Inside a Scripps Ranch office park, a small team of meteorologists routinely checks streams of weather data. They review wind speeds, wind direction, temperatures, humidity, and other information. They also study weather trends and use sophisticated computer models to develop a forecast – a forecast that won’t help you decide whether to carry an umbrella, but one that will tell you about the quality of air you will breathe. The group works for the County’s Air Pollution Control District (APCD).
“We take weather information and turn it into an air pollution forecast,” explains Bill Brick, the senior air pollution meteorologist.
There are four of these specialists who pore over the information used typically by weather forecasters. Much of the data is captured from nine APCD monitoring stations located throughout the county and maintained by APCD. The meteorologists look at conditions that will affect pollutant levels in the air. Smog, for example, does not come directly from your car’s tailpipe and industrial sites, but from the chemical reaction of emissions and solar radiation. Temperatures, cloud cover, and inversion layers all play a role in the formation of smog.
There are two pollutants of primary concern that show up in the meteorologists’ forecasts for San Diego. They are ozone and particulate matter. Vehicles are the primary source of emissions that react with solar radiation to form ozone. Ozone formation can be an issue during summer months when more intense solar radiation creates the highest levels of ground-level ozone.
Particulate matter includes chemicals, soot and dust. This is more likely to occur during cooler weather. At unhealthy levels, it can trigger asthma attacks or aggravate other medical conditions. Children, the elderly, and those with respiratory ailments are especially affected by unhealthy pollution levels
There is more to the forecasts than just making the public aware of current air quality conditions. The forecasts are used to maintain good air quality. The District prohibits planned burns that government agencies carry out as part of wildfire management or agricultural burns farmers conduct to remove waste when the forecast suggests smoke would significantly increase air pollution levels. These APCD bans on burning are separate from a fire agency no-burn declaration that is issued because of the threat of wildfires.
“Part of the job is not just the weather but understanding human behavior,” Brick says. As an example, he points out that they can see a notable increase in particulate levels on Thanksgiving, Christmas, and New Year’s, becaise more people are using their fireplaces on those holidays.
Then there are the really extreme situations, such as the wildfires that swept the county in 2003 and 2007. Brick worked closely with the County’s Public Health Officer to issue warnings about the vast amounts of ash and smoke fouling the air.
Disaster aside, the good news is that San Diego’s air quality overall is steadily improving. If you’re under a certain age, you may have never heard anyone talk about a “smog alert.” That is because it has been more than two decades since the county had high enough pollutant levels to prompt one.
Anyone who takes an interest in how clean the air is may note the forecasts, but they are of particular concern to people with health conditions affected by pollution. Besides being available on the APCD website, various media outlets, both local and national, carry the daily predictions.
“Our ultimate goal is to have good air quality every day for everybody,” Brick said.