The Bay Area Quality Management District is issuing a Spare the Air Alert for today.
The alert, which is the district's first of 2014, advises air quality is expected to be unhealthy today due to high temperatures, low winds and motor vehicle exhaust. These factors are expected to cause unhealthy ozone accumulation in the Bay Area.
The district issues Spare the Air Alerts when ozone pollution is forecast to reach unhealthy levels.
Smog can cause throat irritation, congestion and chest pain, can trigger asthma, inflame the lining of the lungs and can worsen bronchitis and emphysema, according to the district. It can be particularly harmful for young children, seniors and people with respiratory and heart conditions.
During an alert, the district advises outdoor exercise be done in the early morning hours when ozone concentrations are lower.