We recently sold data to Sonoma Technology to study the health impacts of living and working near high traffic

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 US 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.  


Citilabs combines its understanding of transportation simulation with mobile phone data and traffic counts to create Streetlytics. Streetlytics is the measurement of hourly vehicle and pedestrian volumes, speeds and demographics on every segment of road in the US, Puerto Rico, Vancouver and Toronto. Streetlytics also includes the origin-destination pairs for every vehicular trip and the turn by turn path in-between. 

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 assessment 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 on all size roads, and with HERE’s accurate roadway geometry, 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’s traffic data provided 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 effect of vehicle emission exposure on the cardiovascular, respiratory, neurological, and birth outcomes. 

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.


The Interstate Highway System was one of America's most revolutionary infrastructure projects. Unfortunately, highways sliced through the center of many American cities destroying neighborhoods and brought concentrated pollution. Highways did allow Americans to live further from their jobs in the city center but as more people moved to the suburbs, lanes were added to highways to increase capacity and reduce congestion. 

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. 

America recognized negative effects of vehicular travel a couple of decades after the highway system was built.  The Clean Air Act was passed to combat these negative effects and since then:

  • 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

New York City: 1973 vs. 2013 -  EPA

New York City: 1973 vs. 2013 - EPA

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. For the last 10 years, California has provided 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.

1,000 feet from a highway –  LA Times

1,000 feet from a highway – LA Times


What is emitted

Vehicles emit pollutants such as NOx, CO, PM2.5, elemental carbon, organic carbon, and trace metals. These pollutants cause 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 the sheer number of cars on the roads offset these improvements. People can help by driving less. Combine trips, walk, bike, scoot, carpool or use public transportation.

  • 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 (it will take a long time and electric vehicles still emit air pollutants from brake wear, tire wear, and road dust resuspension).