Why is aqi reported

Non-overlapping means that the 8-hour averages do not include any of the same 1-hour values. Obs Number of hour values observations reported for the year. PM10 is typically measured every sixth day, which results in about 60 values per year. Some sites take measurements every day.

Valid Months Number of months meeting minimum data completeness requirements for lead. Max 3mo Avg The maximum of all rolling 3-month averages in the year, in micrograms per cubic meter. Month of Max End month of the maximum 3-month period. Annual Mean Arithmetic mean of 1-hour values. Take the highest 1-hour value of each day, and pick the top four of those values. Required Days 1hr Number of days in the year when ozone monitoring is required. This is normally the length of the "ozone season" -- months when ozone is a potential problem -- at the monitoring site.

In many locations ozone monitoring is required April - October days. Valid Days 1hr Number of days in the year when the requisite number of 1-hour values were reported: at least 9 values between a.

Missing Days 1hr Number of days in the year presumed not to have exceeded the level of the 1-hour standard even though the requisite number of 1-hour values were not available. Obs Number of 8-hour values observations reported for the year. Take the highest 8-hour value of each day, and pick the top four of those values.

Required Days 8hr Number of days in the year when ozone monitoring is required. Valid Days 8hr Number of days in the year having valid 8-hour average values for at least 18 hours of the day. A least six 1-hour values must be available during an 8-hour period to calculate a valid 8-hour average. Actual Exceedances Number of daily max 1-hour values that exceeded the level of the 1-hour standard during the year. Obs Number of hour values reported for the year. Obs Number of days in the year for which values observations were reported.

Many sites take measurements every day. This value is higher than 98 percent of hour values for the year. Annual values Computed by AQS software from hour values. Weighted Annual Mean Arithmetic mean of hour values weighted by calendar quarter, in micrograms per cubic meter. Concentrations are rounded to the nearest 0. Acid Rain and Mercury. Air Quality Index. Principal Pollutants.

Toxic Pollutants. Air Quality Partnership. Ambient Air Quality Report. Particle Pollution: People with heart or lung disease, older adults, and children should avoid prolonged or heavy exertion. Ozone: Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion: everyone else, especially children, should limit outdoor exertion. Everyone else should reduce prolonged or heavy exertion.

Particle Pollution: People with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion. Some content on this site is saved in an alternative format. Scroll for More Quick Links. What is the Air Quality Index? Last Modified: August 23, - pm. Think of the AQI as a yardstick that runs from 0 to 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 or below represents good air quality, while an AQI value over represents hazardous air quality. For each pollutant an AQI value of generally corresponds to an ambient air concentration that equals the level of the short-term national ambient air quality standard for protection of public health.

AQI values at or below are generally thought of as satisfactory. When AQI values are above , air quality is unhealthy: at first for certain sensitive groups of people, then for everyone as AQI values get higher. The AQI is divided into six categories. Each category corresponds to a different level of health concern. Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities.

Each of these pollutants has a national air quality standard set by EPA to protect public health:.