Ozone pollution become much worse during long, hot California summers in the Central Valley that provide longer periods of time for ozone to develop in the sunlight. Because of its high prevalence in Fresno, ozone exposure can exacerbate symptoms of respiratory conditions like asthma and COPD, and even lead to infections and premature death caused by lung damage from ozone. Because ozone is only created when heat from sunlight reacts with pollutants like NO 2 from vehicle exhaust, it’s referred to as a secondary pollutant. When ozone molecules are inhaled, they can cause chemical reactions in lung tissue that irritates the airways and result in symptoms like coughing and difficulty breathing. Ozone, one of Fresno’s most common air pollutants, is a gas that’s made up of three oxygen atoms. NO 2 is a common pollutant that reacts with sunlight to form ozone, A high concentration of NO 2 makes ozone more likely to be generated due to a combination of heat from sunlight and chemical reactions of NO 2 and other precursor pollutants with sunlight. 2Įmissions from passenger vehicles, trucks, and gas-powered farming equipment result in very high concentration of nitrogen dioxide (NO 2) and Nox pollution in Fresno. 1 Furthermore, the tourism industry alone generates about $1.4 billion for hotels, restaurants, and gas stations in Fresno County each year, which reflects the high number of visitors who also contribute to its poor air quality. Nearly 1.5 million largely fuel-inefficient trucks pass through Fresno County each year, contributing to diesel and particle pollution. Vehicle traffic in Fresno is consistent throughout the year due to Fresno’s location as an agricultural and industrial center as well as its importance as a stop for many travelers going between California’s major urban areas and to visit nearby national parks like Yosemite, Sequoia, and Kings Canyon in the Sierra Nevada mountains to the east of Fresno. In August of 2020, major wildfires in Northern California caused the air quality index (AQI) in Fresno to rise well into the “Unhealthy” category, with a daily average of over 150 AQI and peaking at 219 (“Very Unhealthy”) overall in the first weekend after the fires began. Ozone is also often an issue due to the high heat and high levels of particle and gas pollutants that react with sunlight to create ozone, especially during its hot California summers.įurthermore, smoke that travels from wildfires throughout the state often reaches the Fresno area and worsens the city’s already poor air quality, often increasing air pollution levels significantly. Particulate pollution, such as PM2.5, from vehicle emissions from commuter vehicles, logistics and transportation vehicles like semi-trucks, and farming equipment combined with consistent levels of dust and vapors from farming and pesticide use along with a geography that traps pollutants in the low elevations of the Central Valley. What causes air pollution in Fresno?įresno’s role as a major hub for the region’s agricultural industry as well as its confluence of several major state highways, including the California State Route 99 highway that cuts straight through the heart of Fresno and the nearby Interstate 5 about 50 miles to the west, both contribute greatly to its consistent ranking as one of the most polluted cities in the United States. Hyperlocal air pollution levels may vary significantly across the city, especially in areas near farming hubs or highways during peak traffic hours.

Use the Fresno air quality map to monitor air quality and air pollution levels in numerous areas around the city of Fresno and Fresno County.

smoke from nearby wildfires in the nearby mountains or distant forests.

pesticides and other airborne chemicals from agricultural processes.

factory emissions from industry and farming operations.

vehicle emissions from commuters, tourists, and truck traffic.

Located in the heart of the Central Valley in California, an enormous center of the global agricultural trade, Fresno is a city of over half a million people located about 200 miles north of Los Angeles and 180 miles south of the San Francisco Bay Area, the state’s two largest urban centers.įresno’s air quality is affected by numerous factors, including:

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