Headline: Ack! Distant fires leave California's capital city in a haze

No major wildfires are burning near Sacramento but for two weeks a dull haze and the faint smell of smoke from distant blazes has blanketed California's capital region.

It's forced summer campers to stay inside, obscured normally bright skylines and left ash on cars.

Experiencing smoky air from blowing winds is nothing new in many California cities, but Sacramento air quality experts say it's rare for the dirty air to linger for so long, a reality of ever-larger fires that take longer to extinguish.

The haze stretches to the Sierra Nevada mountain range and nearly every major population center in between has suffered air quality considered dangerous for children, the elderly and people with asthma.

Winds often blow smoky air around California during intense fires, but Sacramento air quality experts say it's rare for the dirty air to linger for so long, a reality of ever-larger fires that take longer to extinguish.

There are two major wildfires _ one called the Mendocino Complex Fire that is the largest in California history _ burning more than 100 miles (160 kilometers) north of Sacramento and another huge fire near Yosemite National Park a little farther to the southeast. Firefighters made significant process against the Mendocino Complex for the first time Wednesday but said the blazes will likely continue through September.

Wednesday marked the Sacramento region's 13th straight "Spare the Air" day, when people are encouraged not to drive and add further pollutants to the air _ the longest stretch since at least 2001. A similar warning is effect in the San Francisco Bay Area, and air quality experts in California's Central Valley and areas southeast of Los Angeles are warning residents to limit outdoor exposure because of wildfires there.

A day earlier, dozens of summer campers sat inside watching a movie at a Sacramento YMCA.

"Normally that doesn't happen on a regular day at camp," said Jay Lowden, president of the YMCA for a nine-county region that serves more than 700 kids weekly at 13 summer camps. His counselors monitor the air quality on a daily basis, and Lowden said he may cancel a planned family camp this weekend in the foothills because of the smoke.

Lori Kobza, spokeswoman for the Sacramento Air Quality Management District, said it's hard to predict when things will improve because of the unpredictably of the fires and the winds.

Because the city is located in a valley, it's easier for smoky air to get trapped here when high pressure systems blow in, making Sacramento like a smoke-filled bowl that's had a lid placed tightly on top.

Sacramento, California - 8 August 2018

1. Various of kids playing indoors at YMCA Sacramento day camp (YMCA says parents signed waivers allowing kids to be on camera)

2. Various of playground equipment not being used

3. SOUNDITE (English) Jay Lowden, president of YMCA of Superior California

"The wildfires and the air quality and lack of good air quality has impacted our camps. We have to keep the kids inside more. A lot of the outdoor physical activities we've had to curtail and cut back on. And it's frustrating because the kids are spending more time inside. They get a little bit of cabin fever."

4. California State Capitol building in hazy air

5. Sacramento River and skyline in hazy air

6. SOUNDBITE (English) Lori Kobza, spokeswoman, Sacramento Metropolitan Air Quality Management District

"We're just most concerned right now with the wildfire smoke and the particulate matter. So we do encourage people to stay indoors and limit their outside activities."

7. Screen showing air quality index

8. Kobza on computer showing air quality map

9. Screen showing air quality map of Sacrament region

10. SOUNDBITE (English) Lori Kobza, spokeswoman, Sacramento Metropolitan Air Quality Management District

"Now the Mendocino Complex Fires right now are so huge are burning over 300,000 acres and they are contributing the majority of the smoke. Right now however we are still seeing impacts from the Carr Fire, which is burning up near Redding and the Ferguson Fire which is burning in the Yosemite Valley area."

11. Various of kids playing indoors at YMCA day camp

12. SOUNDBITE (English) Braylin Sligar, YMCA camp director

"So air quality wise, so it limits our outdoor time which is hard during summer because it's all about being outdoors and using the outdoors to have fun and to play. So we've had to incorporate a lot more indoor activities in developing our program to accommodate the weather."

13. Boys playing basketball in gym

14. SOUNDBITE (English) Sean Nolasco, 11, YMCA day camper

"It's a very good idea to have a stay indoors because sometimes the pollution can make us sick and stuff."

15. Kids sitting in gym with camp counselor

Headline: Ack! Distant fires leave California's capital city in a haze

No major wildfires are burning near Sacramento but for two weeks a dull haze and the faint smell of smoke from distant blazes has blanketed California's capital region.

It's forced summer campers to stay inside, obscured normally bright skylines and left ash on cars.

