Maryland Attorney General Opinion 104OAG054

54 [104 Op. Att’y

PUBLIC SAFETY
CARBON MONOXIDE ALARMS – WHETHER CARBON MONOXIDE
ALARMS MUST BE INSTALLED IN ALL RENTAL DWELLING
UNITS
August 1, 2019
The Honorable D. Robert Meffley
President, County Council of Cecil County

Your predecessor as the President of the Cecil County Council
asked for our opinion about the applicability of Title 12, Subtitle
11 of the Public Safety Article, as amended by Chapters 174 and
175 of 2016, to certain rental dwelling units. Specifically, your
predecessor asked whether the subtitle’s provisions requiring the
installation of carbon monoxide alarms apply to rental dwelling
units that do not rely on the carbon-monoxide-producing combustion
of a fossil fuel for heat, ventilation, hot water, or clothes dryer
operation—that is, units that rely solely on electricity, which does
not emit carbon monoxide.1 The Cecil County Attorney has given
advice that Chapter 175 applies to all rental dwelling units,
regardless of whether they rely on appliances that operate by
combustion. For the reasons explained below, we agree. It is our
opinion that the statute, as amended in 2016, applies to all rental
dwelling units, including those that run entirely on electricity.

I
Background

Carbon monoxide is an odorless, tasteless, invisible gas that
results from the incomplete combustion of wood or fossil fuels,
such as kerosene, gasoline, charcoal, propane, natural gas, and oil.2
The gas can be produced by any appliance that burns those types
of fuels, including generators, space heaters, ovens, clothes dryers,
automobiles, fireplaces, and grills. Fiscal & Policy Note, H.B. 849,
2016 Leg., Reg. Sess. Furnaces and water heaters are also potential

1
Chapters 174 and 175 of 2016 were enacted by the passage of House
Bill 849 and Senate Bill 182, respectively. For brevity, we will refer
only to Chapter 175. Also for brevity, we will refer to rental dwelling
units that do not have appliances that rely on the combustion of fossil
fuel as “all-electric” units.
2
Consumer Product Safety Comm’n Fact Sheet, https://www.cpsc.gov/
safety-education/safety-guides/carbon-monoxide/carbon-monoxide-fact-sheet.
Gen. 54] 55

sources of the gas. Id. Carbon monoxide is a leading cause of
unintentional poisoning deaths in the United States. Maryland
Department of Health & Mental Hygiene Position Paper on House
Bill 849 (“DHMH Position Paper”) (citing Centers for Disease
Control and Prevention (“CDC”), Unintentional Non-Fire-Related
Carbon Monoxide Exposures - United States, 2000-2009, 60(30)
Morbidity and Mortality Weekly Report 1014-17 (Aug. 5, 2011)).3
The CDC has found, for example, that at least 430 people die each
year in the United States from unintentional carbon monoxide
poisoning. CDC, Carbon Monoxide (CO) Poisoning Prevention,
https://www.cdc.gov/features/copoisoning/index.html (last visited
July 24, 2019). Similarly, from 2008 to 2012, the Maryland
Environmental Public Health Tracking System identified more than
2,217 emergency department visits and 186 hospitalizations due to
carbon monoxide exposures in Maryland. DHMH Position Paper.
Because of the large number of such incidents, the Consumer
Product Safety Commission (“CPSC”) recommends that every
home have a carbon monoxide alarm on each level and in the
hallway near bedrooms in each separate sleeping area. CPSC,
Carbon Monoxide Toolkit, https://www.cpsc.gov/safety-education/
neighborhood-safety-network/toolkits/carbon-monoxide-invisible-killer
(last visited July 24, 2019).

Since January 1, 2008, Maryland law has required carbon
monoxide alarms in all dwellings for which a building permit was
issued on or after that date if the dwelling “relies on the combustion
of a fossil fuel for heat, ventilation, hot water, or clothes dryer
operation.” 2007 Md. Laws, ch. 401. In recent years, the General
Assembly has amended the law to broaden the scope of the alarm
requirements as applied to hotels, lodging or rooming houses, and
rental dwelling units. For example, the law was amended in 2015
to require carbon monoxide alarms in each guest room in a hotel or
a lodging or rooming house that contains (or is near) a device that
emits carbon monoxide or that is near (or connected by ductwork
to) an enclosed unventilated garage, regardless of the date the
building was built or permitted. See 2015 Md. Laws, ch. 151.
Then, the General Assembly further expanded the law in 2016 to
cover all “rental dwelling unit[s],” regardless of when the building
was constructed or when permits for the building were issued.
2016 Md. Laws, ch. 175 (effective April 1, 2008).

