## 2 Nanomaterials in the Construction Sector
### Impact on Human Health and on the Environment  
The increasing use of NMs also leads to an increased production of waste and residues, with the relevant exposure of operators in the building sector [105]. Approximately 60% of nanomaterials are used in medical-pharmaceutical or industrial applications (e.g., in the textile and electronics industries) with several industrial processes which can lead to waste streams resulting from the cleaning of production chambers [106]. Thus, an in-depth understanding of human and environmental exposure and NPs' toxicological effects is a necessary step to assess environmental and health impacts [107; 108; 109]. Exposure to NPs is often associated with inhalation or absorption through skin contact. Although the dosages required to induce these effects are rather high, toxicological health risks include lung damage, adverse effects on the immune system, disorders related to oxidative stress, and diseases such as cancer, as well as DNA damage, and changes in cell growth and renewal, processes which are essential for healthy organs and tumor prevention [3; 30; 110]. Therefore, there are numerous recommendations for handling NMs during their production, transport, application, and end-of-life disposal process, including the use of gloves, coveralls, air filter masks, and safety goggles [105; 111]. [PERSON] et al. [112] reported that ultrafine particles (<100 nm) of TiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), and carbon black NPs demonstrated higher toxicity than fine particles (<2.5 um). The nano-size may act as an amplifier of the effects, resulting from a higher reactivity or dissolution rate, although the nanostructure is not a sufficient descriptor to correlate with toxicity in the aquatic medium. In fact, the potential toxic effects of NPs depend on their physicochemical characteristics (size, shape, composition, surface functional groups, and surface charges) and can be influenced by the surrounding matrix [113; 114]. Therefore, the environmental impact of these NPs is contingent upon characteristics such as decreased size, which enables their entry into the cellular environment and interaction with proteins. The shape of the particle also influences the cellular uptake mechanism, and the presence of a coating can prevent the leaching of toxic metal ions [114]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{**Nanomaterial**} & \multicolumn{1}{c}{**Synthesis or**} & \multicolumn{1}{c}{**Applications**} & \multicolumn{1}{c}{**Functionality/Improvement**} & \multicolumn{1}{c}{**References**} \\ \hline \multirow{2}{*}{Phase change materials} & \multirow{2}{*}{Sol-gel} & Building components, & \multirow{2}{*}{Thermal resistance} & \multirow{2}{*}{[80; 81; 82]} \\  & & thermal insulation & & & \\ materials, wallboards & & & & \\ \hline \multirow{4}{*}{Silica aerogel} & \multirow{4}{*}{Sol-gel} & \multirow{4}{*}{\begin{tabular}{c} Moortars, concrete, \\ renders \\ \end{tabular} } & \multirow{4}{*}{Decreased thermal conductivity} & \multirow{4}{*}{[83; 84; 85]} \\  & & & & \\ \cline{1-1} \cline{5-5}  & & & & \\ \cline{1-1} \cline{5-5}  & & & & \\ \cline{1-1} \cline{5-5}  & & & & \\ \cline{1-1} \cline{5-5}  & & & & \\ \hline Nano copper & Colloidal methods & Steel mesh & \begin{tabular}{c} Corrosion inhibition efficiency; \\ Formability; Weldability \\ \end{tabular} & [92] \\ \hline \multirow{2}{*}{Aluminum oxide} & \multirow{2}{*}{Sol-gel} & \multirow{2}{*}{\
\begin{tabular}{c} Asphalt concrete \\ \end{tabular} } & Increased serviceability & [93] \\ \cline{1-1} \cline{5-5}  & & &
\begin{tabular}{c} Acceleration on cement hydration; \\ Mechanical improvement \\ \end{tabular} & [33; 42; 48] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._Figure 1 shows the systemization of NMs' impact on the environment and of human exposure during the life cycle stages. This release can occur during all stages of the life cycle: production, manufacturing, use of nanoproducts, and their disposal and recycling [23; 115; 116].