See an air quality report for any address within San Bernardino and Muscoy.

The Traffic Pollution Indicator (TPI) identifies high vehicle emissions that are most likely to impact areas near freeways, given their high traffic density, and communities where sensitive sites such as schools, childcare centers, and health care facilities are of greatest concern. These measurements give us a detailed, scientifically rigorous approach to seeing the patterns that this indicator exhibits.

The TPI  is based on concentrations of carbon monoxide (CO) – which is known to cause harm to public health – and carbon dioxide (CO

) – which is known to contribute to global warming. While the Diesel Pollution Indicator is focused on diesel emissions primarily from heavy-duty trucks and trains, the TPI provides insights into light- and heavy-duty vehicle emissions. Carbon monoxide and CO

 are emitted by the most common vehicles on the road that are powered by diesel, gasoline, and compressed natural gas (CNG) engines, where gasoline engines emit a higher fraction of CO than diesel vehicles per unit of energy.

Aclima has updated the LA 2021 public report to reflect our use of improved calculations for analyzing and mapping the data.

The data mapped from the Los Angeles measurement period, which covered July 1 through September 30, 2021, is now modestly different from those in the first version of the public report, released in February 2022.

The underlying 1-Hz, or 1-second, data as collected by the vehicles is unchanged. However, data products, including products that build on ambient concentration aggregates at the segment and hexagon scale, have changed modestly.

In these final reports, we used a streamlined order of calculations, which were completed using software for increased accuracy.

We improved the base algorithms that are used to calculate the data.

We fixed a timezone error in the final Black Carbon ambient concentrations. Because we use data obtained from a secondary source to normalize our data (see: Methodology), this error affected the normalization process and therefore what data showed in the first version of the report.

Overview of changes and impacts on the report:

The largest changes (~+/- 10%) are seen in BC (Black Carbon) data. There are smaller changes (~+/- 8%) in other pollutants.

Typically, the maps will now indicate that more hexagons are above the local regulatory median and that more segments are impacted by diesel pollution.

The new spatial aggregates reflect higher confidence, improving the spatial representativeness of the data and the ability to see differences between neighboring hexagons.

Now that the calculations are produced by software rather than manual calculations, there is increased accuracy and traceability.

stationary-sources-pm25

Traffic emissions include a range of unhealthy pollutants that Aclima measures, including black carbon and criteria pollutants like carbon monoxide, nitrogen dioxide, and fine particulate matter. Although these emissions most adversely affect the health of young children, older residents, and those with preexisting conditions, they pose health risks for all people. In this report, we identify areas of high vehicle emissions that are most likely to impact communities and sensitive sites such as schools, childcare centers, and health care facilities.

Decisions are only as good as the information behind them. Our high-resolution data provides the measurements required to make more informed decisions about emissions reductions. Aclima deployed its fleet of vehicles driven by local community members to measure air pollution on each block from July through September, 2021. Aclima combined measurements to calculate average pollution levels at any address. In San Bernardino and Muscoy, we looked at carbon monoxide (CO), carbon dioxide (CO

), and black carbon (BC) levels. We analyzed over 20 million data points related to these five pollutants and discovered areas with elevated concentrations of unhealthy air pollutants.

Aclima uncovered where air pollution is the worst across more than 7,600 blocks

The world’s most detailed air quality maps, now available in your neighborhood.

High resolution measurements identify areas where elevated levels of harmful pollutants are typically present. Multiple measurements at each location over time leads to an understanding of 

 air quality. Each block has been measured over 20 times, which has been 

 of the persistent air quality at a given location during the measurement time frame. Mobile mapping is either continuous or performed on a quarterly or annual project basis to establish a baseline. This data can help people reduce exposure and risk where they live, work, and play. Through our hyperlocal measurements, air district regulators are now equipped with the hard data needed to enhance the identification and characterization of sources and improve emissions reduction planning.

Mobile mapping: average air pollution concentrations block by block.