Experiencing smoky air from blowing winds is nothing new in many California cities, but Sacramento air quality experts say it's rare for the dirty air to linger for so long, a reality of ever-larger fires that take longer to extinguish.

The haze stretches to the Sierra Nevada mountain range and nearly every major population center in between has suffered air quality considered dangerous for children, the elderly and people with asthma.

Winds often blow smoky air around California during intense fires, but Sacramento air quality experts say it's rare for the dirty air to linger for so long, a reality of ever-larger fires that take longer to extinguish.

There are two major wildfires _ one called the Mendocino Complex Fire that is the largest in California history _ burning more than 100 miles (160 kilometers) north of Sacramento and another huge fire near Yosemite National Park a little farther to the southeast. Firefighters made significant process against the Mendocino Complex for the first time Wednesday but said the blazes will likely continue through September.

Wednesday marked the Sacramento region's 13th straight "Spare the Air" day, when people are encouraged not to drive and add further pollutants to the air _ the longest stretch since at least 2001. A similar warning is effect in the San Francisco Bay Area, and air quality experts in California's Central Valley and areas southeast of Los Angeles are warning residents to limit outdoor exposure because of wildfires there.

A day earlier, dozens of summer campers sat inside watching a movie at a Sacramento YMCA.

"Normally that doesn't happen on a regular day at camp," said Jay Lowden, president of the YMCA for a nine-county region that serves more than 700 kids weekly at 13 summer camps. His counselors monitor the air quality on a daily basis, and Lowden said he may cancel a planned family camp this weekend in the foothills because of the smoke.

Lori Kobza, spokeswoman for the Sacramento Air Quality Management District, said it's hard to predict when things will improve because of the unpredictably of the fires and the winds.

Because the city is located in a valley, it's easier for smoky air to get trapped here when high pressure systems blow in, making Sacramento like a smoke-filled bowl that's had a lid placed tightly on top.

Sacramento, California - 8 August 2018

1. Various of kids playing indoors at YMCA Sacramento day camp (YMCA says parents signed waivers allowing kids to be on camera)

2. Various of playground equipment not being used

3. SOUNDITE (English) Jay Lowden, president of YMCA of Superior California

"The wildfires and the air quality and lack of good air quality has impacted our camps. We have to keep the kids inside more. A lot of the outdoor physical activities we've had to curtail and cut back on. And it's frustrating because the kids are spending more time inside. They get a little bit of cabin fever."

4. California State Capitol building in hazy air

5. Sacramento River and skyline in hazy air

6. SOUNDBITE (English) Lori Kobza, spokeswoman, Sacramento Metropolitan Air Quality Management District

"We're just most concerned right now with the wildfire smoke and the particulate matter. So we do encourage people to stay indoors and limit their outside activities."

7. Screen showing air quality index

8. Kobza on computer showing air quality map

9. Screen showing air quality map of Sacrament region

10. SOUNDBITE (English) Lori Kobza, spokeswoman, Sacramento Metropolitan Air Quality Management District

"Now the Mendocino Complex Fires right now are so huge are burning over 300,000 acres and they are contributing the majority of the smoke. Right now however we are still seeing impacts from the Carr Fire, which is burning up near Redding and the Ferguson Fire which is burning in the Yosemite Valley area."

11. Various of kids playing indoors at YMCA day camp

12. SOUNDBITE (English) Braylin Sligar, YMCA camp director

"So air quality wise, so it limits our outdoor time which is hard during summer because it's all about being outdoors and using the outdoors to have fun and to play. So we've had to incorporate a lot more indoor activities in developing our program to accommodate the weather."

13. Boys playing basketball in gym

14. SOUNDBITE (English) Sean Nolasco, 11, YMCA day camper

"It's a very good idea to have a stay indoors because sometimes the pollution can make us sick and stuff."

15. Kids sitting in gym with camp counselor

No major wildfires are burning near Sacramento but for two weeks a dull haze and the faint smell of smoke from distant blazes has blanketed California's capital region.

It's forced summer campers to stay inside, obscured normally bright skylines and left ash on cars.

Winds often blow smoky air around California during intense fires, but Sacramento air quality experts say it's rare for the dirty air to linger for so long, a reality of ever-larger fires that take longer to extinguish.

The haze stretches to the Sierra Nevada mountain range and nearly every major population center in between has suffered air quality considered dangerous for children, the elderly and people with asthma.

