The Hidden Chemical Risks in Everyday Scented Products

We rarely think about the quality of the air inside our homes. Most of us spend the vast majority of our time indoors, assuming that closing the windows keeps the outside pollution out and creates a safe environment for our families. To make our living spaces feel fresh and clean, we often rely on scented floor cleaners, laundry detergents, plug-in air fresheners, and traditional items like agarbatti or dhoop. However, emerging environmental health research reveals that the air inside our homes can harbour a complex mix of unseen chemical emissions and fine particles.

To understand what this means for household health, we need to look at three distinct threads of evidence: observational studies linking indoor chemicals to childhood allergies, laboratory measurements of what fragranced products emit, and combustion smoke from burning incense in closed spaces. While each area of research offers valuable insights, it is important to look at what the science actually proves, where its limits lie, and how families in India can take practical, calm steps toward cleaner indoor air.

Disclaimer

This article is for general educational purposes only and does not constitute medical advice. Research findings describe statistical patterns across groups of people and do not prove that any specific product caused an individual’s medical condition. Do not stop, reduce, or alter any prescribed treatments for asthma, allergies, or other respiratory conditions based on this article. Always consult a qualified healthcare professional regarding personal symptoms or concerns about indoor triggers.

Why Indoor Air Matters

Because modern life keeps most people indoors for upwards of 80% to 90% of the day, the quality of indoor air plays a major role in overall daily exposure to environmental elements. Indoor air is not static; it carries a combination of outdoor pollutants that creep inside, emissions from building materials and household products, cooking fumes, and smoke.

Over recent decades, rates of childhood asthma, hay fever (rhinitis), and eczema have risen globally. Because genetics alone cannot account for changes occurring over such a relatively short period, researchers have turned their attention to environmental factors. However, the underlying causes of allergic diseases are complex, multi-faceted, and not fully settled. No single product, pollutant, or lifestyle change explains the global rise in allergies, but examining indoor exposures provides important clues about how our daily environments interact with human health.

What Research Says About Household Chemicals and Children’s Allergies

The Harvard and Swedish Study

A notable study investigating indoor air and child health was conducted by a team of researchers from Harvard University and Karlstad University in Sweden (Choi et al., published in PLoS ONE, 2010). The case-control study analyzed bedroom air samples from 198 preschool children diagnosed with asthma and allergies, comparing them with air samples from 202 healthy control children. The researchers tested for eight specific classes of volatile organic compounds (VOCs).

The findings revealed a distinct pattern: higher bedroom concentrations of a specific class of compounds—propylene glycol and glycol ethers (PGEs)—were associated with a significantly higher likelihood of doctor-diagnosed asthma, rhinitis, and eczema, as well as allergic sensitisation. Children whose home exposures fell into the highest quarter of PGE concentrations had roughly 100% higher odds of asthma, 150% higher odds of eczema, and 320% higher odds of rhinitis compared to those in the lowest exposure group. Interestingly, no similar statistically significant associations were found for the other seven classes of VOCs tested in the study. In follow-up research, higher indoor PGE levels were linked primarily to water-based paints, varnishes, cleaners, and damp housing conditions.

If you are exploring early childhood health, you may also be interested in Rethinking Childhood Allergies, which explains how current evidence has changed advice about food allergy prevention.

What the Study Cannot Prove

It is crucial to interpret these findings within their scientific context. The study was a case-control observational design measuring chemical concentrations at a single point in time across a modest sample of Swedish homes. Because of this design, the study shows an association, not a direct cause-and-effect relationship.

The authors themselves explicitly presented their conclusion as a “novel hypothesis” that requires further prospective research to confirm. Furthermore, the study examined specific glycol ethers from paints and structural cleaners in a Nordic climate; it was not a study on Indian homes, nor was it an evaluation of fragranced consumer air fresheners. Acknowledging these boundaries prevents overstating the results while still respecting the underlying science.

What Is Really in Scented Products

The University of Washington Emissions Study

While the Swedish study measured what was present in room air, other researchers have investigated what consumer products release directly into the air. A landmark emissions study led by Dr. Anne Steinemann (Steinemann et al., 2011, Environmental Impact Assessment Review) evaluated 25 widely used fragranced consumer products, including laundry detergents, personal care items, cleaning supplies, and air fresheners.

Using gas chromatography-mass spectrometry in a controlled laboratory environment, the testing revealed that these 25 products emitted a combined total of 133 different VOCs, averaging around 17 distinct chemical emissions per product. Among these 133 compounds, 24 are classified as toxic or hazardous under US federal environmental laws, and every single product tested emitted at least one of these regulated compounds.