South Coast AQMD has operated one stationary regulatory monitor in the AB 617 SBM area since 1986. Data for CO, NO

. Regulatory monitors collect data continuously at a single location meant to be 

 to be representative of a neighborhood, which by definition covers a distance of 0.3 to 2.5 miles from the San Bernardino monitor. It is considered spatially representative of the middle scale for CO, radius of less than 0.3 miles; neighborhood for O

, a radius of 0.3 to 2.5 miles from the site, and representative of the broader urban area for NO

 data was not available at the San Bernardino 4th Street monitoring site so we used Riverside-Rubidoux (Rubidoux) for comparison since it has similar land and elevation (see 

Where is the nearest local regulatory monitor?

See current air quality, wind direction, and pollution trends over time.

Wind patterns impact the extent to which stationary measurements reflect emissions not immediately upwind. The strongest winds in the San Bernardino, Muscoy Community during our measurement period were between 7-10 mph. They were most prevalent in the late morning, and came most often from the west-southwest. 

 allow pollutant levels to increase as emissions sources continue. Mobile monitoring can capture the influence of sources in all directions that can result in elevated concentrations within the region.

Wind moves pollutants in the air and impacts how well stationary measurements reflect emissions.

Aclima uses climate and economic justice indicators to identify sensitive, underserved, overburdened, and at-risk populations. This map illustrates areas where sensitive populations live based on a calculated index that includes asthma prevalence, cardiovascular disease prevalence, population under age 5, population over 64, and low-birthweight infants. Areas to the south and southwest are primarily commercial and industrial with a major railyard. However, the area directly north of the major railyards is primarily residential, yet has much higher than average DPI, several schools, and some of the highest Sensitive Populations Indices. Prevailing winds are from the south and southwest, suggesting that these sensitive residents downwind of the railyard are primarily impacted by railyard emissions, and the impact is highest closest to the railyards (between W. 5th and W. 6th Streets).

Community risk: we don't all breathe the same air; it affects each of us differently.

Schools, healthcare facilities (hospitals and other), childcare centers, community centers, libraries, public housing projects, and parks are locations where sensitive populations visit and spend their time. Many of these sites are located near major roads and freeways, which often have high fine particulate matter, nitrogen dioxide, black carbon, and carbon monoxide due to emissions from motor vehicles. These areas are also downwind of the industrial, commercial, and railyard located in the west and southwest of SBM. While where unhoused community members live can be difficult to identify on the map, those who shelter under or near freeways are exposed to high levels of PM

 and other pollutants caused by vehicles.

Air quality trends where sensitive populations spend time

The Community Steering Committee (CSC) and community members identified a number of locations where community members live, work, go to school, and spend the majority of their time. The AB 617 San Bernardino and Muscoy Community is impacted by various mobile and stationary sources. A range of stationary sources impact air quality in the region and can affect sensitive population health.

The community’s sensitive sites include, for example 68 schools, 38 licensed daycare facilities, and 11 hospitals among other sensitive sites. Most are in the general residential area in the central and eastern half of the monitoring area with fewer located in the general commercial, industrial area to the west and south. Many however are located close to the I-210 and I-215 freeways. Cars and trucks on freeways emit carbon monoxide (CO), nitrogen oxides (NOx), fine particulate matter (PM

), and black carbon (BC) that cause elevated pollution nearby.

The community has high rates of poverty and unemployment and there are schools in close proximity to pollution sources. General source categories of concern include neighborhood truck traffic, warehouse on-site emissions, omnitrans bus yard, railyards, concrete batch, asphalt batch, and the rock and aggregate plant.

Within this area, consistently high days or a high average level of pollutants over long periods of time can potentially result in health effects like respiratory, cardiovascular, and reduced life expectancy. Some pollutants (like ozone and PM

) have short-term effects like inducing asthma as well as long-term effects.

Sensitive Sites: air quality trends where sensitive populations spend time

Emissions come from a wide range of stationary sources. Regulated facilities are required to keep emissions below a threshold that is believed to keep ambient concentrations at or below safe levels as defined by the 

National Ambient Air Quality Standards (EPA)

. Despite the large number of regulated sources, fugitive emissions can make up a significant portion of primary emissions, especially for PM.

