Seasonal variation in the toxicological properties of size-segregated indoor and outdoor air particulate matter

Mikko Happo (Corresponding Author), Ari Markkanen, Piia Markkanen, Pasi Jalava, Kari Kuuspalo, Ari Leskinen, Olli Sippula, Kari Lehtinen, Jorma Jokiniemi, Maija-Riitta Hirvonen

Research output: Contribution to journalArticleScientificpeer-review

42 Citations (Scopus)


Ambient air particulate matter (PM) as well as microbial contaminants in the indoor air are known to cause severe adverse health effects. It has been shown that there is a clear seasonal variation in the potency of outdoor air particles to evoke inflammation and cytotoxicity. However, the role of outdoor sources in the indoor air quality, especially on its toxicological properties, remains largely unknown. In this study, we collected size segregated (PM10–2.5, PM2.5–0.2 and PM0.2) particulate samples with a high volume cascade impactor (HVCI) on polyurethane foam and fluoropore membrane filters. The samples were collected during four different seasons simultaneously from indoor and outdoor air. Thereafter, the samples were weighed and extracted with methanol from the filters before undergoing toxicological analyses. Mouse macrophages (RAW264.7) were exposed to particulate sample doses of 50, 150 and 300 μg/ml for 24 h. Thereafter, the levels of the proinflammatory cytokine (TNF-α), NO-production, cytotoxicity (MTT-test) and changes in the cell cycle (SubG1, G1, S and G2/M phases) were investigated. PM10–2.5 particles evoked the highest inflammatory and cytotoxic responses. Instead, PM2.5–0.2 samples exerted the greatest effect on apoptotic activity in the macrophages. With respect to the outdoor air samples, particles collected during warm seasons had a stronger potency to induce inflammatory and cytotoxic responses, whereas no such clear effect was seen with the corresponding indoor air samples. Outdoor air samples were associated with higher inflammatory potential, whereas indoor air samples had overall higher cytotoxic properties. This indicates that the outdoor air has a limited influence on the indoor air quality in a modern house. Thus, the indoor sources dominate the toxicological responses obtained from samples collected inside house.
Original languageEnglish
Pages (from-to)1550-1561
JournalToxicology in Vitro
Issue number5
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed


  • ambient air PM
  • cytotoxicity
  • infoor air PM
  • inflammation
  • microbes
  • particulate matter


Dive into the research topics of 'Seasonal variation in the toxicological properties of size-segregated indoor and outdoor air particulate matter'. Together they form a unique fingerprint.

Cite this