Page 377 - Çevre Şehir İklim İngilizce - Sayı 4

Fatih Kara

may be many different reasons for this. It is remarkable that all these areas, that
is, indoor spaces and cities are the places where people are exposed to high
levels of CO . It is also noteworthy that in the past, sanatoriums, especially
2
those used for the treatment of tuberculosis and chronic lung diseases, were
usually built in high/mountainous areas, far from urban centers.
According to the 1968 health standards set by the World Health
Organization (WHO) for residential buildings, it was observed that 5000
3
ppm CO concentrations caused changes in respiratory rates (Goromosov,
2
1968:41). This popular limit value has led to the widespread misconception
that values below 5000 ppm will not have a negative impact on health. it
has also been observed that CO concentration of 1000 ppm in inhaled air
2
also reduces the amplitude of respiratory movements, affects the circulatory
system and significantly changes the electrical activity of the brain (Eliseeva,
1964). Due to this and such findings, it has been recommended for a long
time that CO concentration should be kept below 500 ppm in the inhaled
2
4
air; however, even the global outdoor average has reached 420 ppm today 5
and it is not uncommon to encounter values above 500 ppm in urban CO
2
cages; therefore, it is no longer a realistic expectation that the indoor air
will be drawn below the 500 ppm limit with natural ventilation (Lowther et
al., 2021). In many countries today, the recommended upper limit for CO
2
6
exposure ranges from 600 to 1000 ppm. (Lowther et al., 2021). Although no
consensus has yet been reached on what the safety limit should be for chronic
CO exposure; in the medical literature, we can say that there is a common
2
and serious concern about the negative effects of CO on cognitive and
2
psychomotor performance, respiratory function and the functions of the inner
membranes (endothelium) of the respiratory tract and vessels (Satish et al.,
2012; Allen et al., 2016; Hong et al., 2018; Jacobson et al., 2019; Wargocki et
al., 2020; Lowther et al., 2021).

3 ppm is the English abbreviation for “parts per million” and is used specifically to refer to low gas
concentrations. High gas concentrations are expressed in percentage (%). For example, the nitro-
gen gas in the atmosphere is expressed as 78 percent instead of 780840 ppm (780840 per million).
4 EN 12021:2014 standard
5 For up-to-date records of global atmospheric carbon dioxide concentration, see. UCSD, Scripps
Institution of Oceanography, https://keelingcurve.ucsd.edu/ (Son Access Date: 17.03.2023
6 Also see. https://www.canada.ca/en/health-canada/services/publications/healthy-living/car-
bon-dioxide-home.html (19.03.2021 - Last Access Date: 17.03.2023).

366 The Journal of Environment, Urban and Climate