1134                             Laws of Maryland                      [Ch. 350

(50)    Radiation fallout shelters.—(a) For purposes of this sub-
section a radiation fallout shelter is (i) a structure outside of
another building, or an addition to, or alteration of, an existing
building, or a portion of a newly constructed building which is of a
type of construction more dense than the general type of construc-
tion of the remainder of said newly constructed building, (ii) erected
upon lands occupied for residential purposes by not more than two
families and (iii) constructed in accordance with specifications pub-
lished by the office of civil and defense mobilization of the United
States government for one of the shelter types or designs approved
by said agency as being effective for affording protection from
radiation fallout.

(b)    Any structure outside of another building, or any under-
ground, or partially underground, addition to an existing building,
or any underground, or partially underground portion of a newly
constructed building, which constitutes a radiation fallout shelter,
and which is used for no other purpose, shall be exempt to the full
extent of the increase in assessable value, if any, of the taxpayer's
property, attributable to such radiation fallout shelter.

(c)    All other radiation fallout shelters, than those referred to in
subsection (b) hereof, shall be exempt to the extent of the difference
between the increase in assessable value, if any, attributable to such
radiation fallout shelter as actually constructed, and the increase in
assessable value, if any, had the addition, alteration or portion of a
building constituting such other radiation fallout shelter, been con-
structed in a manner, and of materials, similar to that of the re-
mainder of building, or had the structure outside any existing build-
ing, constituting such other radiation fallout shelter, been constructed
in a manner and of materials similar to that of the principal resi-
dence building on the property.

(51)     Union-owned property in Allegany County.—In Allegany
County for purposes of county taxation the property, real and per-
sonal, owned directly or indirectly by any bona fide labor union or
unions, or by any corporation whose capital stock is exclusively
owned by any bona fide labor union or unions, provided, that such
property is used solely for the mutual benefit of its or their members
and not for profit. Any part of such property which is commercially
rented shall be taxable to the extent of the commercial use on the
fair value of the property so rented.

(52)    Academy of the Arts, Easton, Maryland, Inc.—Academy of
the Arts, Easton, Maryland, Inc., as to property used primarily for
the purposes of the organization, but not as to property used primarily
for revenue or income-producing purposes.

(53)    Frederick Optimist Boys' Foundation, Inc.—Property, real
and personal, owned by the Frederick Optimist Boys' Foundation,
Inc., providing property is not commercially rented. Operation of a
parking lot, even at a fixed charge, shall not be construed to mean
commercially rented. If part of property is commercially rented and
so designated in a lease, the balance of the property is not eliminated
from this tax exemption.

(54)    Real property owned by the Nature Conservancy, or any
chapter thereof, if the property is used to assist in the preservation
of wild nature areas, to establish nature reserves or other protected
areas, or generally to promote conservation, provided such property
is ultimately intended for future public ownership.