A paper was published online in January 2012 by researchers in Scotland assessing children’s exposure to secondhand smoke in cars. The objective of the study was to measure fine particulate matter in the rear passenger seat of cars of both smokers and non-smokers during real-life journeys.
First, a little background in the terminology will help you understand the results of the study. According to the United States Environmental Protection Agency (EPA), particulate matter (PM) is a “complex mixture of extremely small particles and liquid droplets.” Two measurements are used to describe particles: coarse particles, or PM10, and fine particles, or PM2.5.
PM10 includes particles up to 10 micrometers in diameter and is described as “smoke, dirt and dust from factories, farming, and roads,” such as air pollution. They also include “mold, spores and pollen.” Fine particles, or PM2.5, which were measured in this study, are up to 2.5 micrometers in diameter. These include toxic organic compounds and heavy metals. PM2.5 particles are lighter, can stay in the air longer (sometimes for days or weeks), and can travel through the smaller airways of your lungs. Both PM10 and PM2.5 can cause health problems, but PM2.5 particles can travel deeper into the lungs.
The concentration of an air pollutant is given in micrograms (one-millionth of a gram) per cubic meter air or µg/m³, according to both the EPA and the EEA or European Environment Agency.
This study included 14 smokers and 3 non-smokers. All had a device placed at breathing height in the back passenger seat of a car for a period of three days which monitored and logged every minute of their journeys. The participants completed a total of 104 journeys with 63 of them being smoking, and they averaged 27 minutes in the car during their trips. Trips ranged from 5 minutes to 70 minutes in length.
The World Health Organization (WHO) states indoor air quality levels should not exceed 25 μg/m³, yet the levels in the cars averaged 85 µg/m³ for smokers The actual peak concentration levels for the trips were much higher, averaging 385 µg/m³, and even reaching over 880 µg/m³ on one trip. Opening windows and increasing ventilation did not improve air quality. Non-smoker air quality levels averaged 7.4 μg/m³.
The study was able to measure that concentrations of smoke in cars “are high and greatly exceed international indoor air quality guidance values”. Children who are forced to breathe in these high concentrations of smoke are likely to suffer health effects such as bronchitis and pneumonia, and worsening asthma. According to the U.S. Surgeon General says there is no safe level of exposure to tobacco smoke.
A video demonstration produced by the California Tobacco Control Program also demonstrates the effects of secondhand smoke in cars. It can be viewed here: http://vimeo.com/1513382