RENO, Nev. - The Latest on the wildfires and smoky conditions in Nevada (all times local):

4:55 p.m.

Smoke from a series of large wildfires burning in northern California and northern Nevada has created some of the worst air pollution levels ever recorded in the Reno-Sparks area.

The Washoe County Health District said Monday the air quality is now considered unhealthy for all populations.

Alerts have been issued for more than a week since a big fire broke out nearly 150 miles (241 kilometres) away near Yosemite National Park near the California-Nevada line. But those warnings applied to sensitive groups — children, the elderly and people with respiratory issues.

The Air Quality Index for ozone reached an unofficial rating of 172 in Reno late Monday afternoon.

That's worse than the previous record of 164 in 1984, although Health District spokesman Phil Ulibarri says the official AQI is based on a 24-hour average so Monday's number could change. Air quality data in Reno goes back to 1963.

Ulibarri says it's definitely the worst air quality in a decade, and everyone should avoid prolonged activity outdoors.

Sensitive groups remain under alert in Carson City, Fallon and Gardnerville.

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3:20 p.m.

A lightning-sparked fire in the remote mountains northwest of Las Vegas has burned nearly 8 square miles (20 sq. kilometres) near Nellis Air Force Base and the Nevada National Security Site.

Officials at the security site formerly known as the Nevada Test Site said Monday the rugged terrain has prevented firefighters from gaining access to the fire that was reported on Saturday.

The U.S. Bureau of Land Management intends to have an air tanker drop retardant on the blaze by sometime Tuesday.

The fire currently is burning in mostly pinion pines and juniper bushes.

Officials say there's currently no threat to any structures or contaminated areas of the site where nuclear bombs were tested during the 1950s.

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2:20 p.m.

Authorities in northern Nevada have expanded the evacuation zone where a wildfire has burned about 66 square miles (170 sq. kilometres) of mostly high-desert rangeland north of Reno near Pyramid Lake.

Truckee Meadows Fire Protection District spokesman Adam Mayberry said Monday no structures have been damaged but more than 130 people have left their homes because of the fire that at one point threatened as many as 70 residences.

Only eight spent the night at a Red Cross shelter at the Ironwood Events Center in Palomino Valley north of Reno but more than 300 displaced animals are being housed there, including livestock, horses and pets.

About a 12-mile (19-kilometre) stretch of State Route 446 along Pyramid Lake has been closed in both directions between the Pyramid Highway and Nixon.

The fire was about 15 per cent contained Monday afternoon.

News from © The Associated Press, 2018