Thus, as initially enacted, the statute required carbon
monoxide alarms to be installed only in dwellings that were newly

Available at
3
https://www.cdc.gov/mmwr/preview/mmwrhtml/
mm6030a2.htm.
56 [104 Op. Att’y

constructed or had a building permit issued on or after January 1,
2008, and that relied on the combustion of a fossil fuel for heat,
ventilation, hot water, or clothes dryer operation. See 2007 Md.
Laws, ch. 401. Subsequent enactments, however, have created
separate rules that govern two special categories of dwellings: (1)
hotels and lodging and rooming houses, see Md. Code Ann., Pub.
Safety (“PS”) §§ 12-1102(2), 12-1104(b), and (2) rental dwelling
units, see PS §§ 12-1102(2), 12-1104(c).
As amended in 2016, the subtitle now applies to:
(1) a dwelling that:
(i) relies on the combustion of a fossil fuel for
heat, ventilation, hot water, or clothes dryer
operation; and
(ii) is a newly constructed dwelling for which
a building permit is issued on or after January
1, 2008; or
(2) a hotel, a lodging or rooming house, or a
rental dwelling unit.

PS § 12-1102.4 For those dwellings to which the subtitle applies,
the statute then provides in relevant part:

(a) Except as provided in subsections (b) and
(c) of this section, there must be a carbon
monoxide alarm installed in a central location
outside of each sleeping area within a
dwelling subject to this subtitle.
(b) For a hotel or a lodging or rooming house,
on or after April 1, 2017, there must be a
carbon monoxide alarm installed within the

4
The term “rental dwelling unit” is defined by reference to a provision
in the Environment Article, see PS § 12-1101(g), which in turn defines
the term as “a room or group of rooms that form a single independent
habitable rental unit for permanent occupation by one or more
individuals that has living facilities with permanent provisions for living,
sleeping, eating, cooking, and sanitation.” Md. Code Ann., Envir. § 6-
801(t). The term does not include “(i) an area not used for living,
sleeping, eating, cooking or sanitation, such as an unfinished basement;
(ii) a unit within a hotel, motel, or similar seasonal or transient facility;
(iii) an area which is secured and inaccessible to occupants; or (iv) a unit
which is not offered for rent.” Id.
Gen. 54] 57

dwelling [in certain specified places near
devices that emit carbon monoxide].
(c) For a rental dwelling unit, on or after April
1, 2018, there must be a carbon monoxide
alarm installed within the dwelling as follows:
(1) outside and in the immediate vicinity of
each separate sleeping area; and
(2) on every level of the unit, including the
basement.

PS § 12-1104.
II
Analysis

Your predecessor asked whether, under §§ 12-1102 and 12-
1104 of the Public Safety Article, carbon monoxide alarms must be
installed in all rental dwelling units, including units that do not rely
on the combustion of a fossil fuel for heat, ventilation, hot water,
or the operation of a clothes dryer. That question is one of statutory
interpretation. The cardinal rule of statutory construction is to
ascertain and effectuate the intent of the General Assembly, and the
starting point for that process is the plain language of the statute in
question. Ingram v. State, 461 Md. 650, 661 (2018). The meaning
of even the plainest language, however, must be read in light of the
context in which it appears. Id. at 662. Thus, the context of a
statute—the titles of, preambles to, and amendments of the bill that
added the provision in question, its legislative history, and its
relationship to earlier and subsequent legislation—is relevant to
“the fundamental issue of legislative purpose” and therefore to the
meaning of the legislative language. Id. at 663 (quoting Kacz-
oroswki v. Baltimore, 309 Md. 505, 515 (1987)). In this case, the
plain meaning of the words of the statute, the statute’s structure,
and the history and purpose of the 2016 amendments all lead to the
same conclusion: Carbon monoxide alarms are required in all
rental dwelling units, even if those units are all-electric.

We start with the language of the statute. The text of PS
§§ 12-1102 and 12-1104, read together, makes clear that the
subtitle’s requirements apply to all rental dwelling units, including
those that are all-electric. As outlined by § 12-1102, the statute
applies separately to (1) a dwelling that “relies on the combustion
of a fossil fuel for heat, ventilation, hot water, or clothes dryer
operation” and “is a newly constructed dwelling for which a
58 [104 Op. Att’y

building permit is issued on or after January 1, 2008 . . . or (2) a
hotel, a lodging or rooming house, or a rental dwelling unit.” PS
§ 12-1102 (emphasis added). The term “or” is a “disjunctive
conjunction which serves to establish a relationship of contrast or
opposition.” Hoile v. State, 404 Md. 591, 609 (2008) (internal
quotation marks omitted). In this instance, the term contrasts
dwellings that were covered only by the original legislation in 2007
from those types of dwellings (including rental dwelling units) that
were specifically given different treatment by subsequent
legislation in 2015 and 2016. See Ingram, 461 Md. at 665-66
(explaining that the more specific statute is usually an exception to
a more general one). Although § 12-1102(1) expressly limits
coverage under that paragraph to dwellings where fossil fuels are
used for heat or to operate appliances, the separate clause in § 12-
1102(2) that governs rental dwelling units does not mention
reliance on fossil fuels. In other words, the clause in § 12-1102(1)
that excludes all-electric dwellings from that category does not
modify the separate clause in § 12-1102(2) that governs the
applicability of the statute to rental dwelling units.