There are two major wildfires - one called the Mendocino Complex Fire that is the largest in California history - burning more than 100 miles (160 kilometers) north of Sacramento and another huge fire near Yosemite National Park a little farther to the southeast.

Sacramento, California - 8 August 2018

1. Various of kids playing indoors at YMCA Sacramento day camp

2. Various of playground equipment not being used

3. SOUNDBITE (English) Jay Lowden, president of YMCA of Superior California

"The wildfires and the air quality and lack of good air quality has impacted our camps. We have to keep the kids inside more. A lot of the outdoor physical activities we've had to curtail and cut back on. And it's frustrating because the kids are spending more time inside. They get a little bit of cabin fever."

4. California State Capitol building in hazy air

5. Sacramento River and skyline in hazy air

6. SOUNDBITE (English) Lori Kobza, spokeswoman, Sacramento Metropolitan Air Quality Management District

"We're just most concerned right now with the wildfire smoke and the particulate matter. So we do encourage people to stay indoors and limit their outside activities."

7. Screen showing air quality index

8. Kobza on computer showing air quality map

9. Screen showing air quality map of Sacramento region

10. SOUNDBITE (English) Lori Kobza, spokeswoman, Sacramento Metropolitan Air Quality Management District

"Now the Mendocino Complex Fires right now are so huge are burning over 300,000 acres and they are contributing the majority of the smoke. Right now however we are still seeing impacts from the Carr Fire, which is burning up near Redding and the Ferguson Fire which is burning in the Yosemite Valley area."

11. Various of kids playing indoors at YMCA day camp

12. SOUNDBITE (English) Braylin Sligar, YMCA camp director

"So air quality wise, so it limits our outdoor time which is hard during summer because it's all about being outdoors and using the outdoors to have fun and to play. So we've had to incorporate a lot more indoor activities in developing our programme to accommodate the weather."

13. Boys playing basketball in gym

14. SOUNDBITE (English) Sean Nolasco, 11, YMCA day camper

"It's a very good idea to have a stay indoors because sometimes the pollution can make us sick and stuff."

15. Kids sitting in gym with camp counselor

Most schools in San Francisco, Sacramento, Oakland and Folsom will be closed Friday as a deadly wildfire in Northern California sends smoke into the Bay Area.

School districts announced the closures Thursday as the region experienced some of the worst air quality since the fire started a week ago about 180 miles (290 kilometers) north of San Francisco.

An Environmental Protection Agency website says the air quality in Sacramento is "hazardous" Thursday and San Francisco's is "very unhealthy." Many people walking around the cities wore face masks.

Several Northern California universities had announced closures earlier Thursday.

The wildfire that started a week ago has killed dozens of people and charred nearly 220 square miles (570 square kilometers).

Smoke masks. Eye drops. No outdoor exercise. This is how Californians are trying to cope with wildfires choking the state, but experts say an increase in serious health problems may be almost inevitable for vulnerable residents as the disasters become more commonplace.

"It just feels very smoky and full of particulates. I'm definitely worried about my son who's breathing this stuff. We've got air filters at home and we're running them at full speed but I'm not sure it's enough to get rid of all the toxic particulates so I'm definitely worried about the health of my family and the city in general," San Francisco resident Daniel Horn said.

Research suggests children, the elderly and those with existing health problems are most at risk.

Short-term exposure to wildfire smoke can worsen existing asthma and lung disease, leading to emergency room treatment or hospitalization, studies have shown.

Increases in doctor visits or hospital treatment for respiratory infections, bronchitis and pneumonia in otherwise healthy people also have been found during and after wildfires.

Some studies also have found increases in ER visits for heart attacks and strokes in people with existing heart disease on heavy smoke days during previous California wildfires, echoing research on potential risks from urban air pollution.

For most healthy people, exposure to wildfire smoke is just an annoyance, causing burning eyes, scratchy throats or chest discomfort that all disappear when the smoke clears.

But doctors, scientists and public health officials are concerned that the changing face of wildfires will pose a much broader health hazard,

In an overview published earlier this year, Cascio wrote that the increasing frequency of large wildland fires, urban expansion into wooded areas and an aging population are all increasing the number of people at risk for health problems from fires.

Wood smoke contains some of the same toxic chemicals as urban air pollution, along with tiny particles of vapor and soot 30 times thinner than a human hair. These can infiltrate the bloodstream, potentially causing inflammation and blood vessel damage even in healthy people, research on urban air pollution has shown. Studies have linked heart attacks and cancer with long-term exposure to air pollution.

