curb emissions, the sheer scale of industrial growth, combined with geographical challenges, continues to pose a formidable challenge in improving air quality. As the Inland Empire’s logistics industry continues to expand, efforts to mitigate the environmental impact will be crucial in addressing this ongoing public health crisis.