Similarly, under § 12-1104, there is no limitation on the type
of rental dwelling unit to which the statute’s requirements apply.
Section 12-1104(a) sets the basic requirement for the placement of
carbon monoxide alarms in a “dwelling” but makes an exception
for dwellings that are covered either by § 12-1104(b), which sets
the specific requirements for carbon monoxide alarms in hotels,
lodging houses, and rooming houses, or by § 12-1104(c), which
sets the specific requirements for placement of carbon monoxide
alarms in rental dwelling units. In the subsection that governs
hotels and lodging and rooming houses, the General Assembly
specifically provided that carbon monoxide detectors need only be
installed in guest rooms and other areas that “contain[] a device that
emits carbon monoxide,” that are “adjacent to” a room or area with
such a device, or that are “adjacent to” (or connected by ductwork
to) “an enclosed unventilated attached garage.” PS § 12-1104(b).
By contrast, the subsection that governs rental dwelling units
requires carbon monoxide alarms on every level of the dwelling
and outside each sleeping area without any reference to appliances
that rely on fossil fuels or other possible sources of carbon
monoxide. PS § 12-1104(c).

Thus, although the statute’s scope as to most types of
dwellings depends on whether the dwelling employs carbon-
monoxide-producing devices, see PS §§ 12-1102(1), 12-1104(b),
there is no such limitation in the statute as to rental dwelling units.
Where, as here, the General Assembly has “carefully employed” a
Gen. 54] 59

limitation in one part of the statute and excluded that same
limitation in another, we cannot infer the existence of the limitation
where it is excluded. Toler v. Motor Vehicle Admin., 373 Md. 214,
223-24 (2003) (internal citation and quotation marks omitted); see
also Miller v. Miller, 142 Md. App. 239, 251, aff’d sub nom.
Goldberg v. Miller, 371 Md. 591 (2002) (explaining that when a
legislative body “included particular language in one section of a
statute, but omitted it in another section of the same act, it could be
presumed that [the legislature] acted intentionally and purposely in
the disparate inclusion or exclusion”). Based on the plain language
of PS §§ 12-1102 and 12-1104, the statute does not limit its
application to rental dwelling units with appliances that rely on the
carbon-monoxide-producing combustion of fossil fuels.5

That conclusion is also strongly supported by the legislative
history of Chapter 175. As introduced, both House Bill 849 and
Senate Bill 182, which became Chapters 174 and 175, respectively,
required placement of carbon monoxide alarms in rental dwelling
units based on the location of appliances that rely on fossil fuels.
See, e.g., H.B. 849, 2016 Leg., Reg. Sess. (First Reader). As
explained by the sponsor, Delegate Sheree Sample-Hughes, this
original language had been modeled on Chapter 151 of 2015, which
related to hotels and lodging or rooming houses. See Hearing on
House Bill 849 Before the House Env’t & Transp. Comm., 2016
Leg., Reg. Sess. (Feb. 23, 2016). However, both bills were
subsequently amended to change the language to what now appears
as PS § 12-1104(c), removing any limitation on the location of
carbon monoxide alarms based on the presence of a device that
emits carbon monoxide. See H.B. 849, 2016 Leg., Reg. Sess.
(Third Reader); S.B. 182, 2016 Leg., Reg. Sess. (Third Reader).
The fact that the Legislature amended the bills to remove that

5
The only provision that might arguably suggest otherwise is PS §
12-1104(d). That subsection provides that for all dwellings covered by
the statute, including rental dwelling units, the owner may satisfy the
statute by having “a centralized alarm system that is capable of emitting
a distinct and audible sound to warn all occupants” and then installing “a
carbon monoxide alarm within 25 feet of any carbon monoxide-
producing fixture and equipment.” However, in our view, the fact that
the statute allows the owner of a rental dwelling unit with carbon-
monoxide-producing fixtures to satisfy the statute in an alternative way
does not mean that the General Assembly intended to limit the scope of
the requirement only to rental dwelling units with such carbon-
monoxide-producing fixtures. It just means that the owner of a rental
dwelling unit without any such appliances must satisfy the standard
requirements under § 12-1104(c) by installing an alarm on each floor and
outside each sleeping area.
60 [104 Op. Att’y

