*5.1. "Smelly Buildings"*

Following the archives of digital editions of the Serbian daily press and the Beobuild forum [64], the first complaints about the unpleasant smell in the apartments appeared in July 2014. These were preceded by announcements of satisfied apartment owners who moved in during October and November 2013. At that time, most of the discussions at the forum with the topic, "State housing—Settlement in Block 72 (Dr Ivana Ribara)" [64], were about the construction process, the characteristics of apartments, the aesthetics of the accepted solution and the procedure for redistribution of apartments to different categories of tenants.

The problem occurred in 220 apartments within Buildings 1 and 3 (No. 80, 82, 100 and 102), in which the tenants complained of an extremely strong, unpleasant smell of unknown origin [65]. The mentioned buildings were named "smelly buildings." After addressing the Construction Directorate of Serbia, which was responsible for the construction and sale of these apartments, there was a need for a quick response to prevent potential negative effects on the health of tenants. To determine the causes and character of the harmful vapors, the Vinca Institute of Nuclear Sciences, Laboratory of Physical Chemistry and the Institute of Public Health of Belgrade were engaged.

The analyses were performed during July and August 2014. Sampling and testing of air quality in 24-h samples were made at the following sampling sites: indoors in twenty apartments in the subject buildings, one grocery store, control measurements in two apartments where the presence of unpleasant odors was not detected and outdoors at two sampling sites near the subject buildings [18]. Qualitative and quantitative analysis of IAQ in apartments and buildings in which the presence of unpleasant odors was found, as well as control measurements, included the following parameters: formaldehyde, acrolein, polycyclic aromatic hydrocarbons (PAH) of solid and gaseous phases, volatile organic compounds, benzene, toluene, ethylbenzene and isomers of xylene (BTEX) and phenolic compounds. Key results arose from the analysis of the polyurethane foam used for gaseous phase PAH sampling by the GC-MSD technique. This analysis showed the presence of phenols and phenolic compounds, namely phenol, 3-ethyl phenol and 3-methyl phenol, only in the samples taken from the apartments where characteristic odors where reported.

Tests carried out at the Vinca Institute for Nuclear Research showed that the pollution comes from the oil used to coat the formwork boards used for pouring concrete elements [66]. A part of the report of the Vinca Institute, which illustrates the origin of pollution, is shown in Figure 6. Mass spectrum of tested samples confirms the presence of phenol, 3-ethyl phenol and 3-methyl phenol in oil and concrete samples, and as fingerprint, confirms the source of contamination.

**Figure 6.** Mass spectrum of tested oil oplatol in water-up, in methanol-middle and mass spectrum of concrete-down sample. Source: [66].

Comparison with the control measurements showed that the presence of phenolic compounds in the indoor air, as well as the significant presence of phenanthrene, stand out from all the examined parameters. The presence of formaldehyde, acrolein, toluene and PAH of gaseous phases, except phenanthrene, was observed in slightly higher concentrations than in control measurements in ambient air, but, although somewhat higher, the values did not deviate significantly from those observed in control apartments where characteristic odors were not observed. Higher concentrations of these pollutants in indoor air are characteristic of newly built facilities equipped with new interiors [18].

The analysis of the content of the disputed oplatol oil and concrete samples, as stated in the report of the Vinca Institute, unequivocally established that the source of the unpleasant odors was concrete poured into the disputed facilities, while the origin of the pollution was oplatol oil used to coat the formwork boards used for pouring concrete elements. Unlike phenanthrene, which almost certainly originates from contaminated concrete but may have other sources, the presence of 3-ethyl phenol and 3-methyl phenol is characteristic of the indoor air of buildings in which the disputed oplatol was used and can be used as a kind of marker (fingerprint) for oplatol-induced pollution.

Based on the results of the conducted examinations, the expert team at the Institute of Public Health of Belgrade assessed that the apartments in which unpleasant odors were felt did not meet the sanitary-hygienic conditions for permanent residence of people [18].

The Toxicology Department of the Military Medical Academy (MMA) in Belgrade was also engaged to conduct an analysis of the health condition of the occupants of these facilities. The testing covered one-third of the tenants and the results showed that the values of phenol and hippuric acid in urine samples were significantly increased in samples from several tenants, especially children, as well as in samples taken from workers who were exposed to these substances at their workplaces [67].

A similar problem was reported in several other apartment buildings in Belgrade, Novi Sad, Niš and other cities in Serbia, as well as the Bora Stankovi´c theatre in Vranje and a stem cell bank in Belgrade. All these buildings were built around the same time when a disputable batch of "oplatol" was on the market. This 'epidemic' spread all over Serbia during the few months when the notorious batch of oplatol was used. Even though only one batch of oplatol was contaminated, it caused enormous damage which illustrates how a little negligence can produce massive financial and emotional (tenants) damage.
