Md. Code, Labor and Employment § 5-602

(a) (1) In this section the following words have the meanings indicated.

(2) “Confined space” means a space that, by design:

(i) has limited openings for entry and exit; and

(ii) is subject to:

1. the accumulation of a combustible agent;

2. an accumulation of a toxic agent; or

3. a deficiency of oxygen.

(3) “Confined space” includes:

(i) a basin;

(ii) a bin;

(iii) a degreaser;

(iv) a duct;

(v) a pipeline;

(vi) a pit;

(vii) a sewer;

(viii) a silo;

(ix) a tank that is enclosed or has an open top;

(x) a tub;

(xi) a tunnel;

(xii) a vat;

(xiii) a process vessel; or

(xiv) a reaction vessel.

(4) “Maintenance work” means cleaning, inspection, maintenance, painting, repair, servicing, or other similar work.

(b) A person described in § 5–101(d)(2)(ii) or (iii) of this title may not allow or cause an individual described in § 5–101(c)(2)(iii) or (iv) of this title to do maintenance work in a confined space, unless the Commissioner:

(1) grants written authorization based on a satisfactory showing that work practices in effect will protect the health and safety of the individual; or

(2) in accordance with Subtitle 3 of this title, passes an order for a variance.

(c) (1) This subsection applies only to an employer who is a subcontractor.

(2) Each subcontractor who, under an original contract or subcontract, is to do maintenance work in a confined space shall give the Commissioner:

(i) at the commencement of the maintenance work, oral notice of the maintenance work to be performed; and

(ii) within 24 hours after the oral notice, written notice of the maintenance work.