In this paper we describe a wireless system, including smart sensing nodes for indoor air quality and unobtrusive cardiorespiratory
monitoring. The sensing nodes include a set of solid state gas sensors, sensors for temperature and relative humidity, a
microwave Doppler radar sensor for cardio-respiratory function, and appropriate conditioning circuits expressed by active filters
and amplifiers. The analog signals provided by the signal conditioning circuits is applied to a data acquisition module (DAQ)
wireless or wired connected to a computer that works as part of a client-server architecture that allows monitoring the relation
between indoor air quality and the cardio-respiratory function. Measured air pollutants include carbon monoxide (CO), carbon
dioxide (CO2), nitrogen oxides (NOx), ozone (O3), and volatile organic compounds (VOCs). Using signal from a Doppler radar
sensor, the heart rate, the respiratory rate and the heart rate variability is calculated. Evidences on the relation between heart rate
variability and air quality are discussed. The described system for air quality and cardio-respiratory signal monitoring may be a
tool for long term monitoring of the effects of air quality on humans’ organism.