It started two years ago with a simple walk around the neighborhood. It then morphed into a project to collect and test soot and dust for lead, and now it has evolved into a full-fledged scientific experiment conducted by high school students in West Oakland to identify airborne toxic source emissions that foul the air they breathe.

A handful of students in EXCEL High School's Law and Government Academy, their instructor, who first piqued their interest in environmental justice, and representatives from two environmental organizations stood on the roof of McClymonds High School on Thursday to demonstrate how a portable particulate monitor will help identify the heavy metal particulates West Oakland residents are breathing every day.

The machine and another like it will be situated around the school and other sites in the West Oakland community during the next month to gauge the amount and types of emissions coming from Custom Alloy and Scrap Sales (CASS), which makes aluminum parts from scrap metals.

They expect to capture aluminum particulates, but the machine is also testing for metals such as nickel and cadmium, a heavy metal that can cause serious health problems, said Denny Larson, executive director of Global Community Monitor, who is working with the students and residents to set up the tests.

Although the students had to be prodded at first by their teacher, Ina Bendich, to take that walk two years ago, they soon got into

it, especially after they got some alarming results back from their first experiment: a test for lead dust collected in pie plates set outside the school's third-floor windows.

They began to study how environmental pollution can cause health problems, such as asthma and cancers. They formed a youth environmental group called West Oakland Urban Students Uprising against Pollution.

"My sister has asthma, and I can take this information and help educate my family and my peers," said Brittney Hamilton, 18, a senior at EXCEL. "I became aware that I can take action, and people are listening."

Ray Kidd, a resident who is part of a community watchdog group called West Oakland Air Monitors, credited the students with bringing the issue to the city's attention and getting the company to make some changes.

"I used to go by there on my bike all the time; the door would be open, and I would see fire inside," Kidd said. "You don't see that anymore."

Reach Cecily Burt at 510 208-6441 or cburt@bayareanewsgroup.com. Read her blog about West Oakland: www.ibabuzz.com/westside/.