Indoor air quality inside vehicle cabins while commuting in Lisbon

Commuters may be exposed to a variety physicochemical and biological pollutants that could lead to adverse health effects. This study aims to evaluate the indoor air quality (IAQ) while commuting in cars, buses and trains in Lisbon to contribute in the assessment of possible effects on human health.
Particulate matter (PM) with diameter lower than 1, 2.5 and 10 μm, black carbon (BC), carbon monoxide (CO), carbon dioxide (CO2) volatile organic compounds (VOCs) and formaldehyde (CH2O) were measured. In cars the effect of cleaning and three ventilation modes were evaluated: fan off, fan on and air-conditioning (AC). Total airborne bacteria and fungi were estimated, and bacterial isolates identified. The inhaled dose in each vehicle was estimated. In cars, the AC decreased the PM2.5-10 concentration to 0.7 μg/m3, but it increased BC concentration to 4.1 μg/m3. The effect of cleaning was negligible. PM2.5 concentration in buses ranged between 8 – 73 μg/m3, similar to cars under fan off condition. BC concentration in buses was 4.5 μg/m3 similar to cars with AC. CO2, VOCs and CH2O found in cars were higher under the fan off condition. In trains, the concentrations of all pollutants were low, with an exception of VOCs (2516 μg/m3). Fungi and bacterial loads were higher in trains and buses.
In this study the ventilation mode was identified as the main factor affecting the IAQ. Additionally, it was possible to provide a general perspective of the IAQ in public transport.

Type of publication: Master Thesis of the Integrated Master in Environmental Engineering at Instituto Superior Técnico, Universidade de Lisboa, Portugal.