Heat and smoke make for unhealthy air in the Valley

The heat continues this week, and so does the bad air in the central San Joaquin Valley.

Air quality on Thursday in Fresno is forecast to reach a “red” level for the second day in a row, which means unhealthy air for everyone.

And for much of the rest of the Valley, air quality is forecast to be only slightly better at an “orange” level – unhealthy for sensitive groups.

Children, the elderly, and people with asthma, other lung problems and heart conditions should try to stay inside, and anyone who has to be outdoors should avoid rigorous activities.

The biggest pollutant is ozone, which thrives on hot, stagnant air days in the Valley.

At 4 p.m. Wednesday, the temperature in Fresno was 108. The National Weather Service forecast for Thursday and Friday is highs of 107.

The Valley has had temperatures higher than 100 degrees since Saturday. And that isn’t likely to change through next Wednesday. Saturday, the forecast high is 103 degrees, and highs of 102 are forecast on Monday and Tuesday. This would be an 11-day streak of blistering heat with temperatures in the triple digits.

That wouldn’t be a record, though. The Valley had 21 days with temperatures higher than 100 degrees beginning on July 23, 2005, and ending on Aug. 12 of that year.

(Did you notice the beginning of the 2005 heat streak and the beginning of this one? Both started on July 23. Is it just a coincidence?) And will the heat and the bad air stick around to rival 11 years ago?

“I wouldn’t jump to conclusions,” said Christine Riley, a meteorologist at the National Weather Service office in Hanford.

As if the heat isn’t enough, wildfires in Monterey and Los Angeles County continue to worsen the Valley’s ozone-polluted air.

Smoke produces fine particulate matter, which can cause serious health problems, including lung disease, asthma attacks and increased risk for heart attacks and stroke.

The heat and a strong high pressure system are causing smoke to hang close to the ground.

“If you see smoke or smell smoke, stay inside in an air-conditioned environment,” said Jaime Holt, chief communications officer at the San Joaquin Valley Air Pollution Control District.

But ozone by itself is a bad pollutant.

It’s sometimes described as a lung sunburn. Scientists know it causes inflammation in the lungs and kills cells.

Research shows that breathing ozone can, in the short term, cause shortness of breath and trigger asthma attacks. Long-term exposure – even at levels below a health alert – may cause scarring of the lungs, birth defects and other chronic health problems. It’s been linked to early death.

But symptoms of the chemical burn can vary. One person may gasp for air and cough or rub stinging eyes. Another may feel little or no discomfort. And symptoms from breathing ozone also can lessen – and even stop – as exposure is repeated.

The disappearance of symptoms doesn’t mean an individual has developed resistance to ozone, according to the federal Environmental Protection Agency. Ozone can continue to cause lung damage even when the symptoms have disappeared, the EPA says.

The most vulnerable to ozone are children, who breathe more air for their body weight than adults, and older people who can have health conditions that weaken their lungs and heart. But a healthy person exercising can breathe as much as 20 times more air than a person at rest. They also tend to breathe through their mouths, which bypasses the nose – the body’s hair-lined air filter.

Dr. A.M. Aminian, a Fresno allergist, said people were running in the heat Monday. “They should not have been doing that,” he said.

The doctor has seen more patients with asthma and other respiratory problems over the past two weeks. On the weekend, he had calls from patients in distress, he said. “A lot of people are having problems right now.”

“Ozone is just really irritating to people’s respiratory tracts,” he said. “It creates just a feeling of dull aching in the chest, chest tightness.”

People can monitor ozone levels by going to the air district website.

Ozone levels typically peak in the afternoon with the highest recorded between 3 and 6 p.m., Holt said. “Morning is the better choice for being outside, at least for this week that we’re having right now.”

This story was originally published July 26, 2016 at 7:09 PM with the headline "Heat and smoke make for unhealthy air in the Valley."