Blood will be drawn, dental exams will be given, bone density will be checked.

But only for seven weeks. And you can’t walk in, or even make an appointment, unless you’re invited.

The facility is a mobile examination center put together here by a medical team from around the country working for the U.S. Centers for Disease Control and Prevention. Researchers are collecting information on the medical status and daily habits of Saratoga County residents as part of the annual National Health and Nutrition Examination Survey [NHANES].

The survey started 50 years ago as a way to assess Americans’ health and set policies to address problem areas. Past surveys have identified lead in blood samples, hearing loss in adolescents and a significant increase in Type 2 diabetes, said Janis Eklund, a CDC study manager.

In some way, the survey mimics routine medical checkups, with blood pressure monitoring and urine sample tests. In others, it is very different, as researchers seek to understand what Americans eat on a typical day or how smell and taste change with age, among other things.

Counties are selected for participation based on a statistical analysis of the American population, not because the area has a high prevalence of a particular disease or certain environmental factors, said Nora Martinello, a senior study manager.

Because data must be collected from a group that represents a particular segment of the American population, residents must be selected by CDC representatives who have been knocking on Saratoga County doors since May 18. Researchers have identified more than 300 of the 525 people they need, Eklund said. Surveyors will look for more participants even as health exams begin.

Surveyors are still looking especially for seniors, who have been more hesitant than others to participate, but are important to study because their numbers are growing, Eklund said.

All residents should be assured that surveyors from the CDC are legitimate researchers, and that their work has no political agenda, she said. Some households have turned surveyors away because they think the data collection is connected to the health reform law known as Obamacare.

“We have nothing to do with politics — nothing,” Eklund said.

The mobile exam center is constructed from four trailers joined together. During an open house Friday, it could be tough to navigate tight corridors when another person passed. But the space is efficiently laid out, jam-packed with small rooms for checkups and private interviews, a bone density scanner, dentist’s office and blood lab.

The procedures done depend on a person’s age, and participants may opt out of any part of the exam, Eklund said. Individual reports are private, and collected information becomes part of a national database. Even local health officials may not access data specific to Saratoga County, she said.

No medical care is provided, but participants receive exam reports and are referred to area doctors if serious issues are identified. If a screening for depression suggests a participant may be suicidal, for instance, Dr. Helen Yost said she immediately refers the participant to a mental health provider.

A nutritional interview asks people to recall everything they’ve eaten in the last 24 hours, using measuring cups to indicate their portions. For a test of tasting ability, participants swish and spit a small vial of salty, sweet or bitter liquid, then indicate how they found the taste on a range from barely perceptible to extremely strong.

A dental check includes an observation of missing and decayed teeth and a test for human papillomavirus, but no X-rays. A special camera looks for the presence of too much fluoride, which on-site dentist Dr. Stuart Martin said can put someone at risk for cavities. Martin could not contain his excitement when talking about the camera; he said it is one of only seven in the country.

Participants may also opt to complete aspects of the survey at home, for a reimbursement of $40 or $50. These include wearing an activity monitor for seven days and collecting urine samples over a 24-hour period.

The CDC team plans to be at the site through July 28.