By Kay Henderson
PRAIRIE CITY, Iowa (Reuters) - The head of the Environmental Protection Agency said she will decide in July whether to tighten U.S. controls on dust, an issue that has stirred fear in farm country of costly federal regulation.
Livestock and farm groups say it would be impossible to comply with stricter standards on exposure to dust, which they say is a natural part of farming. EPA regulates dust, formally described as particulate matter, under anti-pollution laws.
"It's my decision to make a final recommendation. That'll happen in July," EPA administrator Lisa Jackson told reporters on Tuesday after a tour of two farms and a biodiesel plant in central Iowa.
EPA staff workers have suggested either keeping the current limit, set in 1987, on exposure to dust or lowering it. Their assessment grew out of a periodic review of the dust rule. A panel of outside scientists suggested a stricter limit.
Four U.S. representatives announced a bill on Monday that would temporarily ban the EPA from changing the dust rule. A quarter of the members of the House signed a letter to Jackson on March 29 opposing stricter limits.
Dust regulation is aimed at microscopic particles that can be inhaled and cause serious health problems such as difficult breathing and irregular heartbeat. Sand and particles larger than 10 microns in diameter are not regulated. By comparison, a human hair is about 70 microns in diameter.
Particles regulated by EPA can come from construction sites, fields, unpaved roads, power plants, cars and industry.
While EPA sets pollution limits, state agencies decide how to implement them, Jackson said when asked if rural and urban areas could have different rules.
Agriculture Secretary Tom Vilsack accompanied Jackson on the tour on a cold and rainy day. Hail fell at one point.
Farm groups routinely see EPA as intruding into agriculture and private property. Besides a revision on dust rules, they say EPA may further restrict "spray drift" from pesticides, expand water regulation and aggressively limit runoff from fields.
They say EPA's "pollution diet" for the Chesapeake Bay, set in late 2010, may foreshadow similar regulations elsewhere.
Asked if mandatory controls would be set on runoff into the upper Mississippi River watershed, Jackson pointed to voluntary land stewardship work and said on Tuesday she did not see a need "to move directly to a regulatory mechanism."
(Reporting by Kay Henderson; Writing by Charles Abbott)