Design in a Time of Uncertainty
By Rives Taylor, Principal, Global Resilience Research Lead
Air pollution is a pressing concern that affects our health and quality of life. Traditional ways of measuring ambient air quality have primarily relied on permanent and semi-permanent stationary enclosures. These “fixed” monitors lack resolution in both space and time, limiting their ability to provide air quality data and exposure information at other locations of interest or after emissions events and accidental releases.
HARC has developed a mobile air quality monitoring laboratory (see image below) to allow researchers to analyze “real-world” pollution levels in communities that may be at risk, wherever those communities and sites maybe. The HARC mobile lab, which can be deployed rapidly and used remotely almost anywhere with vehicular access, can simultaneously measure multiple pollutants to a quantifiable standard while both stationary or in motion.
This past January, HARC’s mobile lab completed monitoring work as part of a Health Impact Assessment (HIA) study to assess the potential public health impacts of the planned North Houston Highway Improvement Project (NHHIP), an expansion and realignment of I‐45 in Houston. The study, led by Air Alliance Houston, is one of ten national grantees under the 500 Cities Data Challenge funded by the Robert Wood Johnson Foundation and Urban Institute. The goal of the HIA is to provide a quantitative assessment of the potential benefits and harms to health associated with the proposed changes to the I-45 corridor from Beltway 8 in the north to the I-69 spur south of downtown Houston.
A major component of the HIA was mobile air monitoring along the NHHIP corridor to assess the current and potential future burden of air toxins. This was especially critical as no stationary air quality monitors collect data on air toxins along the NHHIP corridor. A single air quality monitor is located at the northwest corner of I-610 and I-45, but it simply collects data on criteria pollutant such as ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), along with meteorological data. Mobile air quality monitoring was therefore the only feasible option for gathering the requite air toxins data.
The HARC mobile lab monitored for the BTEX pollutants (benzene, toluene, ethylbenzene and xylene), along with carbon monoxide. Benzene, is an especially hazardous air toxin and is classified as a known human carcinogen by the US Environmental Protection Agency (EPA). It is emitted by both the area’s industrial base and vehicles utilizing the study area’s transportation infrastructure. Because of the mobile lab includes an ultrasonic anemometer, data was also collected for wind speed and direction, along with temperature and humidity from those respective sensors. Real-time vehicular traffic data, including speed, traffic volume, and vehicular type, were also collected from Houston TranStrar and incorporated into the analysis.
Monitoring took place over a couple of weeks, with both early morning and late afternoon monitoring runs (see the monitoring route map below). Special attention was focused on monitoring around high-risk schools located within a 150m buffer zone on either side of the freeway.
The lab’s global positioning system (GPS) provides real-time speed and location data on the lab and all its measurements. All data was collected through the mobile labs data acquisition and control system (see image below). Keep an eye out for HARC’s mobile air quality lab, you never know when it might be monitoring air quality in an area near you.
About the HARC Mobile Air Quality Laboratory
The HARC mobile lab consists of a Ford E-350 passenger van outfitted with several innovative technologies that allow it to measure air quality on a second-by-second basis. It is one of the few such mobile air quality monitoring platforms in the country. Key to its ability is the IONICON proton transfer reaction mass spectrometer (PTR-MS). This instrument allows for the fast measurement of various volatile organic compounds (VOC) to parts per billion (ppb) level sensitivity, including many air toxins such as benzene. The van is also equipped with air quality sensors for monitoring various criteria air pollutants such as ozone (O3), nitrogen oxides (NOx), and particulate matter (PM).
The mobile lab’s ability to simultaneously measure multiple gas concentrations, GPS coordinates, and wind velocity, combined with instantaneous Internet data uploads to a cloud server, makes possible real-time anywhere mapping and visualization of the measured results.