Address: 4520 Margaretta Ave.
                St. Louis, MO 63105
County: The city of St. Louis is not part of a county.
Pollutants currently monitored: Sulfur dioxide (SO2), nitrogen dioxide (NO2) and particulate matter (PM10)
Pollutants no longer monitored: Ozone (O3), carbon monoxide (CO) and fine particulate matter (PM2.5)
Date established: Jan. 1, 1999
Site coordinates

   *Latitude: 38.673172°
   *Longitude: -90.239086°
EPA Site No.: 29-510-0086

The Margaretta air monitoring station helps determine the exposure of a segment of the population of St. Louis to air pollutants. 
Specifically, it meets the requirement  in federal regulations for monitoring exposure to nitrogen dioxide of susceptible and vulnerable populations.

Sulfur Dioxide (SO2) Data*

In 2010, EPA established a new one-hour SO2 standard of 75 parts per billion
and introduced a new form for determining compliance with the standard. An area
is in compliance if the design value is at or below the standard. The new form to determine design value
requires three years of data — the average SO2 concentrations from each hour of the day.
The department and EPA calculate the design value using the 99th percentile
of one-hour maximum concentrations, averaged over three years.

Weekly summary of preliminary data from all SO2 sites

Preliminary data from Margaretta monitoring site
   • SO2 data in first column
   • Data from last 10 days through current date
   • Central Standard Time

Preliminary data from all state SO2 monitoring sites
   • Data from last 10 days through current date
   • Central Standard Time

Graph of design values for all SO2 sites, beginning in 2003
   • Design values quantify air quality for an area.

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

Nitrogen Dioxide (NO2) Data*

In 2010, EPA established a new one-hour NO2 standard of 100 parts per billion.
An area is in compliance if the design value is at or below the standard.
The form to determine design value requires three years of data — the average NO2 concentrations
from each hour. The department and EPA calculate the design value, using the 98th percentile
of one-hour daily maximum concentrations, averaged over three years.

Weekly summary of preliminary data from all NO2 sites

Preliminary up-to-date data from Margaretta monitoring site
   • NO2 data in third column
   • Data from last 10 days through current date
   • Central Standard Time

Preliminary up-to-date data from all state NO2 sites
   • Data from last three days through current date
   • Central Standard Time

Graph of design values for all NO2 sites, beginning in 2003

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

Particulate Matter (PM10) Data*

The EPA set a standard for PM10 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 concentration more than once per year,
averaged over a three-year period. The department and EPA express the PM10 design value as "expected number of days
exceeding the standard." The word expected indicates that PM10 is not always measured every day
at every site.

Summary of information available from PM10 monitors

Preliminary up-to-date data from Margaretta monitoring site
   • PM10 data in last column
   • Data from last 10 days through current date
   • Central Standard Time

Preliminary up-to-date data from PM10 sites
    • Data from last three days through current date
    • Central Standard Time

Graph of PM10 design values for all sites, beginning in 2003
    • Design values indicate a region's air quality

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

Related Links

Missouri map with network of air monitoring sites

National standards for pollutants

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

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

EPA Air Sensor Toolbox for Citizen Scientists