Acute and chronic health problems are expected due to exposure to high levels of formaldehyde. The aim of the current study was to evaluate the outdoor and indoor levels of formaldehyde in Cairo in order to assess the carcinogenic and non-carcinogenic risks as a result of exposure to formaldehyde.
Formaldehyde concentrations were measured outdoors and indoors at five residential sites in Cairo, Egypt. The samples were taken during the day (8 AM to 6 PM) and at night (8 PM to 6 AM) for 10 hours during winter and summer seasons of 2018/2019. Chronic daily intakes (CDI), cancer risk (R) and hazard quotient (HQ), were estimated to assess health risks from exposure to formaldehyde.
Outdoor average concentrations of formaldehyde at the selected sites were 24.6 and 22.8 µg/m³ in summer and winter, respectively, which exceeded the value of 15 ppb (18.3 µg/m3) set as an indicator for urban environment. Indoor HCHO concentrations are still far lower than the effective short-term exposure levels of HCHO between 0.5 and 1 ppm (0.62-1.23 mg/m3) which could lead to irritation of throat, nose and eyes. Newly apartments with newly furnished can be a stronger source for formaldehyde emissions than the ambient sources.
The I/O ratios of formaldehyde were above one which demonstrated that the sources in the indoor environment are prevalent at the investigated sites.
The outdoor cancer risk values did not exceed the “alarm level” (R > 1 × 10–4) for formaldehyde, while in living rooms and kitchens they exceeded the “alarm level” by 30% and 55% in winter and summer, respectively.
The results indicated that the levels of airborne and inhaled formaldehyde in Cairo residences should not be underestimated. The current study can help regulatory agencies to establish guidelines for formaldehyde concentration in indoor air.