“Fluorides” means any matter containing the element fluorine in a combined form. Ambient air quality standards for fluorides are those concentrations in the ambient air or in other substances which result in the following values being exceeded: Field Crops. Field crops at any stage or growth may not exceed 35 micrograms F per gram dry tissue in washed samples. Forage. Running averages of 12 monthly samples of forage or hay or silage grown in the area as feed may not exceed 35 micrograms F per gram dry tissue in unwashed samples. The average of any 2 consecutive months' samples of forage or hay or silage grown in the area as feed may not exceed 60 micrograms F per gram dry tissue in unwashed samples. A monthly sample of forage or hay or silage grown in the area as feed may not exceed 80 micrograms F per gram dry tissue in unwashed samples. Fruit Trees, Berries, and Other Commercial Crops. Fully expanded functional leaves may not exceed 50 micrograms F per gram dry tissue in washed samples. Deciduous Trees and Shrubs. Fully expanded functional leaves may not exceed 100 micrograms F per gram dry tissue in washed samples. Conifers and Evergreen Trees and Shrubs. Fully expanded leaves or needles of the current year may not exceed 50 micrograms F per gram dry tissue in washed samples. Leaves and needles of prior seasons may not exceed 75 micrograms F per gram dry tissue in washed samples. Grasses and Herbs. Grasses and herbs not subject to browsing, grazing, or harvest for use in feeds or food may not exceed 150 micrograms F per gram dry tissue in washed samples. Ornamental Planting. Ornamental plants, except trees, shrubs, and turf where §B(4)—(7) applies, may not exceed 40 micrograms F per gram dry tissue in fully expanded leaves in washed samples at any period during the growing season. Other Values. If it considers vegetation sampling to be not practicable, the Department may assume unsatisfactory conditions exist when either: Static limed filter paper samples of 28 to 32 days exposure exceed 2 micrograms F per 100 square centimeters per day for a yearly average of monthly samples; or Gaseous fluorides exceed 1.2 micrograms F per cubic meter of air in any 24 hour sample or any 72 hour average exceeds 0.4 microgram F per cubic meter of air. Monitoring and Measurement of Fluoride. The methodologies to be used for the monitoring and measurement of fluoride shall be those specified in Method 1005 of the Department's Technical Memorandum 91-01, “Test Methods and Equipment Specifications for Stationary Sources” (January 1991), which is incorporated by reference in COMAR 26.11.01.04C.