Where is it all coming from? A look at emissions from known stationary sources.

Stationary and mobile air pollution sources can potentially result in air pollution levels that adversely impact human health. The AB 617 SBM includes a wide range of stationary sources from single point sources that are regulated (industrial stack) to small sources (residential backyard grill) that are not regulated . Sources of most concern are truck idling and truck traffic related to warehousing, BNSF railyard and railroads, warehousing, traffic on freeways and major roadways, omnitrans bus yard, and cement manufacturing (ranked in this order).

Many small stationary sources are not regulated and are considered fugitive (sources that cannot be easily measured since they are individually relatively small and likely spread over a large area). Examples include road and industrial wind blown dust, some non-road equipment (diesel and gasoline), emissions from various mom and pop shops. Air quality modeling attempts to include fugitive emissions based on surrogates, such as population density, diesel fuel sold, sales.

On the other hand, regulated facilities are required to reduce emissions below a threshold that is believed to keep ambient concentrations at or below safe levels as defined by the National Ambient Air Quality Standards (EPA).

San Bernardino and Muscoy is also bisected by two major freeways (see Road Segments), I-210 and I-215, resulting in a major freeway junction at the southeast corner of Muscoy and the central, -northern section of the San Bernardino area. There are freight activities associated with the many warehouses, the large railyard, and others.

Stationary Sources: where is it all coming from? A look at emissions from known stationary sources

When Aclima measurements are aggregated to larger areas, patterns of high pollution emerge, which helps community members take steps to reduce exposure. Values of a hexagon should not be compared directly to the nearest EPA regulatory site measurements, but the levels of 

World Health Organization) air quality guidelines

 can be used as reference points for the measurements taken during the three-month period shown here. Areas emitting higher than area average greenhouse pollutants (CO

) can also be identified for further investigation or reductions.

 (averaged over 3 years) and 22% of the measurement area exceeds this value.

0% of the measurement area has higher nitrogen dioxide NO

 pollution than the EPA threshold of 53 ppb.

100% of the measurement area has higher NO

 pollution than the WHO guidelines of 5.3 ppb and 5 µg/m

, respectively. Extended exposure, possibly at even lower levels, can potentially result in adverse health effects.

Why this matters: compare areas of elevated pollution.

Regulatory air monitors are stationary and report air quality from one location for an entire area. Aclima mobile mapping data is gathered at different times of day and week throughout a community to give a zoomed in, hyperlocal view of how air quality differs from one block to the next. This is why lived experiences don't always match the regulatory site's data. Viewing sensitive sites and stationary sources on these maps helps us understand the potential sources and the impact of emissions on the people who live here. Mobile mapping data complements regional data provided by regulatory monitors with hyperlocal data that reveals average air quality conditions where people live, work, and breathe.

Comparing Aclima maps to regulatory data from stationary monitors.

Exposure to diesel pollution increases the risks of experiencing serious health problems, which is why Aclima developed a Diesel Pollution Indicator (DPI) visualization tool. At the hyperlocal level, we can see in the maps where diesel emissions may potentially affect human and environmental health and where steps may be taken to reduce pollution.

Aclima designed the DPI to track diesel emissions based on black carbon (BC), a component of PM

 are designated as criteria pollutants with established health associations. The DPI is based on these two components because emissions from sources that use diesel fuel, like heavy-duty trucks and railyards (train locomotives and drayage trucks), contain a higher concentration of BC and NO

These measurements give us a detailed, scientifically rigorous approach to seeing the patterns that this indicator exhibits.

Truck routes in the San Bernardino, Muscoy community, as identified by the Department of Transportation, are primarily freeways and clearly show the impact of diesel emissions.

Road segments are categorized into two levels, High and Medium, based on Aclima's DPI. The two major freeways in the community (I-210 and I-215) have a large number of road segments labeled as high impacted, indicating significant truck traffic.

This map shows the DPI for the residential areas suspected to be impacted by diesel pollution.

Impacts on residential areas by diesel emissions may be caused by trucks driving or idling within residential areas, particularly on roads near freeways and railyards. Diesel emissions can also be transported to residential areas by prevailing winds.

In the community during the monitoring period, the winds were consistently blowing from the southwest and south. Based on this, we can infer that residential areas downwind (north and north east) of the BNSF railyard and major freeways may experience higher diesel pollution than areas farther away from these sources.

Diesel Indicator: Residential Areas of Concern

Diesel Pollution Indicator: Residential Areas of Concern

Here we investigate schools with a DPI within a 1,000 foot radius. Percent segments refers to the number of High and Medium DPI road segments divided by the total number of road segments in the 1,000 foot radius. This map only shows High and Medium DPI road segments that are within the circles rather than all segments with High and Medium DPI throughout the map.

Schools near freeways, such as Riley Elementary adjacent to the I-215, and Wilson Elementary and Davidson Elementary adjacent to SR-210, the latter also near I-215 are seen to include diesel DPI road segments within their 1,000 foot circle. Schools near the railyard also can be impacted by DPI, like the Middle College High School directly east of the southern portion of the railyard.

Here we investigate warehouses in the SBM community with DPI within a 3,000 foot radius. Percent segments refers to the number of High plus Medium DPI road segments divided by the total number of road segments in the 3,000 foot radius. This map only shows High and Medium DPI road segments that are within the circles rather than all segments with High and Medium DPI throughout the map.

Based on our DPI indicator, diesel emissions directly associated with vehicles moving to and from the warehouses or idling during loading or unloading in the southern portion of the community have little influence on the surrounding area. High and Medium DPI road segments are observed near several warehouses in Muscoy, but the road DPI road segments are on I-215, although they may be due to a slowdown of traffic at the interchanges at Campus Parkway, University Parkway, and at Pine Avenue North that lead to the warehouses.

The DPI shows High and Medium DPI observed on roads adjacent to the group of railyards, which are located in the northwest section of West Commerce, the largest ones being the neighboring BNSF and Union Pacific railyards. Road segments with higher DPI near railyards may be caused by trains, trucks, and other diesel equipment. Aclima’s DPI shows that diesel emissions can also be transported by prevailing winds from railyards to residential areas.

The State of California has enacted some of the strictest diesel emissions standards in the world and the first-of-its-kind Indirect Source Rule was recently adopted by the South Coast AQMD to address pollution caused primarily by diesel trucks around distribution warehouses and other locations, but actions to immediately reduce exposure must also be taken at the local level. The DPI can help identify streets with the most heavy-duty diesel truck traffic, so that local community and non-profit leaders can continue to work with city and county officials to design or redesign truck-appropriate routes. These officials should consider enacting truck bans on specific heavily-traveled roads in the community that are more likely to expose vulnerable populations to higher levels of diesel pollution, especially when children or other vulnerable populations may be present along key distribution corridors.

In addition to mobile sources of pollution, the DPI can also help identify which specific stationary and off-road sources (warehouses, factories, railyards) may have the highest air quality impact on nearby residents. Individuals should take steps to reduce their exposure to diesel particulate matter whenever possible – be it from mobile or stationary sources.

Installing air filtration devices in buildings near these stationary sources and along heavy truck routes is a near-term option to reduce harmful impacts today, but a systematic solution to eliminating diesel truck pollution is to support the adoption of high-voltage electric vehicle charging infrastructure, which can be prioritized using the DPI and working with the air district and local utility.

The Methane Indicator highlights areas in the community with elevated ambient methane concentrations above the typical background level. While the Indicator reports the levels of methane from all sources, elevated methane levels may reflect emissions from natural gas infrastructure, landfills, livestock, and sewage.

Aclima’s algorithms can identify dangerous leaks that pose a combustion risk, in which case the local gas utility is immediately notified out of an abundance of caution for public safety. The primary concern regarding these levels is the effect methane has on exacerbating global climate change, since it is a potent greenhouse gas second only to carbon dioxide.

Omnitrans carries approximately 11 million passengers each year throughout its 480 square mile service area, covering 15 cities and portions of the unincorporated areas of San Bernardino County.