limitation is strong evidence that the General Assembly did not
intend that the alarm requirement for rental dwellings be limited to
rental dwellings with carbon-monoxide-producing sources. See,
e.g., Harris v. State, 331 Md. 137, 152 (1993); Krauss v. State, 322
Md. 376, 386-87 (1991).
The context surrounding the enactment of Chapter 175 further
reinforces our conclusion. The legislation was enacted, at least in
part, in response to a specific tragedy involving a family in
Somerset County that had been living in an all-electric rental
dwelling. See, e.g., Hearing on H.B. 849 (written testimony of co-
sponsors Del. Sample-Hughes and Del. Holmes). Although that
dwelling was all-electric, the family’s electricity had been cut off
during the winter, and to keep the family warm, the father brought
a generator inside. The generator emitted carbon monoxide, and
the tragic result was that the entire family—the father and seven
children—died of carbon monoxide poisoning. This tragedy was
mentioned numerous times during committee hearings and on the
floor of the House and Senate, and an evident purpose of the
legislation was to prevent similar tragedies in the future. See, e.g.,
id. (written testimony of Delegates Sample-Hughes and Holmes);
Senate Proceedings No. 31, 2016 Leg., Reg. Sess. (statement of
Sen. Mathias); Senate Proceedings No. 65, 2016 Leg., Reg. Sess.
(statement of Sen. Mathias); see also DHMH Position Paper.

If the statute were interpreted so as to exclude all-electric
rental dwellings from its requirements, the law would not solve the
problem that led to the tragedy in Somerset County. That is, the
law would not protect families who have heating systems that
cannot handle severe cold and seek alternate heating methods,6
would not protect families during electrical outages following
natural disasters,7 and would not protect families when the

6
The Maryland Department of Health & Mental Hygiene (now the
Department of Health) noted in its testimony that rates of carbon
monoxide poisoning are highest during the winter months in Maryland.
DHMH Position Paper.
7
DHMH also explained in its testimony that Maryland has
experienced outbreaks of carbon monoxide poisoning in homes during
natural disasters, such as Hurricane Irene in 2011. DHMH Position
Paper; see also Shahed Iqbal, et al., A Review of Disaster-Related
Carbon Monoxide Poisoning: Surveillance, Epidemiology, and
Opportunities for Prevention, 102 Am. J. Public Health 1957-63 (2012)
(concluding that, for the period studied, most cases of carbon monoxide
poisoning occurred within 3 days of a natural disaster and from indoor
use of generators and charcoal grills).
Gen. 54] 61

occupants use things like portable generators, supplemental heating
and cooking equipment, or charcoal grills.8 Thus, the legislative
history supports interpreting the statute to apply to all rental
dwelling units, even all-electric units, for the simple reason that the
primary event giving rise to the bill (and other events like it) would
not have been prevented by a requirement that did not reach all-
electric rental dwelling units.9 In sum, the language of the statute
and the legislative history both make clear that its carbon-
monoxide-alarm requirements apply to all rental dwelling units,
including those that rely solely on electricity.
III
Conclusion
For the above reasons, it is our view that Chapter 175 applies
to all rental dwelling units, including all-electric dwellings.
Brian E. Frosh
Attorney General of Maryland
Kathryn M. Rowe
Assistant Attorney General
Patrick B. Hughes
Chief Counsel, Opinions and Advice
8
The General Assembly had been urged to consider requiring carbon
monoxide alarms in all-electric dwellings when it adopted the original
alarm requirement in 2007. During the hearings on that bill, interested
parties submitted testimony noting that people in all-electric dwellings
were still vulnerable to carbon monoxide poisoning from portable
generators, supplemental heating and cooking equipment, and charcoal
grills. See, e.g., Hearing on H.B. 401 Before the House Envt’l Matters
Comm., 2007 Leg., Reg. Sess. (Feb. 27, 2007) (written testimony of the
National Electrical Manufacturers Association); id. (written testimony of
Gas Appliance Manufacturer Association); id. (written testimony of
Residential Fire Safety Institute). Ultimately, however, this change was
not made, possibly because the state of the bill at the time was the result
of long negotiation, and the sponsor was not willing to open it up for more.
See Hearing on S.B. 535 Before the Senate Educ., Health, & Envt’l Affairs
Comm., 2007 Leg., Reg. Sess. (Mar. 14, 2007).
9
Maryland is not the only state to require carbon monoxide detectors
in at least certain dwellings that do not rely on the combustion of fossil
fuels. See Michigan Comp. Laws Ann. § 125.1504d and f; Montana
Code Ann. § 70-24-303; Oregon Rev. Stat. § 455.360; Vermont Stat.
Ann. tit. 9 §§ 2881 to 2883; Virginia Code Ann. § 55-248.18. Moreover,
the U.S. Consumer Product Safety Commission recommends that carbon
monoxide alarms be installed in all dwellings. See CPSC, Carbon
Monoxide Toolkit.