Sacramento Summer Haze: What Is It?

For the millions of residents living within the Sacramento Valley and surrounding areas, extreme summer heat with temperatures soaring above one hundred degrees is about as natural and native as the valley, interior live, and blue oaks that dot the foothills and the Sacramento valley floor. Though, something not so native or natural has managed to creep its way into the valley in the past century, growing and thriving in the heat just as the oaks do, but only proving harmful to residents. That unnatural thing is the haze that envelops Sacramento during those hot days: photochemical smog and ground-level ozone. Brown and grey, shrouding the valley in a toxic bubble, this invasive element has become so pervasive that Sacramento currently ranks within the top ten cities in the United States for the worst ozone pollution and within the top fifteen for short-term particle pollution. So what conditions in Sacramento are so prevalent as to cause this pollution?

As seen in a previous article regarding Sacramento’s pollution, the northern California topography plays a huge role in advancing Sacramento into the top ten cities for the worst air pollution. Though, what initiates the presence of this pollution in the first place is the abundance of nitrogen oxides within the atmosphere, churned out by the 1.3 million-plus cars registered in Sacramento county. With such a massive amount of cars concentrated in a densely-populated, urban environment, thousands of tons of pollutants are dumped into the surrounding atmosphere each day, the primary being nitrogen oxide and dioxide which are produced as a result of the burning of fossil fuels. As ultraviolet sunlight reacts with these molecules, they are split apart, forming the constituents of photochemical smog such as ozone, aldehydes, and peroxyacetyl nitrates (PANS). Additionally, the dry, relatively arid climate of the Sacramento valley only further fuels this production as it provides a perfect breeding ground for ultraviolet light reactions with little water vapor to impede the pollution production.

As Sacramento continues to grow in population, the number of vehicles within the county may be expected to increase as well, leading to further pollution from photochemical smog and ground-level ozone. With more fossil fuel-run engines belching out nitrogen oxides, pollution will only continue and likely compound, thus producing unhealthy air for the millions that reside within the county. Although photochemical smog and ground-level ozone are the main culprits of this haze and unhealthy air quality, other factors and secondary pollutants contribute to this as well, such as dust particulates stirred into the air from the vast agricultural fields that span the entire valley. As farmers begin to plow and till the soil in preparation for planting, billows of dust are seen whirling across the fields and highways before seemingly disappearing through the means of a dust devil, contributing to the haze. Additionally, ash and PM 2.5 from California’s nearly-annual wildfires also help contribute to this haze, smoking out and infiltrating the skies as vegetation dries out and temperatures soar.

Although a common factor in the day to day life of Sacramentans, haze and pollution are not something that should at all be considered native and here to stay. Instead, it is a current, very serious problem, but one that the California Air Resources Board (CARB) and other agencies work diligently to battle. “Spare the Air” day warnings are a common tool used by this agency, encouraging residents to reduce their need for transportation or fossil fuel burning engines by taking public transit or ride-sharing. No-burn days are also issued, prohibiting citizens from burning any sort of fire in an effort to combat ash and PM 2.5 in the local atmosphere. Through these efforts and the cooperation and education of citizens, Sacramento haze may one day be a thing of the past, permitting unimpeded grand views of the oak-dotted foothills, the golden coastal mountains, and the snow-capped Sierra Nevadas once again.

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© 2019 Weather Forecaster Alexis Clouser