Qualité de l’air à Reno

How is the air quality in Reno, Nevada?

Reno air quality is generally considered healthy. In 2019, Reno averaged an air quality index (AQI) score of 18, well within the US Environmental Protection Agency (EPA) “good” standard that requires a score of 50 or less. Each month in 2019 met this standard, with averages ranging from an AQI measurement of 13 in March to an AQI measurement of 20 in November.

While Reno air quality usually poses little to no risk to health, spikes in PM2.5 and ozone pollution contribute to roughly 12 unhealthy air quality days per year.

Spikes in PM2.5 pollution are usually indicative of smoke from wildfires burning in the Eldorado, Tahoe and Plumas national forests, among others further abroad. During the 2016 to 2018 monitoring period, greater Reno, which includes Washoe, Storey, and Lyon Counties as well as the state capital, Carson City, averaged 2.7 unhealthy PM2.5 days per year.¹ The US EPA targets an annual allowance of no more than 3.2 unhealthy PM2.5 days per year. While Reno met this standard, the city was rated a “D” by the American Lung Association (ALA) for short-term PM2.5 pollution, highlighting room for improvement.

Reno’s warm climate creates the conditions for temporary spikes in ozone pollution. Ozone is formed in the atmosphere when gases (NO₂ and VOCs) emitted from tailpipes, smokestacks, and other sources of combustion pollutants react in sunlight. Since abundant sunshine and heat is required for the ozone-forming chemical reaction to take place, peak ozone season generally runs from July to October when temperatures run highest in Reno’s Washoe County region.

During the 2016 to 2018 monitoring period, Reno averaged 9.7 unhealthy ozone days per year, failing to comply with the federal limit that allows no more than 3.2 unhealthy ozone days per year. Ozone exposure at high levels can produce airway infections, breathing difficulty, permanent lung damage, and premature death. Residents who suffer from lung cancer, asthma, COPD, and cardiovascular disease should stay attuned to Reno’s air pollution levels as well as in surrounding cities such as Carson City, Sparks, and Virginia City.

Discover whether air pollution levels in Reno are healthy or potentially dangerous using the IQAir website and mobile app. An AQI measurement under 50, color-coded “green,” indicates that air quality meets US EPA standards and is considered safe to breathe. Exercise caution and follow health advisories when AQI measurements exceed 50, especially after AQI measurements excees 150 (“unhealthy”).

Does Reno have poor air quality in the summer?

Reno’s summers are hot and arid. Over the course of a year, Reno’s temperatures typically range from 23°F to 90°F.² Global warming, however, is gradually causing higher temperatures in the greater Reno area. 2018 experienced a record-breaking streak of 20 days with temperatures reaching 100 degrees or more. The last record had been set only two years earlier in 2016.³

Heat accelerates the chemical reaction that forms ground-level ozone from ambient precursor pollutants like nitrogen dioxide (NO₂) and organic compounds (VOCs). When temperatures are high (above 84 degrees) and sunlight is abundant, ozone levels tend to rise quickly. In Reno, ozone is the pollutant that causes the highest number of unhealthy air quality days, most of which occur in the summer.

Regional wildfires, although temporary and sporadic, represent another threat to Reno’s summer air quality. Fires across California and Nevada have become more widespread and damaging as a result of climate change, resulting in higher spikes in regional air pollution. The 2018 Perry Fire, for example, which was ignited in July that year, burned a total of 51,000 acres and contributed to the worst air pollution levels ever recorded in the Reno-Sparks area, causing spikes in particulate matter, carbon monoxide, formaldehyde, hydrocarbons, and nitrogen oxide.⁴

April, May, and June are Reno’s windiest months as a result of Washoe Zephyr winds. Warming temperatures cause strong winds to form when hot air on both sides of the Sierra mix together and accelerate as they move down into lower regions.⁵ While winds promote pollution dispersion from the valley, these powerful winds, when combined with low humidity and high temperatures at the start of the wildfire season, can raise the risk severe, fast-growing wildfires.

Where does Reno dust come from?

Dust describes airborne particulate matter, the most dangerous of which is PM2.5, particulate matter that measures 2.5 micrometers in size or smaller. Due to its near microscopic size, PM2.5 can penetrate deep into the lungs when inhaled, sometimes entering the bloodstream, causing far-reaching health effects.

Dust in the Reno area typically blows in from the Smoke Creek and Black Rock Desert areas. Dust storms are more likely to form in dry conditions when there is little moisture in the ground. Such conditions are not uncommon in Reno, which receives relatively little precipitation.