Despite these emissions, only one VOC was listed on any of the product labels, and only two appeared on safety data sheets. This occurs because regulatory frameworks often allow manufacturers to list complex aromatic blends under generic catch-all terms like “fragrance” or “parfum,” which legally protects trade secret formulas without requiring an itemized disclosure of individual chemical constituents. Crucially, the Steinemann study was designed to measure chemical emissions in a lab chamber; it did not evaluate human exposure levels during real-world use or make claims regarding specific health outcomes.

“Natural” and “Green” Labels

Many consumers turn to products marked “natural,” “organic,” or “green,” assuming they are completely inert or chemical-free. However, the Steinemann study specifically tested fragranced products carrying green or natural claims and found that their emissions of hazardous or toxic VOC compounds were not significantly different from conventional scented products.

Plant-derived essential oils and natural botanical extracts consist of complex organic chemical molecules. A chemical compound emitted from a natural source behaves under the laws of chemistry in the exact same manner as its synthetic twin. Therefore, “natural” on a label does not automatically mean zero volatile emissions.

When Fragrance Chemicals React: Limonene, Ozone and Secondary Pollutants

The primary chemicals emitted from a bottle or spray can represent only part of the story. Once released into the air, indoor chemicals undergo atmospheric reactions.

Citrus-scented and pine-scented products heavily rely on terpenes, such as limonene and pinene, to provide a fresh, crisp aroma. When limonene is released into indoor air, it can react with ground-level ozone—a gas that enters homes from outdoor air pollution. Chamber experiments (such as those by Wainman et al., 2000, and Nazaroff et al., 2004/2006 for the California Air Resources Board) have mapped this indoor chemistry in detail.

When limonene and ozone interact, they form secondary pollutants, including formaldehyde (a known respiratory irritant) and ultrafine secondary organic aerosols (tiny airborne particles).

However, context is vital. The comprehensive California Air Resources Board study concluded that under normal, ordinary household use, exposure levels to formaldehyde and fine particles generated from cleaning products and air fresheners alone were not expected to exceed health guideline thresholds. Nonetheless, the researchers cautioned that secondary pollutant formation can become elevated in regions with high outdoor ozone concentrations, and strongly advised against using ozone-generating air purifiers in tandem with terpene-rich scented products.

Scent, Smoke and Indian Homes

Incense, Dhoop and Mosquito Coils

It is essential to separate cold chemical emissions (such as sprays and plug-ins) from combustion smoke. In Indian households, burning agarbatti (incense sticks), dhoop, camphor, and mosquito coils is a deeply ingrained cultural, spiritual, and practical habit. However, burning these materials creates smoke, which introduces an entirely different category of indoor pollution.

Combustion releases heavy loads of fine particulate matter (PM2.5), volatile organic compounds, carbon monoxide, and polycyclic aromatic hydrocarbons (PAHs) directly into living spaces. A comprehensive 2022 review published in the Journal of Inflammation Research (Yadav et al.) systematically detailed how exposure to incense smoke can irritate the airway mucosa and trigger inflammatory respiratory pathways.

Similarly, observational field data—such as a study examining indoor environments in urban slums in Pune—highlighted that daily indoor burning of mosquito coils, incense, or dhoop was associated with a roughly 61% increase in the odds of reported respiratory symptoms among residents. While these observational studies carry inherent limitations due to mixed indoor pollution sources, the particle and combustion hazards of indoor smoke are well-established in environmental medicine. Respecting the cultural significance of these rituals does not mean ignoring simple ways to make the practice safer.

For additional context about respiratory health, read Keep Your Lungs Healthy.

Air Fresheners, Cleaners and Closed Winter Homes

Modern urban Indian homes increasingly combine traditional combustion sources with modern scented products—such as continuous plug-in diffusers, air freshener gels, and heavily fragranced floor cleaners.

During northern India’s harsh winter months, severe outdoor smog forces families to keep doors and windows tightly shut. While this keeps out some coarse outdoor dust, keeping a home sealed causes internally generated VOCs and indoor smoke to accumulate over time.

This creates a delicate balance: opening windows during peak winter smog can let in hazardous levels of outdoor PM2.5, while keeping them closed traps indoor emissions. Because dedicated peer-reviewed studies measuring real-world fragranced product emissions specifically inside Indian homes remain limited, households should rely on sensible ventilation timing rather than assumptions.

What Indian Rules Require

Consumer safety regulations regarding fragrance ingredients vary significantly depending on the product category. In India, the Bureau of Indian Standards (BIS) standard IS 4707 (Part 2) establishes safety criteria, outlining lists of prohibited and restricted fragrance ingredients. However, IS 4707 applies specifically to cosmetic products. For cosmetics, regulatory frameworks require manufacturers to comply with safety restrictions and declare specific known fragrance allergens.

By contrast, household cleaning supplies, laundry detergents, and room air fresheners are not governed by an equivalent mandatory ingredient disclosure list or full fragrance component breakdown under current consumer packaging standards. To address these regulatory gaps across broader product categories, a draft standard published by BIS in 2026 proposed prohibiting 64 specific fragrance raw materials across wider consumer categories, including household care, air care, and incense products. While regulations continue to evolve, consumers currently cannot rely on household cleaner labels to reveal full fragrance composition.

Practical Steps for a Healthier Home

Reducing indoor chemical and particle exposure does not require drastic lifestyle shifts or discarding every product you own. Practical, non-prescriptive adjustments can significantly improve indoor air quality:

1. Adopt a “Less is More” Approach

Consider reducing the total volume of scented products rather than aiming for complete elimination. Opt for fragrance-free or low-fragrance alternatives for daily items like floor cleaners and laundry detergents where readily available. For related household chemical concerns, explore Hidden Chemicals in Our Kitchens.

1. Time Your Ventilation

Ventilate your home strategically. During winter smog periods, open windows briefly when outdoor air quality is at its relative best (often around midday when sunlight helps disperse ground smog), and make regular use of kitchen exhaust fans while cooking.

1. Deploy HEPA Filtration Safely

Use a high-efficiency particulate air (HEPA) purifier in bedrooms to capture airborne particles and smog components. Avoid air purifiers or ionisers that intentionally or unintentionally generate ozone, as ozone reacts with household fragrance chemicals.

1. Modify Incense and Dhoop Practices

If you burn agarbatti or dhoop, keep burning times short, burn fewer sticks at once, and place them in well-ventilated areas or near an open window rather than in closed, unventilated rooms. Keep burning incense away from infants, elderly family members, and anyone with existing respiratory conditions.

1. Avoid Spraying Around Sensitive Individuals

Do not spray aerosol air fresheners, pest sprays, or heavy cleaners near children or individuals with sensitive airways. Never operate ozone devices alongside terpene-based citrus or pine cleaners.

1. Plan Renovations Ahead of Time

Complete painting, varnishing, and major home renovations several weeks or months before a newborn arrives, allowing ample time for wall paints and finishes to off-gas under maximum ventilation.

1. Control Indoor Moisture

Inspect walls and ceilings regularly for dampness and fungal growth. Dampness interacts with household materials and significantly impairs indoor air quality.

Who Should Be Especially Careful

While clean indoor air benefits everyone, certain groups possess airways that are far more sensitive to chemical irritants and fine particulate pollution:

• People with Pre-existing Respiratory Conditions: Individuals diagnosed with asthma, chronic obstructive pulmonary disease (COPD), or allergic rhinitis.
• Infants and Young Children: Developing lungs consume more air per pound of body weight than adult lungs, making children more vulnerable to environmental irritants.
• Older Adults: Age-related changes in respiratory function make senior citizens more susceptible to indoor air triggers.
• Pregnant Women: Protecting maternal respiratory health supports optimal fetal development.

If you notice that coughing, wheezing, sneezing, or skin irritation consistently flares up in specific rooms or immediately after using certain products, bring this observation to your physician. Never self-diagnose an environmental illness or adjust doctor-prescribed medications without professional medical guidance.

Frequently Asked Questions

Are natural or essential-oil air fresheners safer?

Not necessarily. Natural essential oils emit volatile organic compounds just as synthetic fragrances do. Botanical molecules like limonene react with indoor ozone to produce secondary pollutants like formaldehyde. While essential oils offer pleasant plant aromas, they are not emission-free alternatives.

Is incense smoke as bad as cigarette smoke?

Both incense smoke and cigarette smoke involve organic combustion, releasing fine particles (PM2.5), carbon monoxide, and toxic hydrocarbons into the air. While the exposure patterns and frequency differ between smoking and burning incense, both introduce significant particulate pollution into indoor breathing spaces.

Should I stop using floor cleaners with fragrance?

There is no need to panic or throw out your cleaning supplies. Scented floor cleaners can be used safely by diluting them properly, ensuring good ventilation while cleaning, or choosing fragrance-free versions if someone in your home has sensitive airways or asthma.

