Even though "Spare the Air Days" won't start until next month, it's already time to give the atmosphere a breather.
The air quality index, an indicator of pollution in the air, has been increasing with the recent warm weather.
And as the temperature rises, the AQI will only get worse, said Anthony Presto, public information officer for the San Joaquin Valley Air Pollution Control District.
"It was pretty good a week ago," Presto said Wednesday. "When the temperature kicks up, that's when things start to happen."
The local forecast is for temperatures in the low 90s today and Friday. Temperatures will cool down a bit over the weekend, into the low 80s before warming up into the high 80s again next week.
After the sunny, breezy conditions of a few days ago, the recent change in weather pattern has caused the AQI to increase from 87 (moderate) earlier in the week to 101 (unhealthy for sensitive groups) on Wednesday.
An AQI below 50 represents good air quality, 151-200 is unhealthy air for everyone, and 201-300 is considered to be "very unhealthy" air. An AQI of higher than 300 is considered hazardous.
The AQI measures the amount of ozone in the air. When the air heats up, it "cooks" the ozone, creating smog, Presto said.
Presto said more than 50 percent of the ozone that constitutes the AQI is created by automobiles.
"We need to get out of our cars, and find other ways to get around," he said.
But it is not just car engines that are causing smog, he said.
Gas powered lawnmowers, grass blowers and other small engines cause much more than their fair share of pollution, he said.
"Running a lawnmower for one hour is the same as running 40 late model cars for the same length of time," he said.
Running a chain saw for an hour creates as much pollution as driving a car for 200 miles, Presto said.
Presto suggested buying electric lawnmowers, leaf blowers and other tools.
He also recommended "trip-linking," or making sure that a variety of errands are accomplished in a single trip. Cars produce more pollution while they are warming up, and not letting the car cool down between trips helps to reduce pollution, he said.
Julie Soria, of Lodi, suffers from asthma.
"When the weather is very still, I have a hard time breathing," she said.
Sitting at a picnic table amid swirling cottonwood puffs at Lodi Lake, her friend Crystal Segura, also of Lodi, said she has her own opinion about air quality.
"It's the buses and the trucks, when you get behind them you can't breathe," she said.
On Wednesday, the city of Lodi proclaimed "Air Quality Improvement Day." Lodi has replaced 20 of its 25 public transit vehicles with clean-burning CNG models, said Richard Prima, public works director. The new buses serve the GrapeLine and Dial-a-Ride.
The city has also purchased two new dump trucks and a street sweeper, all powered by CNG, Prima said.
So far, the only downside to the changeover is that the new vehicles do not have as great a range as the previous diesel and gasoline models, he said.
The larger vehicles had been diesel powered, while some of the smaller buses had gasoline engines, Prima said.
The city chose the CNG vehicles to improve air quality, he said.
"Besides the overall air quality, it's the local air quality when you're sitting behind a bus," Prima said. "That's pretty important too."
The federal Environmental Protection Agency designates San Joaquin County as having a "severe" air pollution problem. The "severe" designation is one step away from the agency's highest rating of "extreme."
At Lodi Memorial Hospital, the Emergency Room staff has grown accustomed to seeing an increase in patients during periods of days with bad air quality, hospital spokeswoman Carol Farron said.
While the hospital does keep up with reports of air quality conditions, the staff have another way of judging the severity of the problem, she said.
"We see it in the patients who come through our doors," she said.
Jerry Martin, a spokesman for the California Air Resources Board, said there is a type of air pollution that is not measured by the AQI - particulate pollution.
In February, CARB reported increased hospitalizations and emergency room visits for respiratory problems after periods of high particulate pollution. Some of these particles are one-seventh the size of a human hair, small enough to lodge in the lungs.
"From a statewide or national perspective, motor vehicles are the number one cause of particulate pollution," the CARB's Martin said. "The overwhelming majority of that particulate comes from diesel engines."
In regions such as the San Joaquin Valley, dust raised by agricultural operations also contributes to seasonal increases in particulate pollution, Martin said.
And while motor vehicles cause 90 percent of all airborne toxins, diesel engines are responsible for 70 percent of that total, Martin said. Put another way, diesel engines power only 3 percent of the total vehicles on the road, but create more pollution than all gasoline-powered vehicles.
Another problem that plagues the Valley is a meteorological phenomenon called an inversion layer. This occurs when air is warmer above the ground than at ground level.
With a low inversion layer, the air tends to remain still and does not mix with cleaner air that would otherwise come into the Valley over the mountains to the east and west.
Currently, the inversion layer is at about 1,500 feet, said Ken Clark, West Coast forecaster for AccuWeather, a private weather forecasting company. Over the weekend, when things cool down a bit, the inversion layer will rise to around 3,000 or 4,000 feet. However, the inversion layer will likely re-establish itself at a lower altitude by Tuesday, he said.
Martin, of the state Air Resources Board, said no matter what the levels or causes of air pollution in the area, mother nature has the biggest hand in affecting local conditions.
"We are all slaves to the weather," he said.
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