Civil Engineering Reference
In-Depth Information
Inhalation is the main route of exposure to NO
2
at room temperature, even at
temperatures below 21 C it exists as a liquid and, if ingested, it can cause gas-
trointestinal irritation or burns. Being poorly soluble in water, approximately
80-90 % of the inhaled NO
2
is absorbed in the respiratory system (Sandstrom
1995
). Short-term exposure to NO
2
can cause irritation of the eyes, nose, throat,
and respiratory tract, being population with asthma and respiratory diseases more
susceptible (Hesterberg et al.
2009
).
In the absence of indoor sources, indoor concentration of NO
2
is lower than
outdoors, even though outdoor sources such as road traffic or industry contribute to
indoor NO
2
(Pegas et al.
2012
). Main indoor sources are tobacco smoke and poorly
maintained or unvented combustion devices used for heating and cooking pur-
poses, where coal, oil, kerosene or natural gas are burned (WHO
2010
). Incense
burning and candles can also emit NO
2
as well as NO (Loupa et al.
2006
).
Figure
3
summarises NO
2
geometric mean concentration values in indoor
workplaces, and residential indoor and outdoor values in four European cities
taken from EXPOLIS study. Indoor residential NO
2
concentrations were the
lowest in all cities except in Prague, where lowest concentrations were detected in
workplaces (Kousa et al.
2001
; Lai et al.
2004
). The study also reported that
outdoor concentrations of NO
2
, the use of gas for cooking and workplace location
strongly influence the NO
2
exposure, even though smoking is not a strong
determinant.
Similar results were concluded in other works. Uhde and Salthammer (
2007
)
reported higher NO
2
concentrations in kitchens were gas was used (300-3,000 lg/
m
3
) with respect to living spaces in residences (10-200 lg/m
3
). Typical NO
2
range
in public buildings is between 1 and 200 lg/m
3
, but concentrations of up to
1.000 lg/m
3
may be found in traffic-related buildings or with very strong indoor
sources (Kolarik et al.
2012
), where the 1-h guideline value of 200 lg/m
3
may be
exceed (WHO
2010
).
Fig. 3 Nitrogen dioxide
geometric mean
concentration indoors
(workplace and homes) and
outdoors (residential) from
EXPOLIS study: (1) Basel,
Helsinki and Prague (Kousa
et al.
2001
) and (2) Oxford
(Lai et al.
2004
). Bars
indicate geometric standard
deviation
60
50
40
30
20
10
0
Basel,
Switzerland [1]
Helsinki,
Finland [1]
Prague, Czech
Republic [1]
Oxford, UK [2]
Workplace indoor
Residential indoor
Residential outdoor
