About a quarter of San Francisco’s senior citizens, or 40,000 people, are considered poor because they live at or below 150 percent of the $860 federal poverty income level, which equals about $1,300 a month. That mirrors the national figure. About 13,000 of these low-income elders in San Francisco get help from federal and local government housing programs, either living in subsidized units or using special low-income vouchers to meet the rent. And nearly half of low-income seniors get government-subsidized In Home Supportive Services to help with cleaning, bathing and the like. City polls taken throughout the past decade show that only 24 percent of San Francisco elders had children living within 20 minutes travel, compared with 40 percent in other major cities.