Air Quality Index 

The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is and what associated health effects may be a concern for you. The AQI focuses on health affects you may experience within a few hours or days after breathing polluted air. The Tehama County Air Pollution Control District calculates the AQI for ground-level ozone, particle pollution (also known as PM2.5). The EPA has established national air quality standards for each of these pollutants to protect public health. Ground-level ozone and airborne particles are the two pollutants that pose the greatest concern to human health in this country. 

Using the AQI table in Tehama County 

Below you will find the AQI table available on the District website:  Think of the AQI as a yardstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 represents good air quality with little potential to affect public health, while an AQI value over 301 represents hazardous air quality. 

Name Color AQI Concentraion Advisory
Good Green 0-50 PM2.5: 0-12ug/m3

O3: 0-54 ppb
no advisory
Moderate Yellow 51-100 PM2.5: 12.1-35.4ug/m3

Unusually sensitive individuals should consider
limiting prolonged outdoor exertion
Unhealthy for
Sensitive Groups
Orange 101-150 PM2.5: 35.5-55.4ug/m3

O3: 71-85ppb
Children, active adults, and people with respiratory
disease, such as asthma, should limit prolonged
outdoor exertion
Unhealthy Red 151-200 PM2.5: 55.5-150.4ug/m3

O3: 86-105ppb
Children, active adults, and people with respiratory
disease, such as asthma, should avoid prolonged
outdoor exertion; everyone else should limit prolonged
outdoor exertion
Very Unhealthy Purple 201-300 PM2.5: 150.5-250.4ug/m3

O3: 106-200ppb
Children, active adults, and people with respiratory
disease, such as asthma, should avoid outdoor exertion;
everyone else should limit outdoor exertion
Hazardous Maroon 301-500 PM2.5: 250.5-500.4ug/m3 Everyone should avoid all physical activity outdoors.

An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the level EPA has set to protect public health. AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy for certain sensitive groups of people, then for everyone as AQI values increase. 

Data Sources

The District operates several types of air monitors that include permanent Ground Level Ozone and PM2.5 monitors, Temporary PM2.5 monitors and Low Cost PM2.5 monitors.

Monitoring equipment can be described by their precision and accuracy. The Districts permanent PM2.5 and Ozone monitor are required to meet rigorous standards in order to be considered a Federal Equivalent Monitor (FEM). These standards ensure that the data produced is both highly accurate and precise. Temporary monitors do not receive the same degree of review as permanent monitoring stations; however, they can be calibrated by staff to ensure they produce highly accurate data. The District recommends using either permanent or temporary monitoring stations whenever available.

Low cost sensors are relatively new to the air monitoring world. Depending on how the data is processed the quality can vary from low to high precision and accuracy. Issues that can crop up with low cost sensors include, being installed in ways that are not consistent, installed near sources of pollution (installed above a BBQ) or are labeled incorrectly. Sometimes this data is the best available, if you plan to use low cost sensor data we recommend using the sensor data pilot. This map displays data from permanent, temporary and low-cost sensors. Low cost sensor data found on the link above is run through a quality control equation that can increase the quality that is produced.

Accessing Data

The District recommends accessing air quality data from the following sources: