Address: 1709 Lonedell Drive
               Arnold West, MO 63010
County: Jefferson       
Pollutants Monitored: Ozone (O3),
fine particulate matter (PM2.5) and
particulate matter (PM10)
Site Coordinates
   * Latitude: 38.44862
   * Longitude: -90.3958
EPA Site ID: 29-099-0019

Ozone (O3) Data*

The federal ozone season runs from March 1 through October 31.

As of 2015, the federal standard for ground-level ozone is 70 parts per billion. An area is in compliance if the design value
is at or below this standard. A design value for ozone incorporates data from three years. The department and EPA
calculate the design value by 1) ranking the daily eight-hour ozone values for three consecutive years;
2) extracting the fourth-highest value for each year; and 3) averaging the three figures.

Weekly summary of preliminary data from all ozone sites

Preliminary one-hour averages from Arnold West
   • Ozone data in third and fourth columns on each day's first page
      --"P" stands for primary monitor. "S" stands for secondary monitor.
   • Data from 10 days ago through current date
   • Central Standard Time
   • Concentrations of pollutant in parts per million (ppm)

Preliminary eight-hour forward-rolling averages from all ozone sites
   • Hourly data equal average of that hour and following seven hours.
   • Data from 10 days ago through current date
   • Central Standard Time
   • Concentrations of ozone in parts per million (ppm)

Preliminary one-hour ozone averages from all sites

   • Data from 10 days ago through current date
   • Central Standard Time
   • Concentration of ozone in parts per million (ppm)

2016 exceedances for ozone

Graph of design values for ozone sites in St. Louis area, beginning in 2003

Additional information about ground-level ozone

* Technical problems can affect ability to deliver quality data.
Access a table of symbols indicating specific problems.

Fine Particulate Matter (PM2.5) Data*

EPA uses two ways to determine compliance with PM2.5 federal standards. One looks at data
over a 24-hour period, and the other takes into account data for a whole year.

In December 2012, EPA set the annual PM2.5 standard at 12 micrograms per cubic meter,
based on the three-year average of annual means. At that same time, EPA retained the 24-hour
PM2.5 standard of 35 micrograms per cubic meter, based on the 98th percentile of 24-hour measurements,
averaged over three years.

Weekly summary of preliminary data from all PM2.5 sites

Preliminary one-hour averages from Arnold West
   • PM2.5 data in eighth column on each day's first page
   • Data from 10 days ago through current date
   • Central Standard Time

Preliminary one-hour averages from all PM2.5 sites
   • Data from past three days through current date
   • Central Standard Time

Graph of PM2.5 annual design values from St. Louis sites, beginning in 2003

Graph of PM2.5 24-hour design values from St. Louis sites, beginning in 2003

Additional information about PM2.5

* Technical problems can affect ability to deliver quality data.
Access a table of symbols indicating specific problems.


Particulate Matter (PM10) Data*

The EPA's standard for PM10 sits at 150 micrograms per cubic meter of ambient air,
averaged over a 24-hour day. A site does not meet this standard if it exceeds
the level more than once per year, averaged over a three-year period.
The PM10 standard is expressed as "expected number of days exceeding the standard."
The word expected indicates that air monitoring agencies typically do not measure PM10
every day.

Quarterly summary of preliminary PM10 data

Preliminary one-hour averages from Arnold West
   • PM10 data in first column on each day's second page
   • Data from 10 days ago through current date
   • Central Standard Time

Preliminary data from all PM10 sites
   • Data from past three days through current date
   • Central Standard Time

Graph of PM10 values from all sites, beginning in 2003

* Technical problems can affect ability to deliver quality data.
Access a table of symbols indicating specific problems.

Related Links

Missouri's network of air monitoring sites

National standard for pollutants

Real-time views from cameras in Kansas City and St. Louis

Daily Air Quality Forecast (AirNow) shows how current readings
at air monitoring sites rate on the EPA's Air Quality Index.
Click on Missouri in the state box at the top of the home page
to access information.

EPA's Air Sensor Toolbox for Citizen Scientists