When you smell pig waste you are inhaling, into your lungs, fine particulates of pig feces, ammonia, carbon dioxide, carbon monoxide, methane, Volatile Organic Compounds (VOCs), and most seriously hydrogen sulfide. Don't take our word for it, read the articles below. Our Board of Health states that the pigs eat garbage. Since pigs' digestive systems are similar to humans, should their waste be treated similarly, but it isn't. The waste of hundreds of pigs is spread on "fields" adjacent to wetlands in an area where the water table is just feet from the surface. This would be considered an environmental disaster if the equivalent of human waste was spread in this manner in this place. While worries over e.coli and hepatitis have been somewhat alleviated by information from the Board of Health and Mass. Health Dept., no information has been given to alleviate worries about the affects of Hydrogen Sulfide, ammonia, etc. These gases are the primary causes of the nasal-burning odors and of serious concern to many scientist and researchers.

Kids that grow up near pig farms that don't properly treat the waste have been shown to have a higher rate of wheezing, and the particulates in the air can exacerbate asthma.¹

The New York Times reports that there may be very serious health issues for those breathing fumes from pig waste, "including respiratory ailments, from coughing and sniffles to lung scarring and pneumonia".²

Studies documented at the USDA's website shows that exposure to swine dust causes intense airway inflammation. Pig farmers have a higher than normal rate of upper respiratory disease and nasal polyps. It also states that they can even lose their sense of smell over time.³

While the Board of Health and Mass. Dept. of Health say that there is no unusual pattern of respiratory issues here, it must be noted that they did an analysis of the town as a whole, "all Tewksbury Hospitalizations"⁴ and did not contact families in the affected area. Tewksbury is a town of almost 30,000 people, if the few hundred around the farm had respiratory issues it most likely wouldn't be apparent from looking at the town as a whole.

Sources:

Article at Kidshealth.org - Kids in Schools Near Pig Farms Wheeze More
Article by the New York Times - "...the gases, along with the dust of pig dander, particles of feed and of dry manure, cause unusually high incidences of respiratory ailments, from coughing and sniffles to lung scarring and pneumonia, conditions that many have long attributed to weather or allergies
http://www.nal.usda.gov (USDA) - Farmers can have... "...symptoms of smell impairment, and more often had nasal polyps and hyperaemia of the nasal mucosa... (especially dairy farmers and pig farmers)"
MDPH Response

Other Articles

Article in the Boston Globe - Canadian researchers have found that a quarter of the swine at farms and a fifth of the humans who tend to them harbored Methicillin-resistant staphylococcus aureus, a bacterium that's especially feared because first-line antibiotics are useless in treating it.
http://media.www.iowastatedaily.com - The airborne effluent from hog lots, in the end, might harm humans more seriously than do manure spills...
http://www.agr.gc.ca - Hydrogen sulfide is a "dangerous", "poisonous" gas. To date, people have perceived farm odors only as nuisances, but awareness of this problem is now growing. Indeed, some countries have already established regulations regarding allowable odor intensities.
http://www.about-ecoli.com - Article about e.coli spread through the air
http://www.cnn.com - Another article about e.coli spread through the air
http://annhyg.oxfordjournals.org - Assessment of the human health effects of bioaerosols that are produced by composting operations.
http://www.cbsnews.com - Are Hog Farmers Creating A Waste Hazard?
http://www.ncbi.nlm.nih.gov - "There is increasing concern that airborne dust and particulates from animal enterprises which are emitted into the environment may impair the health of people living in nearby residential areas."
http://archives.cbc.ca - Since liquid pig manure is sprayed as fertilizer on fields, it can cause respiratory problems.