Whether exposure to wildfire smoke carries the same risks is uncertain, and determining harm from smog versus wildfire smoke can be tricky, especially with wind-swept California wildfires spreading thick smoke hundreds of miles away into smoggy big cities.

San Francisco - 15 November 2018

1.Two men sit in foreground, barely visible Golden Gate Bridge in background

2. Dogwalker wears masks while six dogs on leashes follow along the beach

3. View of Golden Gate Bridge from smoky Crissy Field

4. Woman wearing mask holds small dog with bridge in background

5. Walking shot of man with dog on Crissy Field beach

6. SOUNDBITE (English) Chloe Allegret, San Francisco resident:

"It's pretty uncomfortable. It's definitely causing shortness of breath, pressure in the sinuses so we're taking it easy."

7. Food delivery workers loading up van while wearing masks

8. Postal worker delivers mail while wearing mask

9. UPS driver wears mask while making delivery

10. SOUNDBITE (English) Daniel Horn, San Francisco resident:

"It just feels very smoky and full of particulates. I'm definitely worried about my son who's breathing this stuff. We've got air filters at home and we're running them at full speed but I'm not sure it's enough to get rid of all the toxic particulates so I'm definitely worried about the health of my family and the city in general."

11. Man walks along city's Embarcadero wearing mask

12. Embarcadero cleaning crew rides by on bicycle while wearing mask

13. Two women sit on park bench wearing masks

14. SOUNDBITE (English) Kylie Garcia, San Francisco resident:

"It sucks for people who are allergic to this stuff. Even me, I'm walking out here and my god, now my throat is feeling raspy. I walk here everyday on my work lunch break. It's crazy. I can't believe it. It's really sad and hopefully they'll be able to stop it. We'll see how long it goes."

15. Fire boat floating on Bay in foreground, Bay Bridge in smog in background

Most schools in San Francisco, Sacramento, Oakland and Folsom will be closed Friday as a deadly wildfire in Northern California sends smoke into the Bay Area.

School districts announced the closures Thursday as the region experienced some of the worst air quality since the fire started a week ago about 180 miles (290 kilometers) north of San Francisco.

An Environmental Protection Agency website says the air quality in Sacramento is "hazardous" Thursday and San Francisco's is "very unhealthy." Many people walking around the cities wore face masks.

Several Northern California universities had announced closures earlier Thursday.

The wildfire that started a week ago has killed dozens of people and charred nearly 220 square miles (570 square kilometers).

Smoke masks. Eye drops. No outdoor exercise. This is how Californians are trying to cope with wildfires choking the state, but experts say an increase in serious health problems may be almost inevitable for vulnerable residents as the disasters become more commonplace.

"It just feels very smoky and full of particulates. I'm definitely worried about my son who's breathing this stuff. We've got air filters at home and we're running them at full speed but I'm not sure it's enough to get rid of all the toxic particulates so I'm definitely worried about the health of my family and the city in general," San Francisco resident Daniel Horn said.

Research suggests children, the elderly and those with existing health problems are most at risk.

Short-term exposure to wildfire smoke can worsen existing asthma and lung disease, leading to emergency room treatment or hospitalization, studies have shown.

Increases in doctor visits or hospital treatment for respiratory infections, bronchitis and pneumonia in otherwise healthy people also have been found during and after wildfires.

Some studies also have found increases in ER visits for heart attacks and strokes in people with existing heart disease on heavy smoke days during previous California wildfires, echoing research on potential risks from urban air pollution.

For most healthy people, exposure to wildfire smoke is just an annoyance, causing burning eyes, scratchy throats or chest discomfort that all disappear when the smoke clears.

But doctors, scientists and public health officials are concerned that the changing face of wildfires will pose a much broader health hazard,

In an overview published earlier this year, Cascio wrote that the increasing frequency of large wildland fires, urban expansion into wooded areas and an aging population are all increasing the number of people at risk for health problems from fires.

Wood smoke contains some of the same toxic chemicals as urban air pollution, along with tiny particles of vapor and soot 30 times thinner than a human hair. These can infiltrate the bloodstream, potentially causing inflammation and blood vessel damage even in healthy people, research on urban air pollution has shown. Studies have linked heart attacks and cancer with long-term exposure to air pollution.

Whether exposure to wildfire smoke carries the same risks is uncertain, and determining harm from smog versus wildfire smoke can be tricky, especially with wind-swept California wildfires spreading thick smoke hundreds of miles away into smoggy big cities.

