Turn a PM2.5 label into an evidence request
For a buyer, the useful question is not simply whether PM2.5 appears in the product description. Ask what the wording means for the offered reference and where the supporting result can be found. A label may identify an intended filtration topic while leaving the measurement basis unresolved.
Preserve the original claim in your inquiry. If the supplier provides a percentage later, ask which particle-size range or test point it describes. Do not automatically attach that percentage to every particle included in the PM2.5 category. The report must establish the relationship between its measurement and the proposed wording.
This article provides a sourcing framework, not a target efficiency or a health recommendation. Its numerical examples are hypothetical arithmetic. No PM2.5 performance is assigned to the MAKEXCAR offered items, and no laboratory result is converted into a guaranteed reduction inside a vehicle cabin.
What the particle-size category means
The US EPA's particulate-matter overview describes PM2.5 as fine particles with diameters generally 2.5 micrometres and smaller. That is a size-category explanation. It supplies no cabin-filter rating and does not mean that all particles in the category have one identical size or composition.
For unit reading, 2.5 micrometres equals 0.0025 millimetres. This conversion translates a unit only. It is not a filter-pore dimension, a capture threshold or evidence that a particular medium removes all particles above or below that value.
When reviewing a test, retain the original particle-size terminology and ask how the cited method defines it. Do not silently equate a report's particle-counting size field with an ambient-air category or delete a qualification that distinguishes the two. The laboratory or supplier should explain which statement its data supports.
Identify the candidate before assessing its claim
Identify the exact offered reference before assessing the PM2.5 wording. Record the supplier code, drawing revision and filter variant from the quotation. Physical dimensions can help distinguish candidates, but they do not establish the filter medium or particle-removal efficiency. A thicker candidate is not automatically a higher-efficiency candidate.
Keep identification and test evidence in separate fields. A catalog entry without a test percentage is an unanswered performance question, not proof that the product cannot filter fine particles. Equally, a familiar shape or family name does not fill the missing result. Ask for the report that applies to the offered item and retain its sample designation.
Do not transfer results between filter technologies
Page 3 of DENSO's cabin-filter range leaflet distinguishes Particle Filters, Combination Filters and ClearAir+ Filters. We use these labels only to illustrate why a range document can discuss different technologies. The leaflet's promotional results are not MAKEXCAR specifications and do not supply a test result for the three references above.
When a source covers several technologies, locate the exact product or tested medium associated with the claim. Do not take a percentage from one section and assign it to another filter because both appear in the same brochure. Ask whether the quoted item matches the tested reference and whether the report concerns a complete filter or a material sample.
A description of gas or odour treatment also does not fill a missing particulate-efficiency field. Keep each performance question connected to its own supporting test and stated scope. This article does not evaluate gas adsorption, biological treatment or health outcomes.
Read the percentage with its measurement basis
A useful result identifies the tested object, relevant particle-size information, method, conditions and reporting basis. Ask whether the percentage describes particle counts, a mass-based measure or another explicitly defined quantity. Do not compare numbers as though the denominators were identical when the documents describe different measurements.
Retain the units and the report's qualification of the size field. If a test supplies results at individual sizes, keep each point with its own percentage rather than creating an unsupported average for the whole PM2.5 category. If the report provides an aggregate result, ask how that aggregate is defined.
Ask what test airflow and sample condition accompanied the result, and preserve any stated deviations. These are questions for interpreting the supplied document, not instructions for performing a test. A standard identifier by itself does not tell you which sample was tested or where the claimed number appears.
A hypothetical calculation and its limits
Suppose an invented count-based comparison uses 1,000 upstream particles and 100 downstream particles in the same defined reporting category and on a consistent basis. The calculated removal is (1 − 100/1,000) × 100 = 90%. If the downstream count is instead 50, the corresponding result is 95%.
| Hypothetical row | Upstream / downstream counts | Calculated removal | Evidence status |
|---|---|---|---|
| A | 1,000 / 100 | 90% | Teaching arithmetic only |
| B | 1,000 / 50 | 95% | Teaching arithmetic only |
The difference is 5 percentage points. Neither row defines an actual particle size, test aerosol, airflow, filter model or PM2.5-category result. The table cannot support a SKU rating. It also cannot establish that a vehicle's ambient PM2.5 concentration would fall by 90% or 95%.
