Different angles show the vastness of the Blair Street air monitoring station.

Address: 3247 Blair St.
                St. Louis, MO 63107
County: The city of St. Louis is not part of a county.
Pollutants Monitored: Ozone (O3); sulfur dioxide (SO2); nitrogen dioxide (NO2); fine particulate matter (PM2.5); particulate matter (PM10); carbon monoxide (CO)
Pollutant monitored in the past: lead (Pb)
Date established: March 1, 1999
Site coordinates
* Latitude: 38.656449°
* Longitude: -90.198548°
EPA site: 29-510-0085

The Blair Street air monitoring station provides data for assessing air quality in the north-central area of St. Louis.
The department established it in 1999, and since 2011, it has been part of the National Core (NCore) Network, which measures multiple air quality and meteorological parameters and provides data to determine compliance with federal standards. The data from Blair Street play a key role in public information, evaluations of mathematical models of air quality, and scientific studies about health and environmental effects of ambient air pollutants. More information on the National Core Network.

The Blair Street station also is part of two other national networks. The Chemical Speciation Network (CSN) measures concentrations of organic and inorganic chemicals that contribute to airborne fine particulate matter (PM2.5). Click for more information on the Chemical Speciation Network. The National Air Toxics Trends Stations (NATTS) Network tracks long-term trends in levels of hazardous air pollutants and air toxics, and sites in the network to provide data for scientific
studies. More information on the National Air Toxics Trends Stations Network.

Ozone (O3) Data*

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.

Although the ozone season runs from March 1 through October 31, the state monitors
ozone all year from Blair Street to meet the requirement for being an NCore site. Ground-level ozone forms when pollutants emitted by cars, factories, power plants and other sources react chemically in the presence of heat and sunlight. Ozone at ground level is a harmful air pollutant as opposed to ozone in the upper atmosphere, which protects us from ultraviolet light.

Weekly summary of preliminary data from all ozone sites

Preliminary one-hour averages from Blair Street in parts per million
• Ozone data in fourth and fifth columns
"P" stands for primary monitor. "S" stands for secondary monitor.
• Data from 10 days ago through current date
• Central Standard Time

Preliminary eight-hour ozone averages from all sites in parts per million
• Forward-rolling averages: Hourly data equal to average of that hour plus the following seven hours.
• Data from 10 days ago through current date
• Central Standard Time
   
Preliminary one-hour ozone averages from all sites in parts per million

• Data from 10 days ago through current date
• Central Standard Time

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

Department's webpage about ground-level ozone
• Effects on health and tips to reduce ground-level ozone
• 2008 and 2015 standards and related documents

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

Sulfur Dioxide (SO2) Data*

Sulfur dioxide is a colorless gas with a suffocating odor. Sources include power plants, industrial processes and off-road engines that burn fossil fuels. Exposure to elevated levels of SO2 can irritate the throat and lungs, leading to difficulty breathing and exacerbating respiratory illnesses.

Since 2010, the federal standard has been 75 parts per billion. An area is in compliance if the design value is at or below the standard. Determining design values requires three years of data — the average SO2 concentrations from each hour of the year. The department and EPA calculate the design value, using the 99th percentile of one-hour daily maximum concentrations, averaged over three years.

Weekly summary of preliminary data from all SO2 sites
• One-hour SO2 design values
• Four highest one-hour SO2 values year-to-date
• Map of monitoring sites

Preliminary up-to-date one-hour averages of SO2 from Blair Street
• SO2 data in sixth column. Each day has three pages of data.
• Data from past 10 days through current date
• Central Standard Time

Preliminary up-to-date one-hour averages from all state SO2 monitors
• Data from past 10 days through current date
• Central Standard Time

Graph of design values for state-operated SO2 sites, beginning in 2003

Graph of design values for industrial SO2 sites, beginning in 2003

Department's webpage about SO2
• Description and health effects
• 2010 standard and related documents

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

Nitrogen Dioxide (NO2) Data*

Nitrogen dioxide is a foul-smelling gas. It comes primarily from the burning of fossil fuels — coal, oil and gas. NO2 combines with volatile organic compounds (VOCs) in the presence of sunlight and heat to create ozone. (VOCs are compounds with carbon that easily become vapors or gases.)

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 monitoring sites    

Preliminary up-to-date one-hour averages from Blair Street
• Data in first column on second page. Each day has three pages of data.
• Data from past 10 days through current date
• Central Standard Time

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

Graph of NO2 design values, beginning in 2003

Department webpage about NO2
• 2010 standard and related documents

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

Fine Particulate Matter (PM2.5) Data*

Fine particulate matter refers to particles smaller than 2.5 microns in diameter. Sources include exhaust from vehicles as well as industrial and residential combustion.

EPA uses two ways to determine compliance. One looks at data over a 24-hour period, and the other takes into account data from a whole year. Since 2012, EPA's annual PM2.5 standard has been12 micrograms per cubic meter, based on the three-year average of annual means. At that 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 up-to-date one-hour averages from Blair Street
• PM2.5 data in sixth column of second page. Each day has three pages of data.
• Data from past 10 days through current date
• Central Standard 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 webpage about fine particulate matter
• Description
• 1997, 2006 and 2012 standards and related documents

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

Particulate Matter (PM10) Data*

PM10 refers to air borne particles smaller than 10 micrometers in diameter. People may inhale them, but they are invisible. This means that the particles can entrench themselves in one's lungs and bloodstream, affecting breathing.

The EPA has set a standard for PM10 at 150 micrograms per cubic meter
of ambient air (150 µg/m3 ), 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 is used
because PM10 is not always measured every day.

Preliminary up-to-date one-hour averages from Blair Street
• PM10 data on second page, sixth column. Each day has three pages of data.
• Data for past 10 days through current date
• Central Standard Time

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

Department webpage about particulate matter
• Description
• 2006 standard and related documents

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

Carbon Monoxide (CO) Data*

Carbon monoxide forms when carbon in fuels does not burn completely. It's a colorless and odorless gas. Exhaust from motor vehicles constitutes the primary source. Breathing air with a high CO concentration reduces the amount of oxygen in our bloodstream, thus depriving vital organs. Carbon monoxide also can increase smog levels by reacting with other chemicals in the presence of heat and sunlight.

Since 1971, EPA has maintained two standards for carbon monoxide. The eight-hour
standard stands at 9 parts per million, and the one-hour standard stands at 35 parts per million.
If design values are at or below the standard, then an area is in compliance.

Summary of preliminary data from CO sites

Preliminary up-to-date one-hour averages of CO from Blair Street
• CO data in third column of first page. Each day has three pages of data.
• Data from past 10 days through current date.
• Central Standard Time

Preliminary up-to-date one-hour averages from all CO sites
• Data from three days ago through current date
• Central Standard Time

Graph of CO one-hour design values for all sites, beginning in 2003

Graph of CO eight-hour design values for all sites, beginning in 2003

Department webpage about CO
• 1971 standards and related documents

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

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