San Francisco - 15 November 2018

1. Two men sit in foreground, barely visible Golden Gate Bridge in background

2. Dogwalker wears masks while six dogs on leashes follow along the beach

3. View of Golden Gate Bridge from smoky Crissy Field

4. Woman wearing mask holds small dog with bridge in background

5. Walking shot of man with dog on Crissy Field beach

6. SOUNDBITE (English) Chloe Allegret, San Francisco resident:

"It's pretty uncomfortable. It's definitely causing shortness of breath, pressure in the sinuses so we're taking it easy."

7. Food delivery workers loading up van while wearing masks

8. Postal worker delivers mail while wearing mask

9. UPS driver wears mask while making delivery

10. SOUNDBITE (English) Daniel Horn, San Francisco resident:

"It just feels very smoky and full of particulates. I'm definitely worried about my son who's breathing this stuff. We've got air filters at home and we're running them at full speed but I'm not sure it's enough to get rid of all the toxic particulates so I'm definitely worried about the health of my family and the city in general."

11. Man walks along city's Embarcadero wearing mask

12. Embarcadero cleaning crew rides by on bicycle while wearing mask

13. Two women sit on park bench wearing masks

14. SOUNDBITE (English) Kylie Garcia, San Francisco resident:

"It sucks for people who are allergic to this stuff. Even me, I'm walking out here and my god, now my throat is feeling raspy. I walk here everyday on my work lunch break. It's crazy. I can't believe it. It's really sad and hopefully they'll be able to stop it. We'll see how long it goes."

15. Fire boat floating on Bay in foreground, Bay Bridge in smog in background

Most schools in San Francisco, Sacramento, Oakland and Folsom will be closed Friday as a deadly wildfire in Northern California sends smoke into the Bay Area.

School districts announced the closures Thursday as the region experienced some of the worst air quality since the fire started a week ago about 180 miles (290 kilometers) north of San Francisco.

An Environmental Protection Agency website says the air quality in Sacramento is "hazardous" Thursday and San Francisco's is "very unhealthy." Many people walking around the cities wore face masks.

Several Northern California universities had announced closures earlier Thursday.

The wildfire that started a week ago has killed dozens of people and charred nearly 220 square miles (570 square kilometers).

Smoke masks. Eye drops. No outdoor exercise. This is how Californians are trying to cope with wildfires choking the state, but experts say an increase in serious health problems may be almost inevitable for vulnerable residents as the disasters become more commonplace.

"It just feels very smoky and full of particulates. I'm definitely worried about my son who's breathing this stuff. We've got air filters at home and we're running them at full speed but I'm not sure it's enough to get rid of all the toxic particulates so I'm definitely worried about the health of my family and the city in general," San Francisco resident Daniel Horn said.

Research suggests children, the elderly and those with existing health problems are most at risk.

Short-term exposure to wildfire smoke can worsen existing asthma and lung disease, leading to emergency room treatment or hospitalization, studies have shown.

Increases in doctor visits or hospital treatment for respiratory infections, bronchitis and pneumonia in otherwise healthy people also have been found during and after wildfires.

Some studies also have found increases in ER visits for heart attacks and strokes in people with existing heart disease on heavy smoke days during previous California wildfires, echoing research on potential risks from urban air pollution.

For most healthy people, exposure to wildfire smoke is just an annoyance, causing burning eyes, scratchy throats or chest discomfort that all disappear when the smoke clears.

But doctors, scientists and public health officials are concerned that the changing face of wildfires will pose a much broader health hazard,

In an overview published earlier this year, Cascio wrote that the increasing frequency of large wildland fires, urban expansion into wooded areas and an aging population are all increasing the number of people at risk for health problems from fires.

Wood smoke contains some of the same toxic chemicals as urban air pollution, along with tiny particles of vapor and soot 30 times thinner than a human hair. These can infiltrate the bloodstream, potentially causing inflammation and blood vessel damage even in healthy people, research on urban air pollution has shown. Studies have linked heart attacks and cancer with long-term exposure to air pollution.

Whether exposure to wildfire smoke carries the same risks is uncertain, and determining harm from smog versus wildfire smoke can be tricky, especially with wind-swept California wildfires spreading thick smoke hundreds of miles away into smoggy big cities.