Nevada is the driest state in the U.S., with a statewide average precipitation of only 10 inches. Washoe County gets about 11 inches of rain over a roughly 52-day span, on average, per year.⁶ Rain can help tamp down dust and pollution during the winter months, but rainfall in this region is rare compared to other sections of the country. In January and February of 2020, Reno’s precipitation rate fell to below fifty percent. Dry conditions, strong Sierra winds, and a cold front from the high desert drove gusts of dust across the region and contributed to unhealthy air quality in Reno.

Dust devils are whirlwinds of dust and dirt, a weather phenomenon common to the area. They are formed when the sun warms the ground and causes ground-level air to rise, creating an area of low pressure. As air flows in to fill the void, it starts circulating to form a funnel.⁷ When dust devils become large, they can take on the funnel-cloud appearance of tornadoes, threatening visibility and air quality.

Breathing in the kicked-up particulate matter, can be hazardous. Dust storms can be miles long and reach thousands of feet high. Sometimes, they’re so enormous they can be seen on satellite images. Red Flag Warnings are often issued by local authorities during such events. When Reno is affected by a dust storm, seal indoor spaces from outdoor pollutants, run an air purifier, and wear a mask during outdoor activities if available.

What causes air pollution in Reno?

Reno makes up part of the sprawling Reno-Sparks metropolitan area. With a population of roughly 260,000, it’s the second-most populous district in Nevada after the Las Vegas Valley. The entertainment hub attracts millions of tourists each year, resulting in increased air pollution through fossil fuel combustion in motor vehicles and planes. In addition to transportation, Reno air quality is frequently subject to natural pollution sources such as wildfires and windblown dust. Construction, industry, and residential emissions such as wood burning, contribute to Reno’s air quality mix, though they represent lesser sources.

Two main components of car exhaust include hydrocarbons from gasoline and nitrogen oxide emitted from hot, internal combustion engines. When these elements are released into the warm desert air, the sun’s heat can bake them into ozone — a key component of smog. Ozone represents the greatest threat in Reno’s air, contributing to 9.7 unhealthy air quality days.

Summer fires and ozone-based smog levels from vehicles have increased Reno air pollution rates in recent years. In September 2020, the Washoe County Health District AQMD issued a Stage 2 Air Pollution Warning — the first ever issued by the Health District Office.

The main pollutant, outlined at the top of this page and updated in real-time, indicates which pollutant currently exists at the riskiest level. Normally, ozone is the main pollutant in the summer months while PM2.5 is the main pollutant in the winter months.

When is Reno air quality the best?

Reno, known as the biggest little city in the world, attracts millions of tourists each year to its casinos and nearby ski resorts.⁸ Seeing images of Reno’s dusty landscape may lead visitors to wonder when air quality in the city is best. Contrary to frequently circulated depictions capturing a dusty landscape, Reno air quality is usually very clean.

Spells of unhealthy air quality are quite rare, and are usually the result of wildfires or wood burning in the late summer and winter. Washoe County Health District Air Quality Management Division has taken action to reduce the risk of air pollution from wildfires by initiating prescribed fires.⁹ These are fires ignited by forest managers during less flammable weather conditions and relegated to control lines in order to clear forest underbrush that may otherwise serve as wildfire fuel. Prescribed fires may temporarily affect air quality, but they have proven to be an effective way to prevent the spread of massive wildfires, significantly minimize smoke impacts, and protect public health.

January and February of 2019 were Reno’s most polluted months. This was because of the increase in daily emissions from winter wood burning and a pollution-trapping weather event common in the winter known as cool-air inversions. Cool air inversions occur when frozen ground-level air, as a result of freezing temperatures or snow coverage, become trapped by a warmer air layer above. When this happens, emissions also become trapped and unable to disperse freely.

Follow Reno’s air quality index in real-time to stay attuned to health risks in the air, and ready to take precautionary measures to reduce pollution exposure.

+ Article Resources

[1] American Lung Association. (2020). State of the Air report.
[2] Weather Spark. (2020). Average weather in Reno.
[3] Spillman B. (2018, September 17). Reno’s sweltering summer was a record-breaker. Reno Gazette Journal.
[4] Sonner S. (2018, July 31). California fires blanket Reno area with historic air pollution. Las Vegas – Review Journal.
[5] Timko S. (2014, May 4). April to June are windiest months in Reno. Reno Gazette Journal.
[6] Best Places. (2020). Climate in Washoe County, Nevada.
[7] Current Results. (2020). Reno temperatures: Averages by month.
[8] McInnis K. (2020, June 25). The ‘Biggest Little City In The World’ was just named The Best Small City In America.
[9] Washoe County, NV. (2020). Smoke management program.