Houston Health Department
Environmental Monitoring and Surveillance
The bureau performs surveillance to assess environmental quality trends, address compliance issues, and follow up on complaints, pollution events and existing issues identified through environmental monitoring. Surveillance includes visits to locations to make observations, ambient monitoring and sampling. Surveillance also includes evaluation of air and surface water monitoring data. Ambient air monitoring data surveillance is used to evaluate air pollutants in various air monitoring sites in the city. Surface water monitoring data surveillance is used to assess watersheds and identify water quality trends.
The bureau, funded through grants from the U. S. Environmental Protection Agency (U.S. EPA) and the TCEQ, operates and maintains an ambient air monitoring network for Houston that follows the U.S. EPA protocols and quality assurance/control procedures. This network is part of a broader and more comprehensive system that includes facilities operated by the TCEQ, area counties, nearby cities and private entities. The bureau is responsible for monitoring up to 20 different parameters at 10 stationary air monitoring sites throughout Houston. The parameters monitored are:
- Sulfur dioxide
- Carbon monoxide
- Nitric oxide
- Nitrogen dioxide
- Oxides of nitrogen
- PM 2.5 (particles with diameters less than or equal to 2.5 micrometers)
- PM10 (particles with diameters less than or equal to 10 micrometers)
- Wind speed
- Resultant wind speed
- Resultant wind direction
- Wind gust
- Standard deviation of wind direction
- Outdoor temperature
- Relative humidity
- Dew point
- Solar radiation
- Ultraviolet radiation
- Barometric pressure
Eight of the 10 stationary air monitoring sites have trailers that house air collection apparatus that includes analyzers, calibrators and a computer data logging system that allows bureau’s investigators and TCEQ personnel to view real time data. Specialized equipment, strategic locations and adherence to U.S. EPA-approved operating standards are among the important influences that allow monitoring stations to be a critical component of the clean air effort. Learn more about what goes on at an air monitoring site.
In some air monitoring sites the TCEQ uses Automated Gas Chromatographs (AutoGCs) to measure ambient levels of around 50 volatile organic compounds (VOCs), including some air toxics.
Maps of air monitoring sites and summary reports of the hourly data collected at each site:
- Daily summary report (TCEQ)
- Monthly summary report (TCEQ)
- Yearly summary report (TCEQ)
- Data collected by AutoGCs (TCEQ)
The U.S. EPA uses the bureau’s ambient air monitoring information and other data to calculate the Air Quality Index (AQI) for reporting daily air quality. It indicates how clean or polluted the air is and relates the associated health effects that may be a concern to humans and the environment. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air.
The U.S. EPA calculates the AQI for five major air pollutants know as criteria pollutants regulated by the Clean Air Act (CAA): ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide and nitrogen dioxide. For each of these pollutants, U.S. EPA has established National Ambient Air Quality Standards (NAAQS) to protect public health. The TCEQ monitors four criteria pollutants using the AQI: ground-level ozone, particulate matter, carbon monoxide and sulfur dioxide.
Criteria pollutants in the City of Houston network:
- Ground-level ozone is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.
- Particulate matter (PM) is a mixture of solids and liquid droplets in the air that vary in size. PM 2.5 or “fine particles” are very small particles with diameters less than or equal to 2.5 micrometers. PM 10 are particles with diameters less than or equal to 10 micrometers. Go to air quality guide for particle pollution (U.S. EPA AIRNow) .
- Carbon monoxide is a colorless, odorless gas that is formed when material containing carbon is not burned completely.
- Sulfur dioxide (SO2) is one of a group of highly reactive gasses known as “oxides of sulfur.”
- Nitrogen dioxide (NO2) is one of a group of highly reactive gasses known as “oxides of nitrogen” or “nitrogen oxides” (NOx).
- Call (832) 393-5612 for the bureau’s morning air pollution forecast recording. The recording is updated each weekday morning by bureau’s personnel, and is based on daily forecasts by the TCEQ. These forecasts are available at today’s ozone forecast (TCEQ) and today’s Texas air quality forecast (TCEQ) . The recording describes the air pollution level for the day as low, moderate, or elevated.
- Houston metropolitan area AQI (TCEQ)
- Houston-Galveston-Brazoria air quality conditions and forecasts (U.S. EPA AIRNow)
- Ozone Viewer (Houston Clean Air Network)
- Texas ozone data (TCEQ)
- Houston-Galveston-Brazoria fine airborne particulates (PM-2.5) levels (TCEQ)
- EnviroFlash (U.S. EPA AIRNow) - Air quality forecasts and ozone watches.
- Ozone email alerts (TCEQ) - Ozone forecasts and warnings.
Mobile Ambient Air Monitoring Laboratory (MAAML)
What does the Mobile Ambient Air Monitoring Laboratory (MAAML) give Houston?
- A means to identify and characterize specific emission sources of air toxics and volatile organic compounds (VOCs)
- A way to monitor for ground-level ozone and particulate matter (PM)
- Assistance in achieving city and bureau’s objectives for improving Houston’s air quality
- Over time, these pollutants can impair lung function, especially in higher risk individuals (age and/or pre-existing conditions)
- The U.S. EPA's Community-scale Air Toxics Monitoring Grant
- The Houston Endowment Inc.
- The Houston Health Department
- • Meteorological (weather) station
- - Wind speed and direction
- Global Positioning System (GPS) location data
- Relative humidity
- Atmospheric pressure
• Ozone monitor
- • Particulate matter (PM) analyzer
- - PM 10
- PM 2.5
- Particle size distribution graphs (0.3 – 20 microns)
• Infrared (IR) and video cameras
- • Gas Chromatograph (GC)/Flame Ionization Detector (FID)/Mass Selective Detector (MSD) analytical platform (Field and Fixed-Base)
- - Analysis of calibrated VOCs
- ○ Near real-time ambient air analyses
○ SUMMA canister sampling and analysis
○ Tedlar bag sampling and analysis
○ Software library for identification of unknown volatile organic compounds (VOCs)
- • Software support
- - Forward and backward trajectories
- Real-time concentration vs. time series plots for multiple pollutants of interest
- Atmospheric modeling
The bureau is a partnering agency with the Texas Clean Rivers Program The program aims to protect the health of river basins and watersheds through water quality monitoring, and provide sufficient and reliable information regarding the water quality in our area while maintaining a focus on ensuring safe, clean water resources for the future of Houston. It is overseen by the Texas Commission on Environmental Quality (TCEQ) , and managed locally by the Houston-Galveston Area Council (H-GAC) . Go to Clean Rivers Program Data (H-GAC).
Surface water samples are taken throughout the year from 133 sample sites on the streams and bayous around Houston and surrounding counties. The samples are analyzed at the City of Houston laboratory for:
- Escherichia coli (E. coli)
- Specific Conductivity
- Total Suspended Solids
- Total Nitrate
- Field parameters measured include:
- Dissolved Oxygen
- Water Temperature
- Stream flow or tidal stage
- Water Color
- Water Surface
- Wind Intensity
- Days since last rainfall
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