San Francisco - 15 November 2018

1.Two men sit in foreground, barely visible Golden Gate Bridge in background

2. Dogwalker wears masks while six dogs on leashes follow along the beach

3. View of Golden Gate Bridge from smoky Crissy Field

4. Woman wearing mask holds small dog with bridge in background

5. Walking shot of man with dog on Crissy Field beach

6. SOUNDBITE (English) Chloe Allegret, San Francisco resident:

"It's pretty uncomfortable. It's definitely causing shortness of breath, pressure in the sinuses so we're taking it easy."

7. Food delivery workers loading up van while wearing masks

8. Postal worker delivers mail while wearing mask

9. UPS driver wears mask while making delivery

10. SOUNDBITE (English) Daniel Horn, San Francisco resident:

"It just feels very smoky and full of particulates. I'm definitely worried about my son who's breathing this stuff. We've got air filters at home and we're running them at full speed but I'm not sure it's enough to get rid of all the toxic particulates so I'm definitely worried about the health of my family and the city in general."

11. Man walks along city's Embarcadero wearing mask

12. Embarcadero cleaning crew rides by on bicycle while wearing mask

13. Two women sit on park bench wearing masks

14. SOUNDBITE (English) Kylie Garcia, San Francisco resident:

"It sucks for people who are allergic to this stuff. Even me, I'm walking out here and my god, now my throat is feeling raspy. I walk here everyday on my work lunch break. It's crazy. I can't believe it. It's really sad and hopefully they'll be able to stop it. We'll see how long it goes."

15. Fire boat floating on Bay in foreground, Bay Bridge in smog in background

SHOTLIST:

1. Mid of women with masks on sifting through ashes of debris of burnt home, pull out

2. Wide of people sifting through debris with masks on

3. Close-up of women with masks on

4. Close-up of debris being sifted

5. Mid of two women walking through fire damaged neighbourhood with masks on

6. SOUNDBITE: (English) Christina Durvis, San Diego resident:

"This is the first time we have really looked up close, so I can't really process how I feel about the smoke, because of the visual images. But it smells horrible and I can feel it in my lungs even with my mask."

7. SOUNDBITE: (English) Laurie Norcross, San Diego resident:

"It's bad, it's bad, but it seems like it's not getting much better at this point. It still feels pretty consistent, it's hard to take a deep breath."

8. Mid of doctor showing how smoke affects your lungs

9. Various shots of hospital

10. SOUNDBITE: (English) Dr Timothy Morris, Service chief for pulmonary medicine at UCSD Medical Centre:

"It can make you a little short of breath. It can make you start to cough or even make you start to wheeze. Now for a normal healthy person, that is usually a minor nuisance. For somebody who has a pre-existing lung condition, it can actually be quite dangerous."

11. Mid of men going through debris with masks on

12. Various of men working with masks on sifting through debris of burnt house

STORYLINE:

As the wildfires in the US state of California die down and residents return home, lingering dust and soot-laden air are making it difficult for many to breathe even a sigh of relief.

Air quality remained poor in the central San Bernardino Mountains and parts of the San Bernardino Valley as well as swaths of Orange and Riverside Counties.

In San Diego County, where only one of four major fires was more than 50 percent contained, the air quality was especially bad on Friday.

"It's bad, it's bad," said Laurie Norcross, who was helping to sift through the debris at a friend's burnt out home. "It seems like it's not getting much better at this point, it feels pretty consistent, it's hard to take a deep breath."

Satellite pictures continued to show a thick haze of smoke hanging over the entire region, affecting schools, events and the health of residents all over Southern California.

Residents staying in areas with bad air were advised to avoid exerting themselves both indoors and outside.

Children and those with heart and respiratory conditions were urged to stay indoors with the windows and doors closed and air conditioners on.

One of the biggest health threats with fires are the fine particles that are not visible to the naked eye.

These particles can get into the lungs and make breathing an even greater struggle for people with asthma, bronchitis and emphysema.

Miles from any of the fires, smoke and dust from surrounding areas continued to hang like a heavy fog over the port city of Long Beach, making the sun appear a deep orange.

In San Diego, where fires still raged, the University of California San Diego Medical Centre saw an increase in patients coming in with breathing troubles they believe were related to air pollution, but they didn't have statistics available, said spokeswoman Jackie Carr.

"It can make you a little short of breath," said Dr Timothy Morris, the service chief for pulmonary medicine at UCSD Medical Centre.

"For a normal healthy person, that is usually a minor nuisance, for someone who has a pre-existing lung condition, it can actually be quite dangerous," he added.