Streetlytics Aides Public Health Studies by Improving Air Pollution Modeling

Sonoma Technology Selects Streetlytics to Study the Health Impacts of Living and Working Near High Traffic Corridors

Sonoma Technology (STI) has selected Citilabs Streetlytics to help investigate the health impacts of living and working around high traffic areas in Southern California. STI is an environmental consulting firm that provides high-quality, innovative, science-based solutions for environmental challenges worldwide, including study design, measurements, analyses, modeling, and software development services. STI is best known for the development and operation of the U.S. EPA’s AirNow Program, which provides the public with easy access to national ambient air quality information using a health-based scale (the AQI) seen everywhere from the Weather Company to the Apple Watch.



STI is also known for its work with universities to assess the air pollution and traffic exposure of pregnant mothers, children, and adults in air pollution health effects studies. These research studies contribute to the scientific knowledge base that is used by the U.S. EPA and World Health Organization (WHO) to establish air quality standards and guidelines. Evaluation of the consequences of exposure to traffic-related air pollution on human health has become an increasingly important area of public health research in the last 20 years.



What is Streetlytics?

Citilabs combines its understanding of transportation simulation with location-based data, traffic counts, and other data to create Streetlytics. Streetlytics measures hourly vehicle and pedestrian volumes, speeds and demographics on every segment of road in the United States, Puerto Rico, and portions of Canada. Streetlytics also provides origin-destination movement and routing information through the roadway system.



How is Streetlytics Being Used?

Until recently, most air pollution health assessments were conducted using only data from regional air monitoring networks, which have sensors located 10 to 30 miles apart in urban areas. Selected studies that included traffic assessments mostly relied on proximity to roadways and roadway density as traffic exposure indicators. These studies ignored the huge variation in vehicle activity on nearby roadways.  Studies that incorporated traffic volumes had to rely on annual average data traffic counts, which were only available for major roads.  Because local motor vehicle activity and emissions are very often the primary factors explaining air pollution variation within communities, most exposure assessments failed to capture the local-scale granularity of pollution within each community. With Streetlytics’ hourly traffic volumes and vehicle speeds for roads of all sizes, STI is able to apply air quality dispersion models to more accurately estimate the motor vehicle emissions’ contributions to air quality at the community scale.  With this approach, concentrations of traffic-related pollutants such as NOx, CO, PM2.5, elemental carbon, organic carbon, and trace metals are estimated at the residences, schools, and work places of health study participants to more accurately characterize their differences in exposures on the relevant time-scales (weekly, monthly, yearly). The rich spatial and temporal coverage of Streetlytics traffic data provides the key to much more accurate maps of community air quality levels.

STI’s community level air quality modeling is being used to evaluate the health effects of living and working near high traffic areas. The current and proposed studies involve the effects of vehicle emission exposure on the cardiovascular, respiratory, neurological, and birth outcomes. In particular, STI is using Streetlytics volumes, speeds, and road network in modeling exposure in Southern California for NIH-funded research with the University of Southern California’s Keck School of Medicine on:

  1. Maternal and Developmental Risks from Environmental and Social Stressors, which is a 5-year study designed to untangle the causes of childhood obesity in low income, urban minority communities.
  2. Lifecourse Approach to Developmental Repercussions of Environmental Agents on Metabolic and Respiratory Health (LA DREAMERs) Study, which is part of the NIH program on Environmental influences on Child Health Outcomes (ECHO).  This study involves subjects from prenatal to age 40 for the study of metabolic and respiratory outcomes.


To combat the negative effects of auto emissions, the Clean Air Act was passed in 1970, giving the United States Environmental Protection Agency (EPA) the authority to regulate transportation-related pollution. According to the EPA, since the implementation of the Clean Air Act:

  • New passenger vehicles are 98% cleaner for most tailpipe pollutants compared to the 1960s
  • Fuels are cleaner. Lead has been eliminated and sulfur levels are more than 90% lower than they were prior to regulation
  • American cities have much improved air quality, despite ever increasing population and increasing vehicle miles traveled
  • EPA Standards have sparked technology innovation from industry

Today, Americans have repopulated urban centers and the neighborhoods divided by highways. More Americans are living next to highly traveled roads than ever before. All metro areas across the country are expected to grow even more over the next few decades, increasing both vehicle usage and exposure to vehicle emissions.


Invisible is Still Dangerous

An MIT study in 2013 found emissions from road transportation are the most significant contributors to air pollution. Vehicular emissions caused 53,000 premature deaths in 2013, almost double the number of people killed in traffic crashes that year.

Scientific studies, like the ones conducted by Sonoma Technology, show that some pollutants can harm public health and welfare even at very low levels. As a result of these studies, the EPA has progressively lowered light and heavy-duty vehicle emissions limits. California in particular, has encouraged a faster transition to cleaner technologies by providing large financial incentives for public and private owners to replace older polluting cars and trucks with modern, clean technology vehicles.

Vehicular traffic causes particularly elevated risks to public health in communities near large roadways. As the traffic increases, vehicle emissions flow linearly in to nearby neighborhoods. Pollution is greatest on the road and diminishes with distance from the road. Public health officials have long warned that traffic pollution can drift well over 1,000 feet from traffic, and more recent research suggests that it may drift more than a mile.


What is Emitted?

Vehicles emit pollutants such as NOx, CO, PM2.5, elemental carbon, organic carbon, and trace metals. These pollutants have been linked to greater instances of asthma, cancer, heart attacks, strokes, reduced lung function, and pre-term births. Recent research has added more health risks to the list, including childhood obesity, autism, and dementia.

Risk Mitigation

Today’s cars emit 98% less pollution per mile driven than they did in 1960. Electric cars and alternative fuels will continue to help, but vehicles still emit some pollutants from brake wear, tire wear, and road dust resuspension. And the transition to electric vehicle will be slow, meaning it could take several years, or even decades, before air pollution sees significant improvements.

  • Avoid homes and work places within 1,000 feet of any major road
  • Avoid opening windows and use air filtration with MERV 13+ rating during times with moderate and high pollution levels
  • Find physical barriers like sound walls and vegetation
  • Avoid exercising near traffic
  • Avoid driving on major roads for long periods of time and always recirculate air in moderate and heavy traffic
  • Avoid truck routes
  • Don’t count on electric cars to solve the problem


With a significant portion on pollutants originating from vehicle usage, Americans will need to become less dependent on the personal vehicle in order to achieve cleaner air. Utilizing alternative modes of transportation or just simply reducing the number of trips altogether will reduce congestion, the amount of time spent on the road, and associated pollution levels.


Please contact us if you would like to find out more about Streetlytics and how it can be used.


Hugh Malkin

(+1) 404 993 4168