456                                  LAWS OF MARYLAND                          [CH. 214

to the completion thereof, excluding any time during which the
equipment is idle.

h. Ringelmann Chart: A chart for grading the appearance, den-
sity, or shade of smoke, as published, with instructions for use, by
the United States Bureau of Mines, in information Circular 7718,
dated August 1955. Any other method for grading smoke which is ap-
proved by the Health Department as the equivalent of the Ringel-
mann chart may be substituted therefor.

i. Smoke: Small gas-borne particles, other than water, in sufficient
number to be observable by sight.

j. Source: Any physical arrangement or structure which may emit
air pollutants. It includes, but is not limited to, stacks, chimneys,
building openings, open fires, vehicles, processes, equipment, struc-
tures and premises.

255. There shall not be discharged into the atmosphere from any
source any smoke in excess of the darkness limitations listed in the
tables below. Emissions of smoke of such capacity as to obscure an
observer's view to a degree equal to or greater than does the smoke
described herein shall be treated in the same manner.

TYPE OF SOURCE                              Darkness Limitation

Domestic installations for heat-
ing, hot water and incineration Ringelmann No. 1 at all times
in one and two family dwell-
ings.

Installations for heating, hot

water, and incineration in Ringelmann No. 1 except Ring-
apartments, schools, office build- elmann No. 3 for 3 minutes any
ings, hospitals, hotels and simi- hour
lar buildings,

All other sources                            Ringelmann No. 2, except Ring-

elmann No. 3 for 3 minutes any
hour

255 A.

a.  Odors. Any condition or operation which results in the crea-
tion of odors of such intensity and character as to be detrimental to
the health and welfare of the public or which interfere unreasonably
with the comfort of the public shall be removed, stopped, or so
modified as to remove the odor.

b.  Dusts from Construction Projects. The general contractor,
the appropriate subcontractor, or both on any construction project
shall employ reasonable methods of equipment necessary to control
dust created by the operation.

c.  Particulate Matter. There shall not be discharged into the atmos-
phere any particulate matter in excess of the quantities shown below:

(1)  From refuse burning equipment: .85 lbs. per 1000 lbs. of dry
gases, adjusted to 12% CO2 or 50% excess air. In any one hour
period this shall not exceed 250 lbs.

(2)  From fuel burning equipment: 1 lb. per million BTU input.

(3)  From any source other than (1) or (2) above: Amounts re-
lated to Process Weight Per Hour according to the following table: