The Bay Area Air Quality Management District has issued a Spare the Air Day for Tuesday -- the second this week.
District officials are encouraging people to take public transit and to reduce their energy use.
Motor vehicle exhaust, gasoline vapors, industrial emissions and household chemicals contain volatile organic compounds and nitrogen oxides that can combine with oxygen. When in the presence of heat and sunlight, it can create ground-level ozone.
On Tuesday, temperatures in Cupertino will reach an average 87 degrees. For the rest of the week, they will hover in high 80s.
Long-term exposure to ozone can reduce lung function and high levels of ozone are particularly harmful to children, seniors and those with heart and respiratory conditions, district officials said.
Today is the second consecutive Spare the Air Day this week and the sixth for 2011.
--Bay City News Service