Plug-In Air Fresheners

Continuous synthetic-fragrance diffusers.

49Moderate burden · out of 100

Cleaner swapOpen a window; simmer herbs; fix the odour source

How this score is built

100Start
77Chemical hazard 5 × 4.6−23
56.6Everyday exposure 6 × 3.4−20.4
49Persistence 3 × 2.6−7.8, then rounded to 49
ModerateThe band49 sits in 40–59.

What each input rests on

The three ratings behind the score, and the studies each rests on
Input	Rating	Evidence
Chemical hazard	5/10	In a 20 m3 chamber, a plug-in air freshener emitted terpenes and glycol ethers; at high ozone (about 50 ppb) its reaction products reached formaldehyde and 4-oxopentanal concentrations the authors judged may give rise to concern about sensory irritation and airflow limitation. Ozone-initiated VOC and particle emissions from a cleaning agent and an air freshener: risk assessment of acute airway effects · Environ Int 2014 DOI 10.1016/j.envint.2014.03.029 · PMID 24769411 · Abstract · read 2026-10-06
Everyday exposure	6/10	In a 50 m3 room ventilated at about 0.5 air changes per hour, air-freshener use emitted d-limonene, dihydromyrcenol, linalool, linalyl acetate and beta-citronellol at 35-180 mg/day over 3 days. Cleaning products and air fresheners: emissions and resulting concentrations of glycol ethers and terpenoids · Indoor Air 2006 DOI 10.1111/j.1600-0668.2005.00414.x · PMID 16683937 · Abstract · read 2026-10-06
Persistence	3/10	unsourced input

Ratings are editorial. A study listed here supports the rating; it did not compute it. How the index is built

What this means for you

It scores as it does mainly because of how much everyday contact it involves. They mask smell by adding phthalates and VOCs to the air you breathe all day. Real ventilation beats masking every time.

Evidence strength: moderate

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