Decisions about How We Grow and Develop Affect Air Quality
Poor air quality is one the most critical problems facing the San Joaquin Valley. For example, 17% of the Valley’s residents now suffer from asthma that is related to air pollution. How our communities grow and develop affects the quality of the air we breathe. Urban sprawl contributes to poor air quality in several ways:
- When homes, schools, shopping and workplaces are widely separated automobile travel is required to get from place to place. The number of miles being driven per year in the San Joaquin Valley has more than tripled since 1980. This amount of driving contributed to an average of 50 “bad air” days across the Valley in 2007.,
- The more spread out development is, the farther people have to drive. In the San Joaquin Valley, there is a direct correlation between the efficiency of urban development (measured by people per acre of developed land) and the total vehicle miles travelled in a community. [chart] On average, there are only about 8 people per acre in the Valley’s urban areas – half to one-third of the number in other regions in California.
- Low density development with neighborhoods that lack connectivity and a mix of uses prevents people from walking and bicycling to access good, services, and jobs. This kind of low-density development also makes public transportation systems economically impractical. Improving public transit systems and increasing their use could dramatically reduce auto use and improve air quality.
To effectively reduce vehicle trips, alleviate congestion, and improve air quality, cities and regions must adopt smarter growth strategies that eliminate the need to drive everywhere. This means creating more walkable urban and suburban environments, a mix of land uses and transit-oriented communities.
For More Information
Air Quality and Land Use Handbook: A Community Health Perspective — CA Air Resources Board (CARB)
CEQA and Climate Change — California Air Pollution Control Officers Association
 2007 California Health Interview Survey.
 Days in 2007 that exceeded the State “8-Hour Standard,” the number of days that the maximum 8-hour average ozone concentration was greater than 0.070.parts per million. California Air Resources Board 2009 Almanac.
 While power plants and industrial manufacturers are some of the largest polluters in the U.S., vehicle emissions is dramatically increasing. Vehicle emissions account for over 75 percent of carbon monoxide pollution; 30 to 50 percent of all nitrogen oxide and volatile organic compound emissions; 30 percent of particulate matter emissions; and almost one-third of green-house gases. See Air Quality and Smart Growth: Planning for Cleaner Air. Funder’s Network for Smart Growth and Livable Communities, Translation Papers. 2005.