Abstract: Air quality is recognized as one of the greatest threats to human health by the World Health Organization, in which aproximately 7 million deaths are attributed to the exposure to air pollutants worldwide. The population is exposed to outdoor and indoor air pollution; however, most of the time (around 90%) people spend indoors.Therefore, it is essential to investigate indoor air quality and the factors that influence the concentration of pollutants in such a microenvironment. The Metropolitan Region of Greater Vitória is highly urban and industrialized area, being affected by emissions from both industrial and urban sources, especially vehicular sources. The air pollution inside homes might be a result of the external infiltration of outdoor pollutants, as well as of pollutants generated by indoor activities, such as cooking, cleaning, consumption of candles, incense and cigarettes. Other factors that influence the concentration of indoor pollutants are residents’ habits, ventilation pattern and window opening. In order to asses these factors implying on particulate matter (PM) indoor air quality, a pilot campaingn was carried out in May 2022, in four houses in a MRGV’s neighborhhod (Jardim Camburi), being three houses choosen for indoor monitoring and one house (external area) near to the other three, choosen as a reference outdoor sampling site. It was conducted the simultaneous monitoring of total suspended particulate (TSP), particulate matter less than or equal to 10 μm (PM10) and particulate matter less than or equal to 2.5 μm (PM2.5) using four ECOPM (Ecosoft, Brazil) real-time monitors installed in the four residences in the Jardim Camburi neighborhood, with the objective of investigating the indoor PM concentrations, and to assess the influence of opening windows on the indoor/outdoor (I/O) ratio, besides the impact of home activities carried out by residents in the PM concentration variability. It was also evaluated whether the current Brazilian air quality standard was exceeded. The results showed that in those houses where windows were predominantly open during the monitoring time, the I/O ratio fortotal suspended particles was higher than in houses that spent more time closed, which corroborates the results observed in the literature. Kitchen activities had a great contribution increasing the PM2.5 concentration, surpassing the outdoor concentrations for the same monitoring period. Cleaning activities also make a significant contribution to indoor concentrations. In this work, the concentration into the three houses did not exceed the state or thenational air quality standard threshold. In the outdoor reference house, the PM10 (24-hour average) exceeded the WHO recommendation of 45 ug/m3 on two consecutive days. This pilot study contributed to gather information and better directions in the sampling strategy for future campaigns.

Keywords: air pollution, air quality monitoring, particulate matter, indoor/outdoor ratio.