." >> frontlinis made possible by contributions to your pbs station from viewers like you. thank you. and by the corporation for public broadcasting. major support for frontliis provided by the john d. and catherine t. macarthur foundation, committed to building a more just, verdant and peaceful world. more information is available at macfound.org. additional support is provided by the park foundation, dedicated to heightening public awareness of critical issues. the john and helen glessner family trust, supporting trustworthy journalism that informs and inspires. the ford foundation, working with visionaries on the front lines of social change worldwide, at fordfoundation.org. the wyncote foundation. and by the frontline journalism fund, with major support from jon and jo ann hagler. (swing squeaking) >> narrator: sara lives with her three siblings: her sisters helen and farah and her brother mohammed. they live with their parents here in this middle-class suburb that's now a front line in syria's largest city, aleppo. (gunfire) some 200,000 residents have fled the brutal

. >> frontlinis made possible by contributions to your pbs station from viewers like you. thank you. and by the corporation for public broadcasting. major support for frontliis provided by the john d. and catherine t. macarthur foundation, committed to building a more just, verdant and peaceful world. more information is available at macfound.org. additional support is provided by the park foundation, dedicated to heightening public awareness of critical issues. the ford foundation, working with visionaries on the front lines of social change worldwide. at fordfoundation.org. the wyncote foundation. and by the frontline journalism fund, with major support from jon and jo ann hagler. and additional support from millicent bell, through the millicent and eugene bell foundation. >> lowell bergman: at the end of the day, when most of the world goes home, a nearly invisible workforce clocks in. millions of janitors clean malls, banks, big box stores, the office where you work. many janitors are women who work at night, in empty buildings, in isolation, and that can put them in d