Address: 73 Hunter Ave.
Ladue, MO 63124
County: St. Louis
Year established: 1993
Pollutant monitored: fine particulate matter (PM2.5)
Pollutants formerly monitored: Ozone from 1993-2004; nitrogen dioxide from 1993-2010. For information:
Site coordinates
* Latitude: 38.65028°
* Longitude: -90.35021°
EPA site: 29-189-3001

The Ladue air monitoring station helps the department determine public exposure to air pollutants in the suburban area. The station stands near a power substation in a suburban area. Just east to the monitor lies the inner-belt expressway Interstate 170. The highway may be the major source of air pollution since retail areas occupy a high percentage of the surrounding area.

Data about Fine Particulate Matter (PM2.5)*

PM2.5 describes particles smaller than 2.5 microns in size. They are microscopic. Particulate matter this small comes from Industrial and residential combustion as well as vehicle exhaust. Fine particles also form in the atmosphere when chemical reactions transform gases, such as sulfur dioxide, nitrogen oxides and volatile organic compounds, into microscopic solid or liquid particles. Fine particles can affect the health of everyone, especially children, elderly and people who suffer from asthma and other pulmonary conditions.

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 from a whole year. In December 2012, EPA tightened the annual PM2.5 standard, setting it at 12 micrograms per cubic meter, based on the three-year average of annual means. 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
• Description and map of state's monitoring network
Annual PM2.5 design values
• 24-Hour PM2.5 design values
• Central Daily Time

One-hour preliminary averages of readings at Ladue
• Data from past 10 days through current date
• Central Daily Time

Preliminary up-to-date 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

Department's webpage about fine particulate matter
• Description of two groups of particulate matter: PM2.5 and PM10
• Information about 1997, 2006 and 2012 standards for PM2.5 plus related documents

*Technical issues can affect ability to deliver quality data.
Click to access a table of symbols indicating issues.

Related Links

Missouri's mapped network of air monitoring stations

National standards for pollutants

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

Department's webpage about air quality provides information on current air quality as well as air quality forecasts for today and tomorrow. In addition, the page contains tips for lowering air pollution and suggestions for handling air quality alerts: days forecasted orange to maroon.

EPA's webpage about air quality ( gives current readings and forecasts for cities across the country during ozone season.

EPA's Air Sensor Toolbox for Citizen Scientists