smoking, cooking, burning of candles, and the use
of combustion apparatuses in poorly ventilated
areas [41]. Still, it was reported in 1990 by
Santanam et al. that on average 19–42% of ultrafine particles indoors were of unknown origin
[42]. Since then, studies have been conducted
suggesting that indoor ozone-terpene reactions
contribute to the SOA found indoors. As previously mentioned, terpenes are emitted from
cleaning agents and air fresheners (these terpenes
include limonene and a-pinene) and are readily
oxidized by ozone (ozone stems from outdoor air
or direct emissions from electronics) to form products with low vapor pressures [41]. These products can form SOA through homogeneous
nucleation, where vapor condenses to form
mass. The formed particles are “fine,” with diameters d < 1 mm.
Smoking directly releases thousands of compounds, both as gases and particulate matter, and
this is referred to as secondhand tobacco smoke
[43]. The compounds in secondhand tobacco
smoke can be deposited on surfaces and then
re-emitted, or they can undergo chemical reaction
and form secondary pollutants. The result of these
two pathways for secondhand smoke creates what
is called thirdhand tobacco smoke [44]. The pollutants in thirdhand smoke include gaseous,
sorbed, and particulate species, hereunder SOA.
The SOA formed from ozonolysis of secondhand
tobacco smoke, including nicotine, are
nitrogenated ultrafine particles, which are likely
Indoor Air Quality: Status and Standards, Fig. 3 Reaction scheme of ozone oxidation of D-limonene [40]
Indoor Air Quality: Status and Standards
145
of combustion apparatuses in poorly ventilated
areas [41]. Still, it was reported in 1990 by
Santanam et al. that on average 19–42% of ultrafine particles indoors were of unknown origin
[42]. Since then, studies have been conducted
suggesting that indoor ozone-terpene reactions
contribute to the SOA found indoors. As previously mentioned, terpenes are emitted from
cleaning agents and air fresheners (these terpenes
include limonene and a-pinene) and are readily
oxidized by ozone (ozone stems from outdoor air
or direct emissions from electronics) to form products with low vapor pressures [41]. These products can form SOA through homogeneous
nucleation, where vapor condenses to form
mass. The formed particles are “fine,” with diameters d < 1 mm.
Smoking directly releases thousands of compounds, both as gases and particulate matter, and
this is referred to as secondhand tobacco smoke
[43]. The compounds in secondhand tobacco
smoke can be deposited on surfaces and then
re-emitted, or they can undergo chemical reaction
and form secondary pollutants. The result of these
two pathways for secondhand smoke creates what
is called thirdhand tobacco smoke [44]. The pollutants in thirdhand smoke include gaseous,
sorbed, and particulate species, hereunder SOA.
The SOA formed from ozonolysis of secondhand
tobacco smoke, including nicotine, are
nitrogenated ultrafine particles, which are likely
Indoor Air Quality: Status and Standards, Fig. 3 Reaction scheme of ozone oxidation of D-limonene [40]
Indoor Air Quality: Status and Standards
145