Use the example to check what a percentage is calculated from, not to predict cabin conditions. If a supplier's summary lacks the underlying measurement basis, ask for clarification instead of borrowing the numbers above. Keep hypothetical values out of quotations, product descriptions and performance comparisons.
Match the report to the offered item
A report must identify its tested object. Compare that designation with the quotation before examining the percentage. A media coupon and a complete filter are different sample descriptions; a photograph does not establish their equivalence. Ask which relationship makes the result applicable to the offered assembly.
| Record from the report | Why it changes the decision | Action if unresolved |
|---|---|---|
| Offered and tested references, revisions | Connects the result to the purchase | Request a documented reference mapping |
| Complete filter or material sample | Identifies the object behind the claim | Ask which assembly wording the evidence supports |
| Size point or defined range | Limits the particle population described | Retain the stated point; do not broaden it to the whole category |
| Percentage, count or mass basis, airflow | Explains the number and its conditions | Obtain the result page and measurement definition |
| Method edition, deviations, report revision | Makes the result traceable | Request the complete applicable report rather than a cropped chart |
Use this worksheet to identify the next document needed, rather than adding up completed boxes into an approval score. A reference mismatch is not resolved by four other populated fields. Attach each supplier reply to the corresponding row so another buyer can reconstruct the decision.
For several offered variants, keep separate rows. If one report is proposed for every variant, ask for the documented applicability explanation. Preserve changes in medium, geometry or revision as questions for the supplier; do not invent a transfer rule from shared packaging.
Keep product claims narrower than whole-cabin conclusions
A documented filter result applies to the tested object and its stated conditions. A claim about concentration throughout an occupied vehicle cabin is a different claim and needs its own applicable evidence. Do not rewrite a component result as an assurance that every passenger breathes air with the same percentage reduction.
Likewise, avoid turning a particulate test into a statement that the product prevents disease or guarantees protection from pollution. This sourcing article makes no such conclusions. When a sales draft extends beyond the report's scope, narrow the wording to the supported result or leave the broader claim unpublished.
If an inquiry requires a vehicle-level result, identify that need explicitly. Ask which document addresses that scope instead of attaching an existing filter percentage to it. Keep component tests and system-level evidence in separate fields so later staff can see what each source actually supports.
When preparing an English listing from a supplier's original document, check that the translation retains the result's qualifications. A phrase about particles at a specified test point should not become a promise to remove every fine particle. Keep the original-language passage and its source page available for review. Resolve ambiguous wording with the supplier rather than smoothing it into a stronger claim.
For several offered variants, maintain a separate evidence row for each. If the same report is proposed for all variants, ask which documented relationship supports that use. Shared packaging, dimensions or family labels alone do not answer the applicability question. Record the supplier's explanation and the unresolved differences before approving product wording.
Frequently asked purchasing questions
A chart shows 95% at one size point
Read the stated size before approving the draft wording. If the chart gives one test point and the sales draft says 95% across PM2.5, ask which evidence supports that extension. Keep the chart's narrow result in the review record while the broader wording remains unresolved.
The report tested a material coupon
Request the sample description and the relationship to the offered finished filter. Do not relabel a material result as an assembly measurement. The next useful answer is how the quoted item is represented by that test, not whether the brochure repeats the same percentage.
A supplier proposes a cabin-air reduction claim
Identify the actual subject of the evidence. A component result cannot establish a vehicle-level concentration change by changing its caption. Ask for applicable vehicle-level evidence or revise the claim to the supported component scope. This is a claim-review decision, not a recommendation about passenger health.
Request a supported particulate claim
Use the following inquiry with a quotation or existing report. It gives the supplier a specific claim to resolve and identifies the documents needed for review.
Candidate: Offered SKU, original reference, variant or revision, vehicle information where relevant, and quantity.
Proposed wording: Copy the exact PM2.5 claim, including any percentage. Identify whether it concerns a component test or a vehicle-level result.
Tested object: Provide the sample reference and state whether it was material or a finished filter. Explain applicability to the candidate.
Measurement: Identify the size point or range, count or mass basis, airflow and relevant stated conditions. Preserve units and qualifications.
Evidence: Supply the report number, revision, method edition and result page. Identify which wording the document supports and which questions remain unanswered.
Browse MAKEXCAR's Cabin Air Filters category and send the inquiry through the contact page. Review the reply against the proposed claim before assigning a particulate-removal percentage to a product description.
