June 2020 SPRAY 27
Water is typically hard to break up into small particle
sprays and there were fewer hydrocarbons to do so. The
result was a coarser spray pattern than before. Some
consumers complained about seeing particles falling onto
tables and floors. Marketers responded by giving directions
to shake the dispenser and then aim it high into the
air before spraying. In some cases, the concentration of
fragrance was increased. The use of MB-U (Mechanical
Break-Up) Reverse Taper actuators and reduced delivery
rates were also helpful.
After several years, CARB determined that 25% VOC
air fresheners were consumer-acceptable. Over strenuous
industry objections, revisions such as the below formula
were created:
Water-Based Air Fresheners (2nd CARB Revision)
n 74.17% Deionized Water or Water USP
n 00.13% Olryl Diethanolamide
n 00.50% Fragrance
n 00.20% Sodium Benzoate
n 25.00% Hydrocarbon Propellant A-60 (VOC)
The higher pressure propellant, containing about
35% propane, provided a somewhat better break-up than
A-46, but also required the use of a more costly DOT 2Q (high strength) can to meet U.S. Dept. of
Transportation (DOT) requirements.
At least one major marketer decided to include HFC-152a (a non-VOC propellant) to help achieve
better break-up. Adding about 6% HFC-152a to a low-pressure hydrocarbon blend produced a near
azeotropic mixture just under the DOT’s legal limit of 180psig (130°F). However, replacing some
water with HFC-152a added cost to the product, which is often difficult to justify for utility
aerosols.
Still unsatisfied, CARB then limited two-phase (water-based) air fresheners to 20% VOCs.
This was their third revision. By this time, the aerosol industry had run out of reformulation
options for manually-operated, hydrocarbon-propelled air fresheners. Single-phase formulas
were marketed, often using DOT 2Q-shaped aluminum cans that were typically filled to
above 55–60 volume-% of their capacity. Two percent to 3% carbon dioxide was generally
the sole propellant. Had any significant amount of hydrocarbon propellant been added, its
partial pressure at 130°F would have significantly reduced the amount of carbon dioxide that
could be added, while keeping the total pressure safely below the DOT 2Q limit of 180psig
at 130°F. Actually, some studies were made incorporating up to about 5% dimethylether
(DME), since its affinity to water would minimize its partial pressure. They were probably not
commercialized.
As would be expected, the sprays from these carbon dioxide air fresheners are relatively
coarse and particles can be seen falling onto floors and furniture. These formulations may
become the new-normal for our air fresheners.
Future aspects
As Doug Raymond has aptly reported (SPRAY, Dec. 2019), CARB has long-range plans for still
further reducing the present 20% VOC limit of manual air fresheners. By Jan. 1, 2023 the
VOC limit will become 10%, and by Jan. 1, 2031 the limit will be 5%. CARB has decreed that
fragrances will now be considered VOCs. There are hopes that a gradual replacement of VOCs
by the more sophisticated MIR (Maximum Incremental Reactivity) approach may be helpful.
However, CARB has promised the EPA certain reductions of air contaminants in terms of tons
per day in its State Implementation Plans (SIPs). These reductions have become the “gold
standard,” superseding everything else.
Despite regulatory impediments, the manual aerosol air freshener category is doing well.
Consumers have a choice of numerous whimsically-identified fragrances in beautifully decorated,
shaped aluminum cans, often presented at eye level on the shelves of major retail stores.
We can be confident that these elegant, low-cost products are here to stay. Spray
New Febreze Ocean
has notes of ginger, waterlily
and hinoki. The
8.8oz. aerosol spray
uses an actuator from
Silgan Dispensing.