The buses at the facility, shown here in the community, operate on pipeline compressed natural gas (CNG). While CNG is naturally odorless, a pungent-smelling gas called mercaptan is added as a leak-detection safety feature. People can smell mercaptan, which contains sulfur and smells like rotten eggs, at very low levels. While these buses use CNG, we do not see an methane impact in the community based on our indicator.

The facility is bordered to the north, east, and west by residences that are home to some of the most sensitive population areas in this AB-617 community. While slightly elevated concentrations of methane were seen on certain streets near Omnitrans during the measurement period, levels were no higher than levels recorded on many segments in other areas in SBM, including most streets in Muscoy.

In addition to actions the local utility and air regulators are taking on a constant basis to ensure public safety, community members can take some specific actions if they are concerned about fugitive methane or natural gas leaks:

Notify the local utility or regional air quality district that they may want to investigate the area to determine whether the methane concentrations identified through the MI are being caused by sources that could be capped.

If landfills, wastewater treatment plants, agricultural waste sites, or sewer infrastructure are determined to be the likely source(s) of fugitive methane, biogas capture could be a viable option.

Work with leadership of Omnitrans, distribution warehouses, and other large vehicle fleet managers to convert to zero-emission electric vehicles. These vehicles could be powered by locally-generated solar energy from rooftops and covered parking areas, which have the added benefit of reducing the heat absorption by pavement.

Call before you dig. The local gas utility will be able to advise on the location of gas lines to avoid.

Residential congestion is not only annoying, it also produces elevated levels of unhealthy pollution where people live and breathe. By focusing on residential roads and arterials, the TPI  can be used to prioritize areas in the community that would most benefit from interventions and policy enforcements. A number of residential streets show high traffic emissions, many of these streets are arteries to major roads and are close to the freeways, while others are located near commercial centers.

Traffic Indicator: Residential Areas of Concern

Traffic Pollution Indicator: Residential Areas of Concern

Here we see warehouses with a TPI within a 3,000 foot radius. Percent segments refers to the number of High and Medium DPI road segments divided by the total number of road segments in the 3,000 foot radius. This map only shows High and Medium TPI road segments that are within the circles rather than all segments with High and Medium DPI throughout the map.

Warehouses in the industrial areas to the north and southeast of the community are prioritized here. Similar to the DPI, High and Middle TPI are observed adjacent to and east of the warehouses in Muscoy that are adjacent to I-215. The higher traffic emissions may be due to traffic slowdown as a result of cars exiting the freeway at University Parkway for the nearby college to the east, or from trucks and cars exiting the freeway towards the warehouses to the west. Medium TPI is also observed in a number of segments to the west of this area where a number of commercial businesses operate.

City and county agencies can utilize the TPI to reduce vehicle traffic near locations where populations that are sensitive to air pollution live and work, such as schools and parks.

The community could provide more support to Omnitrans to  increase the number of electric buses and reduce the use of compressed natural gas. Improving serve on corridors with high TPI could reduce single-occupancy vehicle trips.

Another way to reduce car dependency is to support active transportation choices by working with the city and alternative transportation coalitions (like Safe Routes to School) to provide training and to construct safe cycling lanes along streets with lower pollution levels and adjacent to those where gasoline-powered vehicles seem to travel most frequently.

In addition, traffic signals can be optimized to reduce idling at stop lights, and idling outside of schools, childcare centers, parks, and other sensitive receptor locations should be minimized or eliminated by local law.

The PM Indicator enables air regulators, community members, researchers, and health professionals to see hyperlocal variations in typical concentrations of PM

Inhaling microscopic fine particulate matter has been known to increase the likelihood of negative health effects ranging from respiratory and cardiovascular problems to an increased risk of developing cancer, reproductive and developmental issues, and reduced life expectancy. Studies have confirmed that the miniscule size of PM

 allows the pollutant to enter deep into the lungs – the smallest particles can even enter the bloodstream – and remain in the human body permanently.

 is emitted directly from natural sources, such as windblown dust, and man-made sources, such as vehicles and industry, and it also can be formed by chemical reactions in the atmosphere. Due to the different sources and mechanisms of PM

 formation, it is difficult to address the source of the problem without air quality and meteorological measurements, and a range of statistical and modeling approaches. High spatial resolution measurements by Aclima can support these approaches. These measurements give us a detailed, scientifically rigorous approach to seeing the patterns that this indicator exhibits.

Ambient concentrations measured by Aclima are prioritized by the PM Indicator for continued monitoring and to improve mitigation measures such as provisioning underserved communities with air filtration systems.

Focusing on residential roads and arterials, the PM Indicator can be used to prioritize areas in the community that would most benefit from interventions and policy enforcements. The PMI is more spatially distributed than the other indicators, likely due to the numerous sources of PM in the area, such as industrial, commercial, and wind blown dust, the likely cause for the consistently higher PMI values in Muscoy.

PM Indicator: Residential Areas of concern

Particulate Matter Indicator: Residential Areas of concern

As we saw in our Diesel Pollution Indicator and Traffic Pollution Indicator reports, a number of schools in the San Bernardino, Muscoy community are impacted by elevated particulate matter emissions.

Here we prioritize schools that show elevated levels of particulate matter nearby.

The community of San Bernardino, Muscoy identified particulate matter, fugitive dust, and odors from concrete batch, asphalt batch, and rock aggregate batch plants as air quality concerns.

There are two plants within the community boundary: 

. The higher PM levels observed on the freeway south of the Vulcan Materials Company may be due in part to the general large areas of uncovered soil in the area, including that associated with the Vulcan Materials Company, combined with the adjacent SR-210 freeway traffic.

Particulate Matter: Concrete batch plants

The BNSF railyard appears to be a source of PM and black carbon (a component of PM) due to emissions from related combustion sources and their movement kicking PM on the ground back into the air and the wind transporting those particles within and upwind of the railyard into residential communities.

 concentrations are highest. Analysts can utilize the PMI in conjunction with satellite imagery and meteorological data such as wind behavior to identify likely sources. Since PM

 in the atmosphere results from a range of natural and man-made sources, actions to reduce exposure can include a mix of mitigation and adaptation approaches.

One substantial action could be working with local lawmakers to reduce traffic near sensitive locations like schools and parks, which can significantly reduce emissions, but also avoid brake dust, tire wear, and road erosion , which over time also causes increased PM

 levels and harmful exposure. Road-based PM

 can also be mitigated by increased street sweeping, ideally using vacuum-style equipment to avoid additional dust distribution.

Concrete, asphalt, and aggregate plants can also be major sources of  PM

. These businesses should be encouraged by local regulators to adopt best-available technologies to mitigate fugitive dust and odors, or in certain cases, be incentivized by local governments to relocate to areas zoned exclusively for industrial activities.

 shows up largely in the form of dust and is difficult to mitigate in hot, dry climates, which necessitates adaptation strategies to capture and manage exposure for at-risk populations. Actions could include the distribution of portable indoor filtration devices and/or building retrofits where higher PM

 exposure is measured, using the hyperlocal air pollution data as evidence for increased access to state and regional incentives programs. Since air filtration systems often require more energy use than natural ventilation (e.g. opening windows), efforts should also be made to pair filtration incentives with financial support for solar energy at the home or building scale to reduce energy costs.

Actions to reduce particulate matter pollution can take many forms, and Aclima’s hyperlocal air pollution platform helps identify and prioritize interventions for the vulnerable populations that need them most urgently.

It should always be noted, during discussions and permitting processes with local businesses, that the people who are typically most exposed to harmful and toxic air are those who work in and around sources of these pollutants. Truckers, warehouse workers, railway employees, bus drivers, and those who work in industrial facilities often face long-term health effects of being exposed to unhealthy air. Armed with Aclima's data, EJ leaders can work with these individuals to advocate for themselves that their employers adopt best practices to go beyond compliance and protect everyone’s public health.

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Traffic Pollution Indicator: overview

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