Environment

Particulate matter concentrations refer to the amount of fine particulate matter in the air. Fine particulate matter (PM2.5) is very small, measuring less than 2.5 microns or 1/25 the width of a human hair - yet it poses a significant health risk when inhaled. Air quality standards for particulate matter are designed to protect public health in two different ways: the annual average focuses on long-term (chronic) exposure, while the peak 24-hour average emphasizes short-term (acute) exposure.

Ozone concentrations refer to the quantity of ozone (O3) molecules in the air. In the Bay Area, ozone is measured by numerous monitoring stations that record hourly concentrations at each site. These hourly data are used to calculate eight-hour peak ozone levels. Ultimately, peak ozone levels on the fourth-worst day of the year are used to determine compliance with national standards and serve as the most common indicator of ozone performance.

Greenhouse gas emissions refer to carbon dioxide and other chemical compounds that contribute to global climate change. Vital Signs tracks greenhouse gas emissions linked to consumption from the three largest sources in the region: surface transportation, electricity consumption, and natural gas consumption. This measure helps track progress towards achieving regional greenhouse gas reduction targets, including the region's per-capita greenhouse gas target for surface transportation under Senate Bill 375.

Fatalities from crashes refers to deaths resulting from injuries sustained in automobile collisions. The California Highway Patrol includes deaths within 30 days of the collision that are a result of injuries sustained as part of this metric. Fatalities are measured as an aggregate number (total fatalities) and as a rate (fatalities per 100,000 residents and fatalities per 100 million vehicle miles traveled).

Bay restoration refers to the acreage of San Francisco Bay. This measure reflects either the Bay's expansion from restoration projects (such as wetland restorations) or contraction from projects that fill the Bay to create new land for development. This measure is a key indicator of Bay conservation efforts, as well as nearby development activities.

Vulnerability to sea level rise refers to the share of the historical and current Bay Area population located in areas at risk from sea level rise impacts over the coming decades. Based on the most likely scenarios for current and future flooding above today's mean higher high water mark, projected sea level impacts are presented for four scenarios ranging from a one foot rise to a four feet rise. A neighborhood is considered vulnerable to sea level rise when at least 10 percent of its land area is forecast to be inundated by daily high tides under a given scenario.

Injuries from crashes refers to serious but not fatal injuries sustained in a collision. The California Highway Patrol classifies a serious injury as any combination of the following: broken bones; dislocated or distorted limbs; severe lacerations; skull, spinal, chest or abdominal injuries that go beyond visible injuries; unconsciousness at or when taken from the scene; or severe burns. Injuries are measured as an aggregate number (total injuries) and as a rate (injuries per 100,000 residents and injuries per 100 million vehicle miles traveled).