Sitting on the western edge of Nevada, the city of Reno is some 100 miles from the Ferguson Fire that's burning near Yosemite National Park and about 160 miles from the Carr Fire in and around Redding, Calif.
Yet the air quality in Reno these days is regarded as unhealthy for sensitive groups, with widespread haze expected through Thursday. In Carson City, another 30 miles south, the air is deemed unhealthy for everyone.
The 17 major wildfires currently raging in California, with the still-growing Mendocino Complex Fire in the northern part of the state especially gaining prominence, are severely impacting the breathability of the air well beyond their immediate areas.
The Environmental Protection Agency’s Airnow.gov website shows about a fifth of the state is being exposed to “unhealthy’’ air – the fourth ranking on a six-stage scale that ranges from “good’’ to “hazardous’’ – and it has drifted into Oregon to the north and Nevada to the east.
To some extent, location may not matter when it comes to the harmful effects the fires are having on the ambient air. Redding, for example, is drawing the same ranking as Carson City. The National Weather Service issued an air-quality advisory for Sacramento even though the state capital is no closer than 80 miles to the largest fires.
“The wind brought the smoke here, so distance is not what measures how far an area is impacted,’’ said Xiaoliang Wang, research professor of atmospheric science at the Desert Research Institute in Reno. “The concentration in the area is the main thing to look at.’’
The EPA calculates a daily Air Quality Index based on five major pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide.
The values start at 0-50 for “good’’ and rise in increments of 50 until reaching the fifth category, “very unhealthy,’’ at which point the numbers increase by the hundreds to a maximum of 500.
Anything above 150 is considered potentially harmful for the general public, with adverse health effects that could include respiratory and cardiovascular diseases.
“Exposure to particle pollution can cause serious health problems, aggravate lung disease, cause asthma attacks and acute bronchitis, and increase risk of respiratory infections,’’ the air-quality advisory said, adding that children and people advanced in age are more susceptible and should avoid prolonged exposure.
In Reno, breathing the air outside can have the same deleterious effect as smoking two cigarettes, according to a UC-Berkeley study. Wang said there’s some debate about the accuracy of that conclusion, but agreed the conditions have been a problem, with an AQI rating of 123 on Wednesday.
Because of individual variations, there’s no precise formula for determining how much time people can safely spend outside when the air is not clean. The EPA has set a daily limit of 35 micrograms per cubic meter of particulate matter, or inhalable particles that are 2.5 micrometers and smaller in diameter. The World Health Organization has pegged that number at 10.
In case of doubt, Wang said relying on common sense works as a rule of thumb, and added that using masks with a rating of 95 or above can help people avoid breathing the vast majority of the most harmful particulates.
But he emphasized that simply smelling for smoke won’t provide an accurate indication of whether the air is clean.
“A lot of smoke particles can’t be (detected) by humans,’’ he said. “Some don’t smell. Some chemicals have a higher odor that people are sensitive to, but some are still toxic and don’t have an odor.’’
Instead, Wang suggested checking Airnow.gov for current AQI figures and forecasts for the 50 states broken down by city.
Wes Siler, contributing editor for Outside magazine, noted the improvement in how some websites keep the public informed. He pointed to InciWeb, which combines information from several agencies about fires and other natural resource incidents, as a valuable resource.
“That used to be one of those terrible government web sites that was text-based and just so (dry),’’ he said. “They’ve updated it this year with maps and social media components.’’
Siler, a former Californian who recently moved to Montana, was living in the Los Angeles area when the massive Thomas Fire destroyed more than 282,000 acres in Ventura and Santa Barbara counties last December.
He offers a reminder for those who live in fire-prone areas to check their air filters at home and in their cars, and he stresses that while wood smoke alone has a number of toxins, including some known to cause cancer, the danger is exacerbated when wildfires reach inhabited areas.
“If you start getting into structure fires, a house for example,’’ he said, “paint and plastics, fuels and all sorts of things together are extremely bad for you to be breathing.’’