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San Luis Obispo County skies are typically clear and blue with little of the
characteristic brown haze associated with areas considered to have poor air quality, yet
we still have an air pollution problem. Violations of the state
standard for particulate matter (PM10) still occur several times a year. In order to understand why
we need to work to improve our air, we need to understand how air quality is determined.
Based upon the potential for health and economic effects, certain substances have
been classified as pollutants by the federal and state governments. Air monitoring is
required to measure the amounts of these pollutants that are present in our air. When
the levels are too high, our air is classified as polluted, and we are required to make
efforts to clean it up.
In years past, air quality in our county has exceeded established standards for lead,
carbon monoxide, sulfur dioxide, ozone, and particulate matter. Advancements in emission
controls on vehicles and stationary pollution sources of all kinds have led to
significant improvements in our air quality. As a result, we now meet most of these
standards. With even better emission controls, and with continued help from businesses
and the public, we should be able to achieve all state and federal air quality standards
in the near future.
San Luis Obispo County Attainment Status
On April 28, 2005, the California Air Resources Board (ARB)
approved the nation's most health protective ozone standard with
special consideration for children's health.
Based on monitoring data San Luis Obispo County has
been deemed nonattainment for the new ozone standard.
More
The Air Resources Board maintains a website with
designation maps of California for all criteria pollutants that
are designated for the State and National standards. These maps show
attainment status for all air districts in California and are
updated annually for the State area Designations, as required by the
Health and Safety Code (H&SC) section 39608. The Board makes State
area designations for ten criteria pollutants: ozone, suspended
particulate matter (PM10), fine suspended particulate matter
(PM2.5), carbon monoxide, nitrogen dioxide, sulfur dioxide,
sulfates, lead, hydrogen sulfide, and visibility reducing particles.
Nine air monitoring stations are located at different sites around our county. At
these monitoring stations, we collect information 24 hours per day, seven days per week,
on the ambient levels of pollutants, including ozone (O3), particulate matter (PM10),
nitrogen oxides (NOx), sulfur oxides (SOx), and carbon monoxide (CO). To find out which
pollutants are monitored at each monitoring site location, look at our listing of monitoring
stations. The levels of each of these pollutants are compared to the state and
federal standards in order to determine whether or not we are in compliance. The
District reports all monitoring data to a comprehensive national database maintained by
the Federal Environmental Protection Agency (EPA). The California Air Resources
Board (ARB) then draws all California monitoring data from the EPA for state uses.
For more information, read our
Ambient Air Monitoring Network Review- 2007 Update.
We have many different sources of air pollution in our county. Sources range from
large power plants to small household painting projects. By far the largest contributor
of air pollution in our county is motor vehicles. The pie chart below shows
emission sources of reactive organic gasses (ROG) and oxides of nitrogen (NOx), the main
precursors for ozone formation.
Although many of the substances classified as pollutants do occur naturally at low
concentrations, much higher and unhealthful levels can be created by human activity.
Ozone, for example, is a natural component of our air. Hydrocarbons and nitrogen
oxides released from vehicles and industrial sources however, can react in the presence
of sunlight, forming much higher levels of ozone than forms naturally. These higher
levels of ozone can result in health effects, such as impaired breathing and lung
damage, or economic effects, such as damage to crops and accelerated deterioration of
rubber, plastics and many common building materials.
Particulate Matter (PM10) and Fine Particulate Matter (PM2.5) are fine mineral,
metal, smoke, soot, and dust particles suspended in the air. While particulate matter
also has many natural sources, human derived sources such as vehicle exhaust, road dust,
mineral quarries, grading, demolition, agricultural tilling, and burning are major
contributors to exceedances in our county. In addition to reducing visibility,
particulate matter can lodge in the lungs and cause serious, long-term respiratory
illness and other health problems. The smaller the size of the particle, the
deeper it can penetrate into the lungs, and the more difficult it is to expel.
Air Quality Standards
Standards are set by the California Air Resources Board and United States
Environmental Protection Agency in order to minimize health effects and economic damage.
More
Air Quality Data
The District has compiled weekly or annual summaries and multiple year trend analyses
of air pollution monitoring in our county. More
Monitoring Stations
Air monitoring stations collect data throughout the county. Some of the stations are
larger than others and monitor for a wider number of pollutants. More
Emissions Inventory
Multiple stationary, area and mobile sources release air emissions in our county. The
District compiles an emission inventory of these sources on an annual basis. More
Annual Report
Each year the District reflects on the air quality in our county. Our annual report
contains information on air quality monitoring, and pollutant trends. More
Air Quality and Health
Many air pollutants are a concern because they can result in health impacts to living
systems. Respiratory problems, such as asthma, can often be aggravated due to exposures
of high concentrations of pollutants. More
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Mission