Is it safe to open windows during winter smog?

During severe winter smog, keep windows closed during peak pollution hours (early morning and night). However, keeping a home completely sealed for weeks causes indoor VOCs to build up. Open windows briefly during warmer midday hours when outdoor smog lightens, or rely on mechanical HEPA air filtration indoors.

Key Takeaways

• Association, Not Direct Cause: A key Swedish study linked bedroom concentrations of propylene glycol and glycol ethers (PGEs) to higher odds of childhood asthma, rhinitis, and eczema, but this reflects a statistical association, not proven direct causation.
• Unlisted VOC Emissions: Laboratory testing shows fragranced products emit dozens of VOCs—including regulated hazardous air pollutants—that rarely appear on labels due to broad “fragrance” trade secret rules.
• “Natural” Does Not Mean Emission-Free: Products labeled green or natural emit similar levels of VOCs as conventional products. Citrus terpene molecules (like limonene) can react with indoor ozone to form formaldehyde and fine particles.
• Combustion is a Separate Risk: Incense, dhoop, and mosquito coil smoke release fine particles (PM2.5) and combustion pollutants, creating a well-documented respiratory hazard distinct from cold spray emissions.
• Practical Control: Exposure can be managed by choosing fragrance-free options, timing ventilation smartly around outdoor smog, avoiding ozone purifiers, and burning incense briefly in well-ventilated spaces.

References

1. Choi H, Schmidbauer N, Sundell J, Hasselgren M, Spengler J, Bornehag CG. (2010). “Common household chemicals and the allergy risks in pre-school age children.” PLoS ONE, 5(10), e13423. https://doi.org/10.1371/journal.pone.0013423
2. Steinemann AC, MacGregor IC, Gordon SM, Gallagher LG, Davis AL, Ribeiro DS, Wallace LA. (2011). “Fragranced consumer products: Chemicals emitted, ingredients unlisted.” Environmental Impact Assessment Review, 31(3), 328-333. https://doi.org/10.1016/j.eiar.2010.08.002
3. US Environmental Protection Agency (US EPA). Indoor Air Quality (IAQ) and Volatile Organic Compounds (VOCs) Identification and Management Guide. https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality
4. World Health Organization (WHO). (2010). WHO Guidelines for Indoor Air Quality: Selected Pollutants. WHO Regional Office for Europe. https://www.who.int/publications/i/item/9789289002134
5. Choi H, Schmidbauer N, Sundell J, Bornehag CG. (2010). “Sources of propylene glycol and glycol ethers in air at home.” International Journal of Environmental Research and Public Health, 7(12), 4213-4237. https://doi.org/10.3390/ijerph7124213
6. Harvard T.H. Chan School of Public Health. (2010). Paints, Cleaners in Home Linked to Children’s Asthma, Allergy Risk. News Feature. https://www.hsph.harvard.edu/news/features/paints-cleaners-children-asthma-allergy/
7. Wainman T, Zhang J, Lioy PJ, Weschler CJ. (2000). “Ozone and limonene in indoor air: a source of submicron particle exposure.” Environmental Health Perspectives, 108(12), 1139-1145. https://doi.org/10.1289/ehp.001081139
8. Nazaroff WW, Singer BC. (2004). “Cleaning products and air fresheners: exposure to primary and secondary air pollutants.” Atmospheric Environment, 38(18), 2841-2865. https://doi.org/10.1016/j.atmosenv.2004.02.040
9. Nazaroff WW, et al. (2006). Indoor Air Chemistry: Cleaning Agents, Ozone and Toxic Air Contaminants. California Air Resources Board (CARB) Research Report, Contract 01-336. https://hero.epa.gov/hero/index.cfm/reference/details/reference_id/4682850
10. Yadav VK, et al. (2022). “Health and Environmental Risks of Incense Smoke: Mechanistic Insights and Cumulative Evidence.” Journal of Inflammation Research, 15, 2665-2693. https://doi.org/10.2147/JIR.S347489
11. Bureau of Indian Standards (BIS). (2021). Classification for Cosmetic Raw Materials and Adjuncts, Part 2: List of raw materials generally recognized as safe (GRAS) and restricted/prohibited list (IS 4707 Part 2). https://www.services.bis.gov.in/

Bureau of Indian Standards (BIS Draft Standard). (2026). Prohibition of 64 Fragrance Raw Materials Across Household, Air-Care, and Incense Products. Chemical Departmental Committee Draft. https://globalcosing.chemradar.com/news/detail/fsrg6ld1k2rk