Dollars and Scents: Comparing Indoor Air Quality Impacts of Expensive and Inexpensive Home Fragrance Products

Overview

This study investigated the hypothesis that more expensive "natural" or "non-toxic" branded home fragrance products release fewer harmful air pollutants than inexpensive, “synthetic” alternatives. The experiment compared 6 fragrance methods, including two types of scented candles, two types of incense sticks, and two types of essential oils in ultrasonic diffusers (one expensive “natural” and one inexpensive “synthetic” for each), using a digital Air Quality Monitor to measure their impact on Indoor Air Quality (IAQ). By analyzing the indoor air quality impact in this experiment, we can help consumers decide if the higher price point is a scientific necessity or just clever marketing. IAQ metrics assessed were Particulate Matter (PM1.0, PM2.5, PM10) and Volatile Organic Compounds (VOCs). The fragrance methods were tested under controlled conditions, recording baseline and test pollutant levels. Results showed that burning methods—specifically incense sticks—caused the most dramatic deterioration in IAQ, with both expensive and inexpensive incense resulting in percentage increases in PM metrics exceeding 15,000% in some categories. Scented candles also significantly increased PM levels, with the expensive variant showing a higher increase than the inexpensive one. Essential oil diffusers also caused substantial PM increases (up to 6618%). VOC levels remained low across most products, with the highest percentage increases observed in inexpensive incense sticks and expensive essential oil diffusers. The hypothesis was largely not supported and the data disproves that "natural" ingredients in the tested home fragrance products result in measurably better air quality than their cheaper counterparts. The more expensive home fragrance products marketed as "natural" or "non-toxic" did not consistently result in lower pollutant levels compared to their synthetic, less expensive counterparts, and in some cases, contributed to a greater decline in IAQ. All tested methods, except the control, significantly increased particulate matter in the indoor air.

Competition history

• CSEF 2026 Product Science (Junior Division) · Entry